Palestra 4 - Avanços em tecnologia de fresamento: do fresamento convencional para o HSC.

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Advances in milling Technologies: from convencional milling to HSC.

Palestrante: Msc. Benedikt Gellissen - Instituto Fraunhofer de Tecnologias da Produção - FhG IPT - Alemanha

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Palestra 4 - Avanços em tecnologia de fresamento: do fresamento convencional para o HSC.

  1. 1. Advances in milling Technologies: from conventional milling to HSC Benedikt Gellissen Fraunhofer-Institut für Produktionstechnologie IPT International Seminar: Application of new technologies in the metal mechanic sector Joinville, Brazil, September 2011© WZL/Fraunhofer IPT
  2. 2. Outline of the presentation 1 What is the motivation for advanced milling technologies 2 What is required to realize a successfull implementation of HSC? 3 Advanced roughing possibilities 4 Improved finishing results due to intelligent CAM-Systems and tool adaption 5 Conclusion© WZL/Fraunhofer IPT Page 1
  3. 3. Importance of the milling technology for the molding industry -Comparability of tool types and use of technology Injection moulding Solid forging Deep drawing Stamping and bending Special features Special features Special features Special features n Surface n Material (Temperature) n Surface n Material n Precision n Edge zone n Precision n Precision n Filigree n Precision n Geometrie n Surface Process Process Process Process Milling Milling Milling Milling Turning Turning Turning Turning Grinding Grinding Grinding Grinding Sink EDM Sink EDM Sink EDM Sink EDM Wire EDM Wire EDM Wire EDM Wire EDM Importance Importance Importance Importance Prismatic tool Focus free-form surfaces components© WZL/Fraunhofer IPT Page 2
  4. 4. Driver »tool steel«: Improved materials for the industryImpact of the defect size on the bending resistance Aims bending resistence σb [kN/mm2] powder metallurgical n Reaching an homogeneous structure 4 n Low corn and carbide size for improved wear conventional forging resistance and strength 3 n Reduction of material anisotropy in case of 2 manufacturing conventional founded 1 K 1c σ b = const d 100 200 300 400 500 defect size [µm] Source: Böhler© WZL/Fraunhofer IPT Page 3
  5. 5. Developments in tool steel 50 µm 50 µm µm 50 µmMelted steel Spray formed steel Powder metal steel } Inhomogenity } Nearly no segregations } Homogeneous structure } Segregations } Carbide size < 30 µm } Nearly no segregation } Carbide size < 200 µm } High-carbide alloy } Carbide size < 3 µmProcessing Processing Processing } Direct dependency of } Homogeneous structure leads } Problem: hardness and durability and hardness to better accuracy tenacity at the same time } Big carbides provoke } More abrasion because of } Cutting edge build-up breakouts spreaded carbides possible X155 CrMoV 12 1 mit 62 HRC, different manufacturing processes; Source: Schneider, 2002© WZL/Fraunhofer IPT Page 4
  6. 6. Motivation for complete hard milling processes:The tool manufacturer can “deliver” time Product development minimum throughput time Tool component Tool detail- development construction Tool manufacturing n In this time slot only the tool maker defines the Time- to-Market! Design freeze n During this period only necessary production steps are allowed which can not be standardized Stop of changes SOP n The hard milling process shortens the overall process and therefore the total lead time© WZL/Fraunhofer IPT Page 5
  7. 7. Importance of CAX-processes in tool manufacturingMaterialn Powder metallurgical high-speed steel S 6-5-3 PMn Hardness 65 HRCDemandsn Surface roughness Ra 0,3 µmn Minimum inner radius 1 mmProcessn Complete machiningn Simultaneous five-axis-roughing and -finishingn Solid carbide and CBN toolsn Complete hydrostatic five-axis- machine n Complete hard milling process of standardizesn Process time: roughing 6h, finishing blanks and shortens process chains 5h© WZL/Fraunhofer IPT Page 6
  8. 8. Outline of the presentation 1 What is the motivation for advanced milling technologies 2 What is required to realize a successfull implementation of HSC? 3 Advanced roughing possibilities 4 Improved finishing results due to intelligent CAM-Systems and tool adaption 5 Conclusion© WZL/Fraunhofer IPT Page 7
  9. 9. In the future:Growing importance of five-axis-processes in tool manufacturingDevelopment in tool manufacturing forecast1996 Stand 2007 100 % rate of milling processes 100 % CNC-intersection 3-Axis Roughing/Finishing 75 50 Copy milling HSC-Finishing 3-Axis 25 5-Axis-HSC 5-Axis Measuring point/ grid lines 5-Axis 1970 1980 1990 1996 2000 2010© WZL/Fraunhofer IPT Page 8
