Design Solution for Ingot Handling and Machining

Konceptstudie för hantering och bearbetning av göt

Johan Jönsson

Faculty of Health, Science and Technology

Degree Project for Master of Science in Engineering, Mechanical Engineering

30hp

Supervisor: Mohamed Sadek

Examiner: Jens Bergström

7/9/2021

Abstract

At the electro remelting slag (ESR) facility at Uddeholm, cylindrical steel ingots are produced

in several different sizes. The ESR process requires a “starting step” that consist of a 20mm

thick steel plate and is a little larger than the diameter of the ingot. During casting the steel

plate is inevitably welded to the ingot, also a protective slag layer is also present and flows on

top of the melt when the ingot is produced. This layer is sacrificial and is removed before

forging. The plate consists of a different and unwanted material composition and must be

removed at some point to ensure the best material properties of the ingot. Current process

steps at Uddeholm causes the steel plate to be smeared out on the high-quality ingot. The

“impure” part of the ingot leads to extra waste and costs after forging. The ingots are cast

vertically but needs to be positioned horizontally to be transported to the forge, this is done

using an overhead crane and a clamp. This maneuver exerts excessive stress that damages the

crane and the clamp sometimes fails and drops the ingot. Because of the high-risk steps during

ingot handling as well as the extra waste that is created due to the starting step, the purpose

of this thesis is to develop a solution that can: move the ingots from a vertical to a horizontal

position in a controlled manner, a method to remove the starting step before forging and

reduce the overall risks during ingot handling. The goal is to develop a complete concept that

solves the problems mentioned so that the solution can later be realized.

To get a deeper understanding of the current procedures and problems, visits and meetings at

Uddeholm were carried out. This master thesis builds on the principle of the product

development process. Interviews with operators, managers, and other impacted employees at

Uddeholm were conducted in order to specify a product specification. To make the project

more fathomable, six sub functions were defined. Later a concept generation session using

the principles of brainstorming was held with engineers and managers at Uddeholm to find

new, plausible solutions to the problems. The results from the session were reviewed and some

solutions were discarded directly. Solutions that passed the screening was scored using a

weighted decision matrix based on a Kesselring matrix.

The chosen concepts were: milling to remove the starting step, “rotary axis grab” to rotate the

ingots, a conveyor belt to transport slag, a vacuum and conveyor belt to remove chips, a roll

bed with V-pallets to handle and transport the ingots, and let the slag fall of naturally when

horizontal. These solutions fulfill almost all of Uddeholm’s requirements and will significantly

increase the safety and profitability. The new solutions also bring in high flexibility for

production and will free up time for the operators.

The lifting tool of the solution needed to be structurally verified to prove it is a valid option.

This was done by analyzing the maximum stress in one part of the tool. The results gave that

it was indeed a feasible solution.

The whole product development process has proven helpful for this machine system. It has

especially proven useful for documenting all decisions made throughout the project. This

makes it easier for Uddeholm to adopt the solution and develop it further and later realize it.

Sammanfattning

På ESR-anläggningen i Uddeholm tillverkas cylindriska stålgöt i flera olika storlekar. ESR-

processen kräver ett "startsteg" som består av en 20 mm tjock stålplåt som är lite större än

götets diameter. Under gjutning svetsas oundvikligen stålplattan ihop med götet, förutom

detta finns det ett skyddande slaggskikt som flyter ovanpå smältan när götet produceras. Detta

lager är temporärt och tas bort innan smide. Plattan består av en annan, oönskad,

materialkomposition och måste tas bort någon gång för att säkerställa bästa

materialegenskaperna på götet. Nuvarande processteg vid Uddeholm gör att stålplattan

smetas ut på det högkvalitativa götet. Den "orena" delen av götet leder till extra spill och

kostnader efter smide. Göten är gjutna vertikalt men måste placeras horisontellt för att

transporteras till presssmedjan, detta görs med en travers och en klämma. Denna manöver

utövar överdriven stress som skadar traversen och klämman kan förlora greppet och tappa

götet. På grund av högriskoperationerna vid hantering av göt samt det extra spillet som skapas

på grund av startsteget, är syftet med detta examensarbete att utveckla en lösning som kan:

Flytta göten från en vertikal till en horisontell position på ett kontrollerat sätt, en metod för

att ta bort startsteget före smide och minska de totala riskerna vid hantering av göt. Målet är

att utveckla ett komplett koncept som löser de nämnda problemen så att lösningen senare kan

realiseras.

För att få en djupare förståelse för nuvarande rutiner och problem, hölls besök och möten på

Uddeholm. Det här examensarbetet bygger på principen för produktutvecklingsprocessen.

Intervjuer med operatörer, chefer och andra berörda medarbetare på Uddeholm genomfördes

för att specificera en produktspecifikation. För att göra projektet mer hanterbart definierades

sex underfunktioner. Senare hölls en konceptgenereringssession styrt av principerna för

brainstorming med ingenjörer och chefer på Uddeholm för att hitta nya, troliga lösningar på

problemen. Resultaten från sessionen granskades och vissa lösningar kasserades direkt.

Lösningar som klarade utsållningen gick vidare och rankades med hjälp av en beslutsmatris

baserad på en Kesselring-matris.

De vinnande koncepten var: fräsning för att ta bort startsteget, En “rotating axis grab” för att

rotera göten, ett transportband för att transportera slagg, en dammsugare- och transportband

för att ta bort spån, en rullbotten med tillhörande V-pallar för att hantera och transportera göt

samt att låt slaggen falla av naturligt när götet är horisontellt. Dessa lösningar uppfyller nästan

alla Uddeholms krav och kommer att signifikant öka säkerheten och lönsamheten. De nya

lösningarna ger också hög flexibilitet för produktionen och frigör tid för operatörerna.

En del av lösningen behövde verifieras strukturellt för att bevisa att det är en giltig lösning.

Detta gjordes genom att analysera maximal spänning i en del av verktyget. Resultaten visade

att det var en realiserbar lösning.

Hela produktutvecklingsprocessen har visat sig vara användbar för detta maskinsystem. Det

har visat sig användbart för att dokumentera alla beslut som tagits under hela projektet. Detta

gör det lättare för Uddeholm att ta sig an projektet och utveckla det vidare och senare

förverkliga det.

Table of Contents Abstract ...................................................................................................................................... 2

Sammanfattning ........................................................................................................................ 4

1. Introduction ........................................................................................................................... 1

1.1 Background ....................................................................................................................... 1

1.2 About Uddeholm .............................................................................................................. 1

1.3 Current Procedures ........................................................................................................... 1

1.3.1 ESR ............................................................................................................................. 1

1.3.2 Forging press .............................................................................................................. 4

1.4 Problem formulation ........................................................................................................ 4

1.5 Purpose and Goal .............................................................................................................. 4

1.6 Limitations ........................................................................................................................ 5

2. Theory .................................................................................................................................... 5

2.1 The Generic Product Development Process ..................................................................... 5

2.1.1 Planning ...................................................................................................................... 5

2.1.2 Concept Development ................................................................................................ 5

2.1.3 PFMEA ....................................................................................................................... 8

2.1.4 Concept Selection ....................................................................................................... 8

3. Method ................................................................................................................................... 9

3.1 Planning ............................................................................................................................ 9

3.2 PFMEA ............................................................................................................................. 9

3.3 Identifying Customer Needs ............................................................................................ 9

3.4 Product Specification ....................................................................................................... 9

3.5 Concept Generation .......................................................................................................... 9

3.6 Concept Selection ........................................................................................................... 10

3.7 Further Development ..................................................................................................... 10

3.8 Structural Verification .................................................................................................... 11

4. Results .................................................................................................................................. 12

4.1 Planning .......................................................................................................................... 12

4.2 PFMEA ........................................................................................................................... 12

4.3 Analysis of Current Procedures ...................................................................................... 12

4.3 Product Specification ..................................................................................................... 13

4.4 Concept Generation ....................................................................................................... 13

4.4.1 Search Externally ..................................................................................................... 13

