DSM Engineering Plastics ­ Technical Guide Stanyl® PA46 Recommendations for Injection Molding Machinery: Stanyl® (PA46) can be processed on standard plastic processing equipment. Typically, generalpurpose screw designs with compression ratios of approximately 2.5 : 1 with sliding check rings work best. For unreinforced Stanyl® grades, reversed taper nozzles work well, while reinforced grades typically do better with general purpose, free flowing nozzles. Barrel Temperatures: Due to the high melting point and high crystallinity of Stanyl®, barrel temperatures need to be set high enough to provide a homogeneous melt without getting too near to the degradation point of Stanyl® at 330 °C. The recommendations are given in the sheet below. Screw rotation speeds: Stanyl® has excellent flow properties due to its relatively low melt viscosity. The effect of screw rotation speed on the amount of shear which is transmitted to the melt is relatively low and high screw speeds can generally be used without harm to the polymer. The maximum screw rotation speed must be lower than 6500/D rpm where D = screw diameter in mm. Date: 22.12.2003 1 Disclaimer: All information supplied by or on behalf of DSM in relation to its products, whether in the nature of data, recommendations or otherwise, is supported by research and, in good faith, believed reliable, but DSM assumes no liability and makes no warranties of any kind, express or implied, including, but not limited to, those of TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE or NON-INFRINGEMENT or any warranty arising from a course of dealing, usage, or trade practice whatsoever in respect of application processing or use made of the aforementioned information or product. The user assumes all responsibility for the use of all information provided and shall verify quality and other properties or any consequence from the use of all such information. DSM Engineering Plastics ­ Technical Guide Back Pressure: An effective back pressures of between 20 and 100 bar is recommended for processing Stanyl®, to homogenize the melt and prevent gas entrapment. Injection speeds/pressures: Due to the fast solidification of Stanyl®, high injection speeds are required in order to obtain good packing and surface finish. Generous mold venting is therefore necessary to avoid burning at the end of the flow path. Do not exceed vents of 0.02mm otherwise flash will occur. Holding pressure/holding time: In general, the holding time of Stanyl® is very short compared to other engineering plastics due to its fast solidification. Sink marks and voids caused by volumetric shrinkage can be reduced by adequate holding time and pressure, however the holding pressure should not be so high that stresses are induced. One method of determining the correct level is by increasing the holding pressure until no sink marks are visible, and keep decreasing the holding time until just before the weight starts to decrease. Mold temperature / cooling time: Because of the fast solidification of Stanyl®, the cooling time is very short. For this reason screw recovery time is the determining step for the cycle time. Mold temperatures above 80 °C are recommended for good dimensional stability and flow properties. A mold temperature of up to 120°C may be necessary for reducing post-mold shrinkage, increase flow performance, increase weld line strength, increase toughness and improve surface appearance. Ejection of molded parts: Stanyl® does not stick to mold surfaces and has good ejection properties. The high crystallization rate and the very high stiffness at high temperatures permits the ejection of Stanyl® at relatively high temperatures, such as >200 °C, resulting in short cycle times. Recommendations for Stanyl® 46HF (High Flow grades): Due to their improved flow, these grades exhibit less shear heating and LCP settings may be applied. Melt temperature should be 315-325ºC Increased settings in the compression/metering zone Lower temperatures in the feed zone but at least 280ºC Mold temperatures of 120ºC for optimal dimensional stability High screw rotation speeds Low back pressure, ± 10 bar effective High injection speed Control part fill with screw position or start with low or moderate pressure to avoid overpacking. Use low or moderate holding pressures in case of cushion variations Use reverse tapered nozzles. Adjust nozzle temperature (but do not set too low) to avoid drooling. Material Handling and regrind DSM Sales Offices Date: 22.12.2003 2 Disclaimer: All information supplied by or on behalf of DSM in relation to its products, whether in the nature of data, recommendations or otherwise, is supported by research and, in good faith, believed reliable, but DSM assumes no liability and makes no warranties of any kind, express or implied, including, but not limited to, those of TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE or NON-INFRINGEMENT or any warranty arising from a course of dealing, usage, or trade practice whatsoever in respect of application processing or use made of the aforementioned information or product. The user assumes all responsibility for the use of all information provided and shall verify quality and other properties or any consequence from the use of all such information. ...