Review Jurnal

A Case Study of the Effectiveness of Rolling Process to Manufacture the Strip of Leaf Spring

Kano Springs are crucial suspension elements on cars, trucks, buses etc necessary to minimize the vertical vibrations, impacts and bumps due to road irregularities and create a comfortable ride. This industry is facing severe competition from foreign competitors. To get success in this environment, the industry must significantly improve productivity and quality also reduce scrap and waste during production in addition to economic consideration, the environmental concern and energy consumption requirement, and strongly derive steel industry toward that direction. Therefore, there is an urgent need from steel industry for effective process quality control. The rolling operation is often the last process step of raw materials of several products, hence the scrap at rolling stage is very costly and the quality control of rolling process has a vital role. Any defect in the material may result rejection of final product that leads to major loss in terms of money and sometimes major accidents also.

ISO 9001-2008 Certification shows a frame work to standardize the manufacturing process of product, test the product, employees training, keep records of defects etc. Every customer of the flow process has to put their best effort to minimize defect and improve the quality of the final product. Basic problem solving techniques equipped with quality tools are used for data analysis to solve problems. Every technique has its own merit and demerit. The members of quality control team will need to be trained in the application of these techniques. The commonly used techniques are Brain storming, Pareto diagram, Cause and effect analysis, Data collection and Data analysis. Tools used for data analysis are Tables, Bar charts, Histogram, Circle graphs, Line graph, Scatter graphs, and Control charts.

The annual requirement of the unit at the full capacity of utilization is approximately 36000 MT per annum. Raw material is received from the local market (scrap) and from the SAIL and TISCO etc.

                

If all above process with internal customer ship is followed under ISO 9001-2008 system; consequently external customer will get full satisfaction because internal customer is already satisfied. At every stage of the internal customer ship short coming found are to be taken for analysis hence effectiveness of the rolling process can be improved.

The following points have been proposed to reduce the defects and ultimately rejections during the manufacturing of strip for leaf spring.  Internal, external customer ship type scenario is to be developed by applying recommended statistical quality control tools like, brain storming, pareto diagram & cause & effect diagram to correct the problem and minimize defect level.  Roll surface can be maintained by polishing the roll with oil stone in the running condition of the mill.  Roll reconditioning is to be done once or twice afterwards rolls may be replaced.  Roll to be checked after fix interval of production.  Training is to be imparted to the supervisor and main worker for efficient working and also for improving the skills.  Furnace capacity is low that should be increased. Molten metal poured through plain pipes are to be replaced by sprue so that momentum of the molten metal can be maintained and entrapped gas can be minimized.  Manual pouring is to be replaced by automatic arrangement so that pouring pressure uniformity can be maintained.  Some exothermic material is to be used at the mould face so that end defects on ingot can be minimized.  Some stainless steel grate may be used to avoid slug inclusion in the metal. Slug can be trapped on the grate and can be thrown away. During the idle time, loss of fuel oil is also there that can be reduced by automation of the plant.

In the present work, customer satisfaction among the International Journal of Materials, Mechanics and Manufacturing, Vol. 1, No. 1, February 2013 74 various flow processes as well as internal and external customer ship phenomenon has been established for enhancing the effectiveness of rolling process. During the process, different defects occur either due to method, material, man, equipment/machine. Cause & effect diagram revealed analysis of the defect with their root cause. Serious efforts on the problem by using root causes analysis will eliminate the defects and the quality can be improved. Defect may be occurred in foundry during the ingot casting, to follow reheat furnace. It is hereby also suggested that ingot must be carefully checked for surface defect; length and their proper stock size. If any hidden defect lies within the ingot, specimen should be cut down and should be investigated by non destructive test. Other defect which comes on product must also be taken care at rolling mill area, handling of the material and proper stacking of the product etc.

Pengarang     : P. S. Chauhan dan C. M. Agrawal
           Diterbitkan     : February 2013

Link                : http://www.ijmmm.org/papers/015-E037.pdf

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Ditulis oleh Unknown pada tanggal Kamis, 28 Desember 2017