4.4.2 Search Internally ..................................................................................................... 13

4.5 Concept Selection ........................................................................................................... 14

4.5.1 Removal of Starting step .......................................................................................... 14

4.5.2 Tipping Mechanism ................................................................................................. 16

4.5.3 Slag Removal ........................................................................................................... 18

4.5.4 Slag Handling .......................................................................................................... 19

4.5.5 Chip Removal ........................................................................................................... 19

4.5.6 Handling and Transport of Ingots ........................................................................... 20

4.5.7 Structural Verification of Rotary Axis Grab ............................................................ 22

4.5.8 Combined Concepts ................................................................................................. 25

5. Discussion ............................................................................................................................ 27

5.1 Further Development ..................................................................................................... 28

6. Conclusion ........................................................................................................................... 29

7. Acknowledgements .............................................................................................................. 30

8.References ............................................................................................................................. 31

9. Appendixes ........................................................................................................................... 32

Appendix A- Explanation of Concepts ................................................................................. 32

Appendix B- Preliminary Gantt Schedule ............................................................................ 38

Appendix C- Project FMEA .................................................................................................. 38

Appendix D- PFMEA ............................................................................................................ 39

Appendix E- Product Specification Tipping Mechanism .....................................................40

Appendix F-Product Specification Machining ..................................................................... 41

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1. Introduction

1.1 Background

Electro slag remelting (ESR) is an important step when creating high quality steel. ESR has

been used in the industry since the 1960s because of solidification and chemical homogeneity

control. The process starts with an electrode that is suspended in a mast assembly with vertical

translation control. The electrode is put inside a water-cooled mold with a so-called starting

step at the bottom. The starting step consists of a steel plate and a reactive slag bath. A strong

electric current is passed through the mold and the electrode and an electric arc is formed at

the bottom of the electrode. The electrode starts to melt due to the high temperature and it

starts to drip droplets of molten metal to fill the mold. The molten metal falls through the slag

layer and the mold slowly fills and solidifies. Since the metal is passing through the reactive

slag bath, the material purity is increased and inclusions become very small and evenly

distributed. The slag continuously floats on top of the melt and is later removed once the ingot

solidifies. The remelting of the electrode creates a new ingot [1].

The steel plate that is the starting step is still attached to the ingot. It consists of a different

and unwanted material composition and must be removed at some point to ensure the best

material properties of the ingot. Current process steps at Uddeholm causes the steel plate to

be smeared out on the high-quality ingot. The “impure” part of the ingot leads to extra waste

and costs after forging. Apart from the extra waste material, there are several high-risk actions

during ingot handling, especially the “tipping” of the ingot. During tipping the ingot might fall

and hot slag might fall off and hit nearby operators.

1.2 About Uddeholm

Uddeholm is a global provider and manufacturer of tool steels situated in Hagfors, Sweden.

The history of ironmaking at or near Uddeholm is old, ironmaking started in 1640 and has

continued ever since. Uddeholm has a large plant with several departments such as: steel mill,

ESR, forge, rolling mills, heat treatment facilities, machining, an extensive research and

development department and more [2].

1.3 Current Procedures

At the ESR facility there are several ESR furnaces operating full time. The ingots that are

produced vary depending on customer needs and what furnace is used. Below is a description

of the current standard procedures that Uddeholm is following at the moment.

1.3.1 ESR

ESR is a process where an electrode of the specified composition is remelted using electricity

[1]. A thick slag layer is present at the top of this melt and protects the steel against oxidation.

This produces a higher quality ingot that can later be forged to the right shape and dimensions

[3]. In more detail, ESR uses a two-piece water-cooled casting form that is removable. The

whole ESR process is built upon a starting step. The starting step consists of a round steel plate

that is 20mm thick and has a diameter that is a bit larger than the final cast ingot. The diameter

2

of the starting step is in the range of 400-1500mm. A schematic figure of the ESR setup is

shown in Figure 1.

Figure 1. A schematic figure of the ESR process

After the remelting process, the casting mold is removed and a hot ingot with the thick slag

top becomes exposed. At this stage, the ingot is picked up using a clamp operated by an

overhead crane. The ingot is placed on a cutting table and a cooling hood is placed over it. The

cooling hood protects workers against heat radiation and spatter and falling debris from the

slag top. When the ingot is cooling the differential heat expansion makes the slag top unstable

and it might even spontaneously crack and fall off. Slag and debris around the bottom of the

ingot is scraped off by an operator into the cutting table, which also works as a waste bin. When

the waste bin is filled it is sent away for reconditioning since waste gets trapped and stuck. The

starting step steel plate is oversized and the extra part of the starting step is removed using a

cutting torch. This produces steel rings that are discarded. These steps are shown in Figure 2.

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Figure 2. The figure illustrates how the ingot is picked up and later processed under the cooling hood

After the cutting operation, the ingot is cool enough to remove the cooling hood. The next step

is to remove the slag top, this is done using the clamp and overhead crane. The clamp picks up

the slag top and lifts it to a waste container, this is done after the cooling hood is removed.

There are several risks present during this step: the slag top might be unstable and crack

during the lift, it might fall out of the clamp etc. After the slag top removal, there is just the

ingot and the starting step left. The next step is to pick up the ingot and put it on a pallet for

transportation. This lift is also done with the clamp. The operator grabs the top of the ingot,

places it on the ground and moves it sideways to make it fall over. This operation puts

damaging stresses on the overhead crane and on several occasions, the ingot is accidentally

released from the clamp and falls to the ground. The ingot is placed on a pallet and transported

to the forge. Figure 3 shows the last two steps done in the ESR facility.

Figure 3. Removal of the slag top and the tipping of the ingot

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1.3.2 Forging press

At the forge the ingot is preheated and forged. When the ingot is forged, the starting step is

smeared out on the “good” material. This leads to large cutoffs, since all material containing

the starting step must be removed, costing a lot of money. Uddeholm created a “knife” that

can be used to scrape off the starting step to minimize waste. This solution has been working

quite well but it is hard to use according to the operators and there is always some

contamination left leading to some spill material. On average, only 20-40% of the starting step

is removed by the knife. Forging is time critical since materials properties change with

temperature. There is a small temperature interval where forging can be done and since time

is lost when using the knife this step can lead to problems. It takes on average 1-2 minutes to

remove 20-40% of the starting step. Figure 4 below illustrates these steps.

Figure 4. Press forging process steps with starting step removal using the knife

1.4 Problem formulation

Due to the high-risk steps during ingot handling, a new, safer, procedure is needed. A solution

that can move the ingots from vertical to a horizontal orientation with greater control to reduce

the risks is to be developed. In addition, a solution that can remove the unwanted material

before forging to reduce the extra wastage and costs due to material loss is also meant to be

found. Uddeholm needs a highly reliable solution that can cooperate with all the different

types, compositions, and quantities of ingots currently and in future production. Both

solutions, i.e., a material handling solution and a material removal solution, are to be packaged

in a module that will be installed in a specific area in the ESR-facility at Uddeholm.

1.5 Purpose and Goal

The purpose of this project is to increase safety, efficiency and reliability when handling ESR

ingots at the ESR facility at Uddeholm due to the facts stated in section 1.2.

The goal is to present a finished concept and a model for Uddeholm so that they can later

realize the machine.

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1.6 Limitations

To make this problem more fathomable and feasible, there are some limitations:

● It will be a concept study; the thesis will not include complete drawings and

manufacturing specifications.

● The space and location where the machine are supposed to be installed is defined.

● The machine must be able to be CE marked.

● The thesis is limited to be made on 800hrs of work, this corresponds to 30hp.

2. Theory

2.1 The Generic Product Development Process

The generic product development process can be divided into six different phases [4]:

1. Planning

2. Concept Development

3. System Level Design

4. Detail Design

5. Testing and Refinement

6. Production Ramp-Up

These steps help the product developer work in a systematic way. The reasons for working in

this way is that it can ensure that the project can stay controlled and ensure higher quality in

the end. The systematic approach also leads to good documentation which can help future

development. As stated in section 1.6, only phase 1 and 2 will be in the scope of this project.

