1.Thirteen problems should be paid attention to in PMMA material forming and processing
2. Equipment selection: according to the weight, shape and cycle of the product, select the appropriate injection quantity and mold locking force equipment, such as excessive injection margin and long cycle will affect the product quality.
3. Screw selection: the screw with small heat generation and good plasticity shall be selected. The surface finish of the screw is required to be good for processing PMMA material, and there is no dead angle and wear at the place where the plastic melt flows. For example: transparent lens with barrier function structure can enhance the plasticizing effect. For tinted lenses, pin type screw or pin type rubber head are used to enhance mixing effect.
4. Nozzle selection: adopt open structure, nozzle hole is relatively large, the length should be short rather than long.
5. Material drying: if the circulating hot air drying is adopted, the PMMA aggregate surface is easy to soften and adhere, and agglomerates at the lower part of the hopper, resulting in the difficulty of blanking. It should be noted that the temperature should not be too high and the air volume should be sufficient.
6. Material processing: do not stay in the barrel for too long, stop operation for a long time, and reduce the barrel temperature to below 170 ℃ to avoid melt degradation. Reply to "PMMA" for more articles
7. Nozzle material: the process of taking out, crushing, packaging, storage and mixing of nozzle material shall be strictly controlled to avoid mixing of miscellaneous materials and dust. The proportion of new and old materials depends on the products.
8. Mold cleaning: clean the scale on the surface of mold cavity regularly, and clean up when the finish of products is not enough.
9. Mold gate, runner design: in line with the principle of less shear, smooth flow. Use larger runner and gate sizes. Good exhaust performance, reasonable opening of exhaust holes and exhaust slots.
10. Mold cavity demouldingslope design: in order to ensure the smooth demoulding of parts during forming, the demoulding slope must be set in the demoulding direction during design.
