Stripper mould

A stripper mould is very similar to the standard two-plate mould except for the ejection system. This design has a stripper plate for ejection, whereas the standard one has pins or sleeve as the ejectors. This is illustrated in Figure 4.2. The advantage of a stripper plate is the increased surface area for ejection that it offers. 

PRESS OPEN STRIPPER BACK MOULDING FALLING... 

Figure 8.12. Typical process for the compression moulding of thermosetting plastics, (a) Load, (b) Mould, (c) Eject, stripper in. (d) (After Groves )...

Figure 5.24 Plan and elevation of a t wo-plate mould with twin cavities. The plan shows the moulding projected area. Alternative methods for ejecting a cup moulding are shown the stripper ring and air vent are for very thin moulding.

String Dryer. A tunnel-type dryer, particularly for building bricks, that is operated intermittently in the early stages of drying, the exits and exhaust ducts are closed so that a high humidity is built up. This type of dryer has been used particularly in Texas, USA. Stripper. A person employed in the pottery industry to remove the dried ware from the plaster moulds. 

Ejectors leave witness marks on mouldings, and hence it is preferable that they operate on sidewalls, ribs, or bosses. They should have sufficient diameters. A stripper plate acts on the entire wall of a part and so distributes the ejection force. Cylindrical ejector pins are most commonly used, although in constricted areas rectangular pins or blade ejectors can be used. For thin-walled articles, air-assisted ejection can be used. 

Standard system for small parts During opening stroke in direction of demoulding. Ejeetion with pins, sleeves or stripper plate Various mechanical, hydraulic, pneumatic, manual, machine stop, lifting cylinder, cam, pivot, inclined plane, thrust plate Mouldings without undercuts... 

Direction of ejection towards movable side, stripping is used but usually for circular parts only During opening stroke pull in direetion of demoulding, ejeetion with stripper plate Mechanical, hydraulic, pneumatic, stripper bolt, lifting cylinder, pin-link chain Cup-like mouldings wiA internal gate... 

Demoulding of parts with local undercuts (slide mould) During opening stroke thrust in direetion of demoulding, ejection with pins, sleeves or stripper plate after release of undercut Mechanical, cam pins, slide mechanism Flat parts with external undercuts (threads)... 

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