2.1.1 Planning

The purpose of the planning phase is to give the whole project an overall aim. The planning

phase will result in a project plan that will work as a contract between the different parties.

The project plan is an essential document since it can become a guideline for the remaining

process. The plan will help to estimate and visualize the efforts that are necessary for

completion. It usually contains a background, goals, time plan and a project risk analysis. The

project risk analysis helps the product developer understand what risks are present, and help

reduce them before they become a problem [4].

2.1.2 Concept Development

A product concept is an abstract idea that contains the fundamental form, function and

technology of a final product. According to the book Product Design and Development [4], the

quality of the underlying concepts has a major impact on the final product. The concepts are

based on the product specification, this requires that the product specification is complete and

meets the customer’s needs well.

6

The book also introduces a 5-step process for concept development:

1. Clarify the problem. Understand the issue and decompose it into simpler subproblems.

2. Search externally. Gather information from lead users, experts, patents, published

literature and related products.

3. Search internally. Use individual and group methods to retrieve and adapt the

knowledge of the team.

4. Explore systematically. Use classification trees and combination tables to organize

the thinking of the team and to synthesize solution fragments.

5. Reflect on the solutions and the process. Identify opportunities for improvement in

subsequent iterations or future projects.

2.1.2.1 Step 1. Clarify the Problem

In the first step, the main problem is made simpler and perhaps broken down into

subproblems that are easier to comprehend. This decomposition of the problem can be done

with different perspectives such as: Decomposition by sequence of user actions or

decomposition by key customer needs [4].

2.1.2.1.1 Identifying Customer Needs

David Dunne [6] writes about the importance of customer centered needs. A good relation and

communication between the customer and the project are important to ensure the greatest

outcome that benefits both parties. A systematic approach is important so that the developer

does not miss any information that might be vital for the project. This includes both obvious

needs and latent needs that the customer has a hard time communicating or sometimes

doesn't even know [6]. To understand what the customer wants, the book suggested these

steps [4]:

1. Gather raw data from customers.

2. Interpret the raw data in terms of customer needs.

3. Organize the needs into a hierarchy of primary, secondary, and (if necessary) tertiary

needs.

4. Establish the relative importance of the needs.

5. Reflect on the results and the process.

In short, all of these steps are done so that nothing is missed. It is crucial to understand the

application of the product and listen to what the customer wants and reflect on that result.

After gathering information, it should be analyzed in a positive and systematic manner to

ensure that the customer is in focus.

2.1.2.1.2 Product Specification

When the customer needs are identified and documented, it leads to the product specification.

The product specification allows the project to evaluate precise targets, tell if the product is a

success or failure and understand how different choices will affect the product´s performance.

This is done by taking the perhaps unclear customer needs and transforming them into

measurable and precise specifications. The product specifications tell the project what the

product must do [5]. This document will also become the starting point for the concept

development phase.

7

The specifications can be divided into two main categories. They can be related to the final

product’s assumed function or they can set limitations on what design solutions are possible.

Functional properties are treats that are associated with the function of the product.

Limitations could for example be size and cost of the product, i.e., criteria that limits the

product development opportunities. Furthermore, the product specifications can be divided

into demands and wishes. Demands are specifications that the product must fulfill and wishes

are specifications that are not essential to complete. The wishes should be graded based on

how much the customer would want them to be fulfilled. To call the product complete all

demands must be fulfilled and the wishes may be partly met [4].

In order to visualize and analyze the specifications, they are put in checklists. The lists should

also contain a metric by which the specification can be compared with. Some specifications

are not easily measured but it is favorable to have some metrics. By doing this, the project

team will be able to systematically approach the criteria and what aspects that will be taken

into consideration during the development [4].

2.1.2.2 Step 2. Search Externally

To search externally is the process of finding already existing solutions and adapting them to

the project. This should be done continuously since it can greatly speed up development. If

there already are reasonable solutions, there is no need to spend unnecessary time on that

area. The effort should be focused on other parts of the project that preexisting solutions can’t

solve. Sources for these kinds of solutions can be found in competitive products as well as

technologies with similar functions as the developed product [4].

2.1.2.3 Step 3. Search Internally

Internal search is personal or project group information gathering. All of the knowledge,

competence and ideas of the project members themselves are used in this step. Usually this

becomes a creative process with different methods to explore and produce lots of ideas. One

of these methods could be brainstorming or something similar [4].

2.1.2.3.1 Brainstorming

Brainstorming is a creative internal concept generation process. It was developed in the 1960s

by Alex Osborn. Brainstorming can be done both individually as well as in a group with

different benefits. This method is considered to be good at generating a large number of ideas

in an open-minded way. The large number of ideas may result in several ideas that are non-

relevant and impossible but some might be good ideas worth developing. In order to get an

effective and productive brainstorming session, a good mix of different people with different

backgrounds are desirable [7].

There are some rules that need to be followed according to Osborn:

● No criticism, the ideas that are generated should not be analyzed or rejected during the

session.

● All ideas are welcome no matter how different they may be. All participants should feel

secure to propose any idea that they find relevant.

● To improve and build on other participants ideas are welcome.

● The main objective is to generate as many ideas as possible.

8

Before the session begins, the participants should be informed of the rules and the background

of the problem. Ideas from the participants are passed through the leader of the session that

documents everything. After the session, all of the ideas are looked at again and may be

discarded if they are found to be irrelevant [7].

2.1.2.4 Step 4. Explore Systematically

From step 2 and 3, the project will have several “concept fragments”. These concept fragments

must now be sorted and systematically chosen to create complete concepts. There are several

methods to help organize the number of generated concepts, often several hundred are created

but many of them can be discarded right away [4].

2.1.2.5 Step 5. Reflect on the Solutions and the Process

The last step is supposed to be done continuously throughout the development process.

Questions that the project group should ask themselves could be: Is this relevant? Is it

feasible? Are all possibilities explored? Etc. [4].

2.1.3 PFMEA

PFMEA (Process Failure Mode and Effect Analysis) is a risk analysis of a process and the

equivalent of an FMEA for a product. The method builds upon identifying what risks can occur

during a process, rank the risks, and give proposals for preventions. The first step is to identify

what types of risks that can occur during the process. After that, the risks are given a score

based on the severity of the risk, how often it could happen and how easy it is to discover.

These scores are multiplied and the risk is given a risk score. 1-100 is considered a low risk

(green), 101-300 high risk (yellow) and 301-1000 is the highest risk (red). The yellow and red

risks are given more consideration and solutions to reduce the risk should be proposed. After

the review the risks are reevaluated and given a new risk score [5].

2.1.4 Concept Selection

Concept selection is the process of evaluating concepts. This is done with respect to customer

needs and other criteria, comparing the relative strengths and weaknesses of the concepts, and

selecting one or more concepts for further investigation or development [4].

2.1.4.1 Weighted Decision Matrix

In this decision process all of the relevant criteria are used to decide which concept to use. The

criteria are weighted from 1-5 where 5 is the most important. After the concepts are scored

according to the requirements, the score ranges from 1-5 where 5 is the highest. Then the

weight and scores are multiplied and summarized and the concept with the highest score is

chosen. This type of matrix is based on a Kesselring matrix but with some minor adjustments

to better suit the application [5].

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3. Method

3.1 Planning

The background, problem formulation and goals are already stated in the beginning of this

report. But, to aid the planning of the entire project a project FMEA and a GANTT- schedule

was made to minimize risk and give a rough time span of the different stages of the project. A

GANTT-schedule is a good method of visually represent a timeline with several different tasks.

3.2 PFMEA

A PFMEA was developed by analyzing each process step separately and identifying as many

risks as possible. The document was updated throughout the project as more and more

solutions were implemented. All solutions and improvements were developed through

discussions and brainstorming.

3.3 Identifying Customer Needs

In order to get the information necessary, a visit to Uddeholm was made. The visit was planned

carefully according to previously written section 2.1.3 so that nothing would get missed.

