MCTD Sessional 2012 Revised

SCHOOL OF MECHANICAL ENGINEERINGSUB: METAL CUTTING & TOOL DESIGN [ME 682]

METAL CUTTING & TOOL DESIGN(SESSIONAL)

PAPER CODE-ME682

6TH SEMESTER B.TECH(MECHANICAL)

Teachers

Prof. Simanchal KarProf. Diptikanta Das

Prof. Trupti Ranjan MahapatraProf. Kamal Pal

Prof. Ashok Kumar Sahoo (Coordinator)


ASSIGNMENTS

ASSIGNMENT-1 GEOMETRY OF CUTTING TOOLS

ASSIGNMENT-2 DESIGN OF SINGLE-POINT CUTTING TOOL

ASSIGNMENT-3 DESIGN OF FLAT FORM TOOL

ASSIGNMENT-4 DESIGN OF CIRCULAR FORM TOOL

ASSIGNMENT-5 MECHANISM OF MACHINING

ASSIGNMENT-6 MECHANICS OF METAL CUTTING

ASSIGNMENT-7 DESIGN OF BROACH

ASSIGNMENT-8 TOOL LIFE & MACHINABILITY

ASSIGNMENT-9 DESIGN OF PRESS TOOL

ASSIGNMENT-10 DESIGN OF LIMIT GAUGES

ASSIGNMENT-11 GEOMETRY OF TWIST DRILL & MILLING CUTTER

ASSIGNMENT-12 ESTIMATION OF MACHINING TIME

ASSIGNMENT-13 ECONOMY OF MACHINING


ASSIGNMENT-1GEOMETRY OF CUTTING TOOLS

Q.1 Sketch a single-point turning tool in Tool-in-Hand system and visualize its salient features.

Q.2 Sketch the left and right hand cutting tool and show the principal cutting edge and the direction of feed.

Q.3 Sketch the action (plan view) of a single-point right-hand turning tool, set at an angle Φ with respect to feed direction with a depth of cut of t mm and a feed of s mm/rev.

Q.4 Show by a suitable sketch the rake angle and clearance angle of any cutting tool in a machining work. Also state why these angles are provided.

Q.5 Show the following angles in a single point cutting tool(i) Cutting angle(ii) Positive, negative & zero rake angles(iii) Inclination angle

Q.6 Sketch the following Reference systems with planes & axes.(a) Machine reference system (ASA)(b) Tool Reference systems i.e.(i) Orthogonal rake system (ORS)(ii) Oblique or Normal rake system (NRS)

Q.7 Draw the single-point turning tool and visualize its different rake angles, clearance angles and cutting edge angle in machine reference or ASA system.

(Orientation of face and flank surfaces w.r.to M/C reference system)

Q.8 Draw the single-point turning tool and visualize its different rake angles, clearance angles and cutting edge angle in orthogonal rake system (ORS).

(Orientation of face and flank w.r.to orthogonal tool reference system)

Q.9 Draw the single-point turning tool and visualize its different rake angles, clearance angles and cutting edge angle in normal rake system (NRS). When do normal rake and orthogonal rake of any cutting tool become same?

(Orientation of face and flank w.r.to normal tool reference system)

Q.10 How is the geometry of single-point cutting tool designated or specified in(i) ASA system(ii) Orthogonal rake system (ORS)(iii) Normal rake system (NRS)


Q.11 With the help of simple diagram, how work reference system is different from ASA system w.r.to tool geometry. When use of work reference system (of tool designation) becomes essential and why?

Q.12 Describe the tool represented by 10-10-6-6-8-8-3/64 (inch) in ASA system.

Q.13 Describe the tool represented by (-10)-10-8-8-15-750-1 (mm) in ORS system.

Q.14 During machining of C-40 steel, a double carbide cutting tool of 0-10-6-6-8-750-1mm ORS shape has been used. What is the amount of (a) back rake (b) side rake, and (c) side clearance?

