Question

How is sprue bushing design related to cycle time?

Answer 1

• The bushing is made from a high-conductivity copper alloy. It contains a hardened 420 stainless steel nozzle seat to insulate from nozzle heat and for wear resistance.This is effective in reducing sprue sticking,increasing sprue rigidity for pickers and grabbers, andcutting cycle time. With this sprue bushing, a standard sprue taper of 42 mm/m (0.5 in./ft) has been found to be acceptable for good heat transfer.
• The standard steel sprue bushing has been replaced with a shorter performance-alloy sprue bushing. There is better cooling around the sprue, and more cooling was added in the cavity and the core.
• Hot sprues can be used for amorphous copolyesters.As with hot runners, the keys to proper design are low shear, good cooling at the part or sprue/runner end, uniform heating, and good temperature control.

• •Stainless steel nozzle seat

  –Wear resistant

  – Nozzle heat resistance

  •Rigid sprues for pickers or

  grabbers,Reduces cycle times

  •

  Enhances release of

  molded parts