During the visit, several meetings and interviews with managers, operators and other involved

employees were held to understand their experiences and vision of the problems. All of the

collected data was used to analyze the current procedures and to formulate a requirement

specification.

3.4 Product Specification

With the information given from Uddeholm, visits at the plant and interviews with affected

employees, an idea of what the solution had to solve was formed. The idea was refined using

the methodology of Ulrich [4]. An online meeting was carried out with the supervisor at

Uddeholm to set the first version of the product specification. The product specifications were

divided into two sub functions, the tipping operation and the machining operation. For each

sub function, criterions were set. They were divided into demands, wishes, limitations and

functions. The wishes were weighted according to how important they were to fulfill.

3.5 Concept Generation

The first step in the concept generation phase is to clarify the problem. The problem was

decomposed mainly by the sequence of user actions, but also key customer needs. It was

quickly concluded that no real equivalent applications that are at least publicly accessible that

can give hints of ready-made solutions. The problem spans several fields and is complex with

a lot of underlying functions. Therefore, a brainstorming session was carried out to give a quick

understanding of the different sub functions and their sub problems.

A concept for the tipping mechanism had already been developed by Uddeholm several years

ago. There are drawings and some calculations but according to Uddeholm this information is

to be seen as inspiration and not a complete solution.

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The literature states the importance of both individual and group concept generation sessions,

therefore a session with four employees at Uddeholm was planned and performed. The group

members came from different backgrounds, such as mechanical designers as well as

operational managers. The session started with a presentation of the main problem and the

rules of the session. All of the sub problems that were found during the functional analysis

were used as topics for the discussion. All the participants were also given papers to write or

sketch ideas for themselves or present the to the other participants.

Discussion topics that were presented:

● Tipping Mechanism

● Slag Removal

● Slag Handling

● Chip Removal

● Removal of Starting Step

● Handling and Transport of Ingots

All useful and discussed ideas generated were compiled and documented afterward. A lot of

ideas were generated and therefore quick screening with the concept group was done to

eliminate impossible ideas to minimize the total number of solutions.

3.6 Concept Selection

With that many ideas several thousand combinations of total solutions were possible. To solve

this problem, the sub concepts for each sub function were put into a weighted decision matrix

in order to minimize the number of total solutions. Criteria were taken from the relevant

product specification. However, some of the requirements in the specification were not

directly applicable to each function. Therefore, additional aspects connected to these functions

were added to the chart to keep relevance. Scoring decisions were supported by relevant

knowledge as well as relativity to the other concepts. For example: if one solution is clearly

more expensive than another, that solution will get a lower score compared to the cheaper

option from a cost perspective. After scoring, the winners from the weighted decision matrices

were combined into a complete solution.

Some of the concepts were sketched to better visualize and remember the vital elements

correctly. These visualizations can be seen in appendix A.

3.7 Further Development

The best concept was roughly constructed in SOLIDWORKS in order to visualize the most

important features. The overall layout and positioning of the functions within the machine was

the most important aspect that needed to be analyzed. It is important that the machine system

can fit within the prescribed area and give a good workflow for the rest of production.

11

3.8 Structural Verification

When the concept had been visualized and put into context with the rest of the system, a size

estimate of the machine could be made. The overall size scaled the dimensions of the

individual components, these dimensions were used when calculating critical stresses in one

of the components and altered using the trial and error method [8].

12

4. Results

4.1 Planning

The Gantt-schedule and project FMEA can be found in appendixes B and C. The most critical

risk that was identified was “Bad results”. This refers to results that would require more work

later in the project leading to delays, bad results, etc. Actions to reduce this risk were taken in

the form of a “front heavy” project planning and good communication with people

surrounding the project. Those actions would decrease the risk of miss steps early on and give

confidence that the methods are correct.

4.2 PFMEA

The PFMEA can be seen in Appendix D. The most considerable risk was “slip and fall” with a

score of 560 due to the high-risk effect, high occurrence rate and difficult to detect. Measures

suggested to lower the risk were: clean work floor, fences and railing. After those measures,

the score dropped to 60, which became the highest risk score of all identified risks after

reevaluation.

4.3 Analysis of Current Procedures

To understand and justify the need for a change, an analysis of the current procedures was

made. The analysis was based on the interviews and data that were collected during meetings

and visits at Uddeholm.

The most important aspect that is brought from the current procedures is hazards. Several

steps in the ingot handling in the ESR facility can be classified as highly dangerous. When the

ingots first come out of the mold, they are still 200-600°C and because of their relatively large

thermal mass the heat remains for a long time. The slag that sits on top of the ingot becomes

more and more unstable and has a higher chance of breaking and spalling as the ingot cools.

Since the operators are working so close to the ingot this is not as safe as possible. The most

dangerous moment is the tipping of the ingot, the clamp that is carrying the whole weight of

the ingot requires a good grip that can sometimes be unpredictable. The overhead crane is not

designed to take loads other than vertical. When the operator is tipping the ingot, the crane is

driven sideways to initiate the tipping. This puts lots of stress on the guide ways and

mechanical components of the crane. Which lead to mechanical failures and a shorter service

life. The most serious hazard is that the ingot can fall and roll away, leading to fatal accidents.

Other important factors are the economic benefits Uddeholm can obtain by solving the

starting step problem. High quality tool steel is expensive and waste is supposed to be

minimized. After discussions with one of the managers at the forge it was clear that the waste

problem needed to be fixed. The current procedure with the knife is not favored by the

operators. The operators already have time pressure and do not want to struggle with the knife

tool. It is not uncommon that the knife operation takes too long so that the work piece needs

to be reheated during forging and increases the cost. Also, the knife gets worn very quickly

reducing its performance. The forging press is manual meaning that the operators must

maneuver the work pieces by sight whilst sitting several meters away. This is hard to do and

13

requires skill. Finally, how hard the starting step has been welded to the ingot is dependent on

the ingot material. Sometimes the starting step falls off easily, while other times only a few

percent can be removed giving very little to no benefit to the final result. In summary, several

benefits can be achieved by removing the starting step before forging.

Production states that they would like a solution with a buffer where several ingots can sit and

wait for processing. Right now, there is no certain time interval at which the ingots are

finished. There might be several ingots that are finished at more or less the same time and

creating bottlenecks in production. A solution that can handle several ingots at the same time

would be advantageous since the production volume is expected to rise in the future.

Interviews also gave information on lead times. According to the forging shop manager, the

time between the ingot leaving ESR and arrives at the forge is insignificant. This is because the

forging shop cannot assure that the ingots get put in the preheating ovens immediately and

may rest for several hours before they do so. This implies that the speed at which the ingot

must arrive is non crucial.

4.3 Product Specification

The product specification can be found in appendixes E and F.

4.4 Concept Generation

4.4.1 Search Externally

Extensive searches for already existing solutions were done during the whole concept

development phase. Literature, articles, videos, study visits etc. were analyzed to find ideas or

solutions that could aid the design process. It was quickly discovered that some parts of the

problem formulation involved machinery that is not readily used in other industries, or at least

not publicly accessible information regarding those applications. Instead, a lot of information

was gathered from study visits at Uddeholm, who has been developing unique solutions for

their own problems throughout the years. Solutions regarding chip handling, milling,

clamping methods, pallet systems etc., was found at the machining facility at Uddeholm.

Equipment made to rotate objects were found when searching on the internet. The most

promising solution that was found is a lifting tool called “rotating axis grabs”. Rotating axis

grabs are manufactured by several manufacturers and can be customized for special

applications. Several versions are present with motorized functions and different loading

capacities.

Numerous manufactures that construct and sell rotating axis grabs were found and they were

subsequently contacted on behalf of Uddeholm.

4.4.2 Search Internally

The Brainstorming session was creative and successful, it generated several ideas and aspects

for every single topic. Excluded solutions were excluded before scoring since they were deemed

improbable and might not fulfill the customer demands.

14

4.5 Concept Selection

Here are the results from the concept generation session and the results from the concept

selections (table 1-14).

