Cut to the quick

Achern, Germany-based Kasto is one of the oldest family run businesses in Europe and employs 700 people. Now in its sixth generation, the company has sold 140,000 metalcutting bandsaws and 1,700 storage systems worldwide. Keeping customers is a vital ingredient to the success of any business and in that regard, Kasto ticks all the right boxes. 53% of all customer relationships have existed for more than 10 years.

Kasto UK hosts open house events every couple of years but a noticeable omission from this year’s proceedings was its managing director Ernst Wagner due to a slipped disc endured during a gardening session. However, it takes more than being unable to walk to keep the irrepressible Mr Wagner down – he did make a brief appearance at the event, albeit propped up by a pair of walking sticks. We wish him a speedy recovery.

Infinity and beyond

Pioneering sawing technology is at the very heart of Kasto’s success and at the open house, Kasto UK’s product specialist Glenn Cottrell provided an overview of the company’s new KASTOmicut bandsaws which supercede previous models of pivot-bow saws.

“There are four machines in the KASTOmicut range, from manual to fully automatic and they have slightly larger capacity than the machines they replace – namely the Practical and Functional models,” he explains. “They have higher power motors and greater band tension allowing a 50% increase in cutting force. Significantly, there’s also a large commonality of parts used during manufacture, which means we can keep costs to a minimum and pass these savings onto our customers.”

A further benefit is the machines’ infinitely variable blade speed range of 20-120m/minute allowing many different types of metals to be cut, from ferrous to non-ferrous. “This is a significant advantage as most machines in this category only offer two cutting speeds,” Mr Cottrell adds. “A highly efficient spur gear system ensures a constant cutting force across a wide range of materials.”

KASTOmicut machines are designed for high accuracy cutting to length and mitre cutting of tubes, sections and solid materials. The four models comprise: P 2.6 – with gravity feed and manual clamping; E 2.6 – featuring hydraulically actuated downfeed and manual clamping; and the U 2.6 – which is essentially the same as the E 2.6 but with a hydraulic vice operated via short stroke cylinder. The fully automatic A 2.6 variant will be available soon and features a ballscrew spindle for high positional accuracy and repeatability. Additional goodies are carbide blade guides, electronic blade tensioning monitoring and optional swarf conveyor.

The saws have a cutting range of 260mm for rounds and 310 by 260mm for flat stock. Mitre cuts are possible at continuously adjustable angles from -45 to +60°. A torsionally rigid, vibration-damped, cast iron frame provides support for the saw blade, ensuring top cutting quality, even in difficult-to-cut materials. Many different accessories are available including a rotary table to support the material.

Shortest cut length is 6mm, with a residual length of 15mm for manually cut pieces or 40mm in automatic operation. Cutting accuracy is 0.1mm per 100mm of height.

Win win

Andrew Wright, Kasto UK’s business development manager followed up with a presentation on the KASTOwin pro AC 5.6 – a high-tech, highly efficient bandsaw for use with bimetallic and carbide blades, offering short cutting times, long blade life and intuitive operation.

“The essence of profitable, automated sawing depends largely on two main elements – high cutting performance and short downtimes – and the AC 5.6 was designed to optimise both,” he says. “This automatic machine is ideally suited to a wide range of applications cutting solid material, tubes and profiles, particularly in steel production and stockholding, machine manufacturing and the automotive industry.

“We’ve already seen it can significantly increase production speed and efficiency. Depending on the type of blade and the material being cut, processing times can routinely be reduced by up to 50% and substantially more in some instances.”

An important feature of the KASTOwin pro AC 5.6 is its innovative, electromechanical downfeed controlled via two ballscrews, each with a servo drive, for precise, infinitely variable control. There is a retraction unit for separating the blade from the material to protect the cut surface when the saw head moves back. It also helps to minimise tool wear.

The saw band is driven by an 11kW, frequency-controlled motor, delivering infinitely adjustable cutting speeds from 12 to 150m/minute and providing plenty of capacity for TCT sawing. Helping to dampen vibration are ‘Trum’ guides mounted at the return side of the blade, inside the top of the saw head guarding.

Maximum cutting capacity is 560mm and the smallest dimension that can be cut is 25mm by 25mm. The band guide arm adjusts automatically to material width. Shortest residual length is 10mm for individual offcuts and 35mm in automatic operation, enabling operators to minimise waste.

Having an installed weight of 4.3 tonnes and a rigid welded structure with vibration-optimised ribbing, the KASTOwin pro AC 5.6 ensures quiet operation, short processing times and accurate cutting. A powerful coolant pump and large reservoir serve to reduce wear on the teeth further, especially when sawing difficult-to-machine materials. The bandsaw comes equipped with EasyControl, a high-performance control unit that is easy to use and reduces idle times in automatic operation for maximum output.

The drive unit and sensor are separate from the working area, ensuring reliable and trouble-free operation. At ±0.1mm/100mm, the repeat accuracy of the saw is also impressive.

Efficiency with productivity

Increasing cost pressures, tough international competition and ever-higher customer demands present significant challenges to manufacturers. On one hand, it is important to be able to offer an increasing variety of materials and sizes of the highest quality and from a batch size of one through to series production. On the other hand, unit costs must be competitive so that in-house production is economical. Finding a happy medium is a challenging task.

Sawing technology is continuing to develop against this backdrop. Automatic saws must meet diverse criteria, such as offering high cutting performance, a wide range of applications, minimal idle times, top quality cutting results, high repeatability, ease of use and effective material utilisation. In times of increasing energy costs and ever-longer periods of use, efficiency also plays a key role.

Matthias Eigbrecht, head of the electrical design department at Kasto Maschinenbau in Achern, Germany explains: “Not every measure that improves a machine’s energy efficiency is suitable for a user, as the ideas often come at the expense of production capacity. When launching KASTOwin, we developed a product range that not only offers high cutting performance, but also has incomparably low energy consumption – and at an acceptable capital cost.”

An analysis of all the energy-consuming machine elements and their corresponding power requirements was the basis for the development work. Using the results, Kasto established a series of concepts that would allow energy to be saved in different areas and then evaluated them from a commercial viewpoint.

Mr Eigbrecht continues: “In other words, we weighed the increased investment cost of the energy saving measure against the possible operational savings. We determined certain measures to be meaningful but others less so and we rejected the latter.”

The greatest potential saving lay in the hydraulics system, which is responsible for a significant proportion of the sawing machine’s energy consumption. Initially, Kasto tested and compared equipment from different manufacturers and opted for the most efficient.

To complement this, KASTOwin engineers developed an electromechanical saw downfeed. The hydraulics system is now only responsible for workpiece clamping and saw blade tensioning, so it is actuated far less than in the past. Energy saving in this area is approximately 93%.

Modern drive technology uses energy intelligently

For the saw motors, Kasto uses frequency-controlled drives of efficiency class IE3 and as a result, cutting speeds from 12 to 150m/minute can be achieved. At the same time, the motors are compact and very efficient. Modern servo drives are also used for the material infeed and saw downfeed and linear guideways and ballscrews ensure efficient, precise power transmission.

All drives are controlled by intelligent converter technology. Kasto has fitted the frequency converter with a DC link (as used in its automated material storage systems) so that excess energy, generated when braking the saw motor for example, can be recovered and used elsewhere in the system. In contrast, conventional technology disperses this energy via braking resistance, so it is lost as heat.

Overall, these measures have made it possible to achieve significant improvements in the energy efficiency of KASTOwin machines. Energy consumption is said to be on average 28% lower, depending on the sawing application, compared with previous bandsaw models of equivalent size.

Kasto www.kasto.com