A novel control strategy for suppression of regenerative chatter in conventional lathe

Realizing good quality of machined parts at reduced production time and cost is an important task. Cutting parameters have a major influence on the cost and material removal rate (MRR). Chatter, a dominant phenomenon that occurs during machining, affects the selection of cutting parameters. It is present in almost all machining operations and is a major obstacle in achieving accuracy and productivity. Regenerative chatter, in particular, is the most detrimental to any process and it creates excessive vibration between the tool and the workpiece, preventing possible higher MRR. In addition, it leads to poor surface finish and accelerated tool wear. Either best machining parameters for an existing condition or good machine tool dynamics through minor modification improves MRR. This paper opts for the latter method by modifying the existing tool-post in a conventional lathe with a semi-active biodegradable MR fluid-filled tool-post. Stability lobe diagrams (SLD) prepared through frequency response functions (FRF) for the existing and modified tool-posts revealed that there is an increase of 23% in damping ratio, and furthermore, the chatter-free depth of cut in turning increased from 0.831 to 1.355 mm, i.e., an increase of 63%, irrespective of the spindle speed, along with improved surface finish.