Subcontractor Cleans Components 70 Per Cent Faster, And Cuts Costs

By semi-automating the cleaning and deswarfing of its turned components using a Dürr washing machine from Geo Kingsbury Machine Tools, contract machinist, Unicut Precision, can finish in five hours what used to take 16 hours in a conventional dip tank - a time reduction of around 70 per cent.

The company is also saving labour costs. Previously, a person was employed full-time to lower successive baskets of components into the dip tank, agitate them and subsequently blow any remaining swarf off the components using an airline. Now, after the operator has loaded parts into the Dürr Minio 85C non-halogenated hydrocarbon-based washing machine, the person is free to carry out additional tasks during the automatic washing cycle, which can take up to 20 minutes. Components emerge completely free from oil, grease, swarf and other foreign matter.

The costs of buying the cleaning agent and disposing of it after use have been cut by thousands of pounds a year. Whereas Unicut was using one 208-litre barrel of degreasant per month in its dip tank, only one barrel of Techniclean AS58 per quarter is needed to replenish the Dürr machine, with its continuous vacuum distillation and double filtration of the solvent.

Furthermore, having an enclosed cleaning chamber reduces factory insurance premiums and complies with the latest health and safety regulations.

Commented Jason Nicholson, a director of the Welwyn Garden City-based subcontract firm, "Components we machine are becoming ever more complex and consequently more difficult to clean. Additionally, customers are asking for higher levels of component cleanliness, especially in the aerospace and gas industries where reliability is paramount.

"Before we installed the Dürr machine, delivery of up to 15 per cent of our production output would be delayed because of a bottleneck in the washing department. We often contracted out the more difficult cleaning jobs so that shipments could go out on time.

"Since we started using the Minio 85C, the bottleneck has disappeared. The machine is able to wash in a single shift all of the components produced over two shifts by our 18 CNC sliding-head and fixed-head lathes. In addition, the machine cleans some of the parts produced by our new daughter company, A J Clarke, a precision subcontractor in Bourne End that we bought in early 2006."

Stainless steel, brass and aluminium are mainly processed in the Dürr machine, as well as other materials including plastics. The operator can choose from a menu of eight, editable washing programs comprising combinations of rotary and swivelling movement of the load and injection flood wash, with or without ultrasonics, for various durations and at different temperatures and pressures. Parts come out so clean and polished that customers have commented on the improved cosmetic appearance of their components, occasionally asking if Unicut is machining the parts from different materials than previously.

Conversely, operation of the Dürr washing machine was less successful at the outset, according to Mr Nicholson, despite the equipment being considered as among the best on the market, used by leading manufacturers including major automotive OEMs. It transpired that there was a problem with the relatively high chlorine content of most neat cutting oils used in the UK, compared with those used in Continental Europe.

Only 10 per cent of the cutting oil used by Unicut is soluble, mainly on the bigger diameter bar machines, neat cutting oil being used on all of the smaller capacity lathes including the sliding-head models. It is a better lubricant, resulting in enhanced surface finish and longer tool life, and the absence of water helps to protect the machine bearings and paintwork.

The chlorinated oil used originally by Unicut resulted in hydrochloric acid accumulating in the Dürr system, so the company changed to non-chlorinated cutting oil and there has been no further trouble.

"Geo Kingsbury got on top of the issue straight away", commented Mr Nicholson, "and now that the machine is working as it should, it really eats the work.

"In a very small footprint, it has upgraded our component cleaning function, a key but often undervalued production discipline, and brought it into line with our CNC machining plant, latest inspection equipment and software, in which we have invested over £3 million since 2000."