Q.15 A cutting tool has been ground with a back rake of 80 and side rake of 140. How much is the orthogonal rake & inclination angle? Given approach angle Φ = 750

Q.16 In a turning operation, the principal cutting edge angle is 600. Calculate the side rake so that the cutting can be considered as orthogonal. Given γo = 80

Q.17 Determine the values of orthogonal rake and normal rake of the single-point turning tool whose geometry is designated as: 10o, 0o, 10o, 7o, 15o, 0o, 0 (inch).

Q.18 The geometry of a turning tool is designated in ASA system as 8-14-6-6-6-15-3/64 (inch). What would be the geometrical designation of that tool in ORS?

Q.19 Estimate the value of effective rake angle (γe) for turning a rod at so= 0.24 mm/rev and t = 4.0 mm by a tool of geometry 100, 80, 70, 60, 150, 750, 1.2 (mm) – NRS.

Q.20 Determine the values of orthogonal rake angle, inclination angle of the main cutting edge of the turning tool specified in the ASA system as 10o, -10o, 8o, 6o, 15o, 30o, 0 (inch).

Q.21 Under what geometrical conditions of a turning tool will the values of its side rake, orthogonal rake and normal rake angles be the same?

Q.22 Under what condition of turning and tool geometry, the value of effective rake will be equal to the orthogonal rake of the cutting tool?

DRAWING SHEET-1

Tool Geometry (ASA & ORS)Q.18 of Assignment-1


ASSIGNMENT-2DESIGN OF SINGLE-POINT CUTTING TOOL

Q.1Design a single point cutting tool for rough turning of Mild Steel work piece.

Q.2Design a single point cutting tool for rough turning of Stainless Steel work piece.

Q.3In orthogonal turning of a mild steel bar on a lathe, the feed (f) used is 0.2 mm/rev and the depth of cut (t) is 1 mm. Determine the cross-section of a rectangular tool shank if the allowable stress in the shank material is 7 kg/mm2 and the cutting force can be calculated by the relation Pz = 200 × f 0.65 × t

Q.4A 5 rectangular shank lathe straight turning tool for roughing operation is to be employed for machining of 60 mm diameter work at a cutting speed of 30 m/min. Maximum permissible deflection at tool nose is 0.03mm & maximum allowable bending stress in shank is 8 kgf/cm2. Determine shank cross section (BH) if the tool is subjected to Fz = 120 kgf. Tool overhang is 1.5 H. Standard values of B & H are:

B in mm 10 12 12 16 16 20 25 25 32

H in mm 16 16 20 20 25 25 32 32 40

DRAWING SHEET-2

Design of Single Point Cutting Tool Q.1 of Assignment-2


ASSIGNMENT-3DESIGN OF FLAT FORM TOOL

Q.1What is form tool? What are the different types of form tool? Give neat sketch.

Q.2Design a flat form tool to generate the contour (profile) mentioned below on the mild steel work piece. Dimensions are given below in mm. Solve it both analytically and graphically.

DRAWING SHEET-3

Design of Flat Form Tool Q.2 of Assignment-3


ASSIGNMENT-4DESIGN OF CIRCULAR FORM TOOL

Q.1A vee-groove of 5 mm depth is to be made on a bar of 20 mm diameter using circular form tool of 80 mm diameter. The rake and clearance angles on the form tool are 50 each. Calculate the included angle of the groove in the form tool if the included angle in the job is 600.

Q.2Design a circular form tool to generate the contour (profile) mentioned below on the mild steel work piece. Dimensions are given below in mm. Solve it both analytically and graphically.

DRAWING SHEET-4

Design of Circular Form Tool Q.2 of Assignment-4


ASSIGNMENT-5MECHANISM OF MACHINING

Q.1During turning a mild steel component with a 0-10-7-7-8-90-1.5 mm orthogonal shaped tool a depth of cut of 1.8 mm is used. If feed is 0.18 mm/rev and a chip thickness of 0.36 mm is obtained. Determine the following

(a) chip thickness ratio(b) chip reduction coefficient(c) shear angle

Q.2 What will be the value of average cutting strain in case of orthogonal turning of a ductile rod, if (a) feed = 0.24 mm/rev, (b) principal cutting edge angle = 900, (c) orthogonal rake = 120 and (d) chip thickness = 0.6 mm.

