Causes of defective defects in the optical disc injection molding process, and solutions In the production of optical discs, some discs with poor injection molding often appear. The stationmaster has accumulated the following defects through years of accumulation:
Injection molding dissatisfaction, depression, fusion joint, flow pattern, poor gloss, pores, black spots, overflow, warping deformation, silver, poor mold release, cloud, rough punching, horseshoe shape, small center hole, center hole Large, the substrate is too thick, the substrate is too thin, the birefringence is large, the birefringence is small, the substrate is broken, the flow path is broken, the radial stripe, the disc groove, the halo, the streamline, etc.
Causes of the above defects: mold temperature, punching knife, runner temperature, injection speed, injection pressure, holding pressure, holding time, switching point, clamping force, cooling time, barrel temperature, plasticizing time, plasticizing speed, Back pressure, etc.
Product defects and causes of elimination
â– Bubbles due to the presence of moisture
Cause: The dryness of the pellets is insufficient to cause hydrolysis of the resin.
Treatment method: Fully pre-drying, pay attention to the insulation management of the hopper
â– Vacuum bubble
Cause: The flow in the thick wall is rapidly frozen, the shrinkage is prevented, and the filling is insufficient, resulting in internal vacuum bubbles. The mold temperature is not suitable. The barrel temperature is not suitable. Injection pressure and holding pressure are insufficient.
The treatment method avoids the design of uneven wall thickness structures. Correct the gate position so that the flow material is injected vertically into the thick wall. Increase the mold temperature. Reduce the barrel temperature. Increase injection pressure and holding pressure.
â– Fusion marks
Cause: The temperature of the mold barrel is not suitable. Injection pressure is not suitable. The mold temperature is not disturbed. There is no vent hole in the cavity.
Treatment method: increase the temperature of the barrel. Increase the injection pressure. Increase the mold temperature. Set the vent hole.
â– Dent
Cause: Dent marks due to shrinkage of the thick-walled inner surface with slow cooling rate (unreasonable wall thickness design). Injection pressure is not enough. The amount of injection is not enough. The mold temperature is too high or the cooling after injection is not enough. Insufficient pressure. The gate size is not reasonable. Avoid uneven wall thickness.
Treatment method: increase the injection pressure. Increase the amount of injection. If the mold temperature is reasonable, it is necessary to lengthen the cooling time. The Director held down the time. Magnify the gate size, especially its thickness.
â– Paste (all or part of the color change)
Cause: The barrel temperature setting is not reasonable. Partial storage occurs in the barrel. The resin intrudes into the joint of the barrel and the nozzle (long-term storage). With backflow valve or backflow ring. Hydrolysis due to insufficient drying. The capacity of the injection molding machine is too large.
Treatment: Reduce the barrel temperature. Avoid dead angle structures. Try to eliminate the gap in the joint. Avoid using backflow valves and backflow rings. Pre-drying according to the specified conditions. Choose an injection molding machine of the right capacity.
â– Silver
Cause: The barrel temperature is not suitable. The residence time of the flow material is too long. Injection speed is not suitable. The gate size is not reasonable. The dryness of the pellets is not sufficient. Injection pressure is not suitable.
Treatment: Reduce the barrel temperature. Eliminate the phenomenon of stocking. Reduce the injection speed. Zoom in on the gate size. Pre-drying according to the specified conditions. Reduce injection pressure.
â– ripples at the gate (opaque)
Cause: The injection speed is not suitable. The holding time is not suitable. The mold temperature is not reasonable. The gate size is not reasonable.
Treatment method: increase the injection speed. Shorten the holding time so that there is no more melt injection after filling. Increase the mold temperature. Zoom in on the gate size.
â– Swirling and wave flow marks
Cause: The mold temperature is not suitable. Injection pressure is not suitable. The gate size is not reasonable.
Treatment method: increase the mold temperature. Reduce injection pressure. Expand the gate size.
â– Ejection failure (mold release failure)
Cause: The slope of the core or cavity is not sufficient. The cycle time is not suitable. The barrel temperature is not suitable. The position or number of ejector pins is not reasonable. A vacuum is formed between the core and the finished product. The mold temperature is not suitable. The injection pressure is too high and the amount of filling material is too large.
Treatment: Ensure proper drafting. Cooling time is too short or too long. Reduce the temperature to the appropriate molding temperature value. Reasonable design of the position and number of ejector pins. This phenomenon is particularly likely to occur when the core is very smooth. It is possible to try to replace the ejector structure with a top plate structure and to provide a curved ejector structure. Reduce mold temperature and cycle time. Reduce injection pressure and reduce raw material metering.
â– Embrittlement of molded products
Cause: Dryness is not enough. The mold temperature is too low, and the injection pressure and holding pressure are too high. Internal stress caused by uneven wall thickness and poor mold release. Gap effect. Superheated degradation. Incorporation of impurities.
Treatment: Pay attention to the management of the dryer and the hopper. Choose from a variety of suitable conditions. Eliminate uneven wall thickness to eliminate sharp corners and correct gate position. Reduce the barrel temperature. Clean the hopper and barrel.
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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Product
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Length(mm)
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PP ROD
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0.92
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