Injection Mouldind by Adil Naeem

1. Assignment # 01 Mould Design for Injection Moulding
Department of Polymer Engineering [National Textile University, Faisalabad] Page 1
National Textile University, Faisalabad.
Faculty of Engineering and Technology,
Department of Polymer Engineering.
Title:-
Course Name: Design of mould and die for polymeric products
Course Code: PE-3106
Class: PE-6
Name: Adil Naeem
Registration #: 13-NTU-1002
Submission Date: 24-03-2016
Submitted to:-

2. Assignment # 01 Mould Design for Injection Moulding
Department of Polymer Engineering [National Textile University, Faisalabad] Page 2
Contents
Introduction………………………………………………………………………………………………………………………………………………..2
InjectionMouldingMaterials………………………………………………………………………………………………………………………2
InjectionMouldingDesignForMobile Phone Casing………………………………………………………………………………….2
Mould…………………………………………………………………………………………………………………………………………………………3
Two Plate Mould………………………………………………………………………………………………………………………………………..3
The SplitLine………………………………………………………………………………………………………………………………………………4
Gating…………………………………………………………………………………………………………………………………………………………4
Runner………………………………………………………………………………………………………………………………………………………..4
Ejection……………………………………………………………………………………………………………………………………………………….4
CavityInserts……………………………………………………………………………………………………………………………………………….5
Venting………………………………………………………………………………………………………………………………………………………..6
Water Cooling………………………………………………………………………………………………………………………………………………7
ImpressionCenter……………………………………………………………………………………………………………………………………….7
Main Sectional View…………………………………………………………………………………………………………………………………….8
References……………………………………………………………………………………………………………………………………………………8

3. Assignment # 01 Mould Design for Injection Moulding
Department of Polymer Engineering [National Textile University, Faisalabad] Page 3
Introduction :-
The plastic injection molding is a process that consists of semi-inject the molten
polymer in a closed mold under pressure and cold, through a small hole called a gate. Molten plastic
is injected at high pressure into a mold, which is the inverse of the product's shape. In that mold
material solidifies starting to crystallize polymer. The final part is obtained by opening the mold and
removes the cavity of the molded part. The injection molding is a very popular technique for the
manufacture of different articles and provides low cost at moderate to large quantities. Plastic
molding is an extremely versatile process for producing a wide range of simple or complex plastic
parts with a good finish.
Injection Molding Materials:-
The huge majority of injection molding is applied to thermoplastic
polymers. The polymers are being softened by heat and hardening on cooling even after repeated
cycling. In general, most of thermoplastic materials offer high impact strength, good corrosion
resistance, and easy processing with good flow characteristics for molding complex designs. The
thermoplastic separated into two class that namely crystalline and amorphous. Crystalline polymers
have an ordered molecules arrangement with a sharp melting point which it’s reflect most incidents
light and generally appear opaque. They also undergo a high shrinkage or reduction in volume during
solidification. Crystalline polymers usually are more resistance to organic solvents and have good
fatigue and wear-resistance properties. Besides, these polymers also are denser and have better
mechanical properties than amorphous polymers. Acrylonitrile Butadiene Styrene (ABS) is among
the most popular and versatile of the resins in the styrene family .Its availability, strength, and
limited shrinkage all help make it widely used as the default choice for most plastic products. The
ABS is an amorphous polymer with good impact strength and excellent appearance. It is easy to
process and is widely used for product has poor chemical resistance.
Injection Mold Design for mobile phone casing :-
Specifications:
Component Mobile Phone Casing
Type of tool Two plate mold
Gate type Pinpoint Gate
No. of impression 2
Material ABS/PC

4. Assignment # 01 Mould Design for Injection Moulding
Department of Polymer Engineering [National Textile University, Faisalabad] Page 4
Mold:-
Mold is the common term used to describe the production tooling used to produce
plastic parts in molding. The injection mold is the element of the injection molding system that receives
the molten plastic from the injection unit, forms the shape of the desired plastic part, provides the
necessary cooling to solidify the part and ejects the part. The choice of material to build a mold from is
primarily one of economics, steel molds generally cost more to construct, but their longer lifespan will
offset the higher initial cost over a higher number of parts made before wearing out.
Two-Plate Mold:-
The two plate mold is simple in design, yet versatile. It consists of a front and
stationary half. The cavity or core can be mounted on either half, depending upon the part design and
the location of the location of the knock-out pins. This mold is easily adapted for different designs
and all part ejection methods.
Step by step process:-
The split line:
The split line is a faint line along the finished part that shows where the mold halves
came together during the molding. The flatter the parting line is, the cheaper it is to create tooling.

5. Assignment # 01 Mould Design for Injection Moulding
Department of Polymer Engineering [National Textile University, Faisalabad] Page 5
Gating:
Since mobile phone casing is made by ABS/PC polymer material therefore we use pin
point gate, and gate diameter is 1.2-2.5 mm.
Runner:
Hot runner is used. The shape of runner is circular because it gives more material and
gives best surface of product.
Ejection:
We can eject this part by pins and sleeve ejector. We try to choose the sleeve ejector if the
molding product has hole in it, but in this case the product has no hole in it therefore we use the pins
for ejection.

6. Assignment # 01 Mould Design for Injection Moulding
Department of Polymer Engineering [National Textile University, Faisalabad] Page 6
Cavity Inserts:
Venting:
Venting is a process that is used to remove trapped air from the closed mold and volatile
gases from the processed molten plastic. Trapped air also keeps the plastic from filling in those areas
of the cavity where the air is trapped so a non-filled (or short) part is molded. Volatile gases will be
absorbed by the plastic and will cause voids, blisters, bubbles, and a variety of other defects.

7. Assignment # 01 Mould Design for Injection Moulding
Department of Polymer Engineering [National Textile University, Faisalabad] Page 7
Watercooling:
Cooling channels are provided where thick parts are present so that they completely
solidify in the same time as require solidifying the thinner section. In the case of following part
cooling channels will be as shown in fig given below.
Impression Centre:
In this we use hot runner type because hot runner type is most favorable for two
plate mold and also for rectangular shapes. In given component as it is too large and thin so proper
caring is necessary therefore 4 impressions Centre are established. Then we establish center distance
so that equal conditions apply on all parts.

8. Assignment # 01 Mould Design for Injection Moulding
Department of Polymer Engineering [National Textile University, Faisalabad] Page 8
Main SectionalView:
The complete basic tool design, the main cross sectional view is as shown in
fig given below. In center there is sprue bushing and two impressions are shown in fig. lower is ejection
or moving plate onto which ejection sleeves, ejection plate and ejection pins are attached. On left there
is guiding pillar which control the movement. On injection plate gate is present which fills the part.
References:-
Injection Mold DesignEngineering The Mould DesignGuide
by David O.Kazmer by Peter Jones