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29/06/2009
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KASTO's new cutting process boasts a three-fold productivity gain; LS Starret has developed a new bi-metal blade offering extended life
 Research and development carried out by German sawing machine manufacturer KASTO has resulted in the introduction of a bandsawing process that is three times faster than many other bandsaws on the market and at least 30 per cent faster than its own, unmodified '-tecAC' range of machines.
Called KPC – KASTO Performance Cutting – the new process has been designed specifically for use with tungsten carbide tipped bandsaws, while ways to minimise vibration have been the core focus. The latter delivers a three-fold benefit, raising accuracy, reducing noise, and allowing increases in both band speed and feed rate.
The starting point for KPC was the KASTOtecAC production bandsaw, which is available in four sizes for cutting material up to 800 mm in diameter, or 730 by 830 mm flat stock.
Key steps taken were improvements to blade guidance either side of the cutting area and other measures to dampen vibrations. One such measure, which is central to the step-change in performance, is the 'Trum Guide', or tensioner. This sees two spring-loaded guides mounted at the returning side of the blade, inside the top of the saw head guarding at either end. These guides suppress vibration on the side opposite the cutting action and help maintain blade tension of between 35,000 to 40,000 lbs/sq in, versus a more typical 25,000 to 32,000 lbs/sq in.
Another improvement has been the redesign of the bandsaw blade guides either side of the point of cutting, for which world patents are pending. The changes are characterised by more rigid guidance, more efficient cooling of the blade and of the guides – which now have coolant slots through the middle – and responsive measurement of the cutting force, using a sensor at the back of the blade. Roller bearings used on the back of the blade support greater downforce without 'chilling', or cracking, of the blade.
Taken together, these improvements support blade speed of 200 m/min, versus the more normal 120 m/min, when the optional 15 kW motor is fitted.
KASTO cites a like-for-like comparison between a KASTOtecAC KPC and other makes of bandsawing machine carried out during the BIMU 2008 machine tool show in Italy. Blades used were Wikus Futura Premium and Roentgen For-tec, both of which are carbide coated.
Eighty pieces of 42CrMo4 steel (EN19/ 907M40), 300 mm in diameter, were cut with a feed of 225 mm/min. The KASTOtecAC KPC machine cut 3.7 times faster, compared with the best of the other sawing machines – 400 cm2/min versus 108 cm2/min. And the blade on the KASTO machine was still in good condition at the end, even after sawing 56,500 cm2 of this tough material. Indeed, blade life can actually increase with KPC, says KASTO. For example, when cutting EN19 with a carbide-tipped blade on a KASTOtec unit without engaging KPC, the volume cut per minute is 116 cm2/min with blade life 10 m2, while with KPC engaged cutting rate is 152 cm2/min, with blade life extended to 15 m2. With carbide-tipped bandsaws costing around £200, the savings are not insignificant, and this sort of detail forms part of KASTO's lower cost-per-cut argument.
As standard, KASTO machines fitted with the KPC paraphernalia sport a 'KPC button', which, when selected, raises productivity by around 30 per cent. However, it is possible to push the machines much further by manually overriding these settings. But, as KASTO's UK managing director, Ernst Wagner, explains, it is difficult to get people to believe that such huge improvements can be achieved, so a more 'believable' 30 per cent improvement has been linked to the KPC feature.
Staying with blade life increases, and LS Starrett is reporting outstanding results in field tests for its new Versatix MP bi-metal bandsaw blade featuring triple-tempered M42 cobalt high speed steel teeth.
It is targeted at structural steels, sections, tubes and small solids, and it is also claimed to be suitable for manual, 'pull down' bandsaw machines, where the uncontrolled nature of the feed rate can lead to tooth strippage.
Test successes to date include:
* A decorative railing manufacturer in the south of the UK, which was changing band saw blades every three days. Blade life with Versatix MP is now between three and four weeks;
* A door manufacturer in the north of England, cutting very thin interrupted sections, which was changing blades approximately once a week. Blade life with Versatix MP is now reckoned to be in the region of nine weeks per blade;
* A Scottish engineering firm cutting pipe and structural steels that had tried a range of blades from different manufacturers in an attempt to get around persistent problems with tooth strippage. All its bandsaw machines now run Versatix MP, and it reports no further problems with tooth strippage.
Versatix MP is available via the Starrett distribution network in widths from
19–54 mm (3/4"–2").
Box item
Kaltenbach launches new concept and machines
* Automation concept for structural steel and plate processing – from raw material input to final plant output, including automatic cutting and sorting of ends, for example – offers some 30 per cent better plant utilisation and productivity
* The MSK 471 NA is an ultra-fast, high-performance straight sawing machine for cutting hard, difficult-to-cut metals, including stainless steel
*The KBS1010/KDXS 1015 sawing/drilling system with AS 1000 auto-sorter is a fully automated band sawing and drilling system. High-speed contour marking and the use of solid-carbide drill bits add to the machines overall high-performance efficiency
*The 'silenced' T13 structural transport system employs new technology to reduce 'steel on steel' noise pollution to almost a whisper
*New visualisation software enables operators to monitor work piece position within automated lines
*The KPS 520 is claimed to be the world's fastest strip-fed plate punching and shearing system of its type. The punching and shearing capacity extends up to 500 mm wide plate by 25mm thick, and up to 200 by 200 by 16 mm for angle sections. Optional drilling, plasma cutting and marking functions are also available.
First published in Machinery, May 2009
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Author
Nicki McKenna
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