Processing Machinery
3 조회수
PA6 Screw Back Pressure Control
문제 현상
Air is mixed into the melt and the product has bubbles, or excessive back pressure causes melt overheating and degradation
원인 분석
PA6 viscosity is low; excessive back pressure causes obvious shear heating and slows screw recovery, extending the thermal history; too-low back pressure causes uneven plasticizing and air entrapment in the melt, and the nominal back pressure is only about 0.5MPa
해결 방법
①Keep back pressure at a low value of about 0.5MPa (5bar); ②Screw surface speed not exceeding 0.5m/s, and not exceeding 0.2m/s for flame-retardant grades; ③For plasticizing abnormalities, check back pressure and rotation speed first
핵심 요약
Low back pressure is the basic principle of PA6 plasticizing; low-viscosity materials cannot withstand shear abuse, and the speed upper limit is executed according to the grade; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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