A low-cost aqueous spray wash machine is proving ideal for cleaning components manufactured by model railway specialist Slaters Plastikard. The Matlock-based firm produces the world’s biggest range of model railway wheels.

A long-time user of trichloroethylene (‘trike’), and since 2014 a less aggressive replacement solvent (DuPont’s Vertrel Sion), Slaters Plastikard previously degreased and ‘deswarfed’ components at room temperature by manually dunking a basket of them repeatedly into a tank housed in a ‘fume cupboard’.

Owner and managing director David White said: “It worked well enough for many years, but I was never really comfortable with the potential health risks to our staff, even though they wore a charcoal filter mask and gloves.

Then legislation was introduced that greatly restricted the use of trike.

“Our licence to use that fluid runs out this year, so we took the opportunity to upgrade. In August last year, we got rid of our trike tank and bought a Turbex AV-210 aqueous spray washer, after successful trials at the company’s Alton technical centre.”

About 80% of Slaters Plastikard’s components — including axles, gears and wheels — are turned from brass or steel bar (the remaining parts, such as gearbox housings, are prismatically machined).

Turned axles are especially difficult to ‘deswarf’, as the shafts are from 3 to 6mm in diameter and have drilled and tapped holes ranging from 1.5mm (80UNF) to 2.8mm (6BA) in both ends.

Because swarf was so difficult to remove from these blind holes, an employee had to twist a tap by hand into both ends of every axle after machining to ensure that the threads were clear; half of them were not.

So when the time came to upgrade the cleaning process, assistant works manager Mark Hopkinson spent a lot of time
on the Internet researching aqueous washing equipment, because “there are no user-friendly solvents”.

He rejected ultrasonically-assisted systems, because on-line user comments implied that the accumulation of swarf in the cleaning tanks tends to ‘deaden the oscillations’ and reduce their effectiveness.

He already knew of Turbex Ltd (www. turbex.co.uk) as a provider of industrial cleaning equipment, because the company is a member of the Geo Kingsbury machine tool group, which delivered a 16mm-capacity Traub TNL12 sliding-head auto with a gear-hobbing attachment to Slaters Plastikard in 2007.

A couple of other potential cleaning machine suppliers were also considered.

Successful trials

The decision to purchase the Turbex spray wash machine stemmed from successful trials that involved cleaning a selection of different axles, using water that contains a detergent and a rust inhibitor.

There was no swarf in any of the threads after processing, and all traces of neat oil from machining in the sliding-head lathe had disappeared. Soluble oil residue from fixed-head turning and milling was also effectively removed.

A feature of the Turbex equipment that Mr White particularly likes is the separator, which removes oil from the water. This allows the oil to be disposed of safely, while the remainder of the process fluid can be legally disposed of via the drainage system.

Thousands of different types of turned and milled parts, including gears and wheels, are processed in batches up to 1,000-off in the AV-210 machine at a temperature of 60°C.

Cycle times vary from 15 to 20min, according to the type and level of ‘soils’ — and components come out both clean and dry.

An added benefit of the machine, which was unexpected and has proved to be a big saving, is the ability to clean an electrostatic baffle plate from the sliding-head lathe by placing it on a top wash tray, allowing it to be processed at the same time as components.

Mr White said: “This job can now be done automatically, essentially for free; previously, it took one of our employees a whole day every two to three months to clean the plate, as the deposit on it is difficult to shift.

The labour cost for carrying out this job has been eliminated, and the plate comes out looking like new.”

On the subject of cost savings, he added that the expense of buying trike — or its DuPont equivalent — and of disposing of it when contaminated has also been eliminated, saving around £5,000 per year.

Slaters Plastikard now has plenty of spare cleaning capacity and could treble its throughput before needing another washing machine.

The new cleaning process has proved to be a resounding success, not only saving money but also keeping employees in the packing department happy, as there is no longer any residual oil on the products.