Hall and Pickles is one of the largest steel stockholders in the UK with an annual turnover in excess of GBP 50 million, representing over 120,000 tonnes of throughput. Much of it is processed, which is the industry's term for services such as sawing to length, decoiling, bending, shearing, shot blasting and coating. To streamline the sawing function at its Poynton centre, near Manchester, which processes up to 1,500 tonnes of mainly BS4360-43A and -50B steel per month, the branch has installed its first automatic bandsaw, supplied by Kasto in Southampton.

Called KASTOtec A4, the German-built machine replaced two manually operated bandsaws from the same manufacturer that had been operating successfully for over 25 years.

Two further manual Kasto machines of similar age continue regular sawing duties at the site.

Said Ian Wilson, production planning and control manager at Poynton, 'The programmable KASTOtec A4, which uses conventional bimetal blades, is able to saw twice as much stock as one of our manual machines'.

'It is faster at cutting, but the main saving is in setting up the machine for the next job.' He said: 'With a manual bandsaw, the operator has to measure the cut length with a tape, mark the stock, adjust the stop by hand, set the cutting parameters to suit the material and start the sawing cycle.

In contrast, the new CNC saw can be programmed to cut a sequence of up to 30 orders defined by part length and number required.

The machine is then left to run with minimal attendance.' Apparently, the control knows the downfeed speed and band speed to use to optimise productivity for each type of material and its cross section.

Downfeed is slowed automatically as the blade enters and leaves the material.

The software even calculates the cycle time to complete the cut.

He went on to point out a couple of features that maximise blade life.

When the blade is new, it has to be run in at about half speed for one or two cuts, otherwise the hardened teeth might break.

This action is taken automatically by the KASTOtec A4.

So too is reduction of downfeed speed towards the end of the blade's life.

A deflection monitor detects when the blade starts to dull and run off, and slows the downfeed to maximise the number of good cuts, eventually stopping the machine at the end of the blade's useful life.

Needless to say, accuracy of cut is better with the automatic machine, as human error is taken out of the equation.

Customers normally require a length tolerance of 2 mm total, which the KASTOtec A4 easily achieves.

Manual measurements with a tape can vary by this amount, even if performed as accurately as possible.

Erring on the side of giving the customer longer rather than shorter lengths does not necessarily help either, as for some applications such as fitting steel section inside a frame, slightly undersize is preferable.

Wilson said that as far as he is concerned, the KASTOtec A4 cuts all material perfectly, be it solid or tube, round, square, flats, angles or sections, as if there is any inaccuracy either side of the nominal length, he has no means of measuring such small dimensions.

Kasto in Germany made bespoke roller tables for the input side of the machine to Hall and Pickles' design so that they always have stock waiting to fulfil the next order.

This avoids having to stop the saw while single bars are craned onto a conventional table.

Stock up to seven metres can be accommodated, although the machine at Poynton is generally restricted to cutting up to 2.5m lengths to its maximum capacity of 400mm diameter / square.

Small cross sections are bundle cut, except for rounds, which are sawn two at a time.

The modular construction of Kasto's -tec machine range, in common with other modern metalcutting machine tools, incorporate features such as linear roller guideways and ballscrew actuated material infeed for high precision positioning of the stock prior to cutting.

The double-column design with hydraulic clamping of the material on both sides of the blade ensures precise cutting.

The base and saw head are of heavy, torsion-free welded construction to ensure quiet operation and minimise blade wear.

Owing to the high precision saw band guides, it is possible to cut solids and structural steel members without changing the blade, contributing further to high production rates.