Q.3 By how much angle, the direction of chip flow will deviate from the orthogonal plane if a steel rod is turned in a lathe by a tool of geometry: 100, 50, 80, 70, 150, 750, 0 mm in NRS at feed of 0.2 mm/rev and depth of cut of 3 mm.

Q.4 A mild steel rod was subjected to orthogonal turning at high speed, feed of 0.2 mm/rev and 2 mm depth of cut by a carbide tool of geometry: 00, 100, 80, 70, 150, 600, 0 mm. Assuming coefficient of friction at the chip-tool interface equal to 0.5, determine the following for the above machining: (a) width of cut (b1), (b) thickness of chip before (a1) and after cut (a2) and shear angle.

Q.5 During orthogonal turning a mild steel rod by a tool having 100 orthogonal rake angle and 750

principal cutting edge angle at feed 0.32 mm/rev, the chip thickness was found to be 0.6 mm. Determine the expected value of the chip-tool contact length.

Q.6During turning a mild steel component with an orthogonal tool a feed of 0.75 mm/rev is used at 50 rpm. If the chip thickness is 1.5 mm, determine the chip thickness ratio and chip reduction coefficient. Also find the length of chip removed in one minute if the work diameter is 50 mm before the cut is taken. Assume a continuous chip.


Q.7Determine the time required to turn a brass component 50 mm diameter and 100 mm long at a cutting speed of 36 m/min. The feed is 0.4 mm/rev and only one cut is taken.

Q.8A medium carbon steel bar 40 mm dia. is turned on a lathe with a cutting tool having orthogonal rake of 300 and with a cutting speed of 24 mpm. If the cutting force is 200 kg, feed force 80 kg, feed given to tool is 0.12 mm/rev and length of chip in one revolution is 70 mm, determine the shear angle, chip reduction coefficient and chip thickness.

Q.9During machining of C-20 steel with a triple carbide cutting tool having 0-8-5-5-10-75-1mm (ORS) with a feed of 0.4 mm/rev and a depth of cut of 1.5 mm at cutting speed of 250 m/min, a chip thickness of 0.5 mm has been obtained. Calculate

(a) chip reduction coefficient and shear angle(b) dynamic shear strain

Q.10In an orthogonal turning operation, following data was given:(a) Cutting speed = 80 m/min, (b) cutting force = 20 kg, (c) feed force = 8 kg, (d) orthogonal rake = 150, (e) feed = 0.2 mm/rev and (f) chip thickness = 0.4 mmDetermine the following

(a) shear angle(b) work done due to shear(c) shear strain

Q.11Prove that minimum shear strain occurs when the chip thickness ratio is unity.


ASSIGNMENT-6MECHANICS OF METAL CUTTING

Q.1 In turning, the single (resultant) cutting force is resolved into three orthogonal components for analysis and measurement. Name and schematically show those force components and state their significance roles.

Q.2 Draw a Merchant’s circle diagram (MCD) and visualize in it the various cutting force components that arise during orthogonal turning. Derive the frictional force system at the chip tool interface and force system at the shear plane.

Q.3 Derive, with the help of MCD, simple expression for(a) Force components at shear plane(b) Force components at chip-tool interface

Q.4 Derive using MCD, a simple expression for the main cutting force component Pz (in orthogonal turning) as a function of feed, depth of cut, shear strength of the work material and shear angle only.

Q.5 Deduce starting from MCD, the following expression for the tangential force component Pz under orthogonal turning of ductile metal rod

Pz = t so τs (ζ – tan γo + 1)

Q.6 Show that for metal machining during orthogonal turningWc = Ws + Wf where Wc, Ws and Wf are the total energy, total shear energy and total specific friction energy per unit volume of metal removed respectively.

