Utvärdering av tillverkningsmetoder för svarvbommar
On today?s competitive market, it is difficult to achieve profitability trough high prices on manufactured products. Profitability must be obtained through low manufacturing costs, high quality and short lead times. One of the companies on the market is Sandvik Coromant, manufacturer of tools and chips for metal cutting. This master thesis investigates the methods of manufacturing for boring bars at the manufacturing unit GVH4 at Sandvik Coromant in Gimo, Sweden. Currently the boring bars are manufactured with two different methods, one where the iron bar is hardened and annealed before further processing and one where the hardening and annealing is executed after most of the processing. The location of the hardening and annealing in the manufacturing process will affect the different manufacturing steps and also the material flow in the factory. With a value-flow analysis, the differences in material flow of the two manufacturing methods have been analysed. The value-flow analysis resulted in a mapping of the production lead-times, facts about the manufacturing steps, material flow and information flow. Trough a study of how the differences in cycle-times in the manufacturing steps are affected by the choice of manufacturing method and by economic calculations with an activity-based viewpoint, an analysis has been made to determine the method of choice. To obtain information interviews have been carried out with the personnel at the concerned departments. Observations of the flow of material and buffer stocks were carried out, at the same time the amount of products in work were calculated. The necessary facts for the economical calculations have been collected from the companies? economical follow-up. In some cases where the follow-up has been obscure the writers have been compelled to make there own calculations of the cost in these areas. The result of the value flow analysis became a descriptive map over the current material- and information flow. From this analysis it has been determined how the production led times varies between dependent on the choice of manufacturing method. In conclusion: there is no substantial difference in led times between the two methods with today?s production setup. Measurements of the cycle-times have shown interesting facts about the time for increasing value of the products in the production. The measurements of cycle-times and the activity analysis of the production, has resulted in an economical calculation showing that processing before hardening and annealing is preferable, from an economic point of view. The investigation has shown that difference in total cost choosing this method, is about 6 %. If future increase in production volume is expected, the investigation has also shown that the preferred method is the one where the hardening and annealing is executed after processing. This is because a greater amount of boring bars can be manufactured before costly investments in production equipment become necessary. Furthermore, during the investigation it has become increasingly evident that there are some limitations in today?s economical follow-up regarding analysis of where and why resources are consumed in the production. The structure of the accountancy has limitations when it comes to examining possible economic consequences followed by changes in the production. The gathered material about quality aspects has resulted in a listing of quality aspects that are of importance for the choice of manufacturing method. Some of the quality aspects indicate that the implementation of hardening and annealing before processing is impossible for some products: this is due to requirements concerning hardness of the product. Finally, suggestions of areas to be further investigated before choosing manufacturing method have been made.