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Stamping ground for Bruderer high-speed presses
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Since 2000, precision stampings specialist Batten and Allen has invested in seven new, high-speed presses from Bruderer UK, bringing the total on the Cirencester site to 26. All of the latest machines have long beds that allow the use of complex progression tools with multiple stages Currently up to 14 components can be produced at each blow of the press, some of them with very complex forms and extremely tight tolerances, although a 14-station die would typically produce flat, two-dimensional parts These so-called multi-out tools have revolutionised productivity in the manufacture of electrical, electronic, telecommunications, medical and many other components from a wide range of materials in gauges ranging from 50 micron to 1.2mm. The latest machine, a Bruderer BSTA 300-85B, was installed at the end of 2007 and in common with a majority of the presses on site is of 300kN (30 tonf) capacity. A similar number is rated at either 200kN or 250kn (20 or 25 tonf). In 2006, a 500kN (50 tonf) long-bed press was purchased that allowed Batten and Allen to break into heavier gauge parts for the automotive industry. All presses have pallet decoilers and auto recoilers, as nearly all production is automated reel-to-reel stamping. Shawn Batten, managing director, said: 'Being able to accommodate large, multi-out progression tools on the bed of our most recent presses has allowed us to become much more competitive, helping to keep down the prices we charge to customers.' Batten and Allen is unusual in that it runs its own plating facility comprising eight high-speed, reel-to-reel electro plating lines, the latest installed in 2008. Only a very small amount of specialist work involving gold and other precious metals is subcontracted. Another activity that defines the company's service is its in-house design (using SolidWorks CADCAM) and manufacture of tools, mostly of the interchangeable modular variety. The well-equipped toolroom has EDM machines, grinders, mills and machining centres, plus inspection equipment. New in the first half of 2008 was the installation of a fireproof store to protect the tools when they are not in use. Batten added: 'Our customers' components often require forming tolerances as small as 25 microns. 'This requires complex tools and most of our competitors would struggle to hold such tolerances on blanked dimensions, let alone formed features. 'By making our tools in-house, we ensure they are manufactured economically to the highest quality. 'It is in our own interests not to cut corners, as good tools produce longer runs before they need refurbishing, saving costs and maximising the up-time of the Bruderer presses. 'A typical punch/die set might now be run for eight million blows, up from five million a few years ago. 'This is testament not only to the high accuracy and surface finish of our tools, but also to the precision and rigidity of the Bruderer presses, without which the tools would wear faster, irrespective of how good they are.' He added that further benefits of using top quality tools are minimal returns and scrap. The latter is 30 per cent down in the last four years and decreasing from a very low level by 0.1 per cent annually. Some of this improvement can also be attributed to substantial investment in wire erosion, with three new Agie machines purchased in the last three years. Another initiative in recent years was to install a panel of remote on-off switches in the quality control room to enable any of the 24 Bruderer presses on the shop floor to be stopped immediately if inspection results show that parts are starting to drift out of tolerance. Batten said presses running at up to 1,200 strokes/min can produce a lot of scrap in the time it takes someone to walk out to a machine and press the stop button. The Bruderer presses are capable of significantly higher stroke rates, up to 1,800 strokes/min. Batten and Allen constantly tries to increase production rates - another reason to manufacture its own, high precision tools - by experimenting on its 25th press, a 400kN (40 tonf) development machine. However, there is a trade-off between speed and good components and a fine balance has to be struck. Most important is to increase production efficiency, which has risen by an incredible 40 per cent since 2000, according to Mr Batten. It is due to a combination of factors, including the use of longer, high accuracy, multi-out tools, reduced frequency of tool repair and higher stroke rates. Faster set-up of the presses between batch runs is another factor, especially as runs have been getting smaller in recent years as an increasing number of customers demand more frequent, just-in-time supply of lower quantities. These days it is not unusual for a press to be changed over after 10 hours' production. With Bruderer's latest PC-based B-Control system, a full set of modular tools can be exchanged in 20 minutes, three times faster than on earlier machines. As data on each new tool is programmed into the CNC system, it is a simple matter during a repeat run to call up the number of the tool, bolt it onto the press and follow the on-screen prompts to load the program and make the initial and fine adjustments. Operating under Windows NT, the CNC system uses easy-to-follow menus on the colour screen and provides process visualisation, press force measurement with tool protection, capacity for 500 records including data not only on the tool but on the order and material as well, and control of up to 10 NC axes on the press. A mimic of the press can be called up to indicate the location and nature of a fault. It is often not necessary to wait for a service engineer to attend, so the press is back in production faster. Press operation is constantly monitored for double thickness material, mis-pitching or the malfunction of ancillary equipment. Real-time tool monitoring is fitted on the latest BSTA 300-85B press. A full diagnostics package with modem link to the Bruderer factory in Switzerland allows software issues to be dealt with immediately. For inspection of the dimensional accuracy of punched and formed components, the quality control department boasts four Smartscope video measuring machines, including the latest Vantage 250 model and three Zip 250s. All four machines are fitted with real time SPC capability. Plating is checked in the comprehensive in-house laboratory for environmental testing and on Fischer XRF equipment, which also automatically produces SPC results and RoHS screening. A commitment to quality is part of Batten and Allen's culture. Its comprehensive inspection systems are based on total traceability throughout the whole manufacturing process - a policy that has helped the company to earn EN ISO 9001:2000 and ISO 14001 approvals. Interestingly, the quality assurance function is not departmentalised. One in eight of the workforce is dedicated to inspection on a sample basis, the frequency depending on the complexity of the part and the value of the material. http://www.manufacturingtalk.com/news/bra/bra123.html |
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