Selecting cutting data

Transcription

1 Selecting cutting data xample of how to find the values when calculating spindle speed (n and table feed ( onditions ormulas to be used utter- Insert- Workpiece material R Q40-12M R T3 M-PM 4030 SS n v c 1000 π c z n n hex sin κ r v c In order to get v c, the max chip thickness (h ex for an operation and the oromant Material lassification (M code is needed. See feed recoendations. c z n The cutter selected has a diameter, c, of 125. Number of teeth is found on the same page and zn is in this case 8. The cutter selected has a 45 entering angle (κ r and PM insert geometry will be used. Max chip thickness (h ex for the operation is 0.17 κ r The selected cutter has a 45 entering angle. eed per tooth for the cutter and selected insert geometry. The material is SS and corresponding M code is n eed per tooth Revolutions per minute The cutting speed v c is approx. 283 m/min for M 01.2 (between 325 and 270 m/min for h ex 0.10 and 0.20 respectively. Table feed per minute vf /min This cutting speed is valid for hardness 150. If your hardness is 180 a compensation factor of 0.92 for the deviation of +30 units. The compensated cutting speed becomes x 283 m/min 262-m/min. ardness of workpiece The cutting speeds given on the following pages are valid for a specific material hardness. If the material being machined differs in hardness from those values, the recoended cutting speed must be multiplied by a factor obtained from the table below. ifference in hardness Reduced hardness Increased hardness M No. ardness rinell ( M No. ardness Rockwell (R

2 Terminology and units for milling c l m e v c Q T c z n f n h ex h m utting diameter Machined length ffective cutting diameter utting depth Working engagement utting speed Metal removal rate Period of engagement Total number of edges in the tool eed per tooth eed per revolution Table feed (feed speed Max chip thickness verage chip thickness eneral milling formulas utting speed (m/min m/min cm 3 /min min piece /min z c k c1 n P c η κ r v c0 c vc m c i v c π c n 1000 ffective number of teeth Specific cutting force (for h ex 1 Spindle speed utting power net fficiency Major cutting edge angle onstant for cutting speed orrection factor for cutting speed Rise in specific cutting force (kc as a function of chip thickness inscribed circle piece N/ 2 rev/min kw degrees f n Spindle speed (rev/min n v c 1000 π c z n 8 Table feed (feed speed (/min eed per tooth ( n z n n z n eed per revolution (/rev f n n Κ r 90 Removal rate (cm 3 Q 1000 c h m h ex Specific cutting force (N/ 2 k c k c1 h m -mc verage chip thickness ( (Side and facemilling when / c 0.1 h m c verage chip thickness ( when / c 0.1 h m sin κ r 180 π c arcsin ( c Machining time (min T c l m Net power (kw P c k c η 23

3 ormulas for specific milling cutters acemilling cutters, side and facemilling cutters and endmills These tools are characterized by having straight cutting edges. Max cutting diameter at a specific depth ( e c + 2 tan κ r c e eed per tooth (/tooth, cutter centered h ex sin κ r eed per tooth (/tooth, side milling sin κ r e h ex 2 e ( e 2 2 utters with round inserts Max cutting diameter at a specific depth ( e c + i 2 (i 2 2 c e eed per tooth (/ tooth, cutter centered i h ex e c eed per tooth (/tooth, side milling e i h ex 2 ( e c e ( e 2 2 allnose endmills Max cutting diameter at a specific depth ( e 3 2 ( e eed per tooth (/tooth, side milling 3 h ex 2 e ( e 2 2 eed per tooth (/tooth, cutter centered 3 h ex e 24

