Şekil hafızalı poliüretanın enjeksiyonla kalıplanmasında parça kalitesi

Öz

Akıllı malzemenin bir türü olan şekil hafızalı polimerler (ŞHP) son yıllarda endüstriyel uygulamalarda yaygınlaşmaktadır. Şekil hafızalı polimerlerin bir türü olan termoplastik şekil hafızalı poliüretan (ŞHPU) kolay kalıplanabilme ve tekrar kullanılabilme özellikleri ile ilgi çekmektedir. Mevcut termoplastiklerde olduğu gibi ŞHPU’dan üretilen parçaların da kalıcı şekillerinin verilmesinde enjeksiyon kalıplamanın yaygın kullanılması beklenmektedir. Bu çalışmada, enjeksiyon kalıplamayla kalıcı şekilleri verilmiş ŞHPU numunelerde parça kalitesi; eksik baskı, hava sıkışması ve parça ağırlığı üzerinden araştırılmıştır. Enjeksiyon basıncı, enjeksiyon sıcaklığı, kalıp sıcaklığı, ütüleme basıncı ve süresi, soğutma süresi parametreleri ile kalıpta eksik baskı, hava sıkışması ve numune ağırlığı arasındaki ilişkiler deneysel olarak incelenmiştir. Deney tasarımı, Taguchi L27 ortogonal dizilim ile hazırlanmış, deneysel veriler varyans analiziyle değerlendirilmiştir. Eksik baskı oluşumuna enjeksiyon sıcaklığı ve basıncının etkileri istatistiksel yönden anlamlı bulunurken, hava sıkışması ise enjeksiyon basıncı ve kalıp sıcaklığından etkilenmiştir. Numune ağırlığı üzerinde en etkili parametrelerin ise sırasıyla enjeksiyon basıncı ve sıcaklığı, kalıp sıcaklığı ve ütüleme basıncı olduğu bulunmuştur.

Anahtar Kelimeler

• Şekil hafızalı poliüretan
• Enjeksiyon kalıplama
• Kalıcı şekil
• Parça kalitesi
• Eksik baskı
• Hava sıkışması
• Ağırlık

Part quality in injection moulding of shape memory polyurethane

Abstract

In recent years, as a type of smart materials, shape memory polymers (SMPs) are being popular in industrial applications. Thermoplastic shape memory polyurethane (SMPU), which is a type of shape memory polymers, is become interesting because of the properties which are easily moulding and reusability. As commonly in commercial thermoplastic materials, it is expecting that using injection moulding process for shaping permanent shapes of the parts moulded by SMPU. In this study, the part quality was investigated by using short shot, air traps, and part weight in the permanent shape of injection moulded SMPU specimens. The relationship among injection pressure, melt temperature, mould temperature, packing pressure, and time, cooling time and short shot, air traps and part weight were inspected experimentally. The design of experiment was prepared by using Taguchi’s L27 orthogonal array and experimental data was evaluated by ANOVA. While the effect of injection pressure, and melt temperature on short shot was found to be significant statistically, air traps were affected by injection pressure and mould temperature. It was found that the effective parameters on part weight are injection pressure, melt temperature, mould temperature and packing pressure, respectively.

Keywords

• Shape memory polyurethane
• Injection moulding
• Permanent shape
• Part quality
• Short shot
• Air traps
• Weight

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