Applying linear motors to the X-axis movement of each cutting head can allows accurate control by the CNC with a positioning accuracy as fine as 0.05mm using coils fitted to each head.

Water Jet Sweden is believed to be the first manufacturer of waterjet cutting machines to incorporate linear drives in this technology for customers who have discerned the technical advantages of this option. Increasingly already being applied to advanced machine tool designs, linear drive systems are now being taken up by designers of other types of machinery and equipment used in a variety of manufacturing processes throughout the world. In the case of Water Jet Sweden, the close collaboration enjoyed between themselves and CNC suppliers GE Fanuc over recent years has seen the introduction of a linear drive option across the range of profilers produced at the busy Ronneby factory in southern Sweden.

With the entire linear drive system being sourced from the same supplier as the other drives systems on the machine, plus the CNC control, the whole package is totally integrated and thereby offers assured reliability.

* Great accuracy - when applied to a Water Jet Sweden machine, the whole X-axis is fitted with a single flat magnetic plate.

The X-axis movement of each cutting head can then be accurately controlled by the CNC with a positioning accuracy as fine as 0.05mm by means of coils fitted to each head.

Lennart Svensson, managing director of Water Jet Sweden, said: 'As well as the well-known advantages of such a drive system, it is especially useful for multi-head profiling.' He cited the many cases where nested items need to be cut using the 'common line' method whereby the intermediate heads of a multi-head arrangement are cutting a line that forms both an 'inside edge' of one component and the 'outside edge' of its companion, thereby simultaneously eliminating the wasteful 'picture frame skeleton' left in the sheet.

Significantly, because each of the heads can be easily re-positioned independently, it is far quicker to replace any one or more nozzles as wear takes place.

This nozzle wear can be compensated for automatically which is an attractive time-saving proposition in a busy shop.

* Other advantages Such drive systems cannot be affected by that small element of component wear that might occur over long periods of time with other drive systems.

Additionally, there are no backlash or pitch error problems to worry about.

The improved long-term positioning accuracies achievable are an added incentive to adopt the linear approach.

The application of a linear drive system to a waterjet profiler is a good one because, unlike other metal cutting machines, there is no swarf or coolant present that might pose a risk to lifelong performance.

In any case, the X-axis drive is mounted on top of the cross gantry where it is well above the work interface.

It is, therefore, in the field of multi-head, high-volume work that the linear drive option can really prove its worth, especially when the added advantages of increased positioning speed and acceleration while profiling are taken into account.