Milling 1/111
2/111 Milling A simple choice!
Experts required? No Just follow some basic rules. 3/111
Face milling 4/111
Square shoulder milling 5/111
Disc milling 6/111
Copy milling 7/111
Plunge milling 8/111
High feed milling 9/111
Thread milling 10/111
Solid Carbide milling 11/111
Mini milling cutters A full range cutters from 0,004 up to 0.080 diameter. 62HRc Phone Mold 12/111
Mill Turning Face Turnmilling Cutter off centre-line Peripheral Turnmilling (helical interpolation ramping) External Cutter on centre-line Internal 13/111
Cutting depth a p inch Machine Capability Insert application insert dimensions cutting conditions Power Turbo Super Turbo Micro Turbo Nano Turbo Feed f z inch/tooth (Typical example) 14/111
Nomenclature & Cutter Geometry 15/111
Milling Cutter Nomenclature 16/111
Cutter Geometry Milling cutter geometry Cutting forces Power Metal removal rate Cutting edge geometry Tool life Cutting forces Chip breaking geometry Chip formation Cutting forces 17/111
Cutter positioning Cutter Geometry Entry shock (pressure stress) Exit shock (tensile stress) 18/111
The difference between milling and turning Varying cutting forces (stress). Varying cutting temperatures (tension in insert). Milling has varying chip thickness. Turning has a constant chip thickness. 19/111
Varying Edge Temperature Chipping Thermal cracks 20/111
Cutter Geometry γ p κ γ f Milling cutter geometry = Positioning of the cutting edge Lead angle - κ Axial rake angle - γ p Radial rake angle - γ f 21/111
Cutter Geometry Positive positive Advantages/disadvantages + Smooth cutting. + Good chip removal. + Good surface smoothness. - Cutting edge strength. - Unfavorable entry contact. - Draws workpiece away from machine table. 22/111
Cutter Geometry Negative negative Advantages/disadvantages + Cutting edge strength. + Productivity. + Pushes the workpiece towards the machine table. - Large cutting forces. - Chip obstruction. 23/111
Cutter Geometry Negative vs. Positive Double negative Double positive 24/111
Cutter Geometry Positive negative Advantages/disadvantages + Good chip removal. + Favorable cutting forces. + Wide range of applications. 25/111
Insert nomenclature & cutting edge geometry. 26/111
Milling Insert Nomenclature OFER070405TN-ME15 T25M 27/111
Edge Condition and Rake Angle OFER070405TN-ME15 T25M -E -ME -M -MD 28/111
Ultra High Positive Rake 20 24 29/111
Milling Cutter Application. 30/111
Conventional Climb Conventional milling Used on older machines / unstable conditions. Unfavorable milling process. Climb milling Favorable milling process. Not recommended on older machines / unstable conditions. 31/111
Cutter positioning The basic problem in conventional milling is the insert entry. Cutting edge radius, rubbing the edges away not enough heat! Self-hardening materials Stainless Steel. Chip jamming/obstruction. 32/111
Cutter positioning Climb milling can be used for most processes. The machine must have a stable setup and spindle with no play. (Modern CNC machines) Advantages of climb milling Longer tool life. The chips land behind the cutter on the surface just milled, and will therefore not be machined again. Climb milling causes a downward pressure and therefore does not lift up the workpiece. Better surface finish. Easier chip removal. Requires less power. 33/111
Cutter positioning Conventional milling Central milling Combination of climb and conventional milling. Unfavorable due to varying cutting forces. Unavoidable when slot milling Climb milling 34/111
pitch Arc of tool engagement. Insert spacing. Arc of tool engagement. 35/111
Cutter Engagement Under-formed chip Undesirable, sometimes unavoidable. Thick chip Desirable, better tool life. 36/111
Cutter positioning Entry shock (pressure stress) Exit shock (tensile stress) If possible position the cutter as shown on the right, if you can. 37/111
Cutter positioning Interrupted cut milling Short tool life (cutting edge breakage). Vibration problems. This is often unavoidable! 38/111
