What is compression moulding?
Compression moulding is a traditional method which relies on heat and pressure to mould thermoset plastic materials. Broanmain Plastics has over 60 years’ experience in compression moulding and operates a range of DST, injection, transfer and compression moulding machines, including Bipel, Daniels, Bradley & Turton and Sumitomo Demag (ranging from 25 to 250 tons).
Bulk Moulding Compound (BMC)
Bulk Moulding Compound (BMC), also called Dough Moulding Compound (DMC), is a polyester ‘dough’ material which is manually put into the tool in premeasured amounts. Using pressure, it is then forced into the cavities when the tool is shut. The mould is also heated, and the heat and pressure is maintained until the material is cured.
Sheet Moulding Compound (SMC)
The Sheet Moulding Compound (SMC) is a similar material to BMC, however, it is made into a sheet form before the plastic compression moulding process occurs. In some cases, reinforcing materials, such as glass fibres, are added and it is cut to size prior to moulding.
Advantages of compression moulding
The advantages of compression moulding comes down to its cost-effectiveness. However, there are a number of other benefits to plastic compression moulding, and these include:
- A high heat stability
- A high electrical resistance
- Able to have thicker sections
- Able to use old/existing tooling
What is transfer moulding?
Transfer moulding, although closely related to compression moulding, differs from it in that the mould is closed up and the material inserted before the moulding process takes place. The material is preheated, loaded into the moulding pot and pressure is applied to force the material into the mould cavities. The mould is then held closed until the plastic has cured.
Advantages of transfer moulding
There are several benefits to transfer moulding, and these include:
- Short production cycle
- Allows for more intricate parts
- Lends itself to moulding with inserts
Transfer & compression moulding vs. injection moulding
Moulding through compression and transfer is a process for the moulding of thermosets. They differ from injection moulding in that the mould is heated to form the part rather than cooled to solidify the part, as is the case when moulding through injection.
Transfer & compression moulding products
Broanmain is experienced in all types of thermosetting polymers. As transfer and compression moulders, Broanmain is able to manufacture a variety of different products, including electrical fittings, aerospace components, switches and valves.
Transfer & compression moulding machines
Our Bipel, Bradley & Turton and Daniels compression moulding machines range from 25 to 150 tons and are equipped with vacuum moulding systems.