The increasing requirements for lower production times, higher quality and precision, together with the increasingly stringent standards are the main reasons for companies being forced to invest in avant-garde machines and technologies. This is the case of EvoBus Bohemia s.r.o., a branch of EvoBus GmbH headquartered in Germany, who are specialised in the production of body shell segments for Mercedes and Setra buses. We produce parts for about 50 different bus models at the Holýšov facility - says Mr. Václav Šeterle, Production Manager of EvoBus Bohemia - These range from the single deck urban buses to the suburban and regional double-deckers. The production consists mainly of the shells, that is the front and rear parts and the front and rear panels of the buses that are made of standard steel and are phosphatized after machining".
Up until 2005, all parts were manufactured following a complex production process using "traditional" machines, such as cutting, boring and milling machines, a number of times. With the introduction of the first ADIGE LT 712D laser cutting system, production at the Holýšov facility changed drastically to the point that there are now three laser systems. The advantages were so great that only three months from the first, a second laser system was purchased and then in June 2007 a third system. "Three systems in just over three years is such a short period when compared to the two years that it took to convince us of the enormous potentials and benefits of laser technology to cut tubes and profiles" says Mr. Šeterle. "When BLM illustrated the features of the ADIGE lasertube system back in 2003, we were extremely impressed, but all the same, it took us a year to carry out a thorough analysis before deciding that the LT 712D would have been the most suitable machine to fulfil our needs. Then in the autumn of 2004 we purchased the first system that was started-up the following year". A fundamental element in the choice made by EvoBus was the after-sales assistance provided by ADIGE, thanks to staff of R.D.I. spol. s.r.o., sole agent for the BLM Group in the Czech Republic. "Having chosen to invest in a machine that at the time expressed a level of technological innovation that was new to us - explains Šeterle - the training and assistance received before and after installation was absolutely fundamental. Besides maintenance and choosing the correct technological parameters of the laser, the ADIGE training courses helped us to design and produce "special" parts, exploiting the potentials of the new technological procedure 100%".
With the use of the LT 712D system, EvoBus was able to double the number of parts produced and, by no means of less importance, to reduce the amount of space required for the machines on the shop floor. Operating with a Kanban type production rate, use of the laser has, in fact, reduced the need to handle and manipulate parts, at the same time giving better quality and cutting down on production times that have dropped to 3 days from order compared to the 10 that were previously required. Tubes with lengths of 4 to 6 m are fed into the laser systems to produce the finished product at the end of the process.". These laser systems have therefore replaced traditional machining so that the entire process is now carried out on a single machine, and this has considerably reduced the number of rejects. The laser systems process tubular material from 20 × 20 up to 100 × 120 mm, with a maximum wall thickness of 6 mm. With the most recent laser systems, even open profiles can be machined (U, L). EvoBus Bohemia is now also able to meet the most stringent European standards in matters of safety, thanks to the three Lasertube systems that have substituted the cutting, boring and pressing machines previously used. The production process at the Holýšov u Plzn plant has further been optimised by the installation of a roller table, which conveys entire lots of material without any production downtimes. The laser is also fitted with a suction system that collects waste in suitable containers and thereby avoids handling of hazardous products. EvoBus has also installed a BLM CNC tube bending machine of the DynamicD8 line that allows multiradius bending (variable or fixed) with a single locking system. This machine has brought about a radical improvement in the repeatability of bent parts, which is important for the operations that follow, such as robotized welding of the structures.