The dramatic increase in the use of plastics in industrial applications has brought with it a challenge as to how best to create fastenings to match the ever growing mechanical demands of the materials. Where one can machine fixings (threads etc.) into metals, the same is untrue for plastics materials. However, moulded in fasteners enable not only secure fixings, but the give the ability to optimise the fixing points.
The driver behind the development of moulded in fastenings is a rate of change of plastics usage. If one examines the automotive sector, for example, in 1997 about 1.7 million tonnes of plastics were consumed in vehicle manufacture. According to the Association of Plastics Manufacturers in Europe (APME) it is now in excess of 2.8 million tonnes – a rise of 114% in less than 20 years.
For this reason, Böllhoff developed its IMTEC® range of fasteners. They provide wear-free and resilient metal threads in high-quality plastics and can be inserted to allow for blind hole threads or through hole threads, just as when tapping a metal component. The IMTEC® are used in plastics parts to achieve advantages such as reduced weight, improved corrosion resistance and component cleanliness. IMTEC® moulded inserts are particularly suitable for thermoset and thermoplastic materials
IMTEC® moulded inserts can be placed into a mould manually or by means of a handling system. Indeed, only the core pins of the injection mould have to be geometrically adapted to the IMTEC® moulded inserts.
There are two fundamental configuration of the IMTEC® fasteners.
The IMTEC® CO range has threaded inserts of asymmetric rolled stainless steel A2, which is coiled to a fixed bushing with one flange-type extension. It has some unusual features:
• Magnetic despite being made from of stainless steel: Magnetisation of components is helpful in the moulding process whereby fasteners are inserted on the mould tool’s core pin
• Residual dirt minimisation
• Weight reduction of the component
• Maximised usable thread length
The IMTEC® CF thread inserts with a double flange are produced from steel by cold forming. In-moulding technology requires particularly accurate thread inserts. The deformation area on the IMTEC® CF allows precise adjustment of the length of the thread insert according to the mould dimension. Upon closing, the two halves of the mould compress the IMTEC® CF, which in turn precisely adjusts the length of the component (L ± 0.15 mm). IMTEC® CF is primarily intended for components with through hole threads.
Benefits include
• Very large flange diameters possible
• Deformation area for length adjustment of the insert; close length tolerances < L ± 0.05 mm
• Torque resistance by hexagonal design or knurls
• Pull out resistance by providing significant under cuts
• No metal cutting required in the operation
• Fasteners can be used as compression limiters
The IMTEC® moulded inserts are used in many fields and applications including medical technologythe automotive industry, plastics technology, electrical and electronics manufacturing, fluid power systems and many more.
