COMPLETE PROCESS PAGE OF INJECTION MOLDING MACHINE -1
This page comprises of the most important process parameter.
Cycle time Set
The set cycle time acts as a monitoring time for the completion of cycle. If, due to some reason, the cycle fails to complete within the set time, the machine will signal an alarm.
Actual: The time taken by the machine to complete one cycle. The set cycle time should be higher than the actual cycle time.
Actual: The time taken by the machine to complete one cycle. The set cycle time should be higher than the actual cycle time.
Cycle time - last shot
# The time taken by the machine to complete the previous shot. Useful for checking the effect of a change in the process parameter.
Blocking time
# Blocking time starts after the set cycle time expires. At the end of blocking time the machine goes into shut-off mode as per the switch off matrix setting.Pause time
# The time between two consecutive cycles while the machine is in auto mode.
# Pause time is necessary to prevent mold closing before the ejected components clear the mold area. Delay Injection
# A small delay (of the order of 0.4 - 0.7 sec) before injection compensates for the time required for the nozzle contact force to build-up before injection can start.
Injection Pressure
# The pressure during injection is limited to the set value. The injection pressure should be set by taking the geometry and material of the component being molded.
# Viscous materials like acrylic, poly carbonate and ABS need higher pressures to fill the cavity.
# Long flow paths and thin wall thickness also demand high injection pressure.
Injection Speed (mm/sec)
# Slower speeds should be used for shear sensitive materials (like PVC).
# Slower speeds are also desirable while gating into thick sections to avoid jetting.
# On the other hand, thin walled components with long flow paths need high injection speeds to avoid freezing of the flow front before the cavity is filled up.
# It is advisable to bring down the injection speed just before the switch over point is reached to avoid mold over packing and flashing.
Holding time
# Holding time is dependent on the wall thickness of the component being molded.# Thick walled components need longer holding times.
# Holding time should not be prolonged beyond the gate freezing time of the component.
Holding Pressure
# As a thumb rule, the initial holding pressure can be set at around 75% of the peak injection pressure.# Holding pressure can be progressively reduced for more uniform packing.
# Reducing the holding pressure in steps will also prevent the screw jumping back after the end of holding phase.
Cooling time
# The time to cool the component depends upon a host of factors such as, wall thickness, material thermal properties, cooling channel layout, temperature and rate of flow of the coolant.
# Start with high cooling time and optimize it later.
Dosing delay
# Dosing delay can be set if the cooling time is considerably longer than the dosing time.
# By delaying dosing, the degradation of heat sensitive materials can be prevented.Screw Speed
# Set the screw speed as per the recommendations. Try to match the end of dosing with the end of cooling.# The screw rpm is displayed under the actual column.
Back Pressure Step 1
# Maintaining a suitable level of back pressure behind the injection cylinder is essential for proper homogenization and mixing of the melt and as well as to remove any air inclusions in the melt.# Excessively high back pressures may degrade the material
Back Pressure Manual
# Before the machine is put into auto or semi auto mode the screw should be in the dosing stop position.
# The back pressure requirement during manual mode is usually set lower than what is required during the semi or fully auto mode. This will bring the screw to dosing stop position without drooling.
Comments
Post a Comment