4.5.1 Removal of Starting step

Table 1. Results from the concept generation session of Removal of starting step and reasons for exclusions

Removal of starting step Reason for exclusion

Milling

Thermal Oxygen Lance

Cutting Torch

Turning Will take too much time

Plasma Cutter Material thickness too great

Laser Material Thickness too great

EDM Will take too much time

Bandsaw Will take too much time

Freeze and break

Would require improbable cooling,

uncontrollable

Acid Bath High risk, steam formation

Slag Bath High risk and uncontrollable

Induction Heater Uncontrollable

The reason “uncontrollable” refers to that it is not obvious that all of the starting step is

removed and without taking other material with it. “High risk” refers to excessive danger with

toxic and hot substances that might harm operators. “Improbable cooling” refers to the fact

that the largest ingots weigh more than 26 metric tons and have a temperature of 300°C

cannot be cooled rapidly enough.

15

Table 2. Results from the weighted decision matrix

Concept 1 Concept 2 Concept 3

Project

description:

Milling Thermal Lance Cutting Torch Removal of

Starting Step

Criteria:

Weig

ht

1....... 5

Po

int

1 ....... 3

V x

P

Co

mm

ent

Po

int

1 ....... 3

V x

P

Co

mm

ent

Po

int

1 ....... 3

V x

P

Co

mm

ent

User Friendly 5 3 15 1 5

Requires

manual

operation 3 15

Easy

Maintenance 5 2 10

Requires

some

maintenance 3 15 3 15

Simple/few

parts

Easy

Installation 5 2 10

Requires

rebuilds 3 15 3 15

Easier than

concept 1

Cost 5 2 10

Quite

expensive

initially and

running 3 15 Cheap 2 10

Requires

machinery

CE-Marking 5 3 15 Possible 3 15 Possible 3 15 Possible

Cycle Time 5 3 15 Fast 1 5 Slow 1 5 Slow

Automatic

Operation 4 3 12 Possible 1 4 Not possible 3 12 Possible

87 74 87

The concepts with the highest scores are Milling and Cutting torch. Thermal lance scores the

lowest since it requires manual operation and is not automatable. Milling requires expensive

machinery and high running cost relative to concept 2 and 3. But it offers high controllability

and is the fastest of the three. According to a supplier the cycle time for the milling operation

is less than 5 minutes and the noise level will be lower compared to concept 2 and 3. A specific

cycle time is not determined for concept 2 and 3 but it will be significantly longer compared to

concept 1. Therefore, concept 1 is the chosen concept.

16

4.5.2 Tipping Mechanism

Table 3. Results from the concept generation session of Tipping mechanism and reasons for exclusions

Tipping mechanism Reason for exclusion

"Tipp Chair"

"Seesaw"

"Manipulator"

Rotary Axis Grab

"Flip Truck" Requires extra operators

Details on the concepts are shown in appendix A. The “flip truck” was deemed improbable

because it would most likely require an additional employee to man the truck which is not

necessary for the other concepts. Table 4. Results from the weighted decision matrix

Concept 1 Concept 2 Concept 3

Project description: Tipping Chair Seesaw Rotary Axis Grab Manipulator

Tipping Mechanism

Criteria: Weig

ht 1....... 5

Po

int 1 ....... 3

V x

P

Co

mm

ent

Po

int 1 ....... 3

V x

P

Co

mm

ent

Po

int 1 ....... 3

V x

P

Co

mm

ent

Po

int 1.......3

V x

P

Co

mm

ent

User Friendly 5 3 15 3 15 2 10

Requires

manual

input 3 15

Easy Maintenance 5 2 10

Several

mechanical

systems 2 10

Several

mechanical

systems 2 10

Several

mechanical

systems 2 10

Several

mechanical

systems

Easy Installation 5 2 10

Large

construction 2 10

Large

construction 3 15

No

installation 2 10

Large

construction

Cost 5 2 10

Large

construction 2 10

Large

construction 2 10 2 10

Large

construction

CE-Marking 5 3 15 Possible 3 15 Possible 3 15 Possible 3 15 Possible

Able to Handle Pallet

system 3 2 6

Would be

difficult 2 6

Would be

difficult 3 9 Compatible 2 6

Would be

difficult

Side Motion for

Tipped Ingots 4 2 8

Would be

difficult 2 8

Would be

difficult 3 12 Possible 2 8

Would be

difficult

Slag Removal System

Compatibility 5 2 10

Could be

difficult 2 10

Could be

Difficult 3 15

Does not

matter what

system 3 15

Does not

matter

Automatic Operation 4 3 12 Possible 3 12 Possible 2 8

Would be

difficult 3 12 Possible

96 96 104 101

17

Concept 3 is the winner of the selection. Concept 3 scores highest on easy installation

compared to the other concepts, this is because it is a standalone tool that does not require

foundations or other permanent installations. All of the concepts are given the same score on

cost since no estimation has been determined. Concept 3 is the only concept that is deemed to

be able to use the pallet system. No other concept will easily implement a function that involves

loading pallets. Side motion is graded on the same basis as “be able to use the pallet system”.

“Slag removal system compatibility” refers to the integration with a slag removal system.

Concept 1 and 2 scores lower since they are deemed free access of the slag top, concept 4 gives

free slag end access and concept 3 would transport the ingot further to some other solution

that would handle the slag. Automatic operation could be possible for concept 3 but is deemed

difficult since it utilizes the existing manual overhead crane. More details about the different

concepts can be seen in Appendix A.

The winning concept was concept 3. More details can be seen in Figure 5 below.

Figure 5. "Rotary axis grab"

The rotary axis grab is a lifting tool that can grab and then rotate the grabbed object around

an axis. An overhead crane is used to move and operate the tool and the grabbing and rotating

motion is powered by electric motors that are controlled by the operators remotely. The

moveable arms makes it possible to grab different sized ingots quickly without different sized

jaws. The ingots are supposed to be grabbed around their center of gravity. The grabbing

movement is controlled by a motor that turns a lead screw that moves the grabbing arms. The

clamps are then rotated 90 degrees to make the vertical ingots horizontal. The rotating motion

is made with one motor on each grabbing arm. The rotation is passed through an angled

gearbox that is self-locking for increased safety. When the ingot is rotated, it can then be placed

in a pallet that is loaded onto the next machine for further operations. This tool leaves both

ends of the ingot free, making the rest of the processing easier. Another benefit is that the tool

can be stored away from the rest of the machine and takes up little floor space compared to

the other concept solutions.

18

4.5.3 Slag Removal

Table 5. Results from the concept generation session of Slag removal and reasons for exclusions

Slag Removal Reason for exclusion

Air Jack Hammer

Spike

"Over Rotation"

Fall off Naturally when horizontal

Remove When Liquid Would compromise steel quality

“Remove when liquid” is not an option since the slag forms a protective layer that is necessary

to keep high steel quality.

Table 6. Results from the weighted decision matrix

Concept 1 Concept 2 Concept 3 Concept 4

Project description:

Air Jack Hammer Spike Over Rotation Fall Off Naturally When

Horizontal Slag Removal System

Criteria:

Weig

ht 1....... 5

Po

int 1 ....... 3

V x

P

Co

mm

ent

Po

int 1 ....... 3

V x

P

Co

mm

ent

Po

int 1 ....... 3

V x

P

Co

mm

ent

Po

int 1.......3

V x

P

Co

mm

ent

User Friendly 5 2 10 High Noise 3 15 2 10

Unpredict

able 3 15

Easy Maintenance 5 2 10

Mechanical

Systems 2 10

Mechanical

Systems 3 15

No extra

equipment 3 15 No maintenance

Easy Installation 5 2 10 2 10 3 15

No extra

equipment 3 15 No installation

Cost 5 2 10

Mechanical

Systems 2 10

Mechanical

Systems 3 15

No extra

equipment 3 15

No extra

equipment

CE-Marking 5 3 15 Possible 3 15 Possible 3 15 Possible 3 15 Possible

Automatic Operation 4 3 12 Possible 3 12 Possible 3 12 Possible 3 12 Naturally

67 72 82 87

The winner is concept 4 “Falls of Naturally When Horizontal”. Concept 1 scores lower on the

user-friendly criteria due to the loud noise produced when operating an air jack hammer. This

would impede with the comfort and deteriorate the work environment for the operators.

