Heavy-duty grinder delivers increased flexibility

Now under the wings of Senior PLC as a member of its Flexonics Division, LPE is continuing to invest and diversify as well as increasing the capacity for existing customers within the oil and gas, telecommunications, aerospace and defence, land and sea systems, nuclear and marine industries.

In the past 12 months LPE, which is accredited to ISO 14001 and 18001 and working towards AS9100, has opened a second manufacturing location. This additional 30,000ft² facility takes total floorspace to 121,000ft² and enhances the company’s ability to project manage large, low-volume components on machines with up to 4m capacity as well as higher volume work on two flexible machining systems.

LPE’s work tends to be high-tech, high-added value, metalworking with difficult to machine materials to tight tolerances. Within the new facility is a purpose-built, temperature-controlled, environment for its latest machine tool investment, a Danobat HG-72-3000-B11, a universal heavy-duty grinding machine.

This 3,000mm between centres machine is capable of grinding diameters up to 640mm weighing up to 1.5 tonnes. The integrated torque motor on the CNC-controlled B-axis allows the machine to carry out a wide range of grinding functions, including external and internal thread grinding. The machine’s wheelhead is powered by a 45kW motor that generates speeds of up to 45m/minute on the machine with a maximum wheel diameter of 610mm.

The new Danobat machine was purchased to support a long-term commitment to a longstanding customer, which will be part of a 10-year project. While this work takes priority the additional capacity created will allow new work, that couldn’t previously be ground, to be won.

“The Danobat HG-72-3000-B11 is probably the largest capacity universal CNC grinder available for subcontract work in the UK and this should open up a number of opportunities for us. It is also a very accurate machine that will allow us to grind very large components, many with thin wall sections, to tolerances of 0.01mm,” says Nathan Davies, new product development manager.

While LPE already had a wide range of grinders at its disposal, this is the first Danobat machine that it has purchased. Mr Davies was intending to ‘stick with what he knew’, however, a visit to the Danobat factory convinced him it was time for a change.

“We gave our existing supplier and Danobat three challenging parts to look at, and while the former would only talk about additional costs involved, Danobat simply got on with developing the process. They provided additional cycles for internal thread grinding including probing cycles and committed to working closely with us throughout the project. Some of the parts have bores up to 1.1m deep with wall thicknesses down to 2mm. We are now able to grind these to tolerances of 0.02mm concentricity and 0.01mm on diameter to surface finishes of 0.4Ra.

“Danobat took on responsibility from start to finish and offered solutions to problems, not simply fixed ideas. This gave us the confidence that we had chosen the right supplier.”

To cover all internal grinding applications LPE ordered five spindles, with one having the shaft manufactured from carbon fibre, due to the extreme diameter to length ratio. Also fitted to the Danobat HG-72-3000-B11 grinder is an MDM Danobat Absolute Measuring Unit. This is designed for in-process gauging and enables LPE to measure a wide variety of diameters whether they are solid or intermittent surfaces. Once the grinding cycle is complete, before removing the part from between centres, it can check, post-process, for diameter, faces and geometry within the complete mechanical working range of the machine.

Typical of the partnership between LPE and Danobat were specific machine modifications that were made, such as a dual coolant system that allows LPE to quickly switch from the ‘clean’ coolant required for its long-term customer’s work to regular coolant for general work. The machine’s internal covers are also manufactured from stainless steel to prevent contamination of parts. Service support was also a vital element in the decision making process and the fact that Danobat has UK-based service engineers was further reassurance for Mr Davies.

“Working with Danobat has been an unexpected bonus. Their engineers were willing to change and develop ideas in partnership with us and, while the price of the machine was important, and we presented them with a lot of ‘what if’ scenarios, they took them all in their stride, gave us a fixed price for the machine. This included software support in terms of writing new grinding cycles if we need them during the first 12 months.

“We added to the pressure further by not being able to fully divulge many of the part details in the early stages due to confidentiality clauses. However, when our customer put pressure on us to commence manufacturing Danobat brought delivery of the machine forward by two months.”

DANOBAT
www.danobatgroup.com