Q.7 In an orthogonal turning, if the feed is 1.25 mm/rev and chip thickness after cutting is 2 mm, determine

(a) chip thickness ratio(b) shear angle

The tool bit has a rake angle of 100. If the shear strength = 6000 kg/cm2If shear strength = 6000 kg/cm2Width of cut = 10 mmCutting speed = 30 m/minCoefficient of friction = 0.9Determine

(a) shearing force(b) friction angle(c) cutting force(d) HP at cutting tool


Q.8 During a metal cutting test under orthogonal conditions, it was found that cutting force is 110 kg and feed force is 102 kg when cutting at 165 m/min. The rake angle of tool is 10 0 and shear plane angle was found to be 190. Determine the following:

(a) shear velocity(b) chip flow velocity(c) work done per minute in shearing the metal & work done against friction(d) show that the work input is equal to the sum of work done in shearing and against

friction

Q.9 During turning a ductile alloy by a tool of γ0=100, it was found Pz =1000N, Px = 400 N, Py= 300 N and ζ = 2.5. Evaluate, using MCD, the values of F, N and μ as well as Ps and Pn for the above machining.

Q.10 During turning a steel rod of diameter 160mm at speed 560 rpm, feed 0.32mm/rev and depth of cut 4mm by a ceramic insert of geometry 0o, -10o, 6o, 6o, 15o, 75o, 0 (mm) The followings were observed: PZ =1600 N, PX=800 N and chip thickness=1mm. Determine with the help of MCD the possible values of F, N, Ps, Pn, cutting power and specific energy consumption.

Q.11 For turning a given steel rod by a tool of given geometry if shear force Ps , frictional force F and shear angle β0 could be estimated to be 400N and 300N respectively, then what would be the possible values of Px, Py and Pz? [Use MCD].

Q.12 During shaping like single point machining/turning) a steel plate at feed, 0.20 mm/stroke and depth 4 mm by a tool of λ = γ = 00 and φ = 900 Pz and Px were found (measured by dynamometer) to be 800 N and 400 N respectively, chip thickness, a2 is 0.4 mm. From the aforesaid conditions and using Merchant’s Circle Diagram determine the yield shear strength of the work material in the machining condition?

Q.13 A ductile metal rod of 120 mm diameter is turned at a speed of 320 rpm, feed of 0.24 mm/rev and 3 mm depth of cut by a tool of the following geometry: 0o, 10o, 8o, 6o, 20o, 70o, 0 (mm). The following observations were made: Tangential force (Pz) = 750 N, transverse force (Py) = 200 N, chip thickness (a2) = 0.7 mm. Using MCD, determine the approximate values of(i) Friction and normal force at rake surface (F and N)(ii) Shear force (Ps)(iii) Cutting power consumption (Pc)(iv) Dynamic yield shear strength (τs) of the work.

Q.14 If, an orthogonal turning operation by a tool having γo = 120 and Φ = 600, it is found that Pz = 800 N and ζ = 3, what would be the values of Px and Py? Assume that β o + η – γo = π / 4.


Q.15 During orthogonal turning operations, the following data was obtained:Cutting force = 120 kg, feed force = 30 kg, rake angle = 100, feed = 0.2 mm/rev, width of cut = 2.3 mm, chip thickness = 0.4 mm and cutting speed = 120 m/minDetermine (a) chip thickness ratio, (b) shear angle and (c) shear stress

Q.16 In an orthogonal cutting operation, the following data have been observed:Uncut chip thickness = 0.15 mm, width of cut = 7.2 mm, cutting speed = 3 m/min, rake angle = 120, cutting force = 580 N, feed force = 240 N and chip thickness = 0.28 mmDetermine the following:(a) shear angle, (b) friction angle, (c) shear stress along the shear plane and the power for the cutting operation. Also find the chip velocity, shear strain in chip and shear strain rate

Q.17 The following data from an orthogonal cutting test is available:Rake angle = 120, chip thickness ratio = 0.4 mm, uncut chip thickness = 0.6 mm, width of cut = 4 mm, yield stress of material in shear = 300 N/mm2, average co-efficient of friction on the tool face = 0.8Determine the normal and tangential forces on the tool face

Q.18 During machining of C-35 steel with 0-10-6-6-8-90-1 mm (ORS) shaped carbide cutting tool, the following observations have been made:Depth of cut = 2 mm, feed = 0.2 mm/rev, speed = 200 m/min, cutting force = 1600 N, feed force = 850 N and chip thickness = 0.4 mm. Calculate(a) Shear force (b) normal force at shear plane, (c) friction force, (d) kinetic coefficient of friction and (e) specific cutting energy

