Quality improvement of locally manufactured allen key bolt and nut

Abstract

Industrial sector of Bangladesh has to depend entirely on some impolted spare parts, but it requires long lead time for there procmement. This leads to huge inventoty cost and lot of spares are kept in reserve in the fear of factory shut downs. Allen key Bolts and Nuts are critical spare parts in ceramic industry which has high usage value. 11le quality of allen key bolts and nuts found in the local ma.rket are of very poor. As an attempt to solve this problem the present work wa.s perfonned. Under this work a comperative study of the local and impotted spa.res patts were conducted. Chemical analysis, Vickers hardness, Proof Stress, Microstmcture of the materials of these parts were studied. Apatt Hom that the different pat'ameters of thread of local and import.ed samples are analysed. From the analysis main causes of failure of the local samples at'e identified, suitable materials at'e selected and manufacturing process are developed fl)r their manufacturing. Some Allen key Bolts atld Nuts at'e matlufactured on experimental basis. Different combination of heat treatment such as pack carburizing at different period of time and quenching are petfOl1ned on both locally available and matlUfilctured satnples. 11le proof stress of these samples are checked for quality standard. It was observed that proof stress is increased with the increase of carburizing period for matlUfactured samples but in the case of local samples proof stress is decreased with the increase of cat'burizing period. For mailufactured samples tlle pJ'oof stress was found within acceptable limit. Economic analysis was pedi)nned to evaluate viability of matlUfactut1ng tlle spare locally and it was found that local manufacture of spare parts with the target properties is economically viable and the country save a lot of foreign exchatlge.