Causes discoloration is multifaceted, it
is:
Equipment:
(1) The equipment is not clean. Dust or
other dust deposited on the hopper so that contaminated material discoloration.
(2) thermocouples, temperature control
device or heating system disorder caused by the temperature control failure.
(3) barrel obstructions, easy to promote
degradation of the plastic; cylinder or screw slot card metallic foreign body,
constantly grinding the plastic color.
Molds:
(1) mold venting is bad, the plastic is
adiabatic compression, at high temperature react violently with oxygen, burn
plastics.
(2) mold gate too small.
(3) feed or in-mold lubricants, release
agents too. Necessary regular cleaning cartridge, remove the plastic heat
resistance worse than antistatic additives.
(4) the nozzle orifice, sprue and runner
size is too small.
Technological aspects:
(1) screw speed is too high, pre-plastic
backpressure too.
(2) the barrel, the nozzle temperature is
too high.
(3) injection pressure is too high, too
long, the injection speed is too fast for the products and discoloration.
Raw materials:
(1) the material is contaminated.
(2) moisture and volatile matter content.
(3) a coloring agent, additive
decomposition.
Spots or liquor
The main reason for this defect in
equipment and raw materials:
Equipment
(1) barrel has charred material.
(2) barrel cracks.
(3) a screw or plunger wear.
(4) near the hopper dirty.
Molds:
(1) oil cavity.
(2) penetrate the oil from the top of the
device.
Raw materials:
(1) raw material dirty.
(2) lack of lubricant.
Charred Obscure
Equipment: After injection of
heat-sensitive plastic, barrel or nozzle not clean material mat have resulted
in poor exhaust injection begins.
Molds:
(1) Exhaust poor.
(2) improper or small gate gate location.
(3) of the cavity local resistance, so that
the exhaust gas stream resulting slow convergence difficulties.
Technological aspects:
(1) barrel, the nozzle temperature is too
high.
(2) pre-plastic injection pressure or back
pressure is too high.
(3) injection injection period is too long
or too fast.
Raw materials:
(1) uniform particles, and containing the
powder.
(2) high volatile content of the feedstock.
(3) lubricants, release excessive amount.
more information
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