Effective removal of swarf from narrow, blind holes
A low-cost, aqueous spray wash machine from Turbex is proving ideal for cleaning components manufactured by model railway kit manufacturer, Slaters Plastikard, Matlock. The firm is the second-largest in its sector in the UK and produces the biggest range of model railway wheels in the world.
A long-time user of trichloroethylene (trike) and since 2014 a less aggressive replacement solvent, DuPont 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 commented, “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 runs out this year – so we took the opportunity to upgrade. In August 2016, we got rid of our trike tank and bought the Turbex AV-210 aqueous spray washer, after successful trials at their Alton technical centre.”
Around 80 per cent 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 6 mm in diameter and have drilled and tapped holes ranging from 1.5 mm (80 UNF) to 2.8 mm (6BA) in both ends.
As swarf was so difficult to remove from the 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, as in his words, there are no user-friendly solvents. He rejected ultrasonically-assisted systems, as online user comments inferred that accumulation of significant quantities of swarf in the cleaning tanks tends to deaden the oscillations and reduce their effectiveness.
He already knew of Turbex as a provider of industrial cleaning equipment, as the company is a member of machine tool group, Geo Kingsbury, which delivered a Traub TNL12 sliding-head auto of 16 mm capacity with a gear hobbing attachment to Slaters Plastikard in 2007. A couple of other potential cleaning machine suppliers were also considered.
The decision to purchase the Turbex spray wash machine stemmed from successful trials involving cleaning a selection of different axles. 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 similarly effectively removed.
A feature of the Turbex equipment that Mr White particularly likes is the separator that removes oil from the water, which contains a detergent and a rust inhibitor. It allows the oil to be disposed of safely while the remainder of the process fluid can legally enter the drainage system.
Thousands of different types of turned and milled parts including gears and wheels are processed in batches of up to 1,000-off in the AV-210 machine at a temperature of 60°C. Cycle time varies from 15 to 20 minutes, according to the type and level of soils, and components come out scrupulously 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 so that it can be processed at the same time.
Mr White enthused, “This job can now be done automatically, essentially for free, whereas before it used to take one of our employees a whole day every two to three months to clean the plates, as the deposit on them is a devil to shift.
“The labour cost for carrying out this job is therefore eliminated and the plates come 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 them when contaminated has also been eliminated, saving around £5,000 per year.
Slaters Plastikard now has plenty of spare cleaning capacity and could treble throughput before needing another washing machine. The new process has proved to be a resounding success, saving money and effort as well as keeping employees in the packing department happy, as there is no longer any residual oil on the products.