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Market Report: Sawing & cutting Dazzling qualities Phil Mist considers the advantages that the latest generation of diamond blades can offer in terms of performance and low vibration. Bonded abrasive wheels have traditionally been one of the main accessories sold by tool hirers. Virtually every grinder or disc cutter hired out would be accompanied by a stack of grinding discs or cutting-off wheels, representing a significant revenue opportunity. However, as EHN readers will know, diamond blades have been making huge inroads into this market. Once costing more than £100 each, a 230mm diamond blade was an uneconomic proposition offering poor returns on the initial expenditure. But owing to improvements in quality, changes to diamond segment design, improved production techniques, and more manufacture of diamond blades in China or Korea with consequent price reductions, a major shift away from bonded abrasives has resulted. If selecting a bonded abrasive wheel, there are still only two options: stone or metal. The only other details are the size of wheel, the brand and, of course, the price. Until recently, selecting a diamond blade was more challenging, with considerations having to include the application (manufacturers typically list eight varieties for different purposes), whether to choose a laser welded blade or a sintered version, and wet or dry cutting. The user would also need to check whether the blade would be suitable for hand-held use or for other applications, such as cutting with floor saws. This so confused some hire companies that they have fought shy of becoming involved with diamond blades. However, the latest developments have made everything much simpler, with new general-purpose blades designed to cut all common construction materials. A 300mm-diameter blade of moderate quality may now cost from as little as £10, yet not long ago a similar blade would have cost more than £100. Most astonishing of all, the latest products will almost certainly offer at least 30% better performance. Hirers should not be dazzled by claims regarding genuine (natural) diamond content, since artificial or man-made diamonds can be, and often are, every bit as good as natural ones. Determining the optimum shape and size of the diamonds, the appropriate matrix mix of the main body of the segment, and the usable height of the segment are all paramount. Incidentally, it is important to understand what is meant by the amount of ‘free-back’ on each segment (the part containing no diamond chips). A 6mm segment with an additional 1mm of free-back does not provide 7mm of usable segment, just 6mm. A blade with 10mm segments and no free-back therefore has 40% more usable segment. Recent tests carried out for EHN on a range of diamond blades mounted on two 300mm disc cutters (one Makita, the other Husqvarna/Partner) proved that, while you generally get what you pay for, it is possible to find a bargain. In addition to assessing cutting performance, interest centred on the time taken to complete each cut, and vibration emissions produced by each blade and machine combination. Vibration levels from almost every blade were within the HSE’s exposure limit value, with little variation, and some blades actually gave an improvement on the figures issued by the manufacturers themselves. Massive performance differences However, there were massive differences in the performance of the various blades. Many struggled to cut soft abrasive materials: generally, the softer the material, the longer it took. Therefore, some blades gave low vibration levels, but the extended period of use resulted in the operator being subjected to a much longer period of exposure to vibration. (This phenomenon may be somewhat difficult for people to understand, since it is commonly thought that hard materials are more difficult to cut, but this is not the case.) Hirers should therefore choose carefully. In some cases, it did not matter whether the blade tested had a recommended designation, such as for cutting concrete, because they would cut virtually any material. Despite heavy and prolonged cutting in many difficult materials, it proved virtually impossible to measure any appreciable segmental wear on several of the blades. Hirers, therefore, face another dilemma of whether to sell or hire each blade. The original system of charging every customer hiring a blade anything up to £60/millimetre of worn segment, or part thereof, would seem to be a potential flashpoint with some customers. It is one thing to buy a 300mm bonded abrasive cutting off wheel for a few pounds when hiring a disc cutter, but quite another to be charged significant sums for segment wear. In today’s market, I for one would simply not be prepared to pay this level of charge, preferring to buy a diamond blade than hire one with a grinder or disc cutter. The decision to sell an inexpensive, yet reasonable quality diamond blade may be regarded by many as a measure of the quality of service a hire company has to offer its customers. In addition, stock the right brand of diamond blade and your customers will think it, and your company, are wonderful. • Executive Hire News › Archives › June 2007 › Market Report › Dazzling qualities
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