Microsoft PowerPoint - 46INJECTION MOLDING
• Manufacturing process for making complex shapes from polymeric materials. The process involves heating up the polymer, injecting the molten polymer into a mold, cooling the polymer in the mold, and ejecting the part.
• Injection molding is a complex technology with possible production problems. They can be caused either by defects in the molds or more often by part processing which is molding.
CONT… The common defect are:
Warping Short shot Sink marks
Flash Weld lines
Phone Cover model
are made a lot of accessories as a protector from
damage or made a very nice appearance. The phone
cover also one of the accessories is made to protector
the mobile phone from damage. The whole part for
phone cover (upper and bottom casing, transference
keypad and screen) is not injected in the same mold
simultaneously, they are come batch by batch instead of
their type, which means, for example, the upper and
bottom casing come from one mold and the other pieces
also comes from one mold.
cont
cont
• The main problem is to inject the whole of part
for phone cover (upper and bottom casing,
transference keypad and screen) which come in
diversity of shape, size, and volume in one mold
need the most optimize injection parameter
setting because if one piece is rejected, the set
is not completed, in order to replace the rejected
piece, it needs another injection which will lead
to more cost and higher inventory.
OBJECTIVES
plastic injection moulding process.
plate molds in injection molding process.
Prepare CAD
Saved in x_t file type for MPI simulation
Meshing A continuous surface or volume is broken into many connected but
discrete elements, forming a mesh.
The time required to mesh the part will depend on the size and
complexity of the part.
Type of Gate Chosen
RESULT
AND
DISCUSSION
In order to find the most optimize layout arrangement of
phone cover mold, the result from 2 layouts should be
compared. The selected results of each layout that will cover
are:
6. Volumetric shrinkage.
1. Fill time
The Fill time result shows the position of the flow front at regular intervals
as the cavity fills. At the start of injection, the result is dark blue, and the
last places to fill are red. The shortest time is H-type layout with 3.148s but
two part in H-type layout will get flashing defect. Even fill time in radial-
star layout takes 3.176s, this layout is the most balanced with all the part
filled almost uniformly.
Standard H-Types Radial-Star
953.4cm/s 754.3cm/s
The Average velocity, part show the result of the velocity profile across
the part thickness, calculated at the end of cooling time. From the result,
can see that the H-type layout reach over 953.4 cm/s rather than over
754.3cm/s in radial-star layout
38 tonne 28 tonne
Clamp force is the force required to hold the mold closed while an opposing
pressure is exerted by the plastic injected into the cavity. Clearly can see that
radial star layout just need 28 tonne clamp force, while the stabdard H-type just
need 38 tonne clamp force . This means the parts of radial star layout should be
no defect of flashing.
< 9.875 MPa < 9.053 MPa
The Pressure result is generated from a Fill analysis, and shows the
pressure distribution through the flow path inside the mold at the time
the result was written. The radial star layout got the lowest pressure
which is 9.053 MPa compared to h-type layout which over 9.875 MPa.
This is because radial star layout have bigger runner size and volume.
5. Time to reach ejection
temperature (Cooling Time) Standard H-Types Radial-Star
50.05s 30.19s
Comparison Criteria H-type Radial-star
Advantages & Disadvantages
characteristics in this injection moulding
process.
parts injection molding process.
emphasis in the runner layout and product
configuration in the mold, the proposed
approach is feasible and effective to assist the
today manufacturing industry needed for
complex shape.
REFERENCES
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injection molding process by cad mould rubber. Int. J. Math.
Comput. Simul., 5.5, 413-421 (2011).
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373-375 (2013).
[3] Dang, X.P. Simulation Modelling Practice and Theory 41, 15-27
(2014).
[4] P.K. Bharti et al. Int. J. Eng. Sci. Tech., Vol. 2(9), 4540-4554
(2010).
[5] Shen, C., Wang, L., & Li, Q. J. Mater. Proc. Tech., 183.2, 412-
418 (2007).