Step 2. Set the temperature of the mold.Similarly, the initial mold temperature settings must also refer to the recommended values from the material supplier.Note that the mold temperature here refers to the temperature of the cavity surface, rather than the displayed temperature of the mold temperature controller .In many cases, due to environmental , improper
selection
of
the
mold
temperature
controllers and other reasons, the temperature and the temperature of the mold cavity surface are not consistent. Therefore, before the formal tryout, the improper design of the mold often cause the final
cavity surface temperature must be measured and
product with some defects,especially for injection
recorded. Meanwhile, the different mold cavity
molding part for it need more precise size than blowing
position should also be measured, to verify the
molding and rotational molding often. So, before the
balance temperature at various points, and record
plastic mold modification, usually it need conduct a tryout
the corresponding results, provide to optimize the
or evaluation for optimization of mold design and process
reference data.
parameters, so as to avoid unnecessary errors, achieve
Step
3.
Based
on
experience,
the
initial
good products, then meet the quality requirements of mass
speed, cooling time , screw speed and other parameters
The steps of tryout of plastic mold
be
figured,
and
make
its
appropriate optimization later.
could
Step 4. Have a test to identify the switching point.
Step 1. Set the barrel temperature.It should be
Which is a stage point from the injection stage to the
noted that the initial temperature of the barrel must
packing stage, it may be the screw position, the
be set in accordance with the plastic material
filling time and filling pressure. This is one of the
suppliers’ recommendation. This is because different
most essential and basic parameters of the injection
manufacturers produce different brands of the
molding process . under the actual test, the following
plastic material which may have quite a big
points should be followed:(1) holding pressure and
difference, and those material suppliers often have a
holding time is usually set to zero for the first trial;(2)
very indepth study and understanding of their
products filling depends on the wall thickness of
products.Users can have basic settings according to
products and structural design of the mold;(3) for the
their
the
injection speed would effect the position of switching
appropriate modification on the real production.In
position, so after each change of the injection
addition, it also need use the detector to measure
speed , we must reconfirm switching points, the
the actual temperature of the melt. Because we tend
material flow path in the mold cavity could be found,
to
thereby
recommendations,
set
the
barrel
and
then
temperature
have
effected
by
trapped
air
area
could
be
easily
environmental temperature, type and location of the
determined,then decide how to improve to vent the
depth of the temperature sensors,which does not
mold.
guarantee 100% consistent with the real melt
Step 5. Find the limit of the injection pressure. In
temperature. Sometimes, because of the presence
this process, it should be noted the injection
of oil or other factors, the temperature difference
pressure and injection speed is related.For hydraulic
between the actual temperature of the melt and the
systems, injection pressure and injection speed are
barrel is very large.
interrelated. Therefore, these two parameters can
www.plasticmoulds.net not be simultaneously set best to meet the required conditions.Injection pressure on the screen is a limit of the actual injection pressure, and therefore, injection pressure limit should be set larger than the actual value of the injection pressure . If the injection pressure is set too low, the actual injection pressure is close to or exceeds the limit value of the injection pressure, which would affect the injection molding cycle time.
Step 6. Optimizing the injection speed. Injection speed referred to the speed which could meet the shortest filling time demand and the lowest filling pressure demand.the following points should be noted:(1) Most of the product surface defects, especially defects near the gate, are caused due to the injection speed.(2) multistage injection can not be adopted only when the one time shot couldn’t meet the needs of the process , especially in mold test stage.(3) In the good mold condition, correct switching point setting and the enough injection speed , there is no direct relationship between the injection speed and product flash.
Step 7. Optimization of holding time.holding time is time of the gate solidifying. In general, the holding time may be determined by weighing the products to obtain different time, and optimized holding time is when the products get its max weight.
Step 8. Optimizing other parameters, such as holding pressure and clamping force and so on.Finally, it should be emphasized that the purpose of plastic mold trial is to optimize the tooling and injection processes to meet the requirements of mass production, rather than just a good test sample.