Optical moulding | processing index,” says Klinkenberg.
The shorter cycle times also means the risk of black speck formation is reduced. However, he recommends that standard good practice for processing of optical quality resins is maintained. In particular, screws, non-return valves and screw tips should be fi nished with an appropriate coating such as multi-layer chromium nitride.
Double-Layer
Triple-Layer First layer hot
Triple-Layer First layer cold
COOLING TIME REDUCTION BY MULTI-LAYER MOULDING AS “RULE OF THUMB”
ent thermoplastics is a function of temperature and residence time – in both cases, the higher, the worse – and other factors. Long cycle times lead to long melt residence times in the barrel, so if the cycle time is reduced and the barrel diameter is appropriate for the shot volume, the part will have a lower yellowness
Klinkenberg says many thick wall optical parts can be produced very precisely on a shorter cycle time using a multi-layer moulding technique. However, suitability of an individual part will depend on the geometry – it may not be possible to divide the wall thickness into lay- ers and place the gating points appropriately on all geometries. The expected production volume will also have to be taken into account and balanced against the increased tooling cost.
For more details: Christoph Klinkenberg is an applications development specialist within Bayer MaterialScience at Leverkusen in Germany. He can be contacted here.
www.bayermaterialscience.com
www.gx.kraussmaffeigroup.com
Powerful, user-friendly, with stable value. The new GX Series of KraussMaffei combines innovative technology and first-rate quality in an unprecedented way:
– Maximum productivity thanks to an excellent hydromechanical dual platen clamping unit
– Maximum part quality thanks to the GearX locking device unit and GuideX guide shoe
– Maximum reproducibility with highly efficient plasticizing unit
– Minimum set-up times thanks to easy accessibility – Easy operation with the new innovative MC6 control system
The new GX Series of KraussMaffei: Engineering inspired by passion. First-class machine concept. Best results.
Fakuma, hall A7, booth 7303
The new dimension of injection molding Machines in the GX Series
Engineering Passion
Cooling time reduction (%)
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