Steel-plastic composite parts - WSH COMPOUND - are used in all industrial sectors. The household appliance, electrical and automotive industries are particularly noteworthy.
The thermoplastic components used in WSH COMPOUND have properties that increase the utility of the steel screws to which they are inseparably connected by overmolding.
WSH COMPOUND refers to composite parts made of steel and plastic that combine and utilize the properties and advantages of these two material groups. The result is multifunctional elements that are designed to fulfill specific functions.
Steel gives the screw the necessary strength to withstand all static and dynamic loads. This allows high preload forces to be transmitted to prevent unintentional loosening of the screw.
The head and screw are inseparably joined together by overmolding. This gives the screw additional insulating, haptic and protective advantages. Injection molding technology allows a variety of shapes and therefore a variety of applications that cannot be achieved by forming steel. Multi-component injection molding opens up further possibilities by combining hard components to absorb mechanical loads and soft components as seals, protection or damping. In the simplest case, for example, two different colors.
Plastic heads as knurled, wing or star grips in a variety of application-specific shapes. At high surface pressures, plastics tend to flow in an uncontrolled manner, which leads to loss of preload and loosening of the screw connection. We therefore recommend a design in which the metallic “steel-on-steel” contact between the underside of the head and the component is maintained after plastic overmolding.
In some applications it is necessary to rotate the plastic part, as is the case with various types of adjustable feet, for example. Other typical applications for WSH COMPOUND are stop screws, stop buffers or adjusting screws.
The steel component is usually made of heat-treated materials in accordance with DIN EN ISO 898-1.
Preferred plastics for overmoulding are easy-flowing injection-moulded types such as POM, PA 6.6 and PP. In many applications, these plastics are reinforced with glass fibers. PA 6.6 GF 30, for example, is a polyamide 6.6 with 30 % glass fiber.