Desain Sistem Saluran
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Desain Sistem Saluran
High-performance Mold
A high-performance mold harus memilliki karakteristik
yang baik dalam hal :
High-performance dalam sistem pengisian
High-performance sistem packing
High-performance sistem pendinginan
Contoh Mold Casting System
Konsep Desain Sistem Saluran
Gating system:flow channel to the cavity
Effect:smooth and orderly filling of plastic fluid, fully pass
injection pressure to the various part during filling and
solidification process, get density
Classification:
Common gating system:Cold runner
runnerless gating system:Hot runner, insulated runner
Gating System and their effects
Sprue Runner gate
runner system has a direct impact on the appearance, physical properties and of
dimensional accuracy and cycle time of molded product
Main
runner Branch
runner
Branch
runner
runner
Cavity
Prinsip Desain Sistem Saluran
1. guarantee the quality of parts
(to avoid the common problem of filling)
hesitation is easy to make overpacking on
some part of the workpiece, and underpacking
for other part
Minimize hesitation
From the thickest pouring provide better filling and packing effects
If there are underpacking, the thinner areas will solidify faster than thick
regions
Avoid gate on the region with sudden change of wall thickness, prevent
hysteresis or short shot
不推荐
未凝固处
缩坑
缩坑
浇口 保压不足
gate
Un-cure
Sink mark
Sink mark
Under packing
Prinsip Desain Sistem Saluran
Gate Placed on the Thickest part of Product
1. guarantee the quality of parts
1. guarantee the quality of parts
Meltline exists primarily affect the
appearance, making the poor surface of
product; poor Weld strength
Try to avoid meltline
Prinsip Desain Sistem Saluran
Meltline
Melt Lines
• Melt from different directions, the front part of the molten resin is cooled in the
junction can not fully integrated. Under normal circumstances, affect the
appearance, impact on the coating, electroplating. Severe impact on the
product strength (especially fiber reinforced resin)
1. guarantee the quality of parts
avoid overpacking
and underpacking
poor gating system design or improper operating conditions,
make the melt pressure in the cavity takes too long or too
high
overpacking will make the product density, to increase the
internal stress, or even flash
underpacking
overpacking
Prinsip Desain Sistem Saluran
rib
sink
1. guarantee the quality of parts
Minimize the flow disorderly
flow disorderly make poor workpiece strength and surface flow
Simple Complex
Prinsip Desain Sistem Saluran
Consider Molecules orientation
If the product is long and
narrow shape, provides a
single direction from a
unilateral into the pouring
uniform plastic flow
Although the volume
shrinkage of products at the
different ends is different,
there is no warpage
Molecular distribution in a
different direction often leads
to warping
均匀分子(纤维)定向 翘曲变形小
非均匀分子(纤维)定向 翘曲变形大
均匀
均匀
均匀
均匀
浇口
浇口
不均匀
gate Uniform
Uniform
Uniform
Uniform
Runner
Uneven
Non-uniform molecular orientation
and warpage deformation and large
uniform molecular orientation and
warpage deformation and large
2. Minimize the cross-section and length of gating system
Reduce the amount of plastic and mold size
Minimize heat loss and pressure loss of the plastic melt
3. synchronize filling
For multi-cavity mold, make different cavity melt arrive at the same time, and
equal to the pressure at the entrance of each cavity
Prinsip Desain Sistem Saluran
Filling in the Central
Gate placed in the central of the product are available for same flow
length
Long flow length will affect the required injection pressure
Central pouring makes all directions holding pressure evenly to avoid
uneven volume shrinkage
Symmetry of Gates
Symmetry gates can avoid product warpage
Asymmetric flow will lead to filling first in certain areas, even before solidification
may cause uneven product of the volume shrinkage, which will cause warpage
Sprue Design and Manufacture
Effect:Is a bridge connecting the injection machine nozzle and mold, the first
part for plastic melt filling in
Design points
Sectional shape, taper, length, spherical R, fillet r
shape and size of sprue
Nozzle
diameter
spheric radius
Sprue bushing through two plate should be a
ladder-like, or using gate sets
Sprue Design and Manufacture
Runner Design and Manufacture
Effect:Smooth conversion of flow and filling cavities as soon as possible
Runner section shape
Runner size design
Runner manufacturing points
Runner Road layout
Runner design points
cross-sectional shape of the flow channel will affect the volume of plastic
flow in the flow channel, and flow within the molten plastic
Runner Design and Manufacture
1. Runner section shape
Circular cross-section
Advantage:The shape of flow channel with high efficiency, up to 0.25D
Shortcoming:Increase production costs, flow channel interleaving will
affect flow efficiency
Runner Design and Manufacture
1. Runner section shape
Rectangular cross section
The efficiency of flow channel is nearly
equal to Circular section, 27% area more
than that of Circular, increase injection
waste and demolding force
Runner Design and Manufacture
