1. GENERAL MOULD CONSTRUCTION CONCEPT
PDT317-INJECTION MOLD DESIGN
GENERAL MOULD CONSTRUCTION CONCEPT
PREPARED BY: EN. SHAYFULL ZAMREE BIN ABD RAHIM
( )

2. PDT317-INJECTION MOLD DESIGN COURSE CONTENT & COURSE OUTCOMES
3-5
CHAPTER 2: General Mould Construction Concept
EXPLAIN material in fabricate mould, types of gates, runner and venting; EXPLAIN and DESCRIBE the design of lifter, side pull, parting line, insert mould base size, engraving and texturing process.
CO1: Ability to define and describe basic terminology process in plastic injection molding and mould design.

3. PDT317-INJECTION MOLD DESIGN
Mould Structure
9. Ejector Plate (Knockout bar)
Bolted together with the ejector retainer
plate to form a unit. Acts as a
backup plate for the pins in the ejector
retainer plate.
10. Spacer Buttons
Pressed into the bottom clamping plate,
they are land for ejector pin.
1.Top Clamping Plate
Holds the stationary part of the mold to
the stationary platen of the
injection machine.
11. Pillars
Round bars placed between the support
plate and the bottom clamping
plate, the same height as the parallels.
Bolted to the bottom clamping
plate, they are used as additional support
for the core retainer plate.
2. Locating Ring or Sprue Bushing Retainer Ring
Fits into a counter bore in the top
clamping plate and is used to locate the
mold on the platen of the press so the
nozzle and sprue bushing are
aligned.
12. Sprue Bushing
Butted up against the nozzle of the
injection machine. Has a conicalshape
hole through which the material is forced
into the mold runner.
3. Cavity Retainer Plate
Part of the stationary section of the mold
into which the leader or guide
pins are mounted. Also used to hold
core, cavity blocks and sprue
bushing.
13. Sprue Puller Pin
Pin located directly under the opening of
the sprue. Used to pull the
molded sprue out of the bushing after a
shot has been made.
4. Core Retainer Plate
Top plate of the moveable section of the
mold. Forms the parting line of
the mold with cavity retainer plate. Used
to hold the leader pin bushings
as well as core and cavity blocks.
14. Return Pins (ejector return pins, safety pins, push backs, etc.)
Located in the ejector retainer plate.
Force the ejector plate and the ejector
retainer plate, and therefore the ejector
pins to the bottom position as the
mold closes.
5. Support Plate
Mounted behind the core retainer plate to
keep this plate from bending
under the high pressure used in injection
molding.
6. Bottom Clamping Plate
Hold the moving portion of the mold to the
moveable platen of the injection machine.
15. Leader Pins (guide Pins)
Hardened and ground steel pins pressed
into one of the plates. Align the
two halves of the mold base.
7. Parallels (Rails)
Mounted on the bottom clamping plate
under the support plate to form a
space which allows the ejector bar to
move when the piece parts ejected.
16. Bushings
Hardened and ground steel bushings which are pressed into
one of the plates, serve as bearing surfaces for the leader
pins. (Some injection mold bases are manufactured with the
parallels welded to the bottom clamp plate. The unit thus
formed is called the Ejector Housing).
8. Ejector Retainer Plate (Knockout pin plate)
Counter bored for the heads of the ejector pins,
ejector return pins and sprue pillar pin.

4. PDT317-INJECTION MOLD DESIGN
TYPE OF GATES
1. Direct or Sprue gate
Direct or sprue gate may be used with single cavity molds where the sprue feeds material directly into the cavity. Cold slug must be providing opposite the sprue gate if possible.
This type of gate is recommended for single cavity molds or for parts requiring symmetrical filling.
This type of gate is suitable for thick sections because holding pressure is more effective. A short sprue is favored, enabling rapid mold filling and low-pressure losses.
The disadvantage of using this type of gate is the gate mark left on the part surface after the runner (or sprue) is trimmed off.

