Providing a specialist design, manufacture and refurbishment service for gears, couplings and gearboxes, DePe Gear Co UK has developed its business through a combination of skills and investment in the latest manufacturing technology.

With an ability to grind gears up to 1,250mm in diameter and cut gears up to 2,500mm in diameter, the Stoke on Trent company has built a strong customer base across industries that include rail, energy, aerospace, steel-processing, mining and quarrying.

Its latest investment — in a Robbi Omicron CNC6015 universal grinding machine from Erith-based RK International Machine Tools Ltd (www.rk-int.com) — is part of a drive for greater versatility and productivity.

With its focus on one-off and low-volume production (typically 50-off), DePe Gears requires its production facility to be both efficient and flexible.

However, for internal and external grinding, the company had been relying on dedicated manual machines that did not offer the efficiency required.

The challenge for DePe Gears — and director Nigel Parker — was to find a universal grinder that met all of the company’s criteria: “We needed a machine with sufficient swing and weight-carrying capacity for the work that we undertake, as well as a single internal grinding head and two external heads.

“Every supplier we contacted was unable to meet our needs. At that point, we hadn’t spoken to RK International, but one of the suppliers that had declined to quote suggested it might be able to help.”

Discussions quickly progressed; and using a Robbi Omicron CNC6015 universal grinder as the base machine for the project, RK International and the Italian company Robbi set about creating a bespoke machine that would fulfil 90% of DePe Gears’ requirements.

The basic specification of the Omicron 6015 includes a maximum grinding length of 1,600mm, the ability to hold up to 1,200kg between centres, and a maximum centre height of 300mm.

Machine modifications

The changes made to suit DePe’s requirements included a purpose-built 500Nm work-head with a special bearing configuration (based on Gamet bearings) that gave a weight capacity of 300kg at a distance of 150mm from the spindle nose.

To handle the weight and size of DePe Gears’ components, a special quill was manufactured and the centre height was increased to 350mm.

RK International director Dick Aldrich said: “Most customers have a requirement for 90% external grinding and 10% internal; at DePe Gears, the ratio was closer to 40/60.

“To meet the challenges posed by this, along with the wide variance in bore sizes to be ground, we used a direct-drive 21kW 30,000rev/min internal grinding spindle.

“We also installed power sensors, as the spindle speeds and bore sizes meant that sound sensors alone would not be sufficient to monitor wheel contact.”

Other modifications to DePe Gears’ machine included the fitting of linear scales and incremental linear encoders to all axes, adding a secondary right-hand external grinding wheel, automatic wheel balancing and gap control with in-cycle dressing, Renishaw probing and a 2.5deg indexing facility with a Hirth coupling.

Mr Parker said: “The ease with which we were able to work with RK International made the whole process straightforward; we now have a machine that has replaced two older dedicated machines and brought greater efficiency to our manufacturing process.

“Moreover, having the Robbi Omicron machine has allowed us to free up not only manpower and labour hours, but also floor-space that we can use for further investment in our production processes.”

Capturing experience

The physical attributes of the Robbi Omicron machine were not the only elements that were adapted for DePe Gears.

CNC has played a major role in the company’s production when it comes to turning, milling and gear form production, but internal and external grinding had always been a manual process, which resulted in DePe Gears amassing a vast amount of knowledge and experience over the years.

Working with RK International, the company has started to digitise that knowledge within the software used by the Siemens 840D sl control system.

Mr Parker said: “Working this way is allowing us to transfer our manual skills and knowledge to the CNC.

“The changes being made to the software will eliminate any problems that could arise from operators interpreting processes differently.

“In short, by eliminating manual input, we will generate improved consistency in terms of product quality.”

In conclusion, Mr Aldrich said: “We had not previously had the opportunity to work with DePe Gears, so we were as new to them as they were to us, but by developing a strong relationship, we have had positive three-way communications between ourselves, Robbi and DePe Gears.

“This has smoothed out any issues and allowed us to deliver a machine that is adding to the company’s capabilities.

“Shortly after the machine was installed, DePe Gears allowed us to use it for a demonstration to another customer, which is an indication of how closely we can work together and the strength of the business relationship.”