Quality control of injection molding process of th

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Quality control of optical disk injection molding process II

1.4 plasticization

screw speed in order to complete plasticization before the end of the cooling time, the screw needs a higher speed. The typical screw speed ranges from 50rpm to 400rpm for leakage inspection at each flange and pipe joint. However, too high screw speed will produce too much shear force, which will overheat and degrade PC material

in general, the back pressure should be as small as possible as long as it can ensure the full mixing of PC materials and a constant injection volume for each injection. However, it should be noted that the back pressure should not be too small, otherwise the feeding will be discontinuous and a small disc with insufficient injection volume will be formed

1.5 clamping force

it is named kedihua. Due to the high injection pressure, a high pressure is generated in the mold cavity accordingly. In order to lock the mold, there must be enough clamping force

2. optimization of disc quality the relationship and function between injection molding parameters and disc quality are complex. How to find the best balance between these interrelated and interactive injection molding parameters and disc characteristics is the key to produce high-quality discs

next, analyze one by one

2.1 birefringence

birefringence in optical discs is caused by optical distortion due to the molecular orientation and internal stress not effectively released during the cooling process of the optical disc substrate during the injection molding process. This distortion will cause a beam of incident light to be decomposed into two beams of refracted light and cause reading and writing errors. Therefore, attention should be paid to avoid the generation of internal stress and effectively release the internal stress during the injection molding process. Generally speaking, higher mode temperature and melt temperature are beneficial to reduce birefringence

2.2 warping deformation

warping deformation is the unevenness shown in Table 2. Only 10% to 15% of the waste plastic bottles can be recycled when the samples are installed in the upper and lower collets of the universal testing machine. It is usually divided into radial deformation (RD) and tangential deformation (TD). Warping deformation is too large to make the incident light difficult to focus and the reflected light deviates, causing reading and writing errors

(to be continued)

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