FOCUS ON WELDING for the saw chain ’ s drive links to run through . A portal projection welding system , developed by NIMAK , welds the three sheets . It has delivered several of these huge machines to STIHL . Another system is currently being built , which will also be deployed from Spring 2023 .
Thomas Steegmaier , in charge of procuring production equipment for the STIHL Group and leading the project , commented that “ our trust in NIMAK ’ s technical and developmental proficiency , as well as the performance of the machines they have provided thus far , are unådoubtedly crucial factors in this enduring partnership .”
Despite the high availability of portal projection welding systems , proximity is a significant advantage for such a complicated production process . Malfunctions would have serious consequences , particularly as large quantities of a crucial part for the chainsaws are involved .
Fully automated production
Production of the guide bars is fully automated . A handling system feeds the three metal sheets required for this purpose into the machine and first places them on top of each other so that they can be welded together . The two outer sheets are each provided with several welding projections . This is followed by transport to the projection press , where the welding electrodes press the sheets together and synchronously melt the numerous welding projections , heated as a result by the current flow and the electrical resistance of the parts to be welded .
“ The real challenge lies in the high number of projections that have to be welded uniformly in one stroke ,” Steegmaier emphasized . This is precisely why the company opted for a portal system , he explained . “ The symmetrical force and current distribution through the portal projection welding system provides ideal
Thomas Steegmaier ( right ) is project management at STIHL and is also responsible for the procurement of production equipment . Manfred Ramb ( left ) is head of design at NIMAK .
distribution over the part being welded .” This would not be possible with a conventional C-shaped projection welding machine , as the projections would not be pressed and welded as evenly . But , because
Right : The projection press of the NIMAK gantry system has an extremely high electrode force and is equipped with a hydraulic drive . It is adjustable , enabling the setting of force profiles . of the design of the portal system as well as the parallel left and right feed of the current and centrally distributed pressure that is possible as a result , it is distributed in a parallel and even fashion over all projections . NIMAK has provided six transformers , for the high duty cycle , on each side for this purpose .
Consistency and quality
This feeder is used to transport the three sheets placed on top of each other into the projection press , which joins them by welding lots of welding projections .
The upper and lower sheets require highprecision welding of between 72 and more than 100 welded joints in total , depending upon the length of the parts being produced .
“ To accomplish this , our machine must be capable of producing numerous projection joints consistently day after day ,” emphasized Manfred Ramb , Head of Design , NIMAK .
“ At the same time , meeting extremely high-quality requirements is mandatory . This is because joining the three sheets requires precisely matched pressure and currentcontrolled welding profiles . Moreover , to attain optimum metal structure , significant demands must be met for the forming and laying tolerances during the subsequent tempering and cooling phases . This can only be achieved to such a degree with an automated portal system and would be unthinkable using any
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