1. Runner section shape
Trapezoidal cross section
39% more area than that of circular, and more waste, while with simple
making method
Runner Design and Manufacture
1. Runner section shape
U shaped
Also known as the modified trapezoidal flow channel, combined with the round and
trapezoid advantages, 14% area more than that of circular
Runner Design and Manufacture
1. Runner section shape
Hexagonal cross-section
An area of only 82% of the
circular flow channel, but
manufacturing is not easy, and
seldom used
Runner Design and Manufacture
2. Runner design points
Volume and wall thickness of the products, the Runner section thickness is greater
than the wall thickness of the products
The fluidity of the molding resin, the resin with glass fiber and less flowability, larger
flow channel cross-section needed
Change the direction of the flow channel around the corner, should be properly set
cold slug
make the plastic parts and flow channel in the geometric center of the clamping
force, in the center of projected area
Runner Design and Manufacture
2. Runner design points
Ensure quickly and evenly filling
Runner size as short as possible, easily as small as possible
To facilitate the processing and tool selection
Each branch runner is larger than the next branch
10 ~ 20% (D = d+d × 10 ~ 20%)
Runner Design and Manufacture
3. Runner size design
D>=Product most wall thickness+1.5mm B=1.25D
Runner Design and Manufacture
3. Runner size design
Flow channel diameter is too large: not only a waste of materials, and the cooling
time increased, the molding cycle also grows, resulting in waste costs.
Flow channel diameter is too small: the flow resistance of the material, could
easily lead to the filling or injection pressure must be increased in order to fill.
Runner diameter should be suitable for the weight of the product or the projected
area
Diameter of the
flow channel(mm) Product weight(g)
4 95
6 375
8 More than 375
10
12 Large-scale
Diameter of the
flow channel(mm) Projected area(cm2)
4 Less than 10
6 200
8 500
10 1200
12 Large-scale
Runner Design and Manufacture
2. Runner size design
The length of the flow channel can be calculated by the following empirical
formula:
D =
D——Runner diameter mm W - product weight g L - stream channel length
(mm)
Runner Design and Manufacture
4. Runner Road layout
principle of flow channel array
same distance for molten plastic from sprue to different gate
The cavity center of pressure coincide with the center of injection
molding machine
The layout of the flow channel
Natural balance Artificial balance
Unbalanced Natural balance Artificial balance
Runner Design and Manufacture
Flow Balance
Naturally balanced runner system
The same distance from nozzle and to different cavity, filling all cavities in the
same time under the same pressure
Artificially balanced runner system
Resizing flow channel to complete filling of all cavities in the same time under
the same pressure
filling order for different cavity is extremely complex, not only with the
section size and length of the Runner, and the plastic melt temperature,
pressure, viscosity, mold temperature and viscosity on pressure drop
and temperaturelowering the degree of sensitivity. Gate size of the
balance of each cavity can be fixed after the test mold or mold flow
analysis
Artificially Balanced Runner System
4. Runner
Road
layout balance of Runner arrangement
unbalance of Runner arrangement
Runner Design and Manufacture
Design and Manufacture of Gate
1. role of gate
gate:Gate: a bridge connected Runner and cavity, is the weakest and
most critical part in the system
Design and Manufacture of Gate
•Adjust flow speed •Adjust feed time •Prevent back flow
Gate dimension often determined by experience, take low value first, then revised by trying. generally, the gate area size is about 3-9% of that of runner, with short length about 1-1.5mm, often using rectangle or round section
restrict gate(side gate, point gate, fan gate)
• Melt through the narrow gate, raising speed and temperature growth, good for
filling
• narrow gate first coagulation and closed cavity after Injection and packing,
which reducing the deformation and rupture of plastic parts
• Narrow gate facilitate the separation flow condensate from plastic part
• demolding convenient
Non restrict gate(sprue gate)
Design and Manufacture of Gate
1.role of gate
the suitability of Gate location, number, shape, size has a direct impact on
product appearance, dimensional accuracy, physical properties and molding
efficiency
too large Gate: excess residual
stress around gate, resulting in
deformation or rupture, and the
gate removal difficult
too small Gate : easily lead to the
filling (short shots), sink marks,
weld defects in appearance, and
shrinkage increases too small gate
too big Gate
Dimension
reduced
swell
Design and Manufacture of Gate
2. type and characteristics of gate
Direct gate(sprue gate)
Direct gate is widely used in single-cavity mold
Disadvantages: difficult removal of gate, leave
marks on surface of molding
Design and Manufacture of Gate
side gate
typical size : thickness of 0.4 to 6.4mm,
width from 1.6 to 12.7mm.
