Productivity edge

Sub-contractor GPR, Camberley, Surrey, installed new Haas machine tools and its previous choice of ITC cutting tools, which had already brought productivity benefits to the company, was again positively underlined, as the firm moved from its 7,000 rpm spindle capability to the 12,000 rpm figure, offered by the Haas machines. Image: ITC cutters complemented higher spindle speed Haas machines at GPR Late in 2008, GPR won a contract to produce almost 4,800 instrument cases. Despite only running one shift, the company operates its Haas VF2 and Mini Mill for up to 18 hours a day, 5 days a week, to produce over 450 cases per month. "To operate our machines unmanned takes a lot of confidence in our machines and tooling – the ITC cutters give us that confidence," says GPR's technical and quality manager, Vernon Ward. "The tool life of the cutters has been nothing short of phenomenal. We are only now on our second 12 mm diameter Hanita 49N9 ripper. Considering the tool has been part of a cycle running almost 18 hours a day since September, at 1XD depth of cut and a 7 m/min feed, this is remarkable. "We have a number of jigs that enable us to put four billets on the machine bed at any one time, with 4 parts being machined from each billet (16 parts). While we machine the backs on the VF2, the Mini Mill conducts the end and side operations. As unmanned machining is a necessity for us to fulfil the order, every cutting tool on the job is from ITC, with the exception of thread milling tools." The aluminium components were previously machined with tools provided by an alternate supplier, but these continually failed, it is stated and were incapable of working at the available12,000 rpm. "The performance of our previous tooling was inconsistent and unreliable. So we implemented a full program of ITC tooling. This enhanced cycle times, reduced downtime and, most noticeably, improved surface finishes and component quality," Mr Ward further explained. "We reduced our cycle times for 16 parts from over 10 hours to 8.5 hours, by implementing standard ITC cutters. What then impressed us was the ITC representatives' customer care and attention to detail. Our ITC representative, Dave Cleeve, reviewed the process and suggested we try some of the new Hanita 5103 Alusurf range of cutters. We introduced the 3 and 6mm diameter, three-flute slot cutters, as well as the 4 and 5 mm diameter ITC 2052 Series two-flute cutters. This further reduced our cycle time from 8.5 hours to 7.25 hours. With batches of 450 per month and a total of 4,800 parts, the saving over the life of the job is over 800 hours." The ITC cutters are complemented on the cases by a number of Hanita slot cutters. GPR utilises the 49N9 Series of ripper cutters, as well as the 7N22 1 mm and 2 mm diameter long series slot cutters. "We had a problem pocket milling with previous cutters, as they were either too long or too short. The cutters that were too long gave us considerable chatter that led to poor tool life and an imperfect surface finish. The Hanita tools are the ideal length and they have improved the processes measurably." In Austria, a somewhat physically larger challenge was faced by tooling and carbide specialist LMT Boehlerit (sister to LMT UK). The company was called upon by fellow Austrian company, machine tool builder Weingärtner Maschinenbau, which had been charged to tool up a turn-milling process on its Multi-Product Machining Center to produce 7 m long ships' engine crankshafts having a swing of 1 m. For LMT Boehlerit, the challenge was to develop a milling cutter that would be able to side mill the full length of the web face of each forged steel crankshaft at a 5 mm depth of cut. It also had to accommodate the progressive increase in spiral orbit from the minimum diameter at the journal to the full apex of the 'throw' as the crankshaft is rotated in the spindle of the lathe. There were further technicalities that LMT Boehlerit engineers had to address in the process, because, as the web of the crankshaft is swung past the rotating milling cutter, the circumferential speed varies significantly, due to the length of the throw in contact with the tool, which also means the shank end of the tool is subjected to a far greater feed rate and chip size than at its free end. LMT's solution was to develop an endmill style of cutter having a 120 mm diameter and 300 mm in length, which is able to carry 80 cartridges for the square inserts on its periphery that are able to manage a cross-sectional cut area up to 15 cm². Image: LMT's cutters' insert spacings may look random, but there's a science behind it As a result, the positioning of individual inserts became a critical factor in the design of the cutter and while at first sight they appear to be totally random, each is strategically arranged to account accurately for the varying contact area, according to the rotation of the component. The positioning of the inserts also accommodates any rate of change in the circumferential speed of the web of the crankshaft, right across the length of the tool. Box Item 1 Steering a course for profit Steering system manufacturer Ognibene, Italy, is relying on cutting tools from Ceratizit for milling operations. Already a real breakthrough in production has resulted from the Ceratizit MaxiMill HEC milling system being fitted to all four of Ognibene's CNC Makino machining centre lines. The result is a 25 per cent increase in production and a 39 per cent cost saving, when compared to previous methods. Image: Ognibene rely on cutting tools, from Ceratizit, for manufacturing their steering system components "We were looking for ways to optimise the production of a special component made from GS400, of which we produce about 200,000 pieces per year," says Francesco D'Agostino, process engineer at the €73 million turnover company. "The HEC system from Ceratizit allows us to increase cutting data when rough milling." Data now includes cutting depth of 3.5 mm at a surface speed of 800 m/min, relating to 5,000 rpm, at a feed rate of 0.15 mm/tooth, which gives a traverse rate of 4,500 mm/min. Box Item 2 Fiat chooses Sandvik Capto Fiat Powertrain Technologies (FPT) recently took delivery of 54 CNC lathes equipped with Coromant Capto toolholding systems from Sandvik Coromant. The deal came about following a 12-month period of co-operation between the Sandvik Coromant teams in Germany and Italy, and machine tool maker JG Weisser. The project originated because FPT was planning to refit its Verrone factory, ready for the production of a new type of transmission. FPT is a significant player globally, with annual production of approximately 3.1 million engines and some 2.5 million transmissions and axles. To date, Weisser has installed 32 of its lathes, with the remaining 22 due for delivery next year. The tooling order includes standard and special turning and milling tools, using Coromant Capto as the modular toolholding system for most machines and HSK63 for the centre-facing machines. A Sandvik Coromant team is continuing work with FPT to assist with machining cycles and standardise methods; later, the team will help fine-tune the production processes. Overall, the project is likely to last until the end of this year. First published in Machinery, November 2009