Kapabla Processer i Produktion
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
This thesis project was performed at Bosch Rexroth in Mellansel, a company that manufactures radial piston hydraulic motors in different sizes and specifications.Bosch Rexroth in Mellansel is since a few years back working towards goals for process capability with respect to certain key features of the manufactured components. As calculation of process capability was a new practice at the company the aim of this thesis project was to investigate how capability studies could be used to evaluate, improve and control production processes. The potential difficulties with capability studies were also to be investigated as was the reaction of personnel at a company that introduces the use of capability studies.The production processes for three different parts in the CBM motor family were studied in this project: distributors, cylinder blocks and pistons. Every part had a number of key features for which the manufacturing process had already been confirmed by the quality department to lack in capability. A capability study was performed for each key feature with current data to confirm that the capability goals were still not being met. Possible causes for the lacking capability were then investigated. When causes had been determined improvements were suggested. In the cases were it was possible the improvements were implemented and the results followed up on.In one case a capable process had wrongly been thought to be not capable. In most other cases clear causes of lacking capability were identified and improvements could be suggested. Causes could be related to machine settings as well as standardization of the way of work among the operators.In some cases the measuring systems applied were not capable according to earlier studies. Since process capability studies based on not capable measuring systems likely give a false view of how a process performs, the capability of the measuring systems had to be improved. Causes for the insufficient capability were investigated and improvements were suggested. It turned out that in some cases the experiments used to calculate the measuring system’s capability introduced variation not inherent to the measuring system itself. When the experiments were redesigned the capability of the measuring systems in question was shown to be adequate.It was concluded that capability studies could be powerful tools for improvement and long term process control. The difficulties encountered concerned fitting sample data, sufficient access to data and autocorrelation. It seemed like introducing capability studies at a company not previously familiar with them could bring with it some confusion about the point of capability studies as well as a risk of lacking agreement on how they should be implemented.
Place, publisher, year, edition, pages
2015. , 107 p.
Teknik, Kapabilitet, duglighet, produktionsprocesser, statistisk processtyrning
IdentifiersURN: urn:nbn:se:ltu:diva-50742Local ID: 7f812eb4-e58a-4db0-8fdc-a97786ef4044OAI: oai:DiVA.org:ltu-50742DiVA: diva2:1024104
Subject / course
Student thesis, at least 30 credits
Mechanical Engineering, master's level
Validerat; 20151208 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved