Before starting his own machining business — CNC Subcon Services (www.cncsubcon.co.uk) on the Meltham Mills Industrial Estate in Holmfirth, West Yorkshire — Mick Catherine worked for another sub-contractor that was using a Japanese-built Okuma horizontal machining centre to ‘turn’ large (and often eccentric) components to a dimensional accuracy within 10µm.

Rather than using a rotary table, the machine was programmed to ‘turn-cut’ the features with a single-point turning tool clamped in the spindle; the rotation of this spindle was synchronised with the speed of circular interpolation in the X and Y axes, while the tool was fed forward in Z.

The advanced functions offered by the machine’s proprietary OSP control — together with the high quality of machine build and the proficient back-up provided by Okuma’s UK agent, NCMT Ltd (www.ncmt.co.uk) — left a lasting impression on Mr Catherine, so when he opened CNC Subcon Services in 2017, two early lathe purchases were a Genos L400 and an LB25-II, followed more recently by an MU-6300V-L five-axis mill-turn centre — all manufactured by Okuma.

Mr Catherine said: “In 1989, I joined as an apprentice the sub-contract machinists that later started using Okuma turn-cut technology. When I started CNC Subcon, I decided to specialise in providing technical expertise and advanced manufacturing solutions to the pump and valve sector, including product design. However, we also work for clients in many other industries, and contracts typically involve machining ones and twos at competitive prices and short lead times.”

Paul Neville, sales and operations manager at CNC Subcon, said: “We continue to develop our own components, and we have a number of patents in place for systems that increase pump efficiency. For this and most of our sub-contract work, we need to machine to very close tolerances, for which top-quality equipment like the Okuma MU-6300 mill-turn centre is essential. The rigidity of its bridge-type construction particularly suits the machining of difficult materials.”

The MU-6300V-L at CNC Subcon has a +90/-120deg trunnion carrying a 630mm-diameter table that can turn rotational parts up to 830mm in diameter x 550mm tall at up to 800rev/min. The machine, which can also mill and drill components using fully interpolative five-axis cycles, has an HSK-A100 spindle (rated at 11/7.5kW and with a maximum speed of 8,000rev/min) that is served by a 64-station tool magazine.