Q.19 During machining of C-20 steel with triple carbide cutting tool 0-10-8-8-15-60-1mm (ORS) shape has the following data obtained:Feed = 0.2 mm/rev, depth of cut = 2.5 mm, cutting speed = 50 m/min, chip thickness = 0.6 mm, cutting force = 160 kg and feed force = 50 kgDetermine the following:Pxy, Py, Pn, F, N, μ, Ts, a1, ζ, rc, βo, η, Ps, b1, Uc, Us, Uf, Vf, Vs, Wc, Ws, Wf and prove that Wc = Ws + Wf.

Q.20 Determine, without using MCD, the values of the shear force Ps and the force Pn normal to the shear plane under the following observed conditions: Pz = 1000N, Px = 400N, Py = 200N, γo = 150 and ζ = 2.


ASSIGNMENT-7DESIGN OF BROACH

Q.1Design a HSS circular broach for enlarging a 40 mm dia. hole in a M.S gear hub of 60 mm length to 50 mm. Assume necessary data.

Q.2The bore of an alloy steel component prior to broaching is 35 mm. The bore is to be finish broached to 36 mm diameter. If the length of bore is 50 mm and the cutting speed is 0.3 m/s, determine the following:

(a) Pitch of teeth(b) Length of cutting portion(c) Force to pull broach through work if rise per tooth is 0.025

Number of finishing teeth is 3 and force to remove 1 mm2 of metal is 4800 N.

Q.3A broach is used to cut a key way 9 mm wide, 6 mm deep in a boss 70 mm long. Determine cutting length of broach and no. of teeth on broach.

DRAWING SHEET-5

Design of Broach Q.1 of Assignment-7


ASSIGNMENT-8TOOL LIFE & MACHINABILITY

Q.1 For a cutting tool, the Taylor’s tool life relationship between cutting velocity and tool life is expressed by V Tn = C. In a certain tool test a single point cutting tool had a life of 10 minutes when operating at 240 m/min. At what speed should the tool have to be operated in order to have tool life of 3 hours. Assume n = 0.2.

Q.2 Under a given condition of turning, the tool life was found to decrease from 24 min to 16 min when only the cutting velocity was raised from 200 m/min to 250 m/min. What will be the tool life if the cutting velocity is further increased to 300 m/min under the same machining condition?

Q.3 During turning a brass rod by an HSS tool, the tool life increased from 2 min to 40 min when cutting velocity is reduced from 50 m/min to 40 m/min. At what cutting velocity, the life of the same tool under the same condition will be 30 min?

Q.4 The tool life for a HSS tool is expressed by the relation V T1/7 = C1 and for tungsten carbide (WC) is expressed as V T1/5 = C2. If at a speed of 24 m/min, the tool life is 128 minutes, compare the life of the two tools at a speed of 30 m/min.

Q.5 A tool life of 80 minute is obtained at a speed of 30 m/min and 8 minute at 60 m/min. Determine the tool life equation and cutting speed for 4 minute tool life.

Q.6 Determine the percentage change in cutting speed required to give 60% reduction in tool life (i.e to reduce tool life to 2/5 of its former value). The speed/life relationship of cutting tool is given by V Tn = C. Take n = 0.2

Q.7 During machining 18 mm bar on a lathe at a cutting speed of 110 m/min, the life of the tool is found to be 60 minutes. If n = 0.2, calculate the speed at which the spindle should be run to give a tool life of 5 hours. If a length of 50 mm per component is machined, what is the cutting time per piece and how many pieces can be produced between tool changes? The feed used is 0.15 mm/rev.


Q.8 During a tool life test of HSS tool material used to cut a special die steel, the following values were obtained.Cutting speed (m/min) 52 50 49 46 42Tool life (minutes) 3 4 4.9 10.5 30Use the above values to calculate the constants of the tool life equation V Tn = C.

Q.9 The following data were recorded while turning a W/P on a lathe. Cutting speed = 25 m/min, feed = 0.3 mm/rev, depth of cut = 20 mm, tool life = 100 min. The following tool life equation is given by V T0.12 s0.7 t0.3 = C. If the cutting speed, feed and depth of cut are all increased by 25% each and also correspondingly, what will be the effect on tool life.

