FAQ

What is the difference between BMC and SMC?

SMC is a sheet with longer fibers that is compression molded into larger, stronger parts. BMC is a dough with shorter fibers that flows further and is injection or compression molded into smaller, more detailed parts.

Do you supply both the mold and the parts?

Yes. We design and build the mold and supply the molded parts, so the tool, the trial samples and the production parts are handled by the same project engineer.

What files do you need for a quotation?

A 3D model (STEP or IGES), a 2D drawing with tolerances, the material or performance requirements, the expected annual volume and any surface, color or flame-rating requirements.

Can you review my design before quoting?

Yes. We review the part for BMC or SMC molding and suggest changes to wall thickness, ribs, draft and features before the mold is designed.

Which process should I use for my part?

It depends on size, wall thickness, detail, strength and volume. Large panels and enclosures are usually SMC compression molded; small, detailed parts in volume are usually BMC injection molded.

What happens at sample approval?

After the mold trial you receive sample parts with a dimensional inspection report against your drawing. You approve the samples, or the mold is corrected and new samples are sent, before production starts.

What mold temperature do BMC and SMC need?

Typically about 140–180 °C, depending on the process and the compound. The exact setting is fixed during mold trials.

Are BMC and SMC parts heat resistant?

Yes. As cured thermosets they do not melt and keep their shape at temperatures where many thermoplastics soften, which is why they are used near lamps, motors and electrical contacts.

Can the parts meet flame-retardant requirements?

Flame retardant grades are available, for example grades rated UL 94 V-0 at a stated thickness. We select the grade to match your requirement.

Can you mold in metal inserts?

Yes. Threaded bushings, studs and other metal inserts can be molded in, or added after molding by press-fitting or bonding.

Can the parts be painted?

Yes. SMC and BMC parts can be primed and painted. Molded-in color is also possible with pigmented grades.

How do you ship molds and parts?

Molds are protected against rust and packed in wooden crates; parts are packed to your specification for sea, air or express shipment.

Where are you located?

China United Mould has plants in Huizhou and Dongguan, Guangdong, China.