A Finn-Power LP-6 combination laser cutting and punching machine from Press and Shear has brought major benefits for Cambridgeshire-based St Neots Sheet Metal.

A Finn-Power LP-6 combination laser cutting and punching machine from Press and Shear has brought major benefits for Cambridgeshire-based St Neots Sheet Metal. By purchasing the machine complete with automated loading and parts sorting systems, the company has been able to achieve very high levels of machine usage, much of it unmanned. Moreover, materials utilisation is higher - a benefit of more flexible nesting - while the clean edge available with laser cutting eliminates labour intensive de-burring prior to assembly.

Comments Wayne Matthews, a director of St Neots Sheet Metal, 'Before we installed the LP-6 we were putting a significant amount of complex profiling work out to third parties for laser cutting.

However, when we decided to buy our own machine we were very keen to install a system that provided both laser and punching facilities.

The benefit of the combination machine comes not so much from its ability to punch holes and other shapes very quickly as from its forming capability.

By having access to a single-pick-up profiling and punching / forming resource we have been able to produce highly accurate work, but the lead time on complicated flat patterns is very short.' St Neots Sheet Metal is a well established supplier of high quality sheet metal components and sub-assemblies to a variety of industry sectors.

These include electronics companies, air conditioning system suppliers and point-of-sale display manufacturers.

The family-owned company offers a full range of production, assembly and finishing services from prototype development through to series production.

Manufacture is in batch quantities from one-off to 10,000-off although 100 to 200 is more usual.

Around 85 per cent of material processed is between 1 mm and 2 mm thickness; most of this is mild steel though the company also produces components in aluminium, stainless steel and Zintec.

'We tend to concentrate on precision fabrication work,' said Mr Matthews.

'We regularly maintain feature position tolerances of ñ 0.1 mm, whilst our more general tolerance is ñ 0.4 mm.

Ours is an all-CNC fabrication shop using Finn-Power punching machines as the principal source of flat patterns.

We have operated a TP 2020 from the same Finnish manufacturer for nearly six years and this is partnered by a TP 2525 which is just under five years old.' When it elected to purchase a laser-punch, the company examined all of the options available to it.

There were a number of points in favour of the Finn-Power LP-6 which commended it over the alternatives, as Mr Matthews explains.

'We have had good service from Press and Shear with the other two machines so any alternative vendor would have needed to demonstrate a convincing technical advantage.

As it is, the Finn-Power machines are very advanced in their facilities and also offer the benefit of modular construction.' He continues, 'If at some time in the future we wanted a larger turret or needed to add a tapping attachment, we could have them retrofitted.

We bought the machine with automated loading and the Sub-8 parts sorter which is fed by the work chute, but we may well add an off-load system for skeleton and large parts removal.

An additional advantage for us has been the ability to use our existing tooling on the new machine.' St Neots' LP-6 cell combines 30 kN of punching power via a 20-station turret with a 2.5 kW Triagon laser capable of cutting up to 9 mm thick mild steel.

Maximum punching diameter is 89 mm.

The machine is fitted with Finn-Power's patented upforming station which recesses form tools when not in use and thereby prevents scratching of the material underside.

A brush-type table also preserves surface finish and minimises noise during punching.

Maximum sheet size is 3,000 mm by 1,500 mm and it is loaded automatically by a transfer device which incorporates sheet detection and measurement.

This ensures that each new sheet has separated successfully from the stack.

In addition, the cell incorporates a scheduling system which, given availability of the required tooling and material, allows multiple jobs to be set up for sequential production.

'Automated loading is a big advantage for the operators as it would otherwise be difficult to man-handle large sheets or thick material,' Mr Matthews adds.

'The system has worked very well.

Part of this is down to our having done our homework before we bought the machine to ascertain how it would impact on production.

For instance, we calculated that about 75 per cent of the components we make would fit down the 550 mm square work chute opening to be collected by the Sub-8, so we knew that the machine could operate minimally manned.

We had also identified the existing components that would be best suited to production on the laser-punch.' Production on the Finn-Power LP-6 relies largely on a standard kit of turret tooling with odd shapes or non-standard hole sizes produced by the laser.

Because most of the material is between 1 mm and 2 mm thick, it is possible to use a compromise die clearance to cover the majority of jobs without tool changing being necessary, other than for job-specific forms.

All long edges are laser cut, with the marginal time penalty compared with using slitting tools more than compensated for by the elimination of manual de-burring.

Laser cutting is speeded by the use of pre-punched start holes.

This reduces the energy needed for piercing and eliminates spatter onto the cutting head optics.

It is also invaluable when processing plastic coated materials.

'Nesting and material utilisation have both improved with the LP-6 because we can use common line cutting or position parts more closely together,' Mr Matthews concludes.

'On complicated profiling work the laser is at least twice as quick as nibbling on a turret punch but its greatest value is in the process flexibility and value that it provides.

Components coming off the machine are usually ready for bending with no intermediate work required and this has had a positive impact on our direct costs and competitiveness.'