Contraction marks
First, the injection characteristics of the
surface defects often associated with marks, but also to the surface of the
plastic from the mold shrinkage from the formation.
Second, the reasons for problems that
may occur
(1) The melting temperature is not too high
or too low.
(2) Insufficient mold cavity plastic.
(3) When the cooling phase the contact
surface of the plastic to overheat.
(4) Runners unreasonable, gate-section is
too small.
(5) The die temperature is adapted to the
characteristics of the plastic.
(6) The product structure is irrational
(strengthened into ancient too high, too thick, obviously varying thickness).
(7) The cooling effect is good, continue to
shrink after product release.
Third, the remedies
(1) Adjust the plunger cylinder
temperature.
(2) The adjustment screw speed to obtain
the correct screw surface speed.
(3) Increase the amount of injection. (
4) ensure the use of proper litter;
increase screw forward time; increased injection pressure; increase injection
speed.
(5) Check the stop valve is installed
correctly, because the non-normal operation will lead to pressure loss.
(6) Reduce the mold surface temperature.
(7) Correction runner to avoid excessive
pressure loss; according to actual needs, and expand the cross-sectional
dimensions.
(8) The appropriate mold temperature
control depending on the characteristics of the plastic and the product
structure.
(9). Improve the product structure in the
permit.
(10) Try to make the product has adequate
cooling
Warpage of plastic parts
First, the characteristics of injection
molded parts defects similar to the shape of the mold cavity is a twisted
version but the shape of the mold cavity
Second, the reasons for problems that may
occur
(1). Bend because there are too many
internal stress within the injection molded parts.
(2) mold filling speed.
(3) Insufficient mold cavity plastic.
(4) plastic temperature is too low or
inconsistent.
(5) at the top of injection molded parts
too hot out.
(6). Cooling inadequate or move, scheduled
to die temperature is inconsistent.
(7). Injection irrational structure (such
as ribs concentrated on one side, but far away).
Third, the remedies
(1) Reduce the injection pressure.
(2) Reduce the screw forward time.
(3) Increase the cycle time (especially
cooling time). From the mold after (especially thick injection molded parts)
top out immediately immersed in warm water (38oC) makes injection molded parts
to cool slowly. (4) Increase the injection speed.
(5) Increasing the temperature of the
plastic.
(6) cooling equipment.
(7) appropriate to increase or improve the
cooling conditions of the cooling time, as far as possible to ensure dynamic
and stationary die mold temperature consistent.
(8) In accordance with the actual situation
of improving the structure of plastic parts in the permit. Plastic injection
filling defect characteristics dissatisfied injection molding process is not
complete, because the cavity does not fill plastic injection molding process or
lack of certain details.
Second, the reasons for problems that may
occur
(1) Insufficient injection speed.
(2). Shortage of plastic.
(3) The screw at the end of the trip did
not leave a screw litter.
(4) Changes in operating time.
(5). Plunger cylinder temperature is too
low.
(6) lack of injection pressure.
(7) Nozzle partially blocked.
(8) or plunger nozzle heater does not work
outside the cylinder.
(9). Injection time is too short.
(10) plastic hose attached to the hopper
wall.
(11). Injection molding machine capacity is
too small (ie, weight or plasticizing injection capacity).
(12) The mold temperature is too low.
(13) There is no clean up mold of anti-rust
oil.
(14). Retaining ring is damaged, there is
melt back phenomenon.
Third, the remedies
(1) Increase the injection speed.
(2) checks the amount of plastic in the
hopper.
(3) Check whether the correct set of
injection stroke, needed to be changed.
(4) Check the check valve wear or cracks.
(5) Check the operation is stable.
(6) Increase melt temperature.
(7) Increased back pressure.
(8) Increase the injection speed.
(9) Check the nozzle hole there is no
foreign body or plasticizing plastics.
(10) Check all heaters outer layer ammeter
test energy output is correct.
(11) Increase screw forward time.
(12). Increased cooling capacity hopper
throat area, or lower the temperature after the plunger cylinder area.
(13). Using large injection molding
machine.
(14) The appropriate mold temperature
rises.
(15). Cleaned rust clean the mold.
(16). Inspection or replacement.
more information www.cnmoulding.com www.chinamoldmaker.org
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