Since the mid-1980s, All Gear Services — based in Finch-ampstead, Berkshire — has been making high-quality gears and related products for motor-sport gearboxes and commercial applications. Various materials are processed, including case-hardening steel, stainless steels for marine applications and aluminium for pulleys. Batch sizes range from a one-off gear to repair a broken-down machine to volume manufacture for the motor industry.
As the business grew, Steve Cooper and his co-directors were in the position of turning and gear-cutting in-house while sub-contracting out most other work, which included heat treatment, grinding, milling and super-finishing; the latter operation polishes gears to reduce vibration and extend the life of racing-car gearboxes.
However, All Gear’s approach to gear finishing changed when Mr Cooper went to MACH 2014 and visited the stand of PDJ Vibro Ltd (
www.pdjvibro.co.uk), where he spoke to company director Paul Hurley. The meeting was prompted by the demise of an old drum-type rumbler that was used for cleaning heat-treated steel parts.
Following the meeting, gears were sent to PDJ Vibro’s technical centre in Bletchley for descaling, deburring and edge-breaking in vibratory bowls operated by the company’s sub-contract division. However, as it is Mr Cooper’s policy to bring in-house as many processes as possible, be bought a 300-litre capacity vibratory-bowl finishing machine from PDJ Vibro’s economy range at the end of 2014.
Filled with a ceramic medium, it has cut the processing time from 10hr in the old rumbler to just 4hr — and drastically improved the finish on component surfaces. Moreover, the size of the vibratory machine means that up to 80 parts can be processed at a time, cutting the previous daily rumbling operations to one or two vibratory processes a week.
About 75% of All Gear’s heat-treated components are now finished in the vibratory bowl; only clutch shafts and drive shafts that are too long for the bowl are cleaned by hand. Some of the gears and shafts that are not heat-treated (these account for some 40% of production) are processed in the bowl for a shorter period for deburring and surface improvement.
Mr Cooper says: “Stainless steel is a relatively soft material that tends to burr during machining. After putting these components in the vibratory bowl for an hour, the burrs are removed and the finish becomes lustrous. The appearance is fantastic, and customers often comment on how much better the gears now look. We could process our aluminium gears in the same way, but we would need to change the ceramic medium used; and as aluminium is shiny anyway and often anodised, so far we have opted not to put them in the vibratory bowl.”
On the recommendation of PDJ Vibro, All Gear will be modifying its economy vibratory bowl by adding a switch that reverses the toroidal action of the ceramic medium. This has the effect of bringing components to the surface after processing, making them easier to remove. A timer will also be fitted; this will allow the finishing process to begin in the early hours of the morning so that it will be complete when staff arrive for work.
Super-finishing
Of the components supplied to motor-sport customers (these account for about half of All Gear’s business), 60% are super-finished, although this proportion is continually increasing as teams become aware of the benefits of reducing friction in transmissions — namely increased speed and lower maintenance costs.
Mr Cooper previously sent gears and shafts to a firm specialising in acid-isotropic super-finishing; and while PDJ Vibro sells new machines that use this process — and offers this in its sub-contract department — this method of super-finishing tends to be aggressive, eroding metal surfaces and affecting the accuracy of components.
The company normally recommends the ‘porcelain and paste’ option for super-finishing in a vibratory bowl, as this polishes surfaces efficiently without removing any discernible amount of metal. Mr Cooper sent sample parts to PDJ Vibro for trial processing using this method and was so impressed that all super-finishing is now done this way in the sub-contract facility at Bletchley.
That said, Mr Cooper will be installing a second 300-litre vibratory bowl this year, filled with the appropriate medium for super-finishing; he will thereby complete the re-balancing of production between in-house resource and bought-in sub-contract services.
Previously sub-contracted milling to produce the dogs on the reverse of gears was brought in-house last year, when the company bought a Hurco VM10i machining centre. That said, grinding will continue to be sent to GP Precision in Finchampstead, and TTI in Luton will remain the preferred supplier for heat treatment.