This technique has been used for a great many years, but it has often been at the expense of a slow cycle time and high costs in the final moulding.
Hjerno Tool Factory have independently developed the technique so that the cycle time in particular has improved significantly, while durability and precision are top class. The tools have become more compact – and above all, they have gradually come down to a very reasonable price range.
Unscrewing is used for precision threads often with adjustable thread start and stop, and Hjerno's unscrewing tools are created for fast, unmanned production.