Concept 3 also scores lower on user friendliness since the time it takes for the slag to be

loosened from the ingot varies. It would be difficult to estimate the time the ingot must be in

the over rotated position. This would in turn require an operator's attention and therefore

scores lower than concept 2 and 4. Concept 1 and 2 score lower on maintenance, installation

and cost since the required extra machinery. More parts equal a higher risk of failure, are more

19

complex to install and cost more. CE-marking as well as automatic operation is seen to be

possible for all concepts.

4.5.4 Slag Handling

Table 7. Results from the concept generation session of Slag handling and reasons for exclusions

Slag Handling Reasons for exclusion

Container

Conveyor Belt

Leave on ground Unsustainable

Leaving the slag on the ground is not sustainable.

Table 8. Results from the weighted decision matrix

Concept 1 Concept 2

Project description: Container Conveyor Belt

Slag Handling

Criteria:

Weig

ht 1....... 5

Po

int 1...... 3

V x

P

Co

mm

ent

Po

int 1 ....... 3

V x

P

Co

mm

ent

User Friendly 5 2 10 Requires manual emptying 3 15

Easy Maintenance 5 2 10 2 10 Mechanical System

Easy Installation 5 3 15 2 10 Mechanical System

Cost 5 3 15 2 10 Mechanical System

CE-Marking 5 3 15 Possible 3 15 Possible

Automatic

Operation 4 1 4 Not Possible 3 12 Possible

69 72

The winner is concept 2 “conveyor belt”. Concept 1 scores lower on User friendly and therefore

Automatic operation since a container would require an operator to replace it in some way.

Concept 2 scores lower than concept 1 on maintenance, installation and cost since it requires

extra machinery.

4.5.5 Chip Removal

Table 9. Results from the concept generation session of Chip removal and reasons for exclusions

Chip Removal Reason for exclusion

Screw Transport

Conveyor Belt

Vacuum

20

Table 10. Results from the weighted decision matrix

Concept 1 Concept 2 Concept 3

Project description: Screw Transport Conveyor Belt Vacuum

Chip Removal

Criteria:

Weig

ht 1....... 5

Po

int 1....... 3

V x

P

Co

mm

ent

Po

int 1....... 3

V x

P

Co

mm

ent

Po

int 1....... 3

V x

P

Co

mm

ent

User Friendly 5 3 15 3 15 3 15

Easy Maintenance 5 2 10 Not as well tested 3 15 3 15

Easy Installation 5 2 10 2 10 2 10

Cost 5 2 10 2 10 2 10

CE-Marking 5 3 15 3 15 3 15

Automatic

Operation 4 3 12

Can be

automated 3 12

Can be

automated 3 12 Can be Automated

72 77 77

The winning concept for chip handling is concept 2 and 3.

Concept 1 scores lower on maintenance since Uddeholm already have existing production

systems using based on concept 2 and 3.

4.5.6 Handling and Transport of Ingots

Table 11. Results from the concept generation session of Handling and transport of ingots and reasons for exclusions

Handling and Transport of ingots Reasons for exclusion

V-pallet system

Rails

Walking Beam

21

Table 12. Results from the weighted decision matrix

Concept 1 Concept 2 Concept 3

Project description: V-Pallet System and Roll

Bed Rails "Walking Beam" Handling and

Transport of Ingots

Criteria:

Weig

ht 1....... 5

Po

int 1....... 3

V x

P

Co

mm

ent

Po

int 1....... 3

V x

P

Co

mm

ent

Po

int 1....... 3

V x

P

Co

mm

ent

User Friendly 5 2 10

Requires loading

of pallets 3 15 3 15

Easy Maintenance 5 3 15

Proven

technology 2 10 Heavy wear 2 10

Heavy

machinery

Easy Installation 5 2 10 2 10 2 10

Cost 5 2 10

Mechanical

systems 3 15 Simple 2 10

Mechanical

Systems

Be able to handle

pallet system 4 3 12 Possible 1 Not possible 1 Not possible

CE-Marking 5 3 15 Possible 3 15 Possible 3 15 Possible

Automatic Operation 4 2 8

Requires loading

of pallets 3 12 Possible 3 12 Possible

80 77 72

22

The winner of table 12 is concept 1. Concept 3 scores the lowest of the three in user friendliness

and automatic operation because it requires some loading of the pallets onto the roll bed. Both

concept 2 and 3 score lower on maintenance compared to concept 1 since it is expected to have

heavier wear on machinery since the ingots are in direct contact with the transport system.

Concept 1 is on the other hand an already existing solution at Uddeholm. Concept 1 and 3 score

lower on cost compared to concept 2 since it is a more complex construction with more moving

parts. Concept 2 and 3 does not utilize the existing pallet system and therefore score 1.

4.5.7 Structural Verification of Rotary Axis Grab

The lifting tool has one critical part that requires verification to determine if the concept is

feasible. The stress levels in the grabbing arms must be at a reasonable level so that the tool´s

lifespan will be adequate.

The trial and error-method [5] is a method that involves trying until a final solution. If the

solution does not reach the approved value, the design is modified and tested again. The

iteration continues until the solution is approved. The changed parameters in this case are the

dimensions.

4.5.7.1 Load Case

One of the concept solutions for tipping the ingots is the rotary axis grab. One specific load

case in that tool is presented in figure 5.

Figure 6. The load case in the lifting tool

The clamping force required to grab the ingot is calculated using the following equations:

Force equilibrium:

∑ ↑: 𝑚𝑔 = 2 𝐹𝑓

𝛴 →: 2𝑁 = 2 𝐹𝑐𝑙𝑎𝑚𝑝

Friction force: 𝐹𝑓 = 𝑁 ∗ 𝜇

23

Where:

• m is the mass of the ingot (kg)

• g is the acceleration of gravity (m/s^2)

• µ is the coefficient of friction

Solving for the normal force: ⇒ 𝑁 =𝑚𝑔

2𝜇

The load case [9] can be simplified as a cantilever beam with a force applied on the end of the

beam as can be seen in Figure 7. Cantilever beamFigure 7.

Figure 7. Cantilever beam

Where L is the length and F is the force.

4.5.7.2 Moment of Inertia

The cross section in the lifting arms is a hollow square as can be seen in Figure 8.

Figure 8. Lift arm cross section

The moment of inertia is calculated using the equation below:

𝐼𝑧 =𝑡1𝑏3

6+

1

2𝑡2𝑏2ℎ

24

The maximum stress can be calculated using the equation below:

𝜎𝑚𝑎𝑥 =𝐹𝐿 ∗ ℎ/2

𝐼𝑧

Structural verification using the data from Table 13, gave a maximum stress of 209MPa

Table 13. Structural data

m (kg) 30000

Coefficient of friction 0.5

h (m) 0.3

b (m) 0.3

t1 (m) 0.04

t2 (m) 0.04

Length of beam (m) 1.7

25

4.5.8 Combined Concepts

The winners of the different concept selections were combined into a final concept. The chosen

concepts are presented in table 14. Table 14. The winners of the concept selections

Sub-Functions Winner

Tipping Mechanism Rotary Axis Grab

Slag Removal Fall of Naturally When Horizontal

Slag handling Conveyor Belt

Removal of Starting Step Milling

Chip Removal Vacuum and Conveyor Belt

Handling and Transport of Ingots V-Pallet system with Roll Bed

The visualized final concept can be seen in Figure 9:

Figure 9. Visualization of the final concept

26

This final combined concept is meant to be used in a workflow as can be seen in Figure 10.

