Mike Pragnell, operations director of the Chessington facility, comments: “There are 16 different moulds in the family that range in size from 2,000mm x 1,500mm x 300mm to 750mm x 750mm x 100mm.
“Because of our in-house development of a 5-axis Centeplex and two 4-axis Prismabore PRB machines, each having individual spindles one for deep hole drilling and the other for CNC milling, we are able to mill faces and features, drill, thread mill portings and create sealing faces in a single operation on parts weighing up to five tonnes. This has given us an important advantage in this type of application.”
Each of the heat treatable steel moulds had a variety of 16mm diameter holes for water cooling with depths up to 1,500mm. Most of the holes were interconnecting to enable efficient water flow and here the gundrill process ensures accurate breakthrough with minimal runout (normally within 0.025mm per 25mm depth) that reduces any mismatch.
Mollart has the capability to drill deep holes between 0.5mm and 60mm diameter on these multi-axis combination machines to depths of 3,000mm and at compound angles up to ±15°. However, with probing to re-datum the workpiece, parts can be indexed 180° around the machine table and drilled from the opposite end to enable overall drilling depths of 6,000mm to be attained.