Re-engineering a six-axis machining centre

An iTNC 530 CNC system supplied by Heidenhain (GB) Ltd (www.heidenhain.co.uk) has transformed a 22-year-old milling and boring centre with four axes into a high-speed six-axis machining centre that can undertake complex contour machining operations. Re-engineered by Nutech Machinery Services, Coventry, the Boko F63-100 has been shipped to a customer in North America, where it will work on satellite fuel tanks.

Nutech joint owners John Campbell and Bob Spooner are both former employees of Boko UK, and they bought the F63-100 on a speculative basis some time ago, “but always with the intention of re-engineering it as a six-axis machine,” says Mr Campbell. “Of course, with Heidenhain’s iTNC 530 CNC system being the industry-standard control for high surface definition and accurate contouring, our choice of retrofit CNC was obvious.

“After discussions with the customer revealed the size of the fuel tanks, we extended the column — the Z axis — by 500mm. This had no effect on machine stability or accuracy, because we used a proper casting.” The 1,500mm Z axis is complemented by 2,400mm in X and 1,200mm in Y. The two additional axes are W (a 300mm front milling slide) and B (a head that swivels by +/-90 deg). A Heidenhain rotary encoder fitted to the B-axis centre line has a resolution of 0.001deg.

When the F63-100 arrived at Nutech’s premises, it was totally stripped, and the male slideways were re-ground, while Turcite was applied to the female slideways. All axis ballscrews were refurbished, and the swivel head was rebuilt to incorporate a backlash system. The iTNC 530 control was complemented by Heidenhain motors and drive amplifiers, and the 3,200rev/min main spindle was given a Heidenhain spindle motor package.

All these elements were integrated by Nutech before an electrical panel with all-new switch-gear was fitted to the rear of the machine column (to save on floor space). The end result was a ‘state of the art’ machine for six-axis contouring — supplied for less than half the cost of an equivalent new machine.