Injection moulding warping

In blends of polyamide with styrenics, compatibilization of the phases is generally a prerequisite for acceptable mechanical properties. This can be accomplished by having reactive groups in the PSAN phase that react with the amino groups of the polyamide phase. Blending is used to improve the main weaknesses of the polyamide, namely moisture sensitivity, toughness and warp-age on injection moulding. 

Polymer liquid memoiy plays an important part in determining orientation, anisotropy and warping in injection moulding. In extrusion, the... 

Finally test and burn in sockets must be able to survive the test conditions with a high degree of tolerance and dimensional stahility. ESD grades of PAEK are use together with precision injection moulding for fine connector arrays. Blends of PAEK with amorphous polymers, or less crystalline polymers such as PEKK, can offer a lower tendency to warp and higher dimensional tolerance. 

The trickiest inserts are thermoplastics. They exhibit a relatively low melting or softening temperature that ranges from approximately 60 °C up to 200 °C or higher. In many cases, injection moulded, extruded or press moulded plastic inserts have incorporated residual stresses from their method of manufacture. Such structures, often caused by process induced molecular and/or crystal orientation can relax at elevated temperatures which often leads to warping of the inserts. 

In 1996,20 million lbs of rPET was used in applications in which it was first combined with another resin. This process, known as alloying or compounding, greatly increases the chemical resistance, dimensional stability and abrasion resistance. PET, both rPET and vPET, cannot easily be injection moulded PET will randomly crystallise during normal thick wall moulding thus making the moulded part brittle and subject to warp. The process of adding an impact modifier to PET allows it to overcome these problems and enables it to be used in other applications. 

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