Mollart develops super finishing process achieving 25 micron straightness over 800mm bore depth

The application development team at Mollart Engineering has created a specialised gundrilling operation with the ability to super finish tubular bores in 400 Series stainless steel to 0.8 Ra surface roughness standard while maintaining a straightness tolerance within 25 microns over a bore depth of 800 mm.

The specialised operation to create bores between 6mm and 12mm in diameter in the 11% chromium, 1% manganese Martensitic stainless steel, follows the process development for a customer involving combinations of chip management through the cutting geometry of the gundrill coordinated with spindle speeds and feeds, coolant type and applied pressures.

Explains director of tooling Chris Barker: “This process development can now be applied across several industry sectors including medical, valve, aerospace and defence, hydraulic and automotive related areas where hole straightness and higher orders of surface finish is a growing requirement and especially in more difficult to machine materials.”