GB Precision, specialitsts in precision engineering
GB Precision
Friday 28th July 2013
Hard Metal Machining for Mould Tool Dies

GB Precision is finding that hard metal machining on its 5-axis Roders machine offers an effective alternative to a combination of grinding, jig boring and EDM-work for machining complex components, such as mould tool dies.

The Roders was originally purchased as part of the firm’s automation cell and was selected for its consistent accuracy - with linear motors on all 5 axes, precise temperature control and high resolution optical encoders - and it has more than proved its capabilities in this regard.

However, it has also opened up the possibility of directly machining hardened, heat-treated components. MD Paul Turner explains; “not only can we eliminate several secondary operations, but we can also avoid common problems, for example with distortions during the heat treatment process. Using hard metal cutting, we can produce more accurate components in a significantly reduced overall time.”

One example of this type of work is the machining of mould tool dies, which include bespoke, complex 3D curved geometries within the sides of the part. Because these curves are part of the final moulding, they require a high quality surface finish - 0.4Ra or better. Using traditional methodology, an electrode would be created on the milling machine, the component and electrode would then be loaded onto the EDM machine and the forms created to a finish of approximately 0.8Ra. This would then be followed by a manual polishing operation and then the parts would be machine polished to produce a consistent finish.

Each operation would take a matter of hours, with each step increasing the possibility of error. Using the direct milling technique, the metal is put onto the Roders and the forms are directly machined into the hardened steel. The accuracy and finish are so good that parts come off the machine already in tolerance and very close to the required 0.4ra finish, only a brief machine polish is required to ensure the parts are fully in specification.
© Copyright GB Precision 2017, all rights reserved.