Question: In orthogonal turning of a bar of 100 mm diameter with a feed of 0.25 mm/rev, depth of cut of 4 mm and cutting velocity of 90 m/min, it is observed that the main (tangential) cutting force is perpendicular to friction force acting at the chip‐tool interface. The main (tangential) cutting force is 1500 N. (i) Determine the orthogonal rake angle of the cutting tool. (ii) Determine the normal
Question: An orthogonal turning operation is carried out at 20m/min cutting speed, using a cutting tool of rake angle 15°. The chip thickness is 0.4mm and the uncut chip thickness is 0.2mm. Determine (i) the shear plane angle in degrees, and (ii) the chip velocity in m/min. [GATE 2009] Answer: In conventional machining the workpiece material is removed by shearing as and when the cutting tool compresses it. For simplicity
Question: The rake angle of a cutting tool is 15°, shear angle 45° and cutting velocity 35m/min. What is the velocity of chip along the tool face? [ISRO 2009] Answer: Three velocity terms namely cutting velocity (VC), chip flow velocity (Vf) and shear velocity (VS) are associated with orthogonal machining of ductile material using a sharp cutting tool. These three velocity terms together constitute a vector triangle, which is also
Question: In a single point turning tool, the side rake angle and orthogonal rake angle are equal. φ is the principal cutting edge angle and its range is 0° ≤φ≤ 90°. The chip flows in the orthogonal plane. Determine the value of φ. [GATE 2008] Answer: Although in majority of the analysis for straight turning, it is assumed that the chip is flowing in orthogonal direction, but actually chip flow
Question: During orthogonal turning operation of a hollow cylindrical pipe, it is found that the thickness of the chip produced is 0.5mm. The feed given to the zero degree rake angle tool is 0.2mm/rev. Calculate the shear strain produced during the operation? [GATE 2014] Solution: Cutting stain indicates the shear strain developed during any conventional machining operation due to the shearing of one thin layer of workpiece material over another
Question: Following data correspond to an orthogonal turning of a 100mm diameter rod on a lathe. The orthogonal rake angle is +15°; the uncut chip thickness is 0.5mm, the nominal chip thickness after the cut 1.25mm. What is the shear angle for this? [GATE 2018] Solution: Shear angle (βo) indicates the direction of shear plane with respect to cutting velocity (Vc) vector. During any conventional machining process, the cutting tool
Question: A single point cutting tool with 12° orthogonal rake angle is used to machine a steel workpiece. The uncut chip thickness is 0.81mm. The chip thickness under orthogonal machining condition is 1.8mm. What is the shear angle? [GATE 2011] Solution: Machining is one subtractive manufacturing process where layers of material is gradually removed from workpiece by shearing in the form of chips. Shearing actually occurs throughout a 3-D region;
Question: During orthogonal machining of mild steel with a 10° orthogonal rake angle tool, the chip thickness ratio was found to be 0.4. Determine the shear angle. [GATE 2001] Solution: In conventional metal cutting processes, chip gets thickened after machining, and thus chip thickness (a2) becomes larger than uncut chip thickness (a1). The ratio between uncut chip thickness and chip thickness is termed as Chip Thickness Ratio (CTR). Its value
Rake angle of a cutting tool is defined as the angle of inclination of the rake face from the reference plane as measured on some other plane. Based on the orientation of the rake face with respect to reference plane, rake angle can be either positive, zero or negative. A positive rake offers sharp and narrow wedge at the cutting edge and thus facilitates easy shearing of the workpiece material.