4 alculation of power consumption The example is valid for 0 top rake angle. The power consumption changes 1% per degree of change in top rake. positive top rake angle decreases the power consumption and a negative top rake increases the power consumption. positive cutter with +15 top rake angle requires 15% less power than a cutter with 0 top rake angle. Plunge milling P c x v x K f 60 x 10 6 x η x 3 (slot x S (stepover S xample 45 facemilling of steel, M 01.3 utter diameter, c 125 epth of cut, 5 Width of cut, 100 eed per insert, 0.2 Table feed, 1000 Milling in general or different insert geometries the power consumption must be adjusted. or each degree more positive top rake angle the power consumption will decrease with 1%. or a oromill 245 facemill with M-geometry. The M-geometry has +21 top rake angle. P c K P c(γ P c M γ or an engagement of 80% the K value is 5.4. or a top rake angle of +21 the M γ value is P c(γ kw P c 27.0 kw Optimized power consumption calculation Use multiplying factor from top rake angle to adjust P c values. True rake angle, γ Multiplying factor, Mγ True rake angle, γ Multiplying factor, Mγ When machine power is roblem o from close to coarse pitch, i.e. less number of teeth. positive cutter is more power efficient than a negative. Reduce the cutting speed before the table feed. Warning e aware of the power curve for machining centres. The machine may lose efficiency if the rpm is too low. Use a smaller cutter and take several passes. Reduce the depth of cut. 25

5 onstant K for use in power requirement calculation 1 ISO M No. escription / c / c / c P M S K N Steel 01.1 Unalloyed % % % Low-alloyed Non-hardened (alloying elements 5% ardened and tempered igh-alloyed nnealed (alloying elements 5% ardened tool steel astings Unalloyed Low-alloy, alloying elements 5% igh-alloy, alloying elements >5% Stainless steel erritic/martensitic Non-hardened P-hardened ardened ustenitic Non-hardened P-hardened ustenitic-erritic Non-weldable 0.05% (uplex Weldable <0.05% Stainless steel cast erritic/martensitic Non-hardened P-hardened ardened ustenitic Non-hardened P-hardened ustenitic-erritic Non-weldable 0.05% (uplex Weldable <0.05% eat resistant super alloys Iron base nnealed or solution treated ged or solution treated and aged NIckel base nnealed or solution treated ged or solution treated and aged ast or cast and aged obalt base nnealed or solution treated Solution treated and aged ast or cast and aged Titanium alloys 23.1 oercial pure (99.5% Ti α, near α and α+β alloys, annealed α+β alloys in aged cond. β alloys, annealed or aged 04.1 xtra hard steel ardened and tempered ard steel hilled cast ast or cast and aged 10.1 iron Malleable cast iron erritic (short chipping Pearlitic (long chipping rey cast iron Low tensile strength igh tensile strength Nodular S iron erritic Pearlitic luminium alloys Wrought or wrought and coldworked, non-aging Wrought or wrought and aged luminium alloys ast, non-aging ast or cast and aged luminium ast, 13 15% Si alloys ast, 16 22% Si opper and copper ree cutting alloys, 1% Pb alloys rass, leaded bronzes, 1% Pb ronze and non-leaded copper incl electrolytic copper 1 alculated with an efficiency η mt

6 utting data calculations for milling operations Milling acemilling xample 4 utter Insert Workpiece material κ r R Q40-12M z n 8 R T3 M-PM 4030 SS M alculate spindle speed (n n v c 1000 π c n 721 π 125 rpm To get v c, first find h ex value for -PM geometry. The cutting speed v c for h ex 0.17 is 283-m/min (between 325 and 270-m/min. alculate table feed ( z n n /min h ex sin κ r sin 45 /tooth acemilling with round inserts xample 4 85 utter Insert Workpiece material R Q32-16M z n 6 RKT M0-PM 4030 SS M alculate spindle speed (n n v c 1000 π e π 123 rpm To get v c, first find h ex value for -PM geometry. The cutting speed v c for h ex 0.17 is 283-m/min (between 325 and 270-m/min. e c + i 2 (i e ( alculate table feed ( 45 n z n /min 30 h ex sin κ r sin 30 /tooth Max 100% of max Κ r 45 75% of max Κ r 38 50% of max Κ r 30 25% of max Κ r 21 27

7 Slotting/facemilling with 90 entering angle xample 5 utter Insert Workpiece material R Q22-17M z n 5 R R Q22-17M 04 08M-PM 1025 z n 5 SS R M-PM M alculate spindle speed (n n v c 1000 π c π 63 rpm To get v c, first find h ex value for -PM geometry. The cutting speed v c for h ex 0.15 is 250-m/ min (between 280 and 230-m/min. alculate table feed ( n z n /min Shoulder milling with 90 entering angle xample 5 utter Insert Workpiece material R Q22-17M z n 5 R M-PM 1025 SS M alculate spindle speed (n n v c 1000 π c π 63 rpm To get v c, first find h ex value for -PM geometry. The cutting speed v c for h ex 0.15 is 318-m/ min (between 325 and 310-m/min. alculate table feed ( or sidemilling the feed can be increased with a compensation factor. k1 z n n /min ind the compensation factor, k1, in the table below by calculating c / c 12.6 k c actor k1 28

