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Technical Guidance Reference Technical Guidance Reference References N11 to N42 N N Parts Technical Guidance Guidance Technical N Reference Technical Guidance Turning Edition ................................................ N12 Milling Edition ................................................. N17 Endmilling Edition ........................................... N21 Drilling Edition ................................................. N24 SUMIBORON Edition ...................................... N29 References SI Unit Conversion List ................................... N33 Metals Symbols Chart (Excerpt) .................... N34 Steel and Non-Ferrous Metal Symbol Chart (Excerpt) ... N36 Hardness Scale Comparison Chart .............. N37 Dimensional Tolerance of Standard Fittings .... N38 Dimensional Tolerance and Fittings .............. N40 Standard of Tapers ......................................... N41 Surface Roughness ....................................... N42 N11 Technical Guidance The Basics of Turning, Turning Edition Calculating Cutting Speed Calculating Power Requirements f (1) Calculating rotation speed from cutting speed n : Spindle Speed (min-1) P m c : Power requirements (kW) v n 1,000×vc c : Cutting speed (m/min) D n ø v = D c : Cutting speed (m/min) X×Dm m : Inner/outer diameter of workpiece (mm) vc×f×a p×k c p Pc = f : Feed Rate (mm/rev) X : ≈ 3.14 a 60×103×V References ap : Depth of cut (mm) k : Specific cutting force (MPa) N v D c Example: c=150m/min, m=100mm P H = c H : Required horsepower (HP) 1,000 × 150 Feed Direction n = = 478 (min-1) 0.75 3.14 × 100 V : Machine efficiency (0.70 to 0.85) · n : Spindle speed (min -1) · v : Cutting speed (m/min) (2) Calculating cutting speed from rotational speed c Rough value of kc · f : Feed rate per revolution (mm/rev) D ×D ×n a v X m · p : Depth of cut (mm) Aluminum: 800MPa Parts c = Refer to the above table 1,000 General steel: 2,500 to 3,000MPa · Dm : Diameter of workpiece (mm) Cast iron: 1,500MPa Reference Three cutting force Relation between cutting Relation between feed rate and Technical Guidance Guidance Technical components speed and cutting force specific cutting force (for carbon steel) Rake Angle: -10° 1,600 8,000 Traverse Rupture Strength Ff 800 800MPa Rake Angle: 0° 600MPa 6,000 Principal Force (N) Principal Force 0 400MPa Fp 0 80 160 240 Fc: Principal force Cutting Speed (m/min) Fc Ff : Feed force Fp: Back force Relation between rake 4,000 angle and cutting force D Calculating cutting force P 2,800 k ×q : Cutting force (kN) (MPa) Specific cutting force P = c k c : Specific cutting force (MPa) 2,000 1,000 2,400 q : Chip area (mm2) k c×a p×f = a p : Depth of Cut (mm) 2,000 1,000 f : Feed Rate (mm/rev) Principal Force (N) Principal Force 1,600 20 10 0 -10 -20 0 0.1 0.2 0.4 Rake angle (degrees) 0.04 Feed Rate f (mm/rev) When feed rate decreases, specific cutting force increases. Machined Surface Roughness Relation between corner radius and 3-part force D Theoretical (geometrical) D Ways to improve surface 4000 surface roughness finish roughness 3500 Principal Force h : Theoretical surface (1) Use an insert with a larger corner radius. f 2 h 3 roughness (μm) = RE ×10 (2) Optimise the cutting speed and feed rate 8× f : Feed rate per revolution (mm/rev) Feed Force RE : Corner radius (mm) so that built-up edges do not occur. 1500 h (3) Select an appropriate insert grade. 1000 Cutting Force (N) Cutting Force f (4) Use wiper insert. Back Force RE 500 0.4 0.8 1.2 1.6 Corner Radius (mm) Large corner radius increases D Actual surface roughness back force. Steel: Work Material: SCM440 (38HS) Theoretical surface roughness × 1.5 to 3 Insert: TNGA2204SS Cast iron: Holder: PTGNR2525-43 Theoretical roughness × 3 to 5 Cutting Conditions: vc =100m/min, ap = 4mm, f = 0.45mm/rev N12 Technical Guidance Forms of Tool Failure and Tool Life, Turning Edition Forms of Tool Failure Classification No. Name of Failure Major Causes of Failure Wear caused by the scratching effect of hard grains Failure References (10) (1) to (5) Flank Wear contained in the work material Caused by (9) (6) Chipping Fine breakages caused by high cutting loads or vibration (8) Mechanical (7) Fracture Large breakage caused by the impact of an excessive Factors mechanical force acting on the cutting edge Cutting chips removing tool material as it flows over its top rake at (4) (11) Failure (5) (10) (8) Crater wear high temperatures (6) Caused by (7) (3) (9) Plastic deformation Deformation of cutting edge due to softening at high temperatures N (1) (2) Thermal and (10) Thermal cracking Fatigue from rapid, repeated heating and cooling cycles during Chemical (11) Built-up edges interrupted cutting Reactions Parts Work material is pressure welded on the top face of the cutting edge Tool Wear Curve Guidance Technical Reference Forms of Tool Wear Flank wear Crater wear on rake face (mm) (mm) Bad chip control ) ) T cutting edge fracture B Burrs occur Initial wear Crater wear (KT) Sudden increase Side flank