Figure 10. The workflow of the machine

The process starts immediately when the mold is removed from the ingot. Then the rotary

axis grab tool lifts and flips the ingots horizontally and places them in a waiting V-pallet that

sits on the roll bed. When on the roll bed, the ingots are incrementally rolled forward in order

to make room for succeeding ingots. The roll bed can hold several ingots at a time and let them

cool without any supervision or danger. A conveyor belt runs on the “slag side” of the roll bed

and transports the slag that will eventually fall off from the ingots as they cool and frees the

slag top. On the end of the roll bed there is a milling station. The ingots are lifted using

hydraulic cylinders to position them more accurately for the machining phase. When lifted, an

automatically, numerically controlled mill moves towards the ingot and machines away the

starting step. Close to the milling head runs a vacuum that sucks away most chips. Underneath

the milling machine runs a conveyor belt that transports away the chips that drops down. After

the milling process the ingots are lowered down onto the pallet and rolled away and awaits

transport to the forging shop.

27

5. Discussion

The final concept almost fulfills all requirements set by Uddeholm. The solution will reduce

manual work by: combining the lifting and the tipping in one step, diminishing the need for

an operator to remove slag and the need for an operator to manually cut off a part of the

starting step. It also provides increased capacity by holding several ingots at a time. Manual

operation will be needed when lifting and rotating the ingots. The possibility of utilizing the

existing milling machine is not yet clear, future work will need to determine if it will be

adequate for the application. A hold down mechanism is also unclear if it will be necessary and

is therefore left out in this thesis.

The system will be able to handle all dimensions and current production volumes and will have

good serviceability.

The cost of the new machine will certainly be higher than the current equipment. Several new

machines must be obtained and installed fetching a larger initial cost for Uddeholm. On the

other hand, the material waste costs each year and therefore the investment will have a short

payback period. A real cost estimate is to be determined and quotes from different

manufacturers must be asked for. Another factor will be that there will be less wear on the

overhead cranes in the ESR facility. This will lead to lower maintenance costs and less

downtime. The time saved during forging will also be significant. The need for ingots to be re-

heated before forging will be diminished, this leads to savings in natural gas to heat the ovens

and shorten the lead time. The overall yield for each ingot will be increased and more

predictable, therefore production planning will be easier. Also, the operators have stated a

higher level of stress because of the extra steps and time it takes to use the “knife” in the forge

today. The new solution will certainly reduce the stress of the operators and make their job

easier.

The overall risk of the ingot handling will be reduced. The new method and tool for tipping the

ingots will significantly reduce the risk during the rotation of the ingots. The need for operators

to get close to the ingot and remove slag and cut away the starting step will be eliminated.

While this machine will change the way Uddeholm handles ESR ingots there are some

obstacles that has to be overcome. Milling will be a complex component of the machine and

will require tests in order to find the correct parameters. Some of the operators may also need

to get special training to run the milling machine. Changing tools and general maintenance

that are special for milling machines are not part of the standard requirements for working at

the ESR facility at Uddeholm. Discussions have started with a cutting tool company that is

already present at Uddeholm to develop the process, but this is out of the scope of this thesis.

The pallets that are thought to be used in this machine are nonstandard in order to

accommodate the different sized ingots since Uddeholm is using different pallets right now.

Creating a new standard of pallets is not ideal but necessary for this machine to work

seamlessly, but Uddeholm has stated that this will be a tradeoff that they are willing to make.

The number of pallets that must be produced is still to be determined.

Structural verification of the rotary axis grab arms gave reasonable results in both stress levels

and dimensions for a steel construction. This is seemed like an adequate verification to prove

that the concept will work. Although a much more thorough analysis of the design must be

28

done to further to verify the construction. The grabbing arms were seen as a critical part of the

tool. The verification also gave an estimate of the tool dimensions and they were also within

reasonable limits. A full FEM-model should be made and evaluated to find the critical points

of the design.

5.1 Further Development

To further develop and make the concept feasible for Uddeholm, detailed construction and

certification must be made of the different components. This includes detailed CAD-drawings,

structural analysis of the rotary axis grab, milling machine and roll bed. A cost estimation

would also be necessary for it to be implemented. A lot of the components are to be outsourced

according to Uddeholm; this means that the details for each component must be specified.

Control systems for hydraulics, roll bed and milling machine are to be programmed. A

specifications list for the milling machine needs to be made and in addition, machining

parameters and programming of a control system for the mill must be made. The rotary axis

grab must be specified and built by a manufacturer. Conveyor system capacities and

dimensions are to be specified. Since the machine is to be installed in an already active

workplace the overall layout and changes that must be done within the ESR-facility must be

determined. That could be moving machinery, making foundations, installing electrics and

more. All machinery must also be CE-certified. The PFMEA identified several risks that could

be minimized using fencing and guards. This should also be installed around the machine and

around critical safety components such as the milling machine, roll bed, hydraulics lifts etc.

Another vital aspect is the production planning and logistics that will surround the new

machine. The installation will disturb the production flow and measures to minimize this

impact should be taken into consideration.

29

6. Conclusion

The challenges that Uddeholm has with ESR ingots are set to be solved with the concept

solutions found in this thesis. The result of the concept development and selection resulted

in sub solutions that:

• Reduced the risk during ingot handling

The need for operators to get close the ingot is reduced. A purpose-built tool will

make the tipping operation safer.

• Increases material yield

Since the starting step is completely removed before forging extra waste is

eliminated.

• Increased ingot capacity

The roll bed will be able to carry several ingots at a time, freeing floorspace and

reduces extra tools.

• Decreases manual work

More operations will be automated and the need for extra work in the forge will be

unnecessary.

• Decreases strain on operators

The time critical operations at the forge will be reduced, making it easier for the

operators and minimizes cycle time.

More work is needed to be able to make the concepts feisable. For example: do detailed

design and construction for the different sub functions, get quotas from manufacturers,

perform more extensive structural verifications, find process parameters for the milling

operation, CE-mark the solution, etcetera.

The product development process proved useful and easy to follow and applicable even for

more complex products such as a large machine system like this. It provides a clear

documentation which, for instance, makes it easy to go back for more info regarding previous

decisions. This will be especially useful when Uddeholm is ready to realize this project in the

future. Thus, it can be concluded that the product development process is a useful and well-

established method for generating and selecting new solutions.

30

7. Acknowledgements

A great thanks to Uddeholm and their employees for making this master thesis possible. A

special thanks to Ludvig Lundberg for his guidance and support patience throughout the

project. I would also like to thank the Uddeholm employees for participating in meetings and

answering my questions.

Thanks to my supervisor Mohamed Sadek for the guidance and frequent meetings.

31

8.References

1. Electroslag Remelting Process: Part One :: Total Materia Article. [cited 4 May 2021]. Available: https://www.totalmateria.com/page.aspx?ID=CheckArticle&site=kts&NM=226

2. History - Uddeholm Global. [cited 4 May 2021]. Available: https://www.uddeholm.com/en/history/

3. Crouch IG, Cimpoeru SJ, Li H, Shanmugam D. 2 - Armour steels. In: Crouch IG, editor. The Science of Armour Materials. Woodhead Publishing; 2017. pp. 55–115. doi:10.1016/B978-0-08-100704-4.00002-5

4. Ulrich KT, Eppinger SD, Yang MC. Product design and development. Seventh edition (international student edition). McGraw-Hill Education; 2020.

5. Johannesson H, Persson J-G, Pettersson D. Produktutveckling : effektiva metoder för konstruktion och design. 2. uppl. Liber; 2013.

6. Cooper R. The handbook of design management. Berg; 2011.

7. Anil Mital, Anoop Desai, Anand Subramanian, Aashi Mital. Product Development : A Structured Approach to Design and Manufacture. Amsterdam: Butterworth-Heinemann; 2008.

8. Hippel E von. Democratizing innovation. MIT Press; 2005.

9. Sundström B. Handbok och formelsamling i hållfasthetslära. KTH; 1998.

32

9. Appendixes

Appendix A- Explanation of Concepts

Tipping mechanisms

Concept 1: “Tipping Chair”

The ingots are placed in the

“tipping chair” with an

overhead crane when it is

nearly vertical (approx.

