MRP-Kartawan.ppt

7/30/2019 MRP-Kartawan.ppt

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Material Requirements

Planning


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Materials requirements planning (MRP) is a

means for determining the number of parts,

components, and materials needed to produce

a product

MRP provides time scheduling information

specifying when each of the materials, parts,and components should be ordered or produced

Material Requirements PlanningDefined


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Dependent Demand

The demand for one item is relatedto the demand for another item

Given a quantity for the end item,the demand for all parts andcomponents can be calculated

In general, used whenever aschedule can be established for anitem


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Benefits of MRP

1. Better response to customerorders

2. Faster response to marketchanges

3. Improved utilization of facilities

and labor4. Reduced inventory levels


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Based on a master production schedule, a materialrequirements planning system:

Creates schedules identifying the specific parts

and materials required to produce end items

Determines exact unit numbers needed

Determines the dates when orders for thosematerials should be released, based on lead

times

Material Requirements Planning

System


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Elemen MRP

1. Master production schedule

2. Specifications or bill of material

3. Inventory availability4. Purchase orders outstanding

5. Lead times

Effective use of dependent demandinventory models requires thefollowing


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Master Production Schedule (MPS)

Show quantity each item must beproduced each periode

Specifies what is to be made and when

Must be in accordance with theaggregate production plan

As the process moves from planning toexecution, each step must be tested for

feasibility

The MPS is the result of the productionplanning process


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BOM (Table Example)

Top

Leg

Long Rail

Short Rail


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BOM (Product Structure)

Short Rails

(2)

Table

(End Item)

Long Rails

(2)

Legs

(4)

Top

(1)

Leg Assembly

(1)


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Code

Level Code Component

0 Table (end-item)

1 Leg assembly (1)

2 Short rails (2)

2 Long rails (2)

2 Legs (4)

1 Top(1)


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MRP versus Order-Point Systems

Attribute MRP Order Point

Demand Dependent Independent

Order

philosophy

Requirements Replenishment

Forecast Based on master

schedule

Based on past

demandControl

concept

Control all items ABC

Objectives Meet manufacturing

needs

Meet customer

needs

Lot sizing Discrete EOQ

Types of

inventory

Work in process and

raw materials

Finished goods

and spare parts


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Example of MRP Logic and Product Structure Tree

B(4)

E(1)D(2)

C(2)

F(2)D(3)

AProduct Structure Tree for Assembly A Lead Times

A 1 day

B 2 days

C 1 day

D 3 days

E 4 days

F 1 day

Total Unit Demand

Day 10 50 A

Given theproduct structure treefor A and the lead time and

demand information below, provide a materials requirements

plan that defines the number of units of each component and

when they will be needed


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LT = 1 day

Day: 1 2 3 4 5 6 7 8 9 10

A Required 50

Order Placement 50

First, the number of units of A are scheduled

backwards to allow for their lead time. So, in the

materials requirement plan below, we have to place

an order for 50 units of A on the 9th day to receive

them on day 10.


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Next, we need to start scheduling the components that make up

A. In the case of component B we need 4 Bs for each A.

Since we need 50 As, that means 200 Bs. And again, we back

the schedule up for the necessary 2 days of lead time.Day: 1 2 3 4 5 6 7 8 9 10

A Required 50

Order Placement 50

B Required 200

Order Placement 200

B(4)

E(1)D(2)

C(2)

F(2)D(3)

A

SparesLT = 2

4x50=200

16


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Day: 1 2 3 4 5 6 7 8 9 10

A Required 50

LT=1 Order Placement 50B Required 200

LT=2 Order Placement 200

C Required 100


D Required 400 300

LT=3 Order Placement 400 300

E Required 200LT=4 Order Placement 200

F Required 200


B(4)

E(1)D(2)

C(2)

F(2)D(3)

A

Finally, repeating the process for all components, we have the

final materials requirements plan:

16


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MRP Example

A(2) B(1)

D(5)C(2)

X

C(3)

Item On-Hand Lead Time (Weeks)

X 50 2

A 75 3

B 25 1

C 10 2

D 20 2

Requirements include 95 units (80 firm orders and 15 forecast) of Xin week 10


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A(2)

X

Day: 1 2 3 4 5 6 7 8 9 10

X Gross requirements 95

LT=2 Scheduled receipts

Proj. avail. balance 50 50 50 50 50 50 50 50 50 50

On- Net requirements 45

hand Planned order receipt 45

50 Planner order release 45

A Gross requirements 90


Proj. avail. balance 75 75 75 75 75 75 75 75




B Gross requirements 45

LT=1 Scheduled receiptsProj. avail. balance 25 25 25 25 25 25 25 25




C Gross requirements 45 40


Proj. avail. balance 10 10 10 10 10

On- Net requirements 35 40hand Planned order receipt 35 40

10 Planner order release 35 40

D Gross requirements 100


Proj. avail. balance 20 20 20 20 20 20 20




It takes2 As for

each X


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Day: 1 2 3 4 5 6 7 8 9 10





























B(1)A(2)

X

It takes

1 B for

each X


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A(2) B(1)

X

C(3)

Day: 1 2 3 4 5 6 7 8 9 10





























It takes 3

Cs for

each A


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A(2) B(1)

C(2)

X

C(3)

Day: 1 2 3 4 5 6 7 8 9 10





























It takes 2

Cs for

each B


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A(2) B(1)

D(5)C(2)

X

C(3)

Day: 1 2 3 4 5 6 7 8 9 10





























It takes 5

Ds for each

B

MRP-Kartawan.ppt

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