Injection processing products cracking reason

Date：2015-04-07 10:21:25

1. Processing angle:

(1) The working pressure is too large, too fast, the more filling material, injection, dwell time is too long, too much stress can cause cracking.

(2) adjust the mold to prevent the rapid speed with the pressure caused by the strong pull parts stripping cracking.

(3) due to increase mold temperature, so easy to stripping parts, lowering the material temperature to prevent decomposition.

(4) prevention as weld lines, plastic degradation caused by low mechanical strength and cracking.

(5) the proper use of mold release agents, attention is often attached to the mold surface to eliminate aerosol and other substances.

(6) parts of residual stress, can be carried out immediately after the molding by annealing to eliminate stress and reduce the formation of cracks.

2. Mold angle:

(1) To the top of the balance, such as the number of rams, cross-sectional area should be sufficient, stripping slope should be enough, the cavity surface should be smooth enough, so that it leads to the top of the external force to stop because of residual stress concentration and cracking.

(2) parts structure can not be too thin, the transition should try to adopt some of the arc transition, avoid sharp corners, chamfers cause stress concentration.

(3) minimize the use of metal inserts to prevent the insert parts with different shrinkage caused by stress expand.

(4) of the deep-bottom article should be set appropriately releasing air intake path, preventing the formation of vacuum.

(5) the sprue gate is expected to be large enough to have time to solidify when stripping, so easy to mold.

(6) engages with the nozzle sprue bushing should stop dragging leaving chilled material stuck to the fixed mold parts.

3. Material angle:

(1) recycled material content is too high, resulting in low strength parts.

(2) the humidity is too large, resulting in the emergence of some of the top of the plastic cracking react with moisture, reduce strength.

(3) the material itself is not suitable for the processing of the environment or of poor quality, are infected can cause cracking.

Not the same as the injection mold has different requirements, summed up the mold plastic mold steel performance requirements mainly reflected in: hardness, polishing, etching properties, weldability, wear resistance, toughness, dimensional stability, corrosion resistance and so on.

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