Trumpf laser cuts cookers

Citation

(2000), "Trumpf laser cuts cookers", Industrial Robot, Vol. 27 No. 1. https://doi.org/10.1108/ir.2000.04927aaf.006

Trumpf laser cuts cookers

Trumpf laser cuts cookers

Keywords: Cutting lasers, Beams, Accuracy

A laser has been installed by Trumpf at Stoves plc, one of the UK's most successful independent cooker manufacturers.

The Haas HL353 laser has no competition with respect to its cutting performance when compared to any other laser of its type worldwide, says Gerry Jones, laser product manager, Trumpf UK. A unique design of resonator, or laser amplifier creates a beam capable of better focusing and therefore greater power density and faster cutting rates. This means the laser offers the highest performance to cost ratio.

High beam quality also means a substantial clearance can be maintained between workpiece and the laser head, preventing contamination of the optics and increasing the usable depth of the focus, thereby ensuring reliability. It also means the laser can outperform other laser types by enabling a very fast and accurate cut.

The cutting speed in this particular instance is dictated by the maximum velocity at which the robot can deliver the required accuracy which is 5-6m/min at the quality standard demanded by Stoves plc.

The company, a subsidiary of Stoves Group plc, is the UK's most successful independent cooker manufacturer. From its site on Merseyside it produces some 2,500 models of high quality cooking appliances under its own brand names and for other customers. As Alan Elmer, project leader with Stoves, advises, "the market is becoming more demanding as high street customers expect a wide choice of models". Flexibility is therefore very important to Stoves.

At present, nine sizes are currently produced: for the leisure market, mostly caravans; household models; and, most recently, for the US market, where oven cavities can be up to 600mm wide and 400mm deep, somewhat less modest than UK versions. They are hydroformed from 0.6mm steel blanks and subsequently laser cut by the HL353 to tailor them for gas or electric power and to incorporate features such as interior lights. The tight tolerance afforded by the hydroformed cavity and its welded-on back plate, allows the laser to achieve a cutting accuracy of +0.2mm. To enable it to follow the contours of the cavity, a robot head has been supplied with an automatic height sensor.

Stoves plan to offer a much larger number of sizes in the future and Alan Elmer says the company has invested in a second hydroforming machine which will increase the load on the laser to keep up with production. He continues, "The company chose Trumpf because of its high level of expertise and professionalism. There is always someone to discuss machine operation and other technical help is always readily available."

Haas high-powered continuous-wave solid state lasers feature output powers between 500W and 5,500W and the control system guarantees 350W to 4,000W at the workpiece. Eight models are available in the HL CW-YAG range. The company also supplies pulsed lasers, laser marking machines and laser processing cells.

The HL353 is the lowest powered laser in its range. The first two digits of the number refer to the power delivered to the workpiece (i.e. 350W), and the last digit refers to the core diameter of the fibre optic cable (i.e. 0.3mm) (see Plate 4).

Control of the laser is via a computer fitted with a modem link; therefore software updates can be instantaneous. This ensures the equipment is operating with the latest information for maximum production time at least cost.

Plate 4 The Haas HL353 laser

A PC is used as the display and control trait and can store control functions and laser parameters for up to 79 programs. It is possible to connect up to six laser light cables to any one laser, giving the potential for multiple workstations to operate simultaneously. Cables in excess of 50m can be supplied, and they are monitored for safety over their entire length.

The processing optics can provide focused spot diameters from 150 microns and working distances up to 200mm. The high output power and excellent beam quality make Haas CW-YAG lasers especially suitable for production cutting and welding. Cuts have an exceptionally narrow kerf and burr-free edges. In steel, roughness values of less than 5 microns are possible with oxygen-assist. Welds are characteristically narrow with a very small heat-affected zone. Welding steel is feasible without a shielding gas.

Trumpf points out that when choosing a laser, both the power available at the workpiece and beam quality are key parameters. Although laser units are rated at a certain output, energy loss occurs in fibre optic transmission. The Haas HL353 control system guarantees its rating of 350W at the workpiece, after losses in the fibre optic cable.

Trumpf is the world's largest privately-owned machine tool company. It has built its reputation on professionalism, customer service and the supply of top quality machines. It is now the world leader in fabrication and laser technology and supplies complete flexible sheet metal and processing system solutions through 26 subsidiaries in 17 countries. It has five factories in Europe and the USA and employs some 3,900 people.

For further information contact Trumpf Ltd, President Way, Airport Executive Park, Luton, Bedfordshire LU2 9NL, UK. Tel: (+44) 01582 725335.