Machined precision

Thorlabs Inc is a 600-employee operation with manufacturing centres in a number of countries, including the UK, at Ely, Cambs. Established 20 years ago, Thorlabs is a broad-based optical technologies company, with its 1,500-page catalogue detailing a product portfolio that extends from simple optical and mechanical components to integrated test and mechanical systems. Each of the company's manufacturing centres focuses on a specific activity, which for the UK is nano-positioning systems for high precision alignment applications, along with optical tables/optical breadboards and full vibration isolation systems. Each centre is responsible for sales of the entire Thorlabs range, but it is the manufacturing specialisation at Ely that lies behind the recent installation of a large capacity 24 hp/200-8000 rpm XYZ BRM 60-200 CNC bridge mill, supplied by XYZ Machine Tools (01823 674200). Image: Manufacturing specialisation demanded the installation of this XYZ machine at Thorlabs This fixed bridge/moving table machine tool is equipped with a 1,600 by 5,080 mm table and has a positional accuracy over 300 mm travel (5080 mm - X axis/1559 mm - Y axis) of ±0.025 mm and a repeatability of 0.01 mm. The requirement at Thorlabs UK mainly involves drilling and tapping hundreds of locating holes in large-scale optical tables/optical breadboards. This is why the new machine is equipped with what Harry Southan, quality and process improvement manager, describes as a 'wine rack', holding imperial and metric multi-tool drilling and tapping heads, each weighing 15 kg. b>ANY ORDER, ANY TIME Optical tables/optical breadboards must provide a rigid and vibration-free base for experiments that could be adversely affected by small vibrations, while also allowing optical equipment to be mounted and positioned with a high degree of accuracy. According to Thorlabs, the best overall performance of an optical table is achieved by a sandwich of clad metal honeycomb, which can be up TO 310 mm in thickness, with the 6 mm thick top plate (or breadboard) drilled and tapped in an imperial or metric grid pattern. "We previously opted for batch production – imperial at the beginning of the week and switching to metric mid-way through the week – and therefore lacked flexibility," says Mr Southan. "If a metric order was placed at the beginning of the week, we couldn't begin machining for two or three days. Now we can schedule in any order, at any time." Five suppliers responded to the initial enquiry, but, according to Mr Southan, "after sending a full specification detailing what we do, what we wanted from a new machine and our expectations, in terms of machine performance, we ended up with a shortlist of two. XYZ was really up for the challenge and the new bridge mill has since given us the performance that we were looking for." The end result is that Thorlabs has already taken out four days of buffer stock, while a flow-based production system has replaced the previous batch-based production. "We can now turn a board around within three days from the moment an order comes in," Mr Southan concludes. Specialist Heat Exchangers is now able to produce components quicker than before, following the installation of a Hartford Mirage vertical machining centre (Ward CNC, 0114 276 5411), but, additionally, the 3 by 1.4 m working surface available on the new machine is also allowing the company to tackle larger workpieces in a single set-up – its previous machine could only Tackle parts up to 2 m in length. Engineering director Mike Evans explains that the investment in the new machine was prompted by the company's need to increase its ability to process larger stainless and mild steel headers (which accommodate tubes and plugs), integral components of the range of industrial heat exchangers produced by the company for blue chip customers the world over. Image: Specialist Heat Exchangers is now able to produce components quicker than before, following the installation of a Hartford Mirage vertical machining centre And while the Hartford performs a range of "fairly simple" drilling, tapping and counterboring operations, he adds that "its overall fantastic specification has cut machining times" through having higher spindle speeds (6,000 rpm via an 18.5/22 kW motor) and feed rates (8,000 mm/min) than the machine it replaced (a unit of mid-90s vintage). South Wales-based Carlisle Brake UK has recently invested in its fifth Doosan horizontal machining centre, supplied by Mills CNC (01926 736736). Carlisle Brake designs, develops and manufactures off-highway braking solutions for agriculture, construction, mining and materials handling vehicles, and is the preferred partner to many of the world's leading OEMs operating in these sectors: Caterpillar, John Deere, New Holland, JCB etc. The company is also becoming increasingly involved in developing advanced braking systems for wind turbines. HIGHER SPINDLE SPEED The most recent Doosan machine is an HP 5500, equipped with 50 taper 12,000 rpm spindle, a 60-tool magazine and a twin (500 mm) pallet configuration. "The latest Doosan, unlike the previous four, is machining aluminium castings [as opposed to grey cast iron] for a new range of booster brake products we have recently introduced, and, as such, was specified with a higher spindle speed rating to help us achieve the higher productivity, reduced part cycle times and shorter lead times required," explains Chris Cudlip, operations manager. "Speed, accuracy and repeatability are critically important to us...and the decision to invest in the latest Doosan was made on the back of the performance of the previous four machines – which has been first-class." Image: Doosan number five for Carlisle Brake machines aluminium castings Aluminium castings are machined in small batches on the new Doosan in a single set-up, using specially designed, tombstone-type fixtures. The aluminium parts do need to be honed, as the machines can hit the required tolerances using boring bars. This means that parts are produced more quickly and do not tie up the honing machines. Bore tolerances are typically down to 0.028 mm and can go down to 0.015 mm, while surface finishes are also required, with Ra 0.5 µm or better being the norm. To help guarantee machining productivity and performance, Carlisle Brake has taken out Mills' comprehensive service contract cover on its five Doosan machines. The cover includes a general maintenance programme, which means that all machines are serviced annually – and a specific maintenance programme for each machine that is controlled, actioned and monitored via a predictive maintenance system. Box item Latest product releases [] Mori Seiki (0844 800 7650) has recently unveiled its new X Series of machines, taking in the NTX1000 mill turn centres, the NHX horizontal machining centres, the NLX2500 CNC lathes, and the NVX5000 vertical machining centres. Improved performance, reduced cost plus improved energy consumption are overriding themes of the new X machines. See full feature article at http://chilp.it/4ad570. Designed for complex prismatic metalcutting applications where component quality is paramount, a new, 5-axis, vertical machining centre (VMC) has been introduced by the Japanese manufacturer, Makino. Image: Part of its X series - the NTX1000 mill-turn centre [] Makino's D500 5-axis, vertical machining centre (NCMT, 020 8398 4277) results from a study of 216 different structural configurations for 5-axis machining centres to identify what the machine tool maker believes to be the ideal design. Linear axis travels are 550, 1,000 and 500 mm in X, Y and Z, respectively, direct drive rotary axes provide 360° table rotation (C) and +30 to -120° in the A-axis rapids. Image: Makino's machine is the result of an investigation of 216 different structural configurations [] Hermle (Geo Kingsbury, 023 9258 0371) has added the C 22 U to its range of vertical spindle machines. The machine offers 3 to 5-axis configurations, as well as different options for table, spindle, tooling, coolant delivery, swarf management and automation. Working envelope is 450 by 600 by 330 mm in X, Y and Z. Image: Hermle's C 22 model is at the smaller end of the range of machines available from the company through Geo KIngsbury First published in Machinery, January 2011