Milling cutter pitch pitch : Impact of each tooth. : Vibration amplitude. Normal pitch Differential pitch Differential pitch reduces the risk of vibration. 39/111
Vibrations F F z F x The size and direction of the cutting force for a face milling cutter, 45 entering angle (sum of axial and radial forces perpendicular to cutting edge). 40/111
Vibrations F F z F x The size and direction of the cutting force for a square shoulder milling cutter, 90 entering angle. (sum of axial and radial forces perpendicular to cutting edge). 41/111
Vibrations n = fz = hm D ae (1 sink) fz = hm D ae Change cutter positioning Minimise tool overhang Improve stability (n π D) 12 f = ( z or k) fz v c 12 π D vf = n ( z or k) fz Decrease cutting speed Increase feed Decrease depth of cut Conventional milling Q = ae ap vf 42/111
Vibrations 43/111
Average chip thickness 44/111
Average chip thickness f z Chip thickness = Thickness of the undeformed chip at right angles to cutting edge.. and is constantly changing. 45/111
Average chip thickness f z 46/111
Average chip thickness f z h m Chip thickness = Thickness of the undeformed chip at right angles to cutting edge.. and is constantly changing THEREFORE average chip thickness is important. 47/111
Average chip thickness Calculating the average chip thickness, to achieve the correct cutting data should only be applied when Ae is LESS THAN 50% f z Dc h m Ae = 50% 48/111
Average chip thickness Relationship between feed and average chip thickness. Radial cutting depth - Diameter of the cutter. Cutter positioning. Entering angle. 49/111
Average chip thickness f z f z a e Dc Dc h m a e h m Radial cutting depth Diameter of the cutter (a e /D c ratio) What is happening to the average chip thickness as Ae reduces? 50/111
Average chip thickness f z Which will have the higher feed rate? 51/111
Average chip thickness Formula to calculate f z for square shoulder milling: f z = h m D a e 2.5 =.004.118 =.004 21 = 0.018 legend f z = feed per tooth h m = average chip thickness D = cutter diameter a e = radial width of cut example find the f z of a Turbo mill: h m = 0.004 D = 2.5 a e = 0.118 52/111
Average chip thickness v f = 21.5 v f = 25.8 v f = 48.5 v f = 64.5 v f = 103.2 100% engagement 50% engagement 20% engagement 10% engagement 5% engagement 53/111
Description a e Width of cut a p Depth of cut ( v c ) SFPM (f z ) FPT (h m ) Average Chip (n) RPM (v f ) Feed Rate IPM Slotting 100% Engagement 1.00.1 626 0.003 0.002 2388 21.5 Profiling 50% Engagement.500.1 751 0.003 0.002 2869 25.8 Profiling 20% Engagement.200.1 813 0.005 0.002 3228 48.5 Profiling 10% Engagement.100.1 938 0.006 0.002 3583 64.5 Profiling 5% Engagement.050.1 1001 0.009 0.002 3826 103.2 54/111
Average chip thickness a e Caution! 55/111
Average chip thickness Caution! 56/111
Average chip thickness a e Caution! 57/111
Average chip thickness 90deg 45deg h : 100% h : 70% f z : 100% f z : 100% 58/111
Average chip thickness h = f z x sin (ҳ ) 59/111
Average chip thickness Formula to calculate f z for face milling: D f = h z m a e 1 sinκ 0.004 x 2.236 x 1.41 = 0.013 legend f z = feed per tooth h m = average chip thickness D = cutter diameter a e = radial width of cut κ = setting angle example find the f z of a Octomill face mill: h m = 0.004 D = 4 a e = 0.8 κ = 43 o 60/111
Average chip thickness Relationship between feed and average chip thickness. Radial cutting depth - Diameter of the cutter. Small a e /D c gives larger feeds. Cutter positioning. Single sided cutting gives larger feeds. Entering angle. Smaller angle of engagement gives larger feeds. 61/111
Average chip thickness Feed and average chip thickness Average chip thickness. If too large broken inserts. If too small extra wear. 62/111
Average chip thickness For 90 lead angle cutters only 63/111
Average chip thickness 64/111
Cutting edge geometry 65/111