98°). Then the chair is slid

down the slot and on the

bottom rails to lower is to a

horizontal position. After

that the ingot is lifted to

another position for further

processing.

Concept 2: “Seesaw”

The ingot is placed with an

overhead crane in the nearly

vertical rotating platform.

The center of gravity of the

ingot is approx. at the

rotating axle of the platform.

Then the platform is rotated

to a horizontal position

where the ingot is moved to

another position for further

processing.

33

Concept 3: Rotating Axis

Grab

See explanation in 4.5.2

Tipping Mechanism

Concept 4: “Manipulator”

The ingot is placed or held in

front of the machine with an

overhead crane and is

grabbed with the gripping

claw. The gripping claw is

raised and then rotated and

lowered onto a pallet for

further processing.

Slag Removal System

Concept 1: “Air Jack Hammer”

An air powered jack hammer that is

automatically operated is moved to the slag

end of the ingot and starts hammering in the

center. The slag drops down on a slag

transportation system below.

34

Concept 2: “Spike”

Similar to the Air Jack Hammer but the spike

is simply driven into the center of the slag by

a linear actuator. The slag drops down on a

slag transportation system below.

Concept 3: “Over Rotation”

When the ingot is rotated in the tipping tool

it rotates the ingot end over end. Then the

slag falls off naturally down on a slag

transportation system below. This partial

solution is not compatible with all tipping

mechanism solutions.

Concept 4: “Falls Off Naturally When

Horizontal”

The ingot is left to cool and eventually the

slag will fall off naturally onto a slag

transportation system below.

35

Removal of Starting Step

Concept 1: Mill

The starting step is removed by a horizontal

milling machine that is numerically

controlled. The chips are transported away

with a chip transportation system.

Concept 2: Thermal Lance

A cutting thermal lance is manually operated

and cuts off the whole end of the ingot.

Concept 3: Cutting Torch

An automatically controlled cutting torch

cuts off the end of the whole ingot.

36

Chip Removal System

Concept 1: “Screw transport”

The chips fall down in a trough, in the

bottom there is a screw conveyor that

transports the chips.

Concept 2: Conveyor Belt

The chips fall down in a through and get

transported away with a conveyor belt.

Concept 3: Vacuum

A vacuum head is placed near the milling

head and sucks the chips. The chips are

moved through tubes to an external chip

collection area.

Slag Handling

Concept 1: Container

The slag falls directly down into a container

below.

37

Concept 2: Conveyor Belt

The slag falls down onto a heat resistant

conveyor belt. The conveyor belt transports

the slag to an external slag collection area.

Handling and Transportation of Ingots

Concept 1: “V-pallet System and Roll Bed”

The ingots are placed in standardized V-

pallets keeping them from rolling and

enabling forklifts to move them more easily.

The pallets are placed on a roll bed with space

for several pallets/ingots. The roll bed acts as

the transportation mean to the different

processing stations and an ingot holding

area.

Concept 2: Rails

The ingots are placed directly on a rail. The

ingots are rolled along the rail to the different

processing areas. The rail can accommodate

several ingots.

Concept 3: “Walking Beam”

The ingots are placed on the walking beam.

The walking beam incrementally “walks” the

ingots forward to the different processing

areas. The walking beam can accommodate

several ingots.

38

Appendix B- Preliminary Gantt Schedule

Appendix C- Project FMEA

Johan

Jönsson 2021-05-07 Risk Characteristic AS IS Nr Risk

Possibility Risk Effect Cause of Risk S O D RPN Recommended

action

1. Sickness Delayed work NA 5 1 1 5 Plan for redundancy

2.

Supervisor sick

Delayed work NA

5 1 1 5

Plan for

redundancy,

frequent

communication

3.

Uddeholm closes

Loss of information, not be able to visit

Corona

6 3 1 18

4.

Not passing

Not able to graduate

Bad work

9 2 3 54

Good

communication

with supervisors

5.

Bad results Take longer time, bad result

Lack of pre-study. bad methods. Lack of information

6 3 4 72

"Front heavy"

project, Extensive

literature search,

good

communication

6.

To complex Delays, hard to pass

Insufficient boundaries 6 3 3 54

Good

communication

with supervisors

7.

Takes too much time

Puts pressure on other things, not finishing in time

Bad planning, insufficient boundaries 5 3 3 45

Long term planning

and good

communication

with supervisors

8.

Delays Everything is delayed, more pressure on other aspects of life

Bad planning, lack of communication

5 3 3 45

Plan long term and

with redundancy

and good

communication

with supervisors

39

Appendix D- PFMEA

Johan

Jönsson 2021-05-07

Risk Characteristic AS IS

AFTER RE

EVAL.

Nr Risk

Possibility

Risk Effect Cause of Risk S O D RPN Recommended

action

S O D RPN

1.

Not stable Machine

falls over,

Injures

workers,

Fatality

Vibrations,

not fastened

10 1 4 40

Proper

fastening,

minimize

vibrations

10 1 1 10

2.

Slag falling Hit

workers,

fatality

No

protection 10 1 6 60

Shields, fence

10 1 4 40

3.

Metal chips

flying

Injures

workers

No

protection 4 7 3 84

Shields, fence

4 1 3 12

4.

Workers get

pinched

Injures

workers,

Fatality

No

protection,

no warning 10 1 5 50

Shields, fence,

light and

sound signals 10 1 2 20

5.

Machine total

breakdown

Injures

workers,

Fatality,

Downtime

Bad design,

wrong

calculations,

wrong

materials,

bad

maintenance

10 1 3 30

Competent

designers,

Structural

calculations 10 1 1 10

6.

Power loss Downtime,

Machine

fails,

Fatality

Bad electrics,

Non-Self-

locking

mechanisms

10 2 3 60

Self-locking

mechanisms,

reserve

generator

10 1 3 30

7.

Extreme

Temperatures

Machine

fails,

injures

workers

No heat

protection 6 2 2 24

Shields, fence

6 1 2 12

8.

Slip and fall Injures

workers,

fatality

No good

platforms,

slippery

surfaces, no

railings

10 7 8 560

Clean work

floor, fences,

railing 10 2 3 60

40

Appendix E- Product Specification Tipping Mechanism

Tipping

Machine

Criteria

number Criteria

Demands = D

Wish = W

Function= F

Limitation= L

Weighting

(1 min, 5 max) Comments:

1 CE Marking D L

2

All Wear Parts are to be

made from Uddeholm

steel

W L 2

3 Slag removal system D F

4 Be able to handle pallet

system W F 3

5 Fit in the prescribed

space D L 9000x4100 (mm)

6 Forklift accessible D L Accessible coming

from the outside

7

Be able to handle all

current ingot

dimensions

D L Min-max

dimensions

8 Heat resistant D L Temperature span

9 Operator protection D L

10 Automatic operation W F 4

11 Cycle time (tipping) W L 5 Max cycle time 10

minutes

12 Overhead crane

accessible D L

13 Side motion for finished

ingots W F 4

14 User Friendly D L

15 Easy Maintenance D L

16 Easy Installation D L

17 Cost Efficient

Construction D L

41

Appendix F-Product Specification Machining

Milling

machine

Criteria

number Criteria

Demands = D

Wish = W

Function= F

Limitation= L

Weighting

(1 min, 5 max) Comments:

1 CE Marking D L

2

All Wear Parts are to be

made from Uddeholm

steel

W L 2

3 Chip removal system D F

4

Be able to handle all

current base plate

dimensions

D L min-max

dimensions

5 Heat resistant D L Temperature span

6 Operator protection D L

7 Forklift accessible D L

8 Utilizing the existing

milling machine W L 5

9 Fit in the prescribed

space D L 9000x4100 (mm)

10 Automatic operation W F 4

11 Cycle time (milling) W L 5 max cycle time 5

minutes

12 Overhead crane

accessible D L

13 User Friendly D L

14 Easy Maintenance D L

15 Easy Installation D L

16 Cost Efficient

Construction D L