Block and bar saws from Kirschner Maschinen- und Metallbau are used for the automatic splitting of stone bars. These are complex customised machines that are designed for the respective stone on site. If they are used in industrial processing, they usually run in multi-shift operation. Their axis is supplied with power via energy supply systems from igus®. Despite the extremely harsh operating environments, a downtime of 30 years and longer is expected.

"We have been using plastic-energy chains in our stone saws for at least ten years," explains Alexander Ritzka, mechanical engineer at Kirschner Maschinen- und Metallbau GmbH. "They are stable, resistant to dirt and can take high loads." The particularly robust e-chain® E4.80 from igus® is now used in the block and frame saws. It is part of the extensive product programme of universal energy supply systems of the E4.1 system from igus® GmbH in Cologne. It is characterised, among other things, by its modularity and ease of assembly. It is easy on the cable and ensures a very long service life. The chain has been available for a good five years and has proven itself in a wide variety of the supplier's sawing systems since its market launch.

The medium-sized company Kirschner Maschinen- und Metallbau GmbH employs around 50 people. It specialises in machine and metal construction, individual and high-volume production and agricultural engineering. The customised design and manufacture of a wide variety of saws for the stone industry is one of the company's main areas of expertise.

Sawing for shell limestone blocks
In summer 2014, the special machine manufacturer installed and commissioned two sawing systems at Hemm Stone GmbH Natursteinwerk Kirchheim, a Sto AG company. With its own quarries, modern machinery and manual labour, it offers a wide range of products and services relating to natural stone. "We mainly quarry shell limestone, which has proven itself as a building material for centuries," says Christian Gruber, Head of Project Business and authorised representative. Shell limestone is used as a hard-wearing floor covering for outdoor and indoor areas, for façade design and in gardening and landscaping.

The quarried stones are cut on the block saw to create a straight surface, preparing them for further processing on either the beam saw or the multi-slab saws available in the factory. "The advantage of this sawing technology is that we can utilise the finite raw material much better and cut it more economically," says Gruber, summarising the reasons for the investment. Whereas previously a maximum of two blocks were processed at a time, today up to ten blocks can be placed on the respective system and cut.

energy chain for sawing systems
In addition to shell limestone, sandstone is also processed in the natural stone plant. The circulation speed and the saw blade are adapted to the type of stone. Speed-controlled drives ensure a constant cutting speed of the saw blade. The x-, y- and z-axis are supplied with energy via fully webbed energy chains E4.80 that can be opened on both sides. They have an inner height of 80 millimetres and an inner width of 375 millimetres. The travel distances of the x-axis are 30 metres, the y-axis 5 metres and the z-axis 2.5 metres. While the first two axes are cantilevered applications, the infeed axis is a standing application.

The quarried blocks are cut on the block saw to create a straight surface, which is then prepared for further processing on either the beam saw or the multi-panel saws available in the factory. "The advantage of this sawing technology is that we can utilise the finite raw material much better and cut it more economically," says Gruber, summarising the reasons for the investment. Whereas previously a maximum of two blocks were processed at a time, today up to ten blocks can be placed on the respective system and cut.

A lot of weight is placed on the chain, especially on the x-axis. In addition to the control cable, heavy water, lubricant and hydraulic hoses are also installed. The internal partitioning options are particularly impressive in this application; they ensure that the cable and hose are guided safely and extend their service life many times over. On the long journey, the energy chain also travels in a particularly robust steel guide trough. It is part of the extensive igus® modular accessories system.

In addition to the issue of long-term stability, stone saws also need to be resistant to abrasive materials. When cutting, an extremely large amount of dust as well as smaller and larger pieces of rock are produced, which are deposited in all areas. In addition, splash water finds its way in.

Stable and tight in everyday sawing
The e-chain® E4.80 is robust and its design makes it particularly suitable for applications with high levels of dirt. On the 30 metre travel of the x-axis, the upper run of the energy chain rests on the lower run. A high wear allowance on the one hand and wide contact surfaces on the other ensure that the forces exerted are distributed over a large area. This results in lasting stability and functional reliability. Added to this are the particularly smooth contours. The low abrasion protects the hose and cable inside the chain in the long term. If necessary, the removable crossbars on both sides allow the cable or hose to be replaced quickly and easily.

The double rectangular stop-dog system ensures maximum force absorption and therefore high stability for the long unsupported lengths. Tightly toleranced and large bolt/bore connections are responsible for the high load absorption. An almost complete zero clearance ensures a long service life. The inner/outer plate principle - inner and outer chain links interlock - ensures straight running, high retention forces and extreme tightness. Even the finest dust particles and moisture cannot settle or penetrate into the interior. Added to this are the issues of low vibration and low noise. Built-in brakes on the radius stops are responsible for this.

Convincing test cuts"The first test cuts have already convinced us," reports Gruber. "We are certain that the investment in the technology will pay off." Alexander Ritzka also expects this: "We have been using the robust energy chain in our systems from day one. Our experience has been more than good. To date, we have not had any complaints from customers. There have been no downtimes. The chains are delivered, assembled by us, fitted with the necessary cables and hoses and the saws are then put into operation. The co-operation with igus® has always worked smoothly."