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Note model to shape all sorts of blemish and means of settlement
From;    Author:Stand originally


One, chap

Chap is a kind of blemish with plastic more familiar products, because stress is out of shape,the main reason of generation is be caused by. The stress that basically has leftover stress, exterior stress and generation of external environment place is out of shape.

(- ) the chap that leftover stress causes

Leftover stress is main as a result of the following 3 kinds of circumstances, fill up superfluous, drawing of patterns rolls out what set insert to cause with the metal namely. As in the chap that fills up superfluous circumstance leaves generation, its means of settlement basically can be in proceed with of the following respects:

(1) because loss of straight runner pressure is the smallest, so, if chap is the mainest,generation is near straight runner, can consider to convert runner of much distributinging dot, side runner and means of handle form runner.

(2) in make sure colophony is not decomposed, not below the premise of deterioration, raise colophony temperature to be able to reduce melt viscosity appropriately, increase liquidity, also can reduce inject pressure at the same time, in order to reduce stress.

(3) usually, the model is lukewarm inferior when easy generation stress, answer to raise temperature appropriately. But should inject when rate is higher, although the model is lukewarm a few lower, also but the generation of bring down stress.

(4) inject and dwell time grow to also can produce stress too, shorten its appropriately or undertake Th second protect it is better to press switch effect.

(5) colophony of blame crystallization sex, the colophony that be like AS, ABS colophony, PMMA colophony more crystal sexual colophony if the easy generation such as polyethylene, polyformaldehyde is leftover stress, should give attention.

When drawing of patterns is rolled out, as a result of rake of drawing of patterns small, mould glue reachs punch coarse, make roll out force too big, generation stress, be in even sometimes roll out Bai Hua or burst phenomenon produce all round lever. Want to observe the position that chap produces carefully only, can determine a cause.

Built-in while inject shapes metal when, produce stress the most easily, and just produce chap easily after passing period of time, the harm is great. Because metal and six to one of resinous hot coefficient of expansion produce stress,this basically is, and the elapse as time, stress exceeds gradually the intensity of the colophony material of deterioration and generation crackle. To prevent the chap that arises from this, as experience, mural thick 7" and built-in metal external diameter is general-purpose basically unwell Yu Yi adds polystyrene set insert, and set insert the smallest to the influence of nylon. The hot coefficient of expansion that enhances colophony material as a result of fibre glass is lesser, suit to embed quite.

Additional, before shaping, to the metal insert undertakes warm-up, also have better effect.
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