For a small sub-contractor, buying a new machine tool is something that takes a degree of commitment, with everything needing to be ‘just so’ before proceeding with a major capital investment — as was the case with Heywood and Palmer, a specialist provider of precision and production grinding.
The Ashton under Lyne-based company has built a reputation for delivering high-quality ground components to a wide range of companies, with the emphasis on achieving the highest possible quality and meeting — or exceeding — the stringent delivery schedules required by the customer. Formed in 1989, Heywood and Palmer built up a range of machines capable of grinding diameters up to 350mm, with a maximum between-centres distance of 1m. In later years, when there was an increasing demand for the precision grinding of larger and more-varied components, the company had to decline this work.
In 2008, managing director Keith Palmer considered acquiring additional capacity, with the emphasis on grinding larger components. “We knew that we were limited in choice when it came to a machine that would give us the capacity we required and fit in the limited space we had available. RK International took us to see the Italian grinding machine manufacturer Robbi; and following lengthy discussions with RK International’s Dick Aldrich, it became apparent that Robbi could manufacture a universal grinding machine tailor-made to our specifications. The two companies couldn’t have been more helpful, but something held me back from signing the order. As it turned out, the financial crash was just around the corner.”
Back on track
Having worked through the fall-out from the financial crisis, business was soon back on track at Heywood and Palmer, and the demand for grinding larger components was still there. Erith-based RK International
(www.rk-int.com) arranged a second visit to Robbi, and an order for a Robbi Omicron CNC3615 universal grinder was placed in March 2012; the machine can grind up to 1.5m between centres and has a swing of 455mm.
Fitting a machine with this capacity into Heywood and Palmer’s machine shop would be a challenge, as it needed a floor space of 5.6 x 2.2m (more than any other machine the company possessed), but it was the machine’s height that could well have been the stumbling block, as Mr Palmer recalls.
“When we visited Robbi for training, it was apparent that there would be only a minimum of clearance between the top of the electrical cabinet and the ceiling where the machine was to be installed. When I pointed this out to Robbi, they couldn’t have been more helpful, removing the cabinet and repositioning it without any fuss whatsoever.” This ‘can do’ attitude of the teams from Robbi and RK International extended to the delivery of the machine. Due to the restricted access to the space allocated for this machine, it could not be delivered fully assembled.
RK International engineers visited the site, taking detailed measurements and many photographs in order to make sure that delivery and installation would go smoothly and with minimal disruption. The machine was first delivered to RK International, where it was stripped down to more-manageable sections, then re-assembled at Heywood and Palmer in October 2012.
More enquiries
Mr Palmer says: “Since we’ve had the machine, we have taken on work that we couldn’t have done before — and the level of enquiries is growing. This machine replaced an older grinder with which we struggled to achieve the accuracies that customers were demanding. To replace it, we needed a sturdier and heavier machine; with the Robbi, we got what is almost a bespoke machine, but at an extremely competitive price.”
The Robbi Omicron CNC3615 features a traditional cast-iron structure with hardened and ground slideways, and with longitudinal movement of the table controlled by a centrally positioned recirculating ballscrew. Moreover, the robust build of this machine means that, in most cases, foundations are not required. Its sturdy construction is also evident in the work-head and wheel-head, the latter housing a hydrodynamic spindle.
Positioning of the wheel-head is via a brushless motor that moves the screw and gives a positioning accuracy of 0.001mm over the 250mm stroke length. Control of the machine is provided by a Siemens 840Di sl control system with remote monitoring; it allows full control via programs or can be used as a teach-type system when required. “We have found the machine extremely easy to program and set up,” says Mr Palmer.
“The software is extremely user-friendly and appears to have been written by engineers for engineers. At first, we thought we knew better, given all of our grinding experience, but we quickly realised that the machine’s built-in cycles were much more efficient in terms of cycle and set-up. The Robbi is also allowing us to meet the ever tighter tolerances customers are demanding. For example, one job with a 400mm outside diameter and a 320mm bore has to be ground to a 20µm tolerance, with 15µm for squareness.
“This would have been extremely difficult to achieve before we installed the Robbi machine, but now we just get on with it. We are also pleased that the machine has been trouble-free in its operation. There have only been three occasions when we have had to call for help, all of which related to our lack of understanding of the machine. One of those occasions involved speaking with our contact at Robbi in Italy — at eight in the evening — to ask a specific question. He went to the factory, logged into our control and sorted the problem there and then. The only other two calls were to RK International, and both were also dealt with via the remote monitoring system.”