notch wear Poor surface roughness Rake Face Wear in wear (VN1) Steady wear Face flank notch wear Flank Wear Width (V Flank Wear Crater wear depth (K (VN2) Cutting Time (T) (min) Cutting Time (T) (min) Average flank wear (VB) Flank Wear Edge wear (VC) · Wear increases rapidly right after · Wear increases proportionately to Higher cutting force starting cutting, then moderately and the cutting time. Poor machining accuracy; proportionally, and then rapidly again burrs occur after a certain value. Tool Life (V-T) · This double logarithm graph shows the relative tool life (T) with the specified wear over a range of cutting speeds (Vc) on the X axis, and the cutting speed along the Y axis. Flank Wear Crater wear vc1 vc2 vc3 vc1 vc2 vc3 vc4 vc4 VB KT Tool wear Tool T1 T2 T3 T4 T'1 T'2 T'3 T'4 Flank Wear Width (mm) Flank Wear Cutting Time (min) Crater wear depth (mm) Cutting Time (min) v Invc1 In c1 v Invc2 In c2 v Invc3 In c3 v Invc4 In c4 Tool life Tool InT1 InT2 InT3 InT4 InT'1 InT'2 InT'3 InT'4 Cutting Speed (m/min) Cutting Speed (m/min) Lifetime (min) Lifetime (min) N13 Technical Guidance Cutting Edge Failure and Countermeasures, Turning Edition Insert Failure and Countermeasures Insert Failure Cause Countermeasures Flank Wear · Tool grade lacks wear resistance. · Select a more wear-resistant grade. P30P20P10 References K20K10K01 · Increase rake angle. N · Cutting speed is too fast. · Decrease cutting speed. · Feed rate is far too slow. · Increase feed rate. Crater wear · Tool grade lacks crater wear resistance. · Select a more crater wear-resistant grade. Parts · Rake angle is too small. · Increase rake angle. · Change the chipbreaker. · Cutting speed is too fast. · Decrease cutting speed. · Feed rate and depth of cut are too large. · Reduce feed rate and depth of cut. Reference Technical Guidance Guidance Technical Cutting Edge Chipping · Tool grade lacks toughness. · Select a tougher grade. P10P20P30 · Cutting edge breaks due to chip K01K10K20 adhesion. · Increase amount of honing on cutting · Cutting edge is not strong enough. edge. · Reduce rake angle. · Feed rate and depth of cut are too large. · Reduce feed rate and depth of cut. Cutting Edge Fracture ·Tool grade lacks toughness. · Select a tougher grade. P10P20P30 K01K10K20 · Cutting edge is not strong enough. · Select a chipbreaker with a strong cutting edge. · Holder is not strong enough. · Select a holder with a larger approach angle. · Select a holder with a larger shank size. · Feed rate and depth of cut are too · Reduce feed rate and depth of cut. large. Adhesion/Built-up Edges · Inappropriate grade selection. · Select a grade with less affinity to the work material. Coated carbide or cermet grades. · Cutting edge is not sharp enough. · Select a grade with a smooth coating. · Increase rake angle. · Reduce honing. · Cutting speed is too slow. · Increase cutting speed. · Feed rate is too slow. · Increase feed rate. Plastic Deformation · Tool grade lacks thermal resistance. · Select a more crater wear-resistant grade. · Increase rake angle. · Cutting speed is too fast. · Decrease cutting speed. · Feed rate and depth of cut are too large. · Reduce feed rate and depth of cut. · Not enough coolant. · Supply sufficient coolant. Notch wear · Tool grade lacks wear resistance. · Select a more wear-resistant grade. P30P20P10 K20K10K01 · Rake angle is too small. · Increase rake angle. · Cutting speed is too fast. · Alter depth of cut to shift the notch location. N14 Technical Guidance Chip Control and Countermeasures, Turning Edition Type of Chip Generation Type of chip control Flowing Shearing Tearing Cracking Depth of Cut ABCDE Classification Large References Type of Work Material Work Material Work Material Work Material chip shapes Continuous Chip is sheared Chips appear to be Chips crack before Small chips with good and separated by torn from the reaching the surface finish. the shear angle. surface. cutting point. NC lathe Condition (for automation) HHSSJ General cutting of Steel, stainless steel Steel, cast iron (very low Cutting of general General-purpose lathe to N steel and light alloy (low speed) speed, very small feed rate) cast iron and carbon Evaluation (for safety) HSSS JH Application Large Deformation of work material Small Good: C type, D type A type: Twines around the tool or workpiece, damaging the machined Large Rake angle Small surface and affecting safety. Parts Small Depth of cut Large Poor { B type: Causes problems in the automatic chip conveyor and chipping occurs easily. Large Cutting speed Small Influence factor E type: Causes spraying of chips and poor surface finish due to chattering, along with chipping, large cutting force and high temperatures. Technical Guidance Guidance Technical Factor of improvement of chip control Reference (1) Increase feed rate (f) 4.0 (mm) p a t1 t2 f f 1 2 2.0 Depth of Cut f: When f2 > f1, t2 > t1 When the feed rate increases, the chip thickness (t) 0.1 0.2 0.3 0.4 0.5 increases and chip control improves.
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