5. PDT317-INJECTION MOLD DESIGN
TYPE OF GATES (Cont…)
2. Pin Point Gate
Pin gate actually are small gates located on the parting line that keep blemishes to a minimum. They are especially popular for automatic de-gating in three plate molds because it must be ejected separately from the part in the opposite direction. The gate must be weak enough to break off without damaging the part.
This type of gate is most suitable for use with thin sections. The design is particularly useful when multiple gates per part are needed to assure symmetric filling to all areas of the part.

6. PDT317-INJECTION MOLD DESIGN
TYPE OF GATES (Cont…)
3. Sub-marine Gate
A submarine gate is used in two-plate mold construction. An angled, tapered tunnel is machined from the end of the runner to the core, just below the parting line. As the parts and runners are ejected, the gate is sheared at the part.
A submarine gate is often located into the side of an ejector pin on the non-visible side of the part when appearance is important. To de-gate, the tunnel requires a good taper and must be free to bend. To reduce pressure loss and prevent pre-mature gate freeze-off, the sub-marine gates should be as short as possible. A sharp angle should range between 20° to 30°, with a 60° angle from the runner.

7. PDT317-INJECTION MOLD DESIGN
TYPE OF GATES (Cont…)
4. Ring or Diaphragm Gate
The diaphragm or disc gate are suggested to be used for a cylindrical parts that required good concentricity and the elimination of weld lines (for high strength).

8. PDT317-INJECTION MOLD DESIGN
TYPE OF GATES (Cont…)
5. Edge Gate
Edge gate is the most commonly used type of gate.
Edge gate, both rectangular or round, must be large enough to avoid frictional burning. The edge or side gate is suitable for medium and thick sections and can be used on multi cavity two plate molds.
The gate is located on the parting line and the part fills from the side, top or bottom of the molded part.

9. PDT317-INJECTION MOLD DESIGN
TYPE OF GATES (Cont…)
6. Fan Gate
For the flat mold sections, a modified fan gate may be used that minimizes jetting and significantly reduces the high stresses that occur during mold packing.
Fan gate can be balanced so that they distribute the melt evenly across the land before the melt enters the mold cavity.

10. PDT317-INJECTION MOLD DESIGN
TYPE OF GATES (Cont…)
7. Tab Gate
Tab gate provide a uniform melt orientation, when an application requires a large volume for mold filling. The tab gate help to reduce the effect of residual stress, gate blush and jetting in the gate area.
They are used where flatness is critical or in large surface areas that may have a tendency to warp.

11. PDT317-INJECTION MOLD DESIGN
TYPE OF GATES (Cont…)
8. Flash Gate
A flash gate is a variation of a fan gate. It is used to minimize warping in flat or very large parts. Flash gate extend across a part from 0.38mm (0.015”) to 0.78mm (0.030”) deep and have a chisel taper across the gate land length.

12. Machine Used in Mould Making
PDT317-INJECTION MOLD DESIGN
Machine Used in Mould Making
CNC Machine
Control Panel of CNC Machine

13. Machine Used in Mould Making
PDT317-INJECTION MOLD DESIGN
Machine Used in Mould Making
CNC Machine machining
the copper to EDM core
and cavity insert
Manual polishing for final finishing

14. Machine Used in Mould Making
PDT317-INJECTION MOLD DESIGN
Machine Used in Mould Making
EDM-Wirecut Machine used to wirecut
sub-insert and ejector pin hole

15. PDT317-INJECTION MOLD DESIGN
Mould Components
Sub-insert produced by EDM-Wirecuting
process

16. Machine Used in Mould Making
PDT317-INJECTION MOLD DESIGN
Machine Used in Mould Making
EDM-Die Sinking Machine
EDM the locating ring of the mold

17. PDT317-INJECTION MOLD DESIGN Machine Used in Mould Making
Grinding Machine
Grinding Wheels

18. PDT317-INJECTION MOLD DESIGN Machine Used in Mould Making
Milling Machine
Drilling Machine

19. Plastic Injection Mould
PDT317-INJECTION MOLD DESIGN
Plastic Injection Mould
Mold with complete assembly