Excessive cycle time

The cycle time is the time taken to produce a molded part, which is measured from the start of injection until the end of clamp open time. High cycle times reduce productivity and increase costs.

There will always be a compromise between uniform cooling to assure part quality and fast cooling to minimize part costs. The function of the part will determine whether speed or quality is more important.

Excessive cycle times can be caused by the following conditions:

• High mold and melt temperatures
• Poor cooling system design
• Excessive filling and packing times
• Fast injection rates causing long cooling times

What to do

To reduce excessive cycle time:

• Optimize the filling time
• Optimize the packing time
• Use minimal cooling time
• Optimize the cooling system
• Change the part geometry to cool faster and more uniformly

All of these remedies should be evaluated in conjunction with each other, and with the quality and cost requirements of the part. Compromises may be necessary.