Machining around the clock

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industrial

Machining around the clock

JORNS commissions five-axis Starrag machining centre with four-pallet automation for large part machining

The columns for the bending machines manufactured by JORNS AG are huge welded structures with a displacement circle of up to 2,300 mm. With the five-axis large machining centre STC 1250 from Starrag, the company was able to make the precision machining of these parts much more economical.

JORNS AG – the name stands for bending and double bending machines of Swiss quality, which enjoy the highest recognition worldwide. CEO Marc Jorns explains: “At our headquarters in Lotzwil, we manufacture around 120 swivel bending machines a year of which over 90% are exported. With this volume, we are one of the leading suppliers worldwide of this type of machine”.

Increasing competitiveness with high-quality equipment

The production equipment used must also meet the demands that Marc Jorns places on his products: “In order to be able to survive in an international competitive environment, we need high-quality, highly productive machines”. The most recent investment was the production of the largest machine components, the load-bearing stand elements. Peter Roth, Head of Production, explains: “Our machines do not have a classic machine bed, but arms and stands, which are screwed onto the base frame. These stands are welded structures requiring a displacement circle of up to 2,300 mm for processing”.

Marc Jorns, CEO

“In order to be able to survive in an inter- national competitive environment, we need high-quality, highly productive machines.”

As the previous machining centre used had reached its accuracy and capacity limits, Peter Roth and his team set out to search for a replacement. Both technical and economic factors played a role, with which the Production Manager dealt intensively and competently.

The required travel distance already limited the selection considerably. To operate at JORNS, the machining centre must be able to handle at least a 1,250 pallet size and travel up to 2,300 mm in height. “A few comparisons later, we chose the Starrag STC 1250”, reports Roth, “whose Y-axis was extended to the length we required”. In addition to Starrag, only one other competitor was able to fulfil this customer-specific requirement. “The fact that we finally opted for the STC 1250 was largely due to the better price-performance ratio and the close geographical proximity to the Swiss company Starrag, as well as our shared mind-set”, explains the Production Manager with a slight smile. He also explains that for him the purchase price is not the sole measure of all things: “What counts is the TCO, the Total Cost of Ownership. With regard to the overall costs over the entire life cycle, I view the investment in the Starrag machine as good business”.

Peter Roth, Head of Production

“What counts is the TCO, the Total Cost of Ownership. With regard to the overall costs over the entire life cycle, I view the investment in the Starrag machine as good business.”

Reliable processing, accurate repeatability and extremely productive

Of course, the decision rests on a broad range of criteria. In addition to the size of the five-axis machining centre, the basic requirement was process reliability and accurate repeatability. “For example, we need to create deep holes with an H7 fit, which is only possible with absolutely precise manufacturing,” explains Roth. “We have almost fully exploited the high precision of the STC 1250.” The robustness of the machine is also important, which is put to the test by the welded structures – in part a combination of different materials. “No problem for the Starrag STC 1250”, says Peter Roth about his new machining centre, which was originally developed for the aviation and energy industry, i.e. for heavy-duty cutting of steel, titanium, corrosion-resistant steels and special materials, such as Hastelloy and Inconel. “We were sure that its static and dynamic properties would also be sufficient for our purposes”.

Finally, the Starrag STC 1250 also stood out thanks to its efficient five-axis capability. In addition to the three dynamic linear axes, the CNC rotary table acts as the fourth simultaneous axis. It has a high-torque, a high-damping drive and can be clamped hydraulically. The swivel head is the simultaneously controlled fifth CNC axis. Thanks to the robust screw drive and the stable roller bearing on both sides, it is particularly suitable for heavy-duty cutting. To create optimal operating conditions, JORNS prepared a new foundation for an underground installation. The STC 1250 can thus be ergonomically approached and loaded at floor level. In July 2020, the bending machine manufacturer finally put it into operation, and since the beginning of September, production has taken off.

“We have almost fully exploited the high precision of the STC 1250”.

Peter Roth, Head of Production

“In the meantime, we have reprogrammed our parts step by step”, explains Peter Roth. This was necessary because the previous five-axis centre had an orthogonal head – in contrast to the swivel head of the STC 1250. This requires other processes, as the machining specialist Roth points out: “We are enthusiastically getting to know the machine, adjusting to the new possibilities and, if necessary, even changing the designs and the clamping devices”.

Significantly increased capacities

In terms of economic operation, the Starrag machine scores highly in two respects. Firstly, the processing times are shorter. “Until now, we needed around four hours for our large parts”, says Roth. “According to Starrag, we will soon be able to remove them from the machine after two and a half hours. We have not yet reached this level during the start-up phase. But even three hours would be a huge improvement, and we’re very close”.

JORNS achieved the second increase in productivity by configuring the Starrag STC 1250 with a four-fold pallet system, which enables setting up during the machining time. “Our large parts are so heavy that we have to load them with the crane. Together with the clamping and alignment etc., this takes a long time. If the process has to take place – as before – in the machine room, the set-up times become machine downtimes, which we absolutely want to avoid. After all, a machine is only profitable when it is machining”.

But now the JORNS production team’s wish is set to become a reality and the large machining centre could soon be working around the clock. “We are planning a lightly manned shift for the future”, says Peter Roth. “Towards the evening, we load the four pallets full of long-running parts, which are then converted in the morning by our skilled workers for further processing”.

While up to now the machine capacities have been rather tight, Production Manager Roth expects interim overcapacities: “My calculations have shown that we can currently utilise the Starrag STC 1250 with our own single-layer components to 100%. During other shifts, we could take on external orders and thus achieve further profit i.e. reduce machine hours costs. There are not many service providers in our area that can process such large parts”.