Fastener manufacturer cuts steel to ±1mm

Saw News

	KASTO circular saws replace cropping machines for rapid cutting to length
One of the KASTOspeed C9 circular saws at Cooper and Turner. Easy access to the working area allows rapid blade changeover and contributes to maximising productivity.

Founded in 1912, Cooper and Turner is one of the UK’s leading manufacturers of industrial bolts, nuts and washers for the rail, tunnelling and construction industries. It produced high strength steel fasteners for the Channel Tunnel rail link and the new Wembley stadium, for example, as well as for many prestigious projects overseas including the Tsing Ma suspension bridge in Hong Kong.

The company started supplying the wind energy sector in 1987 and has seen this side of its business grow in recent years as a result of global warming. In 2005, a large contract was received for the supply of thread-rolled tower bolts, which require one end to be turned so that the thread, as it expands, matches the rest of the outside diameter.

A majority of Cooper & Turner’s products are hot- or cold-forged from lengths of cut bar, or pins, that are accurate to ±5 mm, but wind energy fasteners generally have to be cut to a five-fold tighter tolerance. This was difficult to achieve using the company’s three cropping machines, as the shearing action left a rag on the underside of the pin that made subsequent turning problematic.

The use of existing bandsaws on the Sheffield site was considered. However, to achieve a reasonable output rate, bundle cutting of the bars would have been essential. To prevent them from splaying when clamped, they would have needed to be welded together at the back, wasting both time and material.

Cutting area of a KASTOspeed C9 at Cooper and Turner.

Production Director, David Brown, decided that circular sawing was the way to go and reviewed a number of suppliers. He eventually chose a German-built, automatic KASTOspeed C9 due to its robust construction, speed and accuracy. He was particularly reassured after visiting a Corus cutting shop in Birmingham, where similar machines have been used successfully in a demanding environment for several years.

Additionally, KASTO was one of the few suppliers able to supply a practical handling device for transferring automatically each cut pin directly into a Danish-built Akea lathe of 48 mm diameter capacity, where the OD for the thread is turned. On the input side of the saw is a five-tonne capacity bundle loader for feeding the raw stock automatically.

Each KASTOspeed C9 at Cooper and Turner directly feeds cut pins into an Akea lathe for turning the thread diameter.

Installed in 2005, the sawing machine is a horizontally acting type on which Cooper and Turner uses disposable, TCT (tungsten carbide tipped) blades of 250 mm or 285 mm diameter to cut steel bar up to a maximum diameter of 64 mm. (With a 315 mm blade, the saw’s 7.5 kW drive motor will cut stock up to 90 mm at infinitely variable speeds from 20 to 225 m/min.)

Andy Gale, Cooper and Turner’s Threading Manager, who is in charge of the sawing section at the Sheffield factory, describes the action as “like a knife through butter”, despite processing steels as tough as EN24.

The success of the first production cell prompted the installation one year later of a second, identical KASTO saw and linked Akea lathe. At the same time, a KASTOdisc U7, manually fed circular saw was supplied. It uses high speed steel blades for cutting stock up to 660 mm diameter in small batches from one- to 100-off for smaller production runs of special fasteners.

In 2008, Cooper and Turner’s expertise in the wind energy sector resulted in the award of another contract, this time for the supply of blade-to-hub studs in large volumes with effect from early 2009.

Two more KASTOspeed C9s were consequently ordered, one for stand-alone use and another for linking to an Akea lathe of larger, 80 mm diameter capacity. As with the first two C9 cells, they will be run over two shifts, but the Sheffield works is a 24/6 operation so there will be spare capacity for future expansion.

The centrally located operator panel on the KASTOspeed C9 requires only a few keystrokes to enter the data necessary to instigate the batch run. It contains knowledge of the optimum parameters for cutting the commonly used steels. To achieve quiet operation, the machine frame is filled with vibration-damping polymer concrete. Consistent with large volume production, particular care has been taken with swarf management to ensure smooth flow of chips from the point of cutting to the conveyor.

Mr Gale said that, in his opinion, the circular saws are up to 10 times more productive at cutting steel bar than a bandsaw and much more accurate than their cropping machines, which have now been sold off. After the 15 mm or 25 mm trim cut at the start of each bar, every pin cut on the KASTOspeed C9s is of top quality. The saws run with minimal supervision except for topping up the bundle loader and patrol inspection.