Q.10 During a tool life test by turning a C20 steel rod by a sintered carbide tool at a given speed-feed-depth condition, the following observations were made:

Total time of machining (T), min 1 2 5 10 15 20Average flank wear, Vb (mm) 0.1 0.15 0.2 0.24 0.28 0.36

Draw Vb versus T curve and determine tool life for the above condition.

Q.11 Determine the values of the constant C and index n of Taylor’s tool life equation if the value of tool life decreased from 40 min to 10 min due to increase in cutting velocity from 80 m/min to 160 m/min in turning mild steel rod by a coated carbide insert under a given condition.


ASSIGNMENT-9DESIGN OF PRESS TOOL

Q.1Sketch and design a progressive die to manufacture a circular washer of 20 mm outside diameter with 10 mm hole from 1 mm thick mild steel sheet. The ultimate shear strength of the material is 300 N/mm2.

Q.2A steel component 20 mm × 60 mm is to be made from 2 mm thick sheet. Sketch the scrap strip layout. Also determine percentage of stock used.

DRAWING SHEET-6Design of Press tool

Q.1 of Assignment-9


ASSIGNMENT-10DESIGN OF LIMIT GAUGES

Q.1 Design the workshop, inspection and general type of GO and NOGO gauges for checking the assembly Φ 30 (mm) H7/f8. Fundamental deviation for f shaft = - 5.5 D 0.41. Diameter step for Φ 30 = 18-30 mm. Fundamental tolerances for IT7 and IT8 are 16i and 25i respectively. Wear allowance is 10% of gauge tolerance. Also determine (i) type of fit (ii) allowance for the above fit (iii) other shafts giving the same type and same degree of fit (iv) equivalent fit in shaft-based system.

Q.2 Determine actual dimension to be provided for a shaft and hole of 90 mm size for H8e9 type clearance fit size 90 falls in the diameter step of 80 and 100. F.D for e type shaft = -11 D 0.41. Also design GO and NOGO gauges.

Q.3 A hole and shafting system has the dimension 60 H-7/m-6. Diameter step of 60 is 50-80 mm. The multipliers are

Grade 6 7

Multiplier 10 16

F.D for fit m is given by + (IT7-IT6). Find (i) class of fit and application (ii) sketch the fit and show actual dimension.

DRAWING SHEET-7Design of Limit Gauge Q.1 of Assignment-10


ASSIGNMENT-11GEOMETRY OF TWIST DRILL & MILLING CUTTER

Q.1 Sketch a twist drill designated as 20.00-IS: 5101-HS-N-118 having a tapered shank (1:100) and a neck of length and diameter 15 mm each. Show the end view of the drill point and rake angles at various points on the cutting edge. Assume, overall length =200 mm, shank length =70 mm, flute length =110 mm, helix angle =300, lip relief angle =120 and chisel edge angle =1250.

Q.2 Find the drilling power for 50 mm diameter drill having a feed of 0.50 mm/rev. The cutting speed is 0.75 m/s. The material factor for brass is 0.55. Determine also the drilling thrust. Assume BHN of brass as 60 and point angle of drill as 1080

Q.3 Draw and sketch the front view and side view of a helical plain milling cutter having the following dimensions. Arbor diameter = 50 mm, thickness of the cutting ring = 20 mm, height of the cutting teeth = 30 mm, helix angle =250, radial rake angle =150, relief angle =70. Assume other necessary data.

Q.4 A 20 teeth, 10 cm diameter, cutter operate at 80 rev/min with a feed of 16 mm/rev. The material to be cut is medium C.I. The width of the cut is 1.25 cm and the depth of cut is 0.125 cm. Calculate: (a) the horsepower at the cutter, (b) the horsepower at the motor if the efficiency is 40%. Take machinability factor is as 15 cm3/min/hp.


ASSIGNMENT-12ESTIMATION OF MACHINING TIME

Q.1 State the procedural steps that are followed for estimation of time required for straight turning a rod in a centre lathe.

