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Stieber Installs Schunk Quick-Change Jaw To Optimise Productivity
Stieber Installs Schunk Quick-Change Jaw To Optimise Productivity
Stieber Installs Schunk Quick-Change Jaw To Optimise Productivity
Stieber Installs Schunk Quick-Change Jaw To Optimise Productivity

Stieber Installs Schunk Quick-Change Jaw To Optimise Productivity

Added to MTDCNC by SCHUNK Intec Ltd on 12 February 2016

During reorganisation of its soft machining department, Stieber GmbH in Heidelberg systematically examined its processes with the goal of increasing productivity, flexibility and eliminating unnecessary waiting and set-up times. The Schunk Pronto jaw quick-change system turned out to be particularly efficient in delivering results for this customer.

German based Stieber GmbH is a world leader in the production of freewheels and escapement mechanisms. As part of the Altra Industrial Motion Group, a worldwide leading manufacturer of mechanical drive elements, Stieber is focused upon delivering quality with maximum customer satisfaction. In pursuit of this goal, the focus is equally on processes, systems, materials and employees. The main motivating forces are Kaizen and the continuous improvement process.

Higher flexibility and lower costs

During a Kaizen event with the Altra group management at Stieber in Heidelberg, Andreas Sandmaier, who is responsible for production control, transformed the conventionally organised soft machining department into a cell production system. The aim was for workpieces to pass through all stations without lengthy waiting times. ‘Instead of receiving prepared blanks for sawing, our machining now starts with sawing of the pre-machined part and ends shortly afterward with the completed part,’ Sandmaier explains. 

The result is that processing times are reduced by two to three weeks. Short-term orders can be produced with much higher flexibility. ‘Today we can respond to customer requirements much quicker and part throughput has increased significantly without putting stress on the employees,’ the specially trained Kaizen leader confirms. 

The team recognised early on that the set-up times on two lathes slowed the process considerably. ‘There are days when the early shift has to change the set-up six times. That takes between 15 and 20 minutes each time,’ Sandmaier summarizes. If covers are machined in quantities between five and twelve, the number of set-up processes is even higher. The first step was to equip all existing jaws with bolts and T-nuts, to allow faster changing. ‘That saves a few minutes, but in the end each set-up process still takes 12 to 15 minutes.’ 

One hour of set-up time saved per day 

The Schunk Pronto quick-change jaw system finally provided the solution: ‘We were still in the middle of reorganizing when Schunk launched the new change system,’ the team leader relates. The first test resulted in significant savings potentials. The standard system was further optimised in cooperation with Schunk. Today the team needs only two to five minutes to change from one product to another. Due to the parts spectrum, usually only the clamping attachments have to be changed, which takes only a few minutes. The savings in set-up times for each lathe now add up to over one hour per day, according to Andreas Sandmaier. ‘The system increases the productivity on our existing lathes by 10 to 15%, without the necessity for extensive investments. With one small step we have made huge progress.’

The Schunk Pronto was developed for conventional lathe chucks with bolt-on jaws. It reduces the absolute set-up time for a complete jaw set to only 30 seconds, which is about 95% less than with conventional solutions. It combines serrated supporting jaws (1/16’’ x 90° or 1.5 mm x 60°) with special quick-change inserts that allow expansion of the clamping diameter within seconds by up to 55mm on soft jaws and by up to 45mm on claw jaws, without having to move the base jaw. That is eight times more than with conventional power chucks. 

For fast jaw changeovers with repeat accuracy, the operator only has to loosen the interchangeable insert with an Allen key, remove the insert and replace it with another one. This eliminates the risk of incorrect positioning. In a locked state, six-sided form-fit clamping ensures maximum process stability and enables high force and torque transfer. Different supporting jaw variants are available for small, medium, and large clamping areas, depending on the particular application. 

Complete line of quick-change jaws

The quick-change jaw system can be retrofitted on chucks sizes 200, 250 and 315, regardless of the manufacturer. A specially developed set-up cart provides for orderly storage and fast accessibility of all claw inserts, soft interchangeable inserts, supporting jaws with mounted bolts and T-nuts as well as the adjusting sleeves. A clearly structured table book enables fast selection and mounting of the single components. 

The Schunk Pronto is especially advantageous when it is necessary to increase the productivity of existing lathes. ‘Instead of replacing our existing lathe chucks with quick-change chucks, I would much rather invest in the quick-change jaw system,’ Sandmaier ascertains. ‘That is much more economical. Pronto fits our philosophy exactly: Fast, simple, short distances with everything in its place. It is the final touch in our strive for short set-up times.’

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