Generally opened in the parting surface,
suitable for multi-cavity mold, convenient
gate removal; but the pressure loss, shell-
shaped venting inconvenience, easy to
produce the weld.
Design and Manufacture of Gate
2. type and characteristics of gate
overlap gate
typical gate size: thickness 0.4 to 6.4mm,
width from 1.6 to 12.7mm.
Overlapping gate and side gate is similar,
there is overlap between gate and the
finished wall or finished surfaces
Design and Manufacture of Gate
2. type and characteristics of gate
fan gate
Typical gate size: thickness 0.25-1.6mm, width of 6.4 to 25% of the length
of the cavity sidewall.
Design and Manufacture of Gate
2. type and characteristics of gate
disk gate or dish gate
Disc gate is often used for forming the inside of the
opening of the cylinder or round products
This type of gate for concentric, demanding strict
dimension, and not allow Weld line
Typical gate thickness : 0.25 to 1.27mm
Design and Manufacture of Gate
2. type and characteristics of gate
ring gate
melt flow freely along the center part of ring
gate, and then melt down to filling the mold
Typical gate thickness: 0.25 to 1.6mm.
Design and Manufacture of Gate
2. type and characteristics of gate
spoke gate
Spoke gate, also known as 4-point gate or cross gate.
Mostly for tubular plastic products, and gate removing
easy and material saving
Disadvantages: may produce weld line , not possible to
create perfect roundness
Typical gate thickness: 0.8 to 4.8mm, width from 1.6 to
6.4mm.
Design and Manufacture of Gate
2. type and characteristics of gate
film gate
Similar to ring gate, with straight edge of the plastic parts
Applies to flat and large area, warping reducing
Typical thickness: 0.25 to 0.63mm, with short length, approximately 0.63mm
Design and Manufacture of Gate
2. type and characteristics of gate
tab gate
Normally used in tablet-shaped and thin moldings,
in order to reduce the shear stress
Gate around high shear stress is limited to
the secondary tabs, tabs will be removed
Convex tablets gate is widely applied to
the PC, SAN, and ABS resin molding
Tabs on the minimum width of 6.4mm,
the minimum thickness for 75% of the
cavity depth.
Design and Manufacture of Gate
2. type and characteristics of gate
pin point gate
Suitable for multi-cavity, three boards
and two open mold, the mold point
gate off automatically.
Small Gate with high pressure loss,
which need higher injection pressure
Design and Manufacture of Gate
2. type and characteristics of gate
Banana gate
Gate in core side, cut off during
ejection, L>L1+L2, and L1
could not too short
2. type and characteristics of gate
Design and Manufacture of Gate
Gate design principles
A good gate can make fast, uniform and better single-directional flow, and
suitable gate solidification time
⑴To prevent the gate at the jet
phenomenon in the filling process,
the traces of the corrugated.
To prevent the approach: increase
the gate size or impact-type gate.
Non-
impact
gate
impact
gate
Core
Design and Manufacture of Gate
Gate design principles
⑵Symmetric gate can prevent warping
⑶gate location good for melt flow and feeding
Not recommended Recommend
Set up multiple gates to reduce the deformation
Design and Manufacture of Gate
Gate design principles
Gate location good for venting
Gate location good for venting, which
prevent short shot, burnt, or high
pressure in the gate
Design and Manufacture of Gate
Gate Location Options
Gate Location Options
Gate Location Options
Location of
the gate
Reasonable
location of the
gate
Gate location example
TUGAS (Work in Pairs)
Part diatas akan dibuat sand casting dari aluminum casting alloy.
Buat desain sistem saluran dengan mempertimbangkan shrinkage
dan machining. Dapat menggunakan software yang anda miliki.
Desain dibuat dengan 2 jenis pola, yaitu :
A. Pola 1 bagian
B. Pola 2 bagian (atas dan bawah)