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Contacted by a longstanding customer to help produce a first batch of components destined for use in the Large Hadron Collider (LHC), the world’s largest particle accelerator at Cern Laboratory near Geneva, Kent- based subcontractor Inca Geometric was commissioned to produce a series of key positional holes just 3mm diameter through 177mm thick plate. With a depth to diameter ratio of nearly 30:1, drill wander was a real concern as Solutions reports.
forms and cutouts around the part’s periphery.
The initial order for six 800mm by 400mm blanks made from EN 100 involved the plough ground plates being loaded to Inca’s Mazak VTC-300C- ll travelling column vertical machining centre where two datum edges were milled for process location and the 3mm diameter holes drilled. Once complete the components were shipped to the customer for its EDM operations to be performed and then returned to Inca for a series of milled cut outs and drilled and tapped holes to be produced around the outer profile.
Due to the depth-to-diameter ratio of the 3mm holes reaching
he drilling operation was to enable the wire EDM profiling of a complex series of
almost 30:1, Inca was naturally concerned over possible errors caused by drill wander and especially any drill breakage in the hole so it called in its primary tool supplier Sumitomo Electric Hardmetal. As a result, a trial of the tooling company’s latest Super Multi-drill XHT was set-up and when the application was discussed in detail, it was decided to drill each hole to a set depth and then turn the component over, reposition against the datum and then drill to break through in the centre.
The Super Multi-drill XHT has been specifically developed to incorporate Sumitomo’s totally new HT cutting geometry that introduces a ‘Double Margin’ on the leading edge and heel of the tool land. This feature adds stability to the tool when applied in deep hole drilling cycles and lowers the level of thrust required from the machine drive system.
In addition, the new tool geometry helps to reduce the size of chips produced which are then more effectively evacuated through the special design of fluting on the tool. As a result and as proven in the Inca trials, the likelihood of drill wander is reduced which was a help for the precise targeting from hole to hole breakthrough some 90mm inside the part. Also, the Sumitomo Super ZX low friction, multi-layer TiAlN/ Al CrN PVD nano coating,
which requires a minimal level of through-the-tool coolant feed, helps to extend the in-cut life and, while this was not a priority in this application, enable higher penetration rates to be maintained.
Using a Sumitomo MDW-PHT pilot hole drill to ensure the start position and create a ‘bushing’ to stabilise the initial penetration and acceleration of the tool, the Multi-drill was run at 8,500rpm and at a feed rate of 0.06 mm/ revolution. Says Tony Clifford, Inca’s works manager: “As we only had six blocks to produce with six holes on each side, initially it was leadtime that was of the essence. We drilled to depth on one side, relocated the part and just before we reached the breakthrough of the two drilled holes from the second side, took the precaution of going into hand feed on the Mazak. This was to ensure there was no snagging that might cause the tool to break as it was such a small diameter. When we checked the breakthrough we were very surprised how straight each hole had been produced and even after a combined drilling depth of some 6,500mm covering the complete batch, we found any wear on the tool was minimal.”
Inca Geometric which has its 18,000ft² machine shop in Chartham, near Canterbury is a special purpose machine
tool and general engineering subcontractor covering a wide area of engineering skills. It was set up in 1956 to design and produce multi-drill heads and in the mid-1960s it added subcontract machining services for an automotive pump manufacturer. It then progressed into retooling and the design and build of special purpose machine tools that were sold around the world.
Inca still retains its special purpose design and retooling capability while subcontract machining services, which supplies assemblies and components from miniature ball stops used in gaming machines to fabricated and machined generator bed frames some 6m by 2m, has become an important revenue earner. This was substantiated in 2010 when it invested over £500,000 in new machine tools which included the 4-axis Mazak VTC-300C- ll travelling column vertical machining centre with strokes of 1,740mm x 760mm x 660mm and a 2,000mm by 760mm table.
Due to the wide variety of work passing through in support of its customers in the automotive, off road, pump and valve, defence, leisure, oil and gas and
general engineering, tool supply and close support is viewed as a necessity. “We have the same working relationship with Sumitomo for the supply of most of our turning, milling, drilling and threading tooling as we have with our key customers,” Mr Clifford explains. He adds: “Quite often jobs can be rushed due to emergency breakdowns at customer plants or we are faced with specific problems such as when milling and drilling large stainless blades.” But he maintains that floor-to-floor times are not always the most critical, while service and support to obtain the right tooling is vital. “What we need and are getting from Sumitomo is first class quality and cutting ability and the performance of tools which are very predictable.” Following the machining of the blocks for the LHC the Super Multi-drill XHT was returned to Sumitomo at Princes Risborough for regrinding and recoating so it was in ‘as new’ condition ready for the next batch of parts.
Diamond Tools for Cutting Composites
Circular saws now extend to 19 - 1,000mm.
Routers for piercing & trimming.
Holesaws with a variety of ejection mechanisms.
Jigsaw blades to suit all popular jigsaw machines.
chamfering and radiusing.
Bandsaw blades made to order.
Countersinks with high speed steel & carbide pilot drills.
Applications include: Aerospace, Wind Turbines, Wall Cladding, Boatbuilding & Formula 1
Cranden Diamond Products Ltd Mounts Hill, Benenden, Cranbrook, Kent TN17 4ET, UK
Tel: 00 44 1580 241252, Fax: 00 44 1580 241838
Email:
info@diamondtoolsuk.com Web:
www.cranden-diamond.com
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