8 Side and facemilling xample 14 ( 23 ( utter Insert Workpiece material R Q40-12M z n 8 R T3 M-PM 4030 SS M alculate spindle speed (n n v c 1000 π c This gives n 720 π 125 rpm To get v c, first find h ex value for -PM geometry. The cutting speed v c for h ex 0.17 is 283-m/min (between 325 and 270-m/min. alculate table feed ( n z c This gives z c Number of effective edges z n /2 or N S40M z n 10 z c 5 /min factor k1 h ex The factor k1 can be found in table below c actor k1 c fz k1 1.3 /tooth 29

9 Profile milling xample 4 utter Insert Workpiece material R z n 2 R T3 M-M 4040 SS M alculate spindle speed (n n v c 1000 π e n 6130 π 16 rpm To get v c, first find h ex value for -M geometry. The cutting speed v c for h ex 0.15 is 308-m/min (between 310 and 295-m/min. ind effective diameter, e Select axial depth of cut in this diagram. o horizontally across the diagram to the curve representing the tool diameter. Move down vertically to the axis and read the effective diameter. alculate table feed ( z n n /min according to table below. In stable conditions the feed can be increased. When working with long tools and difficult conditions the feed can be lowered. xial depth of cut ( e ffective tool dia.( 50 Recoended feed, iameter, Start value Range Recoended radial steps and depth of cut for ball nose endmills Large cuts It is not recoended to exceed the values below for radial step and axial depth of cut. Small cuts With the same axial depth of cut as for large cuts, surface can be improved by decreasing the radial step. utter dia. Max. recoended 3 Radial step epth of cut utter dia. 3 Radial step Radial step Radial step

10 Method for internal circular interpolation alculated version e n z c Tool centre feed, /min e h ex sin Κ r e 2 ( e 2 2 eed per insert, 2 2 m w 4 ( m e Radial depth of cut, Simplified version n z c Straight line feed, /min 1 1 K Tool centre feed, /min K m + c m The values can be taken from the table below utter diameter c ole diameter m actor K

11 Method for external circular interpolation alculated version e n z c Tool centre feed, /min e h ex sin Κ r e 2 ( e 2 2 eed per insert, 2 2 w m 4 ( m e Radial depth of cut, Simplified version 1 n z c Straight line feed, /min 1 K Tool centre feed, /min K m + c m The values can be taken from the table below utter diameter c ole diameter m actor K

12 Mounting dimensions for milling cutters Milling Style ia ia. 80 ia. 100 Mounting diameter (d entre bolts 1 or all Modulmill cutters and for R/L262.2L the dimensions are 22.0 and 10.4 respectively. Style Mounting diameter (d ia. 125 entre bolts + washer Style Mounting diameter (d ia. 160 ia esign with single pcd ( 4 bolts Mounting diameter (d ia esign with double pcd ( 8 bolts 33

13 Insert mounting with Torx Plus Sandvik oromant has introduced the Torx Plus system on all insert screws to ensure an improved and secure clamping. The new Torx Plus screws will keep their previous codes, while the keys will change the code. ll keys for insert clamping are concerned screwdrivers, T-style keys, L-style keys, flag-style keys and combination keys (Torx Plus/hex. ross section Torx Plus Torx Torque wrench for Torx Plus screws The torque wrench for Torx Plus screws offers ossibility to always ensure correct torque value, in the machine shop as well as in the tool-room environments. orrect torque values are imperative especially when clamping ceramic and N inserts. lways use protective goggles when using ceramic inserts. Note! Torx Plus is a registered trademark of amcar-textron (US. Wrench benefits ergonomic handle consisting of two materials, one of which has a rubber base for best grip a "click" function when tightening the screws - is impossible to over tighten. a fixed stop in counter clockwise direction, making it easier to loosening screws design of blade tip has been optimised for best screw fitting blade material consists of a higher class of material grade Note! The new Torx Plus keys and screw-drivers do NOT fit into the standard Torx screws. owever, the standard Torx keys and screw-drivers will fit the new Torx Plus screws. Milling cutter mountings oromant apto provides the best stability and thus basis for high productivity, reliablity and quality. utters are available as over-size in relation the the coupling for extended tooling. est choice, especially for long edge milling. ylindrical shanks Recoended for use with precision chucks like ororip for best stability and precision. xtra long tools available. Weldon established tool mounting but not recoended as first choice if productivity and precision are issues. rbor established tool mounting and the only solution for large-diameter cutters. ives good stability for high productivity. Threaded modular system with exchangeable cutting heads. Silent tool solution and carbide shank adapters for extended tooling. 34

