KASTO bandsaw is twice as fast at cutting hardened steel shafts

Saw News

	Overall cycle times are two or even three times shorter using the KASTO machine.
The KASTOtwin L4 automatic, long-bed bandsawing machine cutting chrome-plated, pre-hardened steel bar for JCB at the Rotherham works of special steels stockholder, IMS UK.

There can be few sawing applications more challenging than the production of hydraulic ram shafts for JCB off-road vehicles at special steels stockholder, IMS UK, Rotherham. Various factors make the job particularly difficult. For a start, pre-hardening of the steel to 50 - 55 HRc dictates the use of carbide-tipped saw blades, which normally require coolant. However, the cardboard sheath protecting the chrome plating on the bars prevents coolant from being used, as the board would become soggy and clog the machine.

Another problem is that cut blanks are up to 3.5 metres long, which on most bandsaws would involve feeding the bar through from the input roller table to the blade in as many as six successive movements of the back vice. This compromises productivity by increasing the non-cutting time as a proportion of the overall cycle.

The solution to these problems was the installation of a KASTOtwin L4 automatic, long-bed bandsaw. First, the machine is able to advance the stock by up to 1.5 metres in a single stroke, typically two and a half times more than on most bandsaws. Secondly, the machine supplier modified the blade guides to reduce the tension and fitted a high-speed motor to drive the blade faster. Together with the use of Wikus negative-rake saw blades designed for cutting hardened steel, the result is more efficient dry cutting with less heat generation and hence longer blade life.

The JCB contract has been running for some years, but in May 2004 the quantities being ordered increased sharply. The existing carbide bandsawing machine was no longer able to cope, so IMS UK invested in a second machine to work alongside it.

The original machine is able to pull the seven metre long bars from the input table towards the saw blade by a maximum of only 600 mm per stroke. So while it is efficient at producing blanks of this length and shorter, most of the shafts are longer. For these, overall cycle times are two or even three times shorter using the KASTO machine. The higher productivity derives from a combination of quicker material feeding and 30 per cent faster cutting time.

Two identical bars are cut simultaneously, the diameters ranging from 45 to 70 mm. Cut time for two 60 mm bars is around one minute, for example, and tolerance is -0, +1mm, a level of accuracy made possible in part by hydraulic clamping of the material on both sides of the blade. The machines have to be manned when producing the JCB blanks owing to the frequent handling needed when producing shaft lengths as opposed to short billets. However, the saws perform an unmanned ghost shift using a bimetal blade to cut shorter lengths of other materials up to the machine’s 400 mm diameter capacity.

IMS UK, a major distributor of special steels and nickel alloys operating to the ISO 9001:2000 quality standard, is a long-term user of KASTO bandsaws at Rotherham, formerly James Fairley Steels. There is a total of 10 machines of various capacities on site including large programmable magazine bandsaws, a forged bar saw for 860 mm material and vertical bandsaws.