Bulk Moulding Compound (BMC) and Continuous Impregnated Compound (CIC) is usually injection moulded. But also other compounds such as Sheet Moulding Compound (SMC) and are often moulded in a tool / injection moulding machine under injection moulding.
Injection moulding is used predominantly to manufacture thermoplastic parts, and it can produce very complex parts very quickly. Also thermoset materials such as BMC and CIC are widely used to produce small electrical devices such as switch gears or most of the headlamp reflectors of cars and trucks.
The mould usually comprises two sections held together by a clamp strong enough to withstand the pressure of injected material, with channels for heating.
The BMC or CIC is filled into the compaction unit of the injection moulding machine and fed into the tool by a screw. Speed or pressure determines the part quality regarding mechanical properties or surface quality. The less force is applied the higher the mechanical properties will be – the faster the injection occurs the better the surface will appear.
Used for high volume | Easier automation | Lower mech. Propertiers vs. compression moulding SMCInjection moulding of BMC and CIC is a perfect way to fully automate the production process of large volume series of parts. The machine and its peripheral devices can handle material feed, moulding, de-moulding and often post-moulding operations easily.
Use always the same process parameters.
Make sure every cycle is identical in time (from placement of charge to mould close) and process parameters. Maintain uniform mould surface temperature +-2°C.
Make the part come off easy at de-moulding. If this is not the case please check for ejector pins and undercuts. Check parallelism of ejector plate too.
Take off the part carefully and place part in cooling fixture to cool down in well defined position (nominal part contour, no clamping) and shape.
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