The transfer molding process is similar to compression molding to instead of pressurized in mold cavity, the pressurized mold is separated and it is used for thermosetting plastics. In this process the charge(preform) is pressurized or forced and after pass to molding. The complex part can be produced in this transfer molding machine.
The Transfer Molding Machine Configuration:
In transfer molding machine having the main part of cylinder, plunger(or) Ram, sprue, heater, mold cavity, ejector pin. The cylinder part is used to store the charge and pre heated by heater. The plunger to compressed(or) pressurized the charge and pass to the mold die through sprue. The cylinder is connected to the mold cavity through sprue. The ejector pin is mounted in lower part of mold. In this ejector pin is used to eject the part after molding process completed.
The schematic diagram of that molding process
Working of transfer molding process:
First the plastic charge (or) preform stored in the cylinder. The plunger is down together. And charge heated by heater. Now the plastic is start the cross link formation in this molecules. The plunger is continuously compressed (or) pushed the plastic into mold die. Through sprue with high pressure.
Now the plastics metal is injected to the mold die through sprue with high temperature and acclerate the cross-linking reaction. The pressure is continued, the plastic go to require mold cavity and ejected from mold closed after curing process completed. It is usually used to produce Electrical component where high heat stability to allowed.
Transfer Molding Process Parts Produced:
In this transfer molding process used for following product can be produced,
Common advantages of transfer molding machine for produce part,
- Lower molding pressure required compare to compression molding.
- To use multi cavity are easier.
- Part have gates, the engineering a flow path is possible.
Some Disadvantages of produce the product by this method,
- The mold is more complex
- Plastic flow induced and orientation problems.
- The good housekeeping is difficult.