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EdgeCAM Cuts Saw Point Programming Times 

ONTARIO, Calif. AUGUST 16, 2000 Ernest Bennett Saws is one of the UK's leading manufacturers of specialist circular saw blades. The company has over 7,000 designs of blade variants in its portfolio while over 90 per cent of its business involves custom manufacturing. However, following the installation of the EdgeCAM off-line programming system from Pathtrace, the company has been able to significantly streamline its production routines. Blade manufacture is a complex, multistage process often embracing a high degree of customizing to meet the application needs of individual users and the materials they work with. Tasks, such as the laser profiling of saw blanks previously, took over half an hour to program and now can be performed in just two minutes. The efficiency of EdgeCAM is such that, for a repeat order, it can be quicker to draw and program a blade from scratch than to look up a previous drawing! Founded in 1956, Sheffield-based Ernest Bennett Saws has facilities in New Hampshire, where over 140 are employed. Managing Director and son of the founder, Martin Bennett, points out: "Far from being a mass-produced item, we often manufacture in batches of between one to five for a wide customer base. These range from companies involved in metalworking, through kitchen cabinets. The saw is critical to their production process, for if the saw stops, the whole production line stops. So, while we hold certain stock for many customers, we need to minimize our financial exposure and keep our lead times as short as possible while maintaining high levels of customer service. "Martin Bennett points out that there is little scope for reducing actual manufacturing times because automation is difficult and could be very expensive with such high variety and low batch quantities. CNC laser cutting of the various blade profiles derived from hardened and tempered steel strip, using design data developed on AutoCAD made significant inroads to process improvement eliminating eight separate operations and reduced production lead times to under three weeks from the previous six to eight weeks. However, very few refinements can be expected for the rest of the process which involves flattening, surface grinding, and welding of carbide tips, which then are ground and sharpened, followed by laser etching of product information. "This meant that further lead-time reductions would need to concentrate on pre-production processes," explains Martin Bennett. "A year or so ago," he explains, "we realized that the existing blade design software was out of date and the design process itself, time consuming. There are a few simple fixed parameters, but the main profile was created largely by experience. Each blade design took at least 15 or 20 minutes to program with an additional 10 minutes for the post-processor to generate a CNC program for the laser. We needed to reduce these times, as well as build our experience into the software to produce something largely 'foolproof,' so people could be trained quickly to use the system. "Approaches made to vendors, to Martin Bennett's amazement were fruitless. "We did not receive a particularly great response until Pathtrace arranged a demonstration of the EdgeCAM off-line programming software. "The demonstration was based on gear cutter design, which is a broadly comparable process and involves many parameters. These are either independently variable or interdependent, and can be applied to similar looking objects. "This started us thinking of how we could apply this approach to our saw blade production," adds Martin Bennett. "We then produced stage drawings of each manufacturing operational process and arranged them in an order we thought would suit EdgeCAM. From this, Pathtrace developed a program that was, more or less, 'right first time'." The design process of a saw blade has a number of elements and parameters. Some are known in advance - such as blade diameter, number of teeth, size of the central drive bore, with or without keyways, and the need for one or more array of pinholes around a given pitch circle diameter. However, the remainder - the form of the tooth profile with rake and clearance angles, radii of gullets and fillets, the type and position of expansion slots and cooling holes - draws largely on experience. "This is the type of information we needed to capture in the software from which it could be automatically post-processed in the correct sequence," says Martin Bennett. "Our previous system involved considerable time consuming manual selection, was open to error and very inconsistent," he adds. The EdgeCAM system, which has been operating successfully at Bennett for around a year, uses an Excel spreadsheet on which the operator inputs blade parameters supplied from the office on a job card. Information includes the diameter of the saw blade, number of teeth, size of drive bore and tooth hook angle, which varies according to the material the blade is intended to cut. The process calls on various tables and formulae to generate other parameters automatically, derived from the basic information, with manual override if required. The number and type of expansion slots, number, size and bolt hole of any pin holes, part number, work order, and customer information also are entered. EdgeCAM then generates the profile using this data, which the operator can accept or reject - or he may choose to zoom in to examine a feature more closely. He can also change parameters if required. Although the system has a high incidence of 'right first time' design, the eyeball method still comes into play. This is especially the case at the extremes of the range because tooth pitch can be anywhere between 6 mm and 150 mm and, particularly on small diameter blades with larger pitches, the normal 'rules' may not apply. When the operator is satisfied, EdgeCAM displays the laser profile path and simultaneously generates the CNC code. This is then downloaded onto disk ready for laser cutting. Martin Bennett also sees other benefits. Although the same operator is the primary user of the new system, it has been structured so that anyone can use it with minimal instruction. He says: "The old system was so long-winded, if you weren't using it regularly you could forget how it worked." In addition, Martin Bennett says that the operator's time has now been freed up to such an extent that he is now able to assume responsibility for ensuring compliance with the company's ISO 9002 registration. "Although there are no current plans to do so, if increased business created a need for a second CNC laser cutter, the new system could effortlessly keep that fully employed as well. "Pathtrace Systems Inc., a subsidiary of Pathtrace PLC, is the developer of EdgeCAM, an extremely powerful, but easy to use software solution devoted to automating the process of NC programming for metal cutting machine tools. EdgeCAM is Windows NT/95/98 compliant and has over 16,000 users worldwide. For information: Pathtrace Systems, 2143 Convention Center Way, Ontario, CA 91764; telephone: (909) 937-1222; FAX: (909) 937-1229; website: www.pathtrace.com; email: usinquiry@pathtrace.com

 

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