BPF® Control - Filling method by natural flow of moten resin
■BPF®Control（Balance Pressure Filling Control）
By stopping screw rotation at V/P switchover position for a short period of time and using restoring force of compressed resin, filling balance is kept in good state. Molted resin spreads evenly inside mold.
Advantage of BPF® Control
◆ Prevention of flash, short shot
◆ Non-uniform molded parts with multiple-cavity mold.
◆ Improved mold release
Molded part: IC Tray
High hold pressure is applied to create sharp edge around holes but flash occurs. Hold pressure is lowered to avoid flash, then, it causes short shot. By BPF Control, proper balance of melt flow reduces flash even with high holding pressure applied.
BPF Control is effective for flash and short shot problem.
Molded part: Lens (6 cavities)
Pictures in upper row show 6 lenses molded by regular filling. Pictures in lower are lenses molded by BPF Control. With regular filling, the size of sink mark varies influenced by gate position. With BPF Control, filling balance in the mold is improved and sink marks are more identical.
BPF Control is effective for uneven filling of multiple-cavity mold.
Molded part: Thick-walled light guide
Left picture shows a dent made by ejector. High holding pressure is applied to avoid sink mark but it caused higher resin pressure inside the mold which resulted in creating larger mold release resistance. Pressure of ejector pin made a dent on molded part. By BPF Control, formation of skin layer on part surface is improved and sink mark is prevented even with high holding pressure. Mold release resistane is reduced when resin pressure inside mold is high. Molded part is released without dent shown on the right picture.）
BPF Control improves mold releasability.