Infrastructure & Services

Polycarbonates are a group of thermoplastic polymers containing carbonate groups in their chemical structures.

Polycarbonates used in engineering are strong, tough materials and some grades are optically transparent. They are easily worked, moulded and thermoformed.

Properties of PC:

• Highly impact resistant at least 250 times stronger than glass.
• Light Transmittance.
• Easy to shape
• Suitable for intensive use.
• Resistance to high temperatures
• Bondable
• Easy to process
• Unbreakable and non-flammable

Modular Switches SP CARB PC grades compounds consist of high gloss, spark shield inside them to conceal high sparking and avoiding any damage or short circuiting due to leakage of current, insulation resistance, shock proof and easy to remove or refit and of the same brand as that of a modular switch.

PC PROCESSING

• MELT TEMPERATURE is 270 to 300 deg C
• INJECTION SPEED: Relatively fast injection moulding, such as parts of electric switches, is usually adopted.

The injection molding usually shows a slow to high-speed pattern.

PC has a high water absorption rate, so it has to be preheated and dried before processing. It is recommended that the pure PC is dried at 120 deg C for 3 hours.

Usually an empty shot is performed to see whether it is sufficiently dried.

The proportion of Recycled PC can reach upto 20%.Under some circumstances 100% recycled material is allowed with the actual proportion depending on the product quality requirements.

The recycled material cannot be concurrently mixed with different masterbatches otherwise the properties of the final product will be seriously compromised.

Mold and Gate Design

• The commonly used mold temperature is 80 deg C to 100 deg C for PC and 100 deg c to 130 deg C for reinforced PC.
• The pinpoint gate is usually used for small sized products and gate depth should be more than 70% of the thickest part.
• Other gate types include ring gate and rectangle gate.
• The larger the gate, the better so as to minimize defects caused by excessive plastic shearing.
• The depth of vent holes should be less than 0.03 to 0.06 mm, the runner should be designed as short and round as possible and the draft angle usually stands at around 30’ – 1 deg.

BACK PRESSURE

The back pressure of about 10 bar is recommended which can be appropriately reduced when there are no jetting marks or color mixing.

RESIDENCE TIME

• If the residence time at a higher temperature is too long, the material will be degraded with CO2 released and color turning into yellow.
• Use PS instead of LDPE, POM, ABS, PA to clean the barrel.