− My opinion is that Gränges gained trust in us, when we were able to convince them that the construction department in Finspång and the machine workshop in Avesta could jointly carry out the renovation from start to finish. We produced dimensioning, calculations, plans and material selection and discussed a solution on how the actual emergency renovation and assembly of the reel shaft would be carried out, says Martin Andersson, Regional Manager for Maintenance South at Jernbro.
At normal production rate, the renovation would have taken 4-5 weeks, but now it was completed in 1.5 weeks instead. Mainly, has Jernbro’s large arbor mill and large lathe been involved in the work on Gränge’s 4 m reel shaft.
− We wanted to start the renovation as quickly as possible, so we did. The shaft, which had come straight off in two parts, was spliced together into one piece. We did that by drilling a hole in each part, into which we inserted a tube. However, the hole was a hundredth of a mm smaller than the shaft, which therefore needed to be heated to widen in tolerance. In order to then shrink the material, so the tube sitting next to it would become solid with the original material, we cooled it down to -115 degrees with nitrogen. So now things are really tight, says Andreas Löfgren, Head of Department at Jernbro’s machine workshop in Avesta.
The machine workshop in Avesta has done many similar jobs over the years. But this is the largest, making it by far the most advanced. Another parameter to the complexity was that the unusually long shrinkage in each part was 600 mm, which can be compared to 300 mm, the most usual one. Furthermore, the shrinkage had to line up exactly with the keyways. Avesta achieved this by constantly measuring and checking when exactly the right temperature and expansion occurred. If it had failed, they would have had to start over and the work would have been delayed a few weeks.
− In addition to splicing and welding the parts together, the surface has been machined by milling in the arbor mill to the correct tolerances. This is because we wanted tohand over a good-looking product. There are actually no visible signs that the axle has been removed, but it looks like the original, Andreas says.
− Since it was a complicated project with many major risks in all the different stages, we had a close dialogue with Gränges. Through good planning, good competence in all areas and excellent cooperation with the customer and between Jernbro in Avesta and Finspång, we managed to complete everything to 100%. All staff have given 100% of their time and expertise. It has been priceless for the entire project and has enabled a good delivery all the way and a final result that we are proud of, Andreas says.
− I think that the cooperation and the execution show that we have the right skills, big muscles and can help the customer in urgent situations, from the first contact until the production has restarted. It is a statement of strength that Jernbro can gather strength from different cities and can solve such a large and urgent mission together. The customer is satisfied because they received help quickly and since we cut 3 weeks off the job compared to the usual schedule. Other reasons are that the axle was repaired with quality and that we kept what we promised, Martin continues.
− I am particularly satisfied with the repair itself and that we were helped so quickly by Jernbro, who rearranged their own production to be able to help us. Also because Jernbro found the right material and the repair method itself, which was developed at the same time, Tomas adds.
Although the repair of the damaged axle was successful, a completely new one has begun to be manufactured in Avesta.
– We are grateful that we also have been trusted to make the brand new axle, which goes into our regular production. We have upgraded the material selection together with the customer and it will be manufactured according to the customer’s plan. The new shaft is large and makes the manufacturing complex, Martin says.
