Papers by Author: Mohammed Sarwar

Abstract: Broaching is a precision multipoint metal removal operation normally employed for manufacturing variety of complex parts having either internal or external features. Broaching can produce high precision and good surface finish at a high metal removal rate. The unique feature of a broach tool is that the feed/depth of cut for the teeth is built into the broach unlike other cutting tools. The tool design (e.g., rise per tooth and tooth geometry) play a vital role in the broach performance. A specially adapted machine tool modified to investigate a single broach tooth has been used. Cutting forces and material removal rate have been measured during experimental work for different combination of broaching parameters and broach tool geometry. The effect of the parameters on the surface quality produced has been established. The characteristics of chips formed have also been defined. Finally, optimum tooth geometry and rise per tooth have been recommended for tool performance, broached surface quality and efficient chip formation. The information provided in this paper will be beneficial for broach tool designers and manufacturing engineers.

Abstract: The benefits of applying advanced coatings on both single point and multipoint cutting tools such as improvement of productivity, tool life, machined surface quality etc. have been realised by the surface engineering researchers [1], commercial coaters [2-4] and end users [5]. The demand for advanced coatings in cutting tool industries is continually growing to meet the challenges of high speed machining, dry machining, near net-shape machining, machining of hard-to-cut materials etc.. Advanced coatings with excellent properties on flat coupon in a laboratory deposited by modern deposition technologies should not be taken for granted in improving the performance of complex shaped cutting tools [6] in aggressive cutting environments. This is because the end performance of coated cutting tools is not only dependant on the coating itself but also on the tool substrate material, geometry, surface finish and cutting edge conditions prior to coating deposition. The paper presents case studies with examples of successes and failures of advanced coatings on different multipoint cutting tools (e.g., milling cutters, bandsaws, circular saws, holesaws etc.). The future strategy for developing successful coating technology for cutting tools should be directed towards adopting a systems approach to bridge the communication gap amongst the cutting tool manufactures, tool coaters and end users.

Abstract: This paper reports experimental data on the wear of high-speed steel bimetal bandsaw blades cutting austenitic 17-7 stainless steel bars. Several different methods of assessing the wear modes and mechanisms are evaluated; Cutting and thrust force components, Set width, Kerf width, “Out-of-square” cutting, Wear modes and mechanisms and Chip characteristics. The wear mode established in the current work when bandsawing austenitic stainless steel with a bimetal blade is flank and corner wear together with formation of a cutting edge radius. The cutting edge radius increases as the wear progresses, reaching 25-50 mm after 300 cut sections. The established wear mechanism for the initial stages of wear is mild adhesive wear of the flank surface together with built-up edge formation and break-down. As the wear reaches steady-state the mechanism is adhesive wear of the flank surface with tempering/softening of high-speed steel layers. When the wear reached the steady-state region the level of thrust and cutting force were equal and relatively high. The kerf width appears to be less than the total set width of the blade, meaning that there is compression of the set teeth as they pass through the kerf. There is segmented chip formation with an increasing amount of vibration as the teeth wear, probably due to the increasing size of cutting edge radius. This work should be of great interest to the tool designer and user associated with bandsaws.