14 Tool wear ause Remedy lank and notch wear a. Rapid flank wear causing poor surface finish or out of tolerance. a. utting speed too high or insufficient wear resistance. Reduce cutting speed. Select a more wear resistant grade. a a. Too low feed. Increase feed. b c b/c. Notch wear causing poor surface finish and risk of edge breakage. b/c. Work hardening materials. b/c. Skin and scale. Reduce cutting speed. Select tougher grade. Increase cutting speed. rittering Small cutting edge fractures (frittering causing poor surface finish and excessive flank wear. rade too brittle. Insert geometry too weak. Select tougher grade. Select an insert with a stronger geometry. uilt-up edge. Increase cutting speed or select ositive geometry. Reduce feed at beginning of cut. Thermal cracks Small cracks perpendicular to the cutting edge causing frittering and poor surface finish. Thermal cracks due to temperature variations caused by - Intermittent machining. - Varying coolant supply. Select a tougher grade with better resistance to thermal shocks. oolant should be applied copiously or not at all. uilt-up edge (.U.. uilt-up edge causing poor surface finish and cutting edge frittering when the.u.. is torn away. Workpiece material is welded to the insert due to Low cutting speed. Low feed. Increase cutting speed. Increase feed. Negative cutting geometry. Select ositive geometry. Poor surface finish Too high feed. Reduce feed. Wrong insert position. hange position. eflection. heck overhang. ad stability. etter stability. Vibrations Wrong cutting data. Reduce cutting speed. Increase feed. hange cutting depth. ad stability. Reduce overhang. etter stability. 35

15 If problems should occur Some typical problems in milling and possible solutions xcessive vibration 1. Weak fixture Possible solutions ssess the direction of cutting forces and provide adequate support or improve the fixture. Reduce cutting forces by decreasing cutting depths. Select a coarse and differentially pitched cutter with a more positive cutting action. Select an L-geometry with small corner radius and small parallel land. Seplect a fine-grain, uncoated insert or thinner coating 2. Weak workpiece onsider a square shoulder cutter (90-degree entering angle with positive geometry. Select an insert with L-geoemetry ecrease axial cutting force lower depth of cut, smaller corner radius and parallel land. Select a coarse-pitch cutter with differential pitch. 3. Long tool overhang Minimize the overhang. Use coarse-pitch cutters with differential pitch. alance radial and axial cutting forces 45 degree entering angle, large corner radius or round insert cutter. Increase the feed per tooth Use a light-cutting insert geoemtry L/M 4. Milling square shoulder with weak spindle Select smallest possible cutter diameter. Select positive cutter and insert. Try up-milling. heck spindle deflection to see if acceptable for machine. 5. Irregular table feed Try up-milling Tighten machine feed mechanism. Unsatisfactory surface finish 1. xcessive feed per revolution Set cutter axially or classify inserts. heck height with indicator. heck the spindle run-out and the cutter mounting surfaces. ecrease the feed per rev to max. 70% of the width of the parallel land. Use wiper inserts if possible. (inishing operations 2. Vibration See section on vibration. 3. uilt-up edge formation on insert Increase cutting speed to elevate machining temperature. Turn off coolant. Use sharp cutting edge inserts, with smooth rake side. Use positve insert geometry. Try a cermet grade with higher cutting data. 36

