When Sub CNC got the call from Rolls Royce to quote on two plastic parts for the Ventilator Challenge UK it was in full production within two days.
Sub CNC was one of the companies it contacted, having been given its name by turning machine supplier Citizen UK, which had identified it as a possible supplier.
Joint owners and managing directors of the contract machining operation, Yian Stavrou and George Dingley, received an email request from Rolls-Royce late in the evening on the last Wednesday in March. Drawings came in the following morning, quotes were issued quickly and by the afternoon provisional orders had been issued.
Mr Stavrou recalled, "Everything happened at breakneck speed. We prepared the two programs, bought in cutting tools and ordered plastic bar that had to be ground so it would feed through the guide bushes on the sliders. Citizen loaned us a number of milling toolholders that we did not have and we were in production around the clock by the Friday morning.
"Process capability studies were completed, the paper trail put in place and the 9,000 plastic parts were machined, inspected and delivered on the following Monday to meet the contract conditions."
One of the reasons for Sub CNC winning this plastic turn-milling work, as well as subsequent urgent medical contracts, was the option to use LVF chipbreaking software on its Citizen sliding-head lathes. The prevents stringy swarf wrapping itself round the tool and component by oscillating the tool to break the swarf into small pieces.
The two components for Rolls-Royce required the use of sliders capable of turning 32 mm diameter bar. The only machine of this capacity at Sub CNC equipped with LFV is an L32-VIII, which was deployed for producing the most difficult part with drilled and milled features. The other, less challenging component was put on a Cincom M32, with the long swarf broken traditionally using high pressure coolant to prevent machine stoppage.
Overall, about half of the subcontractor's lathes have been made over to producing parts for ventilators and other medical products. The remaining half of the turning capacity serves manufacturers in other industries that are continuing to operate during the Covid-19 crisis.
Co-director Mr Dingley added, "We are fortunate that our activities are split across two sites in Dunstable and one in Luton, so machines are fairly spread out and our operators can socially distance easily. It is a credit to our staff the way they have stepped up to tackle this urgent medical work, which involves coming in at nights and weekends, including over the whole of Easter. Day to day it is more or less business as usual for Sub CNC, except that the workload is unusually high.”