The need to add more capacity while also having the benefits of precision and programming flexibility provided by CNC has resulted in HB Bearings Ltd installing an additional Kellenberger Vista universal grinding machine.
The Huddersfield-based company, one of the UK’s foremost bearing designers and manufacturers, specialises in very-high-precision low-volume bearing production for ‘highly targeted’ industries.
Established almost 50 years ago, HB Bearings has a global customer base and an archive of bearing design specifications, drawings and data that is ‘probably unsurpassed in Europe’.
Managing director Graham Hirst said: “A highly skilled workforce and a commitment to quality are obviously vital, but we have always been prepared to invest in ‘state of the art’ machine tools, and this latest Kellenberger — our fourth CNC grinder — is testimony to that.”
Mr Hirst added that more investment is imminent. “HB has recently acquired Gamet Bearings, which is a renowned manufacturer of super-precision taper-roller bearings.
“We are relocating the Gamet operations from Colchester to our Huddersfield site, and further investment in high-precision grinding capacity will be necessary.
“As we are working to 1.5µm running accuracy tolerances on Gamet products, we will be looking to invest in additional Vista CNC machines, such is our confidence in them.”
HB Bearings has three Vista UR 75/1000 CNC machines — now joined by the Vista SE — all of which have been supplied by Rugby-based Jones & Shipman Hardinge Ltd (www.hardinge.com
), the UK subsidiary of Hardinge Inc.
Based on the UR 75, but with enhancements to the guarding and the control package, the Vista SE machine features a ‘UR’ wheel-head for external, internal and face grinding.
This swivelling wheel-head features pre-stressed high-precision spindle bearings to ensure that the highest levels of surface finish can be maintained, along with long operational life.
Moreover, the machine can undertake grinding between dead centres, as well as chucked work. HB Bearings also specified an HF dresser on the upper (X-axis) table.
Designed to be a cost-effective CNC alternative to hydraulically controlled cylindrical grinders, Vista machines offer a simplified programming sequence, thanks to the Kellenberger Kel-Easy and Kel-Iso menu-based system that is integrated in the Fanuc 0i control system.
Key machine features include the ability to ‘micro-adjust’ the tailstock in the range ±60µm, linear guides on the X axis, a ‘classical’ slide arrangement for the Z axis, and the ability to accommodate workpieces weighing up to 100kg.
As the designation implies, the distance between centres on the Kellenberger machines supplied to HB Bearings is 1,000mm, as is the grinding length.
Other features of these compact machines include a coolant tray that is separated from the machine base, an integrated transport system and a swivelling upper table.
Furthermore, the use of ‘thermally optimised’ bearings ensures the highest levels of roundness and dimensional accuracy.
Mr Hirst added: “We purchased the Vista SE to accommodate an increasing workload; and given our previous positive operating experience with the Vistas, it was an easy choice — particularly as they offer the sustained accuracy that is so essential to our business.
“The norm we work with is 5µm, but we can meet demands down to 2µm if needed.
“Moreover, all our Vistas are capable of grinding highly complex high-precision profiles while maintaining the tightest of tolerances, as well as the highest levels of accuracy of concentricity — all vital to our products.”
The materials machined by HB Bearings are usually based on SAE 52100, although certain motor-sport applications may require more-specialised bearing steel, such as AMS6444 (52100 VIM-VAR) — a ‘super-clean steel’ that is also used for the manufacture of special bearings.
Occasionally, materials such as Cronidur are used; this has a level of corrosion resistance that exceeds 52100 by a factor of 8-10.
“The common denominator with all the materials we process is that they are difficult to machine, while achieving the micron tolerances and exact repeatability.
“Our Kellenberger machines have been more than up to the challenge — an excellent investment.”