Q.2 What is the procedure of analytical determination of time required for drilling a through hole in a given metal plate?

Q.3 Describe the method of calculation of total time that may be required to finish the two flat surfaces of a rectangular plate of given dimensions by shaping.

Q.4 The top surface of a cast metal plate is to be finished by plain milling. How will you estimate the span of time that will be required for the said purpose?

Q.5 Briefly state the procedure of calculation of time required for completing the teeth of a spur gear from a given blank in a gear shaping machine.

Q.6 Determine the actual machining time required to reduce the diameter of a rod from 200 mm to 195 mm over length of 200 mm at cutting velocity of 220 m/min and feed of 0.2 mm/rev. Assume, approach A = 5 mm and overrun O = 5 mm.

Q.7 Determine the actual machining time that will be required to drill a through hole of diameter 25 mm in a 60 mm thick plate at cutting velocity of 55 m/min and feed of 0.24 mm/rev by a HSS drill of cone angle of 1200. Assume approach and overrun = 2 mm.

Q.8 Determine the actual machining time that will be required to remove, by shaping, a layer of 2 mm thickness from a cast iron of length 100 mm and width 60 mm at cutting velocity of 40 m/min and feed of 0.2 mm/rev. Assume approach and overrun along width = 2 mm and along length = 5 mm, quick return ratio of the shaping machine is 2/3.

Q.9 Determine the actual machining time that will be required for plain milling a rectangular surface of length 200 mm and width 50 mm by a helical fluted plain HSS milling cutter of diameter 70 mm, length 75 mm and 6 teeth. Assume A = O = 5 mm, cutting speed (v) = 44 m/min and feed (s) = 0.2 mm/tooth.

Q.10 Estimate the minimum time that will be required to generate all the teeth of four cast iron straight-toothed spur gears of 50 teeth, 3 module and 25 mm thickness by a HSS gear shaping cutter of 20 teeth. Assume: st = 0.4 mm/stroke, sr = 0.04 mm/stroke. A = O = 12.5 mm.


ASSIGNMENT-13ECONOMY OF MACHINING

Q.1 How much time in total will be required per piece if(i) Idle time per piece = 5 min(ii) Actual cutting time = 20 min(iii) Life of each tool tip = 10 min(iv) Time of changing a tool tip = 2.5 min

Under the machining condition given above, determine the optimum value of the cutting velocity for minimum total machining time per piece, if the Taylor’s tool life equation for the tool-work combination is considered to be VTn = 500. Also determine the life of each tool tip when machined at the optimum cutting velocity.

Q.2 Evaluate the machining cost per piece in a batch production by turning if(i) Idle time per piece = 5 min(ii) Actual machining time per piece = 10 min(iii) Life of each tool tip = 10 min(iv) Time of changing a tool tip = 5 min(v) Man-machine hour rate, K1 = Rs. 60 per hour(vi) Cost of each new tool tip, K2 = Rs. 5

Under the machining condition given above, determine the optimum cutting velocity and the corresponding tool life for minimum machining cost per piece, if the Taylor’s tool life equation is VT0.2 = 200 and values of K1 = Rs. 2 per min and K2 = Rs. 5 per tool tip.

Q.3 Calculate the total machining cost per piece if(i) Operation cost = Rs. 250/hr(ii) Machining time = 0.3 min(iii) Tool life for cutting tool = 3 min(iv) Machine down time = 5 min(v) Cost of tool tip = Rs. 45


REFERENCES

1. Metal Cutting Theory & Practice – A.Bhattacharya

2. A Text Book of Production Engineering – P.C.Sharma

3. Tool Engineering & Design – G.R.Nagpal

4. Tool Design – Donaldson

5. Metal Cutting Principles – M.C.Shaw

6. Metal Cutting – E.M.Trent & Wright

7. Fundamentals of Metal Cutting & Machine Tools – Juneje & Sekhon

8. Metal Cutting Theory & Practice – Stephenson David A & Agapiou John S

9. Fundamentals of Machining & Machine Tools – Boothroy & Knight

10. Tool Design – ASTME

11. Tribology of Metal Cutting – V. P. Astakhov

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