Thermoforming of Large PA Parts
Semi-finished glass fibre-reinforce PA 6 goods can be thermoformed into large parts. The production method represents an inexpensive alternative to injection moulding – especially for smaller production quantities.
Glass fibre-reinforced PA can be thermoformed into large parts economically, especially when smaller quantities are to be produced. The special PA 6 sheet stock employed in the process (Durethan DP2-2140, Manufacturer: Lanxess) is available from Sustaplast KG, Lahnstein. This material is a branched, impact-modified PA 6 that is reinforced with glass fibres. While conventional PA forms very easy-flowing melts, the Durethan is characterised by very high melt stiffness – the attribute that is decisive for thermoforming. Previously, the material was available with only 15 % glass content; now, a grade with 25% glass has been developed that is even stiffer, stronger and more dimensionally stable. Parts produced from the material can withstand sustained use at temperatures up to 140°C, and brief exposure to temperatures up to 170°C.
Melt stiffness decisive
Thermoforming represents an inexpensive alternative to injection moulding, because the moulds are relatively simple to produce. The resulting cost savings become even more noticeable, the smaller the production quantities. The protective covers for marine engines produced by Reiss Kunststofftechnik, Tettnang are one example. The covers that are thermoformed from glass fibre-reinforced PA are dimensionally stable and resist warping. Additional benefits include the low weight, high breaking strength and resistance to oils and other chemicals. The PA engine covers replace sheet metal designs. The largest part is 920 millimeters long and 400 millimeters wide, with a weight of 1.25 kilograms. It is produced – as are the other parts – from five millimeter thick sheet stock in a drawing ratio of 1: 2.5.
The glass fibre-reinforced PA 6 sheet stock is available in thicknesses of 2 to 6 millimeters and delivered in a standard size of 2000 x 1000 millimeters. Special sizes can also be produced. Additional potential applications in the automotive sector include noise-reducing components and air guides in the engine compartment, underbody assemblies and wings. Even structural components for the luggage compartment that are laminated with carpet or fabric can be thermoformed from such sheet stock.