What must be the smallest tunnel gate inserts ever to have been manufactured will be making their début at Euromold (Frankfurt/Main from 5th to 8th December 2007). Developed and manufactured by i-mold GmbH & Co. KG, Brensbach/Germany, these tunnel gate inserts are used for the virtually invisible gating of miniature parts typically weighing between 0.1 and 5 g. Such parts are required to an ever increasing extent, for example, in the automotive industry, in the electrotechnical and electronics industries and in the medical devices industry. The various versions of these mini tunnel gate inserts are particularly suitable for multi-cavity moulds. They afford the processor the advantages of side or bottom gating and of reducing the distances between the cavities. The result is a smaller, less costly mould that can then be mounted on a smaller machine with reduced hourly costs. Moreover, sprue waste is minimized through the extremely low channel volume. In cases where the mould has a very large number of cavities, a further reduction in sprue waste can be achieved in conjunction with a common hot runner with each hot runner nozzle feeding several tunnel gate inserts.
The new mini inserts are basically suitable for all thermoplastic polymers, even if filled, reinforced or flameproofed, and for all thermoplastic elastomers. Some of them are contourable and hence adaptable to specific mould technologies and configurations. Table 1 provides an overview of the available types, dimensions and max. shot weights. Like the larger types, these mini inserts come in a choice of two hardness grades: U (40 HRC) and H (60 HRC); the SGC-XS and SGC-S inserts have a hardness grade of 54 HRC. The TGR6, TGR8 and TGS8 mini inserts are available optionally with a machining allowance of up to 0.6 mm (Version S1) or with a conical vestige (Version S2).