Compression Moulding Flashcards
Compression moulding
Compression Moulding is the method of moulding in which the moulding material which is generally preheated is first placed in an open heated mould cavity. The mould is closed with a top force then pressure is applied to force the material into contact with all mould areas while heat and pressure is maintained until the moulding material has cured. The process uses thermosetting resins in a partially cured stage either in the form of granules or preforms.
The Moulds used
The three types of moulds used are the;
flash plunger-type
straight plunger-type and the “landed” plunger-type moulds.
The compression moulds process
The compression moulding starts with an allotted amount of plastic or gelatin placed over or inserted into a mould. Afterwards the material is heated to a flexible state in the mould. Then after the hydraulic press compresses the flexible plastic against the mould it resulting in a perfectly moulded piece, retaining the shape of the inside surface of the mould. After the hydraulic press releases an ejector pin in the bottom of the mould quickly ejects the finished piece out of the mould and then the process is finished. Depending on the type of plunger used in the press there will or won’t be excess material on the mould.
Process
Compression moulding is a forming process in which a plastic material is placed directly into a heated metal mould then is softened by the heat and forced to take the shape of the mould as the mould closes.
