Choosing a BMC Vertical Injection Molding Machine

What is BMC?

BMC (also called DMC), or bulk molding compound, is an unsaturated polyester dough-like premix made from chopped glass fiber (GF), unsaturated polyester resin (UP), mineral filler (MD) and various additives. It offers excellent electrical and mechanical properties, heat resistance and chemical resistance, and suits a range of molding processes.

Compression press vs. automatic-feed injection

BMC parts are usually made either on a hydraulic compression press or on an automatic-feed BMC injection machine. On a press, material is weighed and loaded by hand for every shot — dirty, tiring, hot work, and BMC causes skin irritation on contact.

An automatic-feed BMC injection machine is particularly suited to BMC parts with inserts or parts requiring high hardness. Its hopper takes 15 kg of material at a time and the machine doses each shot automatically according to the controller settings, so it can run continuously like a standard injection machine — typically needing only two or three refills a day.

Advantages

• Automation replaces manual weighing and loading, greatly increasing productivity.
• Lower material and labor costs, with better quality and yield.
• The injection system can be matched to the strength required: automatic-feed plunger type, automatic-feed screw type, or screw-plunger compound type — reducing glass-fiber breakage to maintain part strength.
• A cleaner, less physically demanding job helps manufacturers attract and keep workers.