16 4. ack-cutting heck spindle tilt (Tilt spindle approx 0.10/1000 xial run-out of spindle should not exceed 7 microns during finishing. Reduce the radial cutting forces (decrease the depth of cut Select a smaller cutter diameter. heck the parallelism on the parallel lands and on wiper insert used. (Should not be standing on heel or toe Make sure the cutter is not wobbling adjust the mounting surfaces. 5. Workpiece frittering ecrease feed per tooth. Select a close or extra-close pitch cutter. Re-position the cutter to give a thinner chip at cutter exit. Select a more suitable entering angle (45-degrees and lighter cutting geometry. hoose a sharp insert. Monitor flank wear to avoid excessive wear. Insert fracture in general milling 1. xcessive chip thickness at cutter exit Minimize the chip thickness at exit by changing the cutter position in relation to workpiece. Use down-milling ecrease the feed per tooth. Select a smaller cutter diameter. Use a stronger insert geometry (. Insert fracture in square shoulder milling 1. Swarf follows cutter in up-milling, getting stuck between shoulder and edge. hange to down-milling. Use compressed air. Use a sharper insert to facilitate re-cutting of chips. Monitor flank wear to avoid excessive wear. 2. own-milling with several passes. onsider performing the operation in one pass. 3. hip jaing between shoulder and edge. Try up-milling Select a tougher insert grade. Select a horisontal milling machine. 37

17 Milling Selection and application process 1 efine the operation Identify the type of operation acemilling Shoulder milling Profile milling Slot milling Then select the most suitable tool considering productivity, reliability and quality. 2 P M K N S efine the material efine workpiece material according to ISO Steel (P Stainless steel (M ast iron (K luminium (N eat resistant and titanium alloy (S ardened material ( Select cutter concept ssess which concept is the most productive for the application oromill 245, oromill 210, oromill 390, oromill 290. Select the milling cutter hoose cutter pitch and mounting. Use a close pitch cutter as first choice. Use a coarse pitch cutter for long overhang and unstable conditions. Use an extra close pitch cutter for short chipping materials and super alloys. hoose a mounting type. Select the insert hoose the insert geometry for your operation eometry L Light or light cuts when low forces / power are required eometry M Medium irst choice for mixed production eometry eavy or rough operations, forging, cast skin and vibrations Select insert grade for optimum productivity. efine the start values utting speeds and feeds for different materials are given on the insert dispensers and in the tables. The values should be optimized according to machine and conditions! 38

18 39

19 Operations tool recoendations eneral facemilling Material/ pplication Steel Stainless steel ast-iron luminium Super alloys ardened steel P M K N S inishing Semi-finishing Roughing eavy roughing oromill 245 oromill 245 oromill 245 T-MX 45 oromill 245 oromill 245 oromill UTO-* oromill 245 UTO R oromill 245 (18 oromill entury oromill entury oromill oromill 245 oromill 300 oromill 300 T-Max 45 oromill 245 oromill 245 oromill 300 oromill 200 * oromill entury Thin walls lose to fixture Long overhang P M K S N oromill 390 oromill 390 P M K S N oromill 210 (R/oroMill 245 ( oromill entury oromill entury oromill 390 ack facing P M K S N oromill 331 igh feed milling P M K S oromill 210/oroMill 300 eneral shoulder milling Material/ pplication inishing Semi-finishing Roughing Steel Stainless steel ast-iron luminium Super alloys ardened steel P M K N S oromill 390 oromill 390 oromill 390 oromill 390 oromill 390 oromill 390 UTO- oromill 290 oromill 290 oromill entury oromill 790 oromill 790 oromill Plura oromill 390 oromill 390 oromill Plura oromill 290 oromill 290 Repeated shoulder milling eep shoulder milling dging/ ontouring P M K S N oromill 390 oromill 790 oromill Plura (Small ae (ae/c< oromill 390 L-11 oromill 390 L- 18 oromill 390/oroMill Plura Large ae (ae/c>.. or diameters smaller than 20, oromill Plura solid carbide endmills are first choice generally for all materials. 40

20 This catalogue has been split into smaller parts to enhance downloading speeds. If you want to view the next page please click R! (To go back to the last viewed page, use the integrated green arrows at the bottom of the crobat user interface