. Cutting edge geometry Difficult machining strong edges D MD SE.. AFTN -MD15 SE.. AFTN -D16 M SE.. AFTN -M14 SE.. AFTN -M15 SE.. AFTN -M16 Easy machining sharp edges ME E SE.. AFN -E07 SE.. AFTN -ME10 SE.. AFN -E12 SE.. AFTN -ME13 SE.. AFTN -ME15 10 15 decreasing chip thickness increasing 66/111
Cutting edge geometry The vertical axis specifies the degree of difficulty in the machining operation (i.e. E = Easy, M = Medium etc.) The horizontal axis denotes the application range. The numbers indicate the average chip thickness in mm, 10 meaning 0.1mm or 0.004 13 meaning 0.13mm or 0.005 etc. XOMX 180608TR-ME13 F40M 67/111
Cutting edge geometry -ME06 example ME06 geometry is for medium easy machining operations h m should be kept at 0.06mm (0.002 ) under normal conditions and for average material (Seco material group 3-5) 68/111
Cutting edge geometry -M10 example M10 geometry is for medium machining operations h m should be kept at 0.10mm (0.004 )under normal conditions and for average material (Seco material group 3-5) 69/111
Cutting edge geometry To maintain maximum tool life, it is crucial to exceed or at least equal the edge protection chamfer. Cutting speed can also be increased in side milling operations thereby optimizing the application. 70/111
Milling methods 1. Peeling Method 2. High speed machining 3. High feed machining 4. Plunge milling 71/111
Peeling method Small radial cutting depth Deep cutting depth High cutting speed Spiral Cutter Roughing method which normally eliminates semi-finishing 72/111
Peeling method Ae=.060 Ap= 0.600 MM12-12015-B90A30-E05 Rpm=6630 Vf= 70 inch/min 73/111
High speed machining Small cutting depth Small radial cutting depth Small average chip thickness High cutting speed Sharp cutting edges in hard grades 74/111
High feed milling Small cutting depth Very high feed per tooth High cutting speed Good method in hardened steel and difficult material Roughing method which normally reduces the cutting depth for semi-finishing 75/111
High feed milling Minimaster high feed insert R227.21 high feed cutter Jabro high feed cutter 76/111
Plunge Milling Method mostly for long overhang or weak machines Normal cutting speed Good method for difficult material like Inconel Roughing method which normally increase productivity 77/111
Plunge Milling Tool 1 Tool= R220.79-0080-12 V= 524 sft/min Fz= 0.006 per/tooth Side step = 3/8 Tool 2 Tool= L217.79-3250-13 V=524 sft/min Fz= 0.005 per/tooth Side step= ½ Tool 3 Tool= R217.79-2532-09 V= 524 sft/min Fz= 0.004 per/tooth Side step= ¼ then.040 78/111
Trochoidal Milling The Trochoidal method is a fast and productive method for slotting operations. D c Step over Width 79/111
Surface Finish Small radius corner insert Large radius corner insert Faceted corner insert Faceted insert plus Wiper insert 80/111
Surface Finish Axial run-out with a non adjusted cutter. Cassettes give a better surface finish when correctly adjusted. 81/111
Surface finish & tool life. Tool life Tool tolerances Measured with a reference insert Modern Classic Run - out influences The tool life. The surface finish. Machining noise level. Axial/radial run-out (Typical example ) 82/111
Milling insert clamping Common method uses a screw though the insert. The insert is clamped in the centre, screw head below insert! This system is commonly used for modern milling cutters. This system allows the use of modern chip face geometries. 83/111
Maintenance Always clean the insert seating before clamping a new insert in place. Always replace damaged anvils or the tool if the insert seating is damaged. Never use re-built (welded) tools. Replace damaged screws and keys. Lubricate moving parts regularly. Always use the correct keys (dynamometric keys). Always position the insert carefully before clamping it in place. Make sure the insert fits flush against the supports. If the insert is not positioned correctly, it will not be clamped properly (insert breakage). 84/111
Milling 85/111