Products frangible large part is due to the
stress caused. Many causes brittle hair products, are:
Equipment:
(1) barrel are dead or obstacles, easy to
promote melt degradation.
(2) machine plasticizing capacity is too
small, plastic barrel in plastics is not sufficient; too much capacity plastics
machinery, plastic barrel by the shear heat and time is too long, plastic easy
to aging, so that products become crisp.
(3) the top of the device is tilted or
unbalanced, dry top small cross-sectional area or improperly distributed.
Molds:
(1) gate is too small, you should consider
adjusting the gate size or the addition of auxiliary gate.
(2) shunt is too small or improperly
configured, a reasonable balance should be arranged or increased shunt size.
(3) mold caused by poor molding cycle
unusual structure.
Technological aspects:
(1) barrel, nozzle temperature is too low,
raise it. If the material is easily degradable, it should raise the barrel,
nozzle temperatures.
(2) reduce the pre-plastic screw back
pressure and speed, so that the material slightly loose and reduce degradation
of plastic due to overheating caused by shear. (3) The mold temperature is too
high, stripping difficulties; mold temperature is too low, plastic premature
cooling, poor weld fusion, easy to crack, especially high-melting plastics such
as polycarbonate even more so.
(4) cavity core have appropriate stripping
slope. When stripping the core difficult to raise the temperature of the
cavity, shorten the cooling time; when the cavity impunity, to reduce the
cavity temperature, prolonged cooling time.
(5) minimize the use of metal inserts, such
as Polystyrene hematocrit cold brittle plastic, but can not join the insert
molding.
Raw materials:
(1) raw materials mixed with other
impurities or doped with inappropriate or excessive solvent or other additives.
(2) Some plastics such as ABS, etc., in the
damp heat condition can occur with moisture catalytic cracking reaction, the
occurrence of large parts of the strain.
(3) plastic recycling too many times or
recycled materials content is too high, or in the machine barrel heating time
is too long, can cause brittle parts. (4) The plastic itself is poor quality,
such as molecular weight distribution of a large, non-uniform structure
containing ingredients rigid molecular chain possession excessive; or
contaminated, poor additive pollution, dust and other plastic doping impurity contamination
is caused by brittle the reason.
(1) products with sharp corners prone to
stress cracking, or the thickness of the gap very different parts.
(2) product design too thin or too hollow.
(2) product design too thin or too hollow.
In the process of injection molding, there are still many problems. For example
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