The processing steps of the white pmma abs sheet
With the development of society, people who know about the white pmma abs sheetknow that it has a wide range of applications and even has been involved in all aspects of our; at the same time, the white pmma abs sheet also has a very strong comprehensive performance, below I will take you to understand the processing steps of white pmma abs sheet, I hope to share the content of help.
1. Drying of white pmma abs sheet.White pmma abs sheet moisture absorption and moisture sensitivity are greater, so before processing, the need for adequate drying and preheating, so not only can eliminate water vapour caused by the surface parts of the fireworks-like bubble and silver wire but also help plastic plasticizing reducing the surface of parts and more spots. White pmma abs sheet raw materials to control moisture below 013%, because the existence of trace water vapour resulting in parts surface fog spot is often ignored as a problem, so it is best to change the machine hopper into a hot air hopper dryer to avoid dry abs plastic in the hopper again moisture absorption;
2. Injection temperature. The relationship between temperature and melt viscosity of white pmma abs sheets differs from other amorphous plastics. When the melting temperature increases, its melting reduces very little, but once it reaches the plasticizing temperature, if it continues to raise the temperature blindly, it will certainly lead to the heat degradation of the white pmma abs sheet, which is not too high in heat resistance but increases the melting viscosity instead, this made injection moulding more difficult. The mechanical properties of the parts decreased. Some poor temperature control of injection moulding machine, when the production of ABS plastic to a certain amount, often found in the parts embedded with yellow or brown coke particles, and it is difficult to use new materials such as injection into the air to eliminate its discharge;
3. Push pressure. Not all white pmma abs sheets apply high pressure. Small, simple structures, the thickness of large parts can be used with lower injection pressure. In injection moulding, the surface quality and the degree of silver filamentous defects are often determined by the pressure in the cavity at the moment of gate sealing. The pressure is too small, plastic shrinkage, and the cavity surface is out of contact with the opportunity of large parts surface atomization. The pressure is too big, the plastic and the cavity surface friction effect is strong, easy to cause the sticky mould;
4. Injection rate. In the production of the plate, or to ensure that there is a high enough injection speed, otherwise, it isn't easy to fill;
5. Mold temperature. ABS moulding temperature is relatively high, and mould temperature is relatively high. In the injection of a larger, complex plate configuration, the mould should be considered special heating. To shorten the production cycle and keep the relative stability of the mould temperature after the parts are taken out, the cold-water bath, hot-water bath or another mechanical shaping method can be used to compensate for the time of cold fixing in the cavity
6. Material Control. When a white pmma abs sheet is injected into a general injection moulding machine, the injection amount is only 75% of the standard injection amount each time; to improve the quality and dimensional stability of the parts, the surface gloss and colour uniformity, it is advisable to require the injection amount to be 50% of the calibrated injection amount.
To sum up, this is all the processing steps of the white pmma abs sheet, and I hope to help with your purchase.