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A three plate mould has two parting planes and the mould splits into three sections,
providing flexibility in gating location and be placed anywhere along part surface.
Insert Mould : an over-mould to mould plastic around other materials, such as
metals or even other plastic inserts, such as sleeves for drill housings, screw drivers,
handles, electrical plugs, others
2-Shot Moulds (also 3-Shot and 4-Shot Moulds) : a cost-effective way to produce
parts with 2 or more colors moulded at the same time; eliminates a secondary
process to add logos, graphics or text
Stack Moulds : high production moulds for multiple parting lines; can produce
multiple parts more economically over a large production run
Unscrewing Moulds- to produce parts with internal or external threads, such as
nuts, nut augers, sprinkler heads
Other types of Injection moulds are Stripper Ejector Mould, Split Cavity Mould
and Slide mould.
The runner is situated in the mould and is heated to keep temperature above the
melting point of the plastic. This provide for very less or No scrap, so No wastage or
regrind. Hot runners moulds are popular in high multi cavities moulds. A major
disadvantage of a hot runner is that it is much more expensive, requires costly
maintenance and more skill to operate.
Hot Runner Moulds: Injection moulds in which the runners are kept hot and
insulated from the chilled cavities. Plastic freeze off occurs at gate of cavity while
runners are in a separate plate and are not ejected with the piece. A hot runner
system is divided into two parts: the manifold and the drops. The manifold has
channels that convey the plastic on a single plane, parallel to the parting line, to a
point above the cavity. The drops, situated perpendicular to the manifold, convey the
plastic from the manifold to the part. They are very popular in high production moulds
with lot of cavities.
Types of Hot Runner Moulds: In the externally heated type, molten plastic runs
within a solid manifold and within the nozzles. In the internally heated, (now
obsolete) the plastic flows directly over slender heaters inside oversized runners.
Externally heated hot runner channels have the lowest pressure drop of any runner
system, are better for colour changes and provide consistent plastic melt in the
runner system. There are no places for material to hang up and degrade, so are good
for thermally sensitive materials. Hot runners mould are expensive but provide
savings by reducing plastic waste and cycle time.
HOT RUNNER
Advantages Disadvantages
No runners to remove or regrind Leakage
Reduces the possibility of contamination Heating element failure
Lower injection pressures Complex initial setup
Lower clamping pressure Breakdowns
Shorter cooling time Higher initial start-up costs
Shot size reduced More complex and expensive

DAVE TECHNICAL SERVICES 101