“CAPLON” Nylon-6 is supplied in moisture proof packing & filled under nitrogen to prevent any moisture during packing operations. However Nylon-6 is hygroscopic & absorbs moisture quickly from humid air. The moisture in Nylon-6 has adverse impact on moulding or extrusion operations. In such cases, predrying with hot air at 85-90 degree Celsius for 3 hours is recommended. Extra care should be taken to seal half used bags & predry them before moulding to reduce moisture less than 1000 PPM (0.1%), oxidation induced deterioration of properties become more prominent as the temperature & drying time increases. In some cases, Nylon-6 chips will turn yellowish eventually leading to the more serious problem of lowering the degree of polymerization thus deteriorating the product.
Although Nylon-6 can be moulded over wide range of temperatures, however for general moulding 70-80 degree Celsius temperature of mould is recommended. The filled grades like Glass filled, mineral filled etc. with high HDT requires slightly higher temperatures in the range of 80-110 degree Celsius for smooth surface finish.
“CAPLON” Nylon-6 with a melting point of 220 degree Celsius is processed in broad range of 225-265 degree Celsius; however reinforced grades require high temperature. Profile of 260-290 degree Celsius zone wise temperature range is given below in chart. However processing parameters depend on size, condition & type of machine.
Injection rate depends upon grade of CAPLON used for moulding. Generally higher injection rate is required to avoid premature freezing. Surface appearance is main criteria to adjust pressure, the reinforced grades require higher injection rate over unfilled grades. Although general guidelines are given in processing chart, however optimization depends on type/size & grade of Nylon-6 and also weight & shape of component to be moulded.
Generally auxillary equipments required are:
Online scrap grinder facilitates continuous mixing of scrap with fresh granules & also avoid moisture absorption. Regrind level up to 20-25 % hardly influence properties of moulded item. However uniform size of regrind is recommended to avoid any moulding defects.