By investing in three Valk Welding welding robot systems and the offline programming software DTPS during the past four years, Rustek - a Danish pellet stove manufacturer - has succeeded in ensuring that its quality keeps pace with the rising demand.

General subcontractor Rustek A/S, which has been a member of the Danish wood pellet stove manufacturer NBE Production Group since 2010, specialises in the production of the internal parts of these wood pellet stoves. Rustek reserves another 20 percent of its capacity to general supplies for third parties. In recent years the company - which employs only 13 people - has invested substantially in automating crucial parts of its production process.

Complex welding tasks
The use of a wood pellet stove for heating has risen sharply in recent years, not only in Danish households but also throughout the rest of Europe. "The sharply growing demand caused us production problems, partly as a result of the relatively complex welding work on the internal steel parts of the stoves. "Many of the components are built up of several plate sections with complex welding details", explains CEO René Ramsdahl. "Each product easily involves about 15 to 20 metres of welding that has to be pressure-resistant and in some cases has as many as four different connections in each product. That calls for professional knowledge and the right processing
strategy.

Experience gained with 'Mini cell'
"In 2012 we made a start with the robotised welding of small stainless steel products on a Valk Welding 'Mini cell'. When the volume rose to over 2,000 units a year we took the step a year later to using a larger welding robot on an H-frame. That gave us the extra capacity we needed to weld the frames for the internal parts of the wood pellet stoves with the robot. This has also significantly improved the quality of the welding. "The welding robot produces a very precise weld that is the same for each product", says René Ramsdahl.

Third welding robot
The production volume has risen sharply in a period of four years. As well as automating the cutting and welding process, Rustek has also automated the bend processing with a robot on the press brake. "The increase of volume also made it necessary to extend the capacity of the welding department. The third welding robot runs on a track and moves back and forth between the two stations. This solution enabled us to work more
flexible and also helped with the implementation of the larger products", says the CEO. The third welding robot system supplied by Valk Welding features the latest Panasonic TA-1900WG3 welding robot, which is designed
especially for arc welding.

Software is the key
The investments in software and its optimisation form an important component of the annual budget. "Although it sometimes feels like a big black hole, the investments in software ultimately save us a lot of time. Each update takes the optimisation of the production process a step further", explains René Ramsdahl. That also applies to the welding department, where we program the welding robots increasingly smartly offline with the DTPS package from Valk Welding. This not only yields time savings in the form of shorter cycle times, but results in a longer working time for the welding robots. (DTPS upgrade cost less then 1,000.- Euro a year)

All in all, believes René Ramsdahl, without the automation efforts the company would not be able to exist in Denmark. The production processes are now automated from bending to welding and everything in between. That enables us to deliver a high quality product that is also cheaper and above all better than that of our competitors", he adds. www.rustek.dk