  10. 10. Technology often develops evolutionary – but not always predictable 75% 20 % 60 rate of HSC-milling in 15 45 30 10 manufacturing 15 5 0 0 < declining growing > 04/05 06/07 08/09 Importance of HSC Years Interview of 2002 Actual development 75% 20 % 60 rate of sink-EDM in 15 45 manufacturing 10 30 15 5 0 0 < declining growing > 04/05 06/07 08/09 Importance of sink-EDM YearsSource: Interview of companies (Euromold 2002 and benchmarking database of awf)© WZL/Fraunhofer IPT Page 9
  11. 11. Key-turn solutions quickly get into manufacturing 75% 70 % Availability of potential 60 60 45 50 automation 30 40 2008 15 30 2009 0 2010 20 < declining growing > 10 »Wire »Sink Importance autom. process chain »Milling« 0 EDM« EDM« Interview of 2002 Actual development 75% 75% CAM-programming 60 60 45 45 (milling) 30 30 15 15 0 0 < declining growing > 04/05 06/07 08/09 Importance autom. process chain YearsSource: Benchmarking database of awf© WZL/Fraunhofer IPT Page 10
  12. 12. Process features of cutting process steps Roughing (HPC) Pre-finishing Finishing (HSC) Aim Aim Aim n maximum metal removal rate Qt n Machining a even stock n maximum metal removal rate = vf • ae • ap allowance for the finishing step At = vf • ae Process features Process features Process features n Mechanical load limit for tools n Critical process status because n High dynamic and thermal and cutting machine of uneven allowance stress for tool cutting materials and n Use of big tool diameters and n Use of ambitious process resistant cutting materials strategies n Use of small tool diameters and thermal resistant cutting n Three-axis machining n Use of different tool diameters materials n (Rth = 0,1-0,5 mm) n (Rth = 0,05-0,1 mm) n Application from Pre-finishing programs for the finishing with reconfiguration n High data volumes of the NC-programs n (Rth = 0,002-0,005 mm)© WZL/Fraunhofer IPT Page 11
  13. 13. What is HSC? Engagement conditions n Finishing process n Low chip cross section n High speed (factor 2 bis 10) n low cutting forces Work piece n Very good surface quality for curved areasInfluence of speed: n High variety of materials, hard materials Metal removal Machine requirements n High spindle speed n High feed rate and acceleration Surface quality Tool Cutting forces n High-performance coating (cutting speed) Tool life travel path n High temperature resistance of the cutting edge n Low tool heat influence speed vcSource: Schulz; Hochgeschwindigkeitsbearbeitung© WZL/Fraunhofer IPT Page 12
  14. 14. Influence of cutting speed on cutting temperatures vc = 25 m/min JSS 325°C = v = 75 m/min c JSS 605°C = v = 100 m/min c JSS 655°C =20 20 20µm µm µm 0 0 0-10 -10 -10 -10 0 µm 20 -10 0 µm 20 -10 0 µm 20 vc = 150 m/min JSS 690°C = vc = 300 m/min JSS 910°C = v = 600 m/min c JSS 1195°C =20 20 20µm µm µm 0 0 0-10 -10 -10 -10 0 µm 20 -10 0 µm 20 -10 0 µm 20Material: X180VCrMo951PM (57 HRC) Source: Dissertation Steffen Knodt© WZL/Fraunhofer IPT Page 13
  15. 15. Qualitive influence of different process parametersDefinitionen time and costs quality barriern Spindle capacity: Material Tool life surface precision Cutting P = F * 0.5 * D * n removal time [Lf] [Rz] forces [F] rate [Q]n Theoretical roughing depth: Cutting speed [vc]n with X: fz or ae Cutting depth [ap] 2 2 DT æ DT ö X Rth = - ç ÷ - Cut width 2 è 2 ø 4 [ae] Feed rate per tooth [fz] Number of teeth [Z]© WZL/Fraunhofer IPT Page 14
  16. 16. Basic factor: Process controlmachined area [cm²] 220 fz= 0,01 mm = const 180 140 100 60 Initial situation 20 coated carbide material 0 50 100 150 200 250 300 350 Cutting speed vc [m/min] Tool: Torus D3R0,5, CBN; Werkstoff: 1.2343, 55HRC© WZL/Fraunhofer IPT Page 15
  17. 17. Basic factor: Process controlmachined area [cm²] CBN: Optimum cutting speed is 220 fz= 0,01 mm = const fz= 0,01 mm 180 140 100 60 Initial situation 20 coated carbide material 0 50 100 150 200 250 300 350 Cutting speed vc [m/min] Tool: Torus D3R0,5, CBN; Werkstoff: 1.2343, 55HRC© WZL/Fraunhofer IPT Page 16
  18. 18. Basic factor: Process control machined area [cm²]machined area [cm²] Optimum cutting speed is fz= 0,01 220 220 fz= 0,01 mm = const mm 180 selected point 180 140 140 100 100 60 60 Initial situation 20 20 coated carbide material vc= 200 m/min = const 0 50 100 150 200 250 300 350 0,01 0,008 0,006 0,004 0,002 0 Cutting speed vc [m/min] Feed rate per tooth fz [mm] Tool: Torus D3R0,5, CBN; Material: 1.2343, 55HRC© WZL/Fraunhofer IPT Page 17
  19. 19. Basic factor: Process control Machined area [cm²]Machined area [cm²] Optimum cutting speed is fz= 0,01 220 220 fz= 0,01 mm = const mm 180 Selected point 180 140 140 100 100 60 60 Initial situation 20 20 coated carbide material vc= 200 m/min = const 0 50 100 150 200 250 300 350 0,01 0,008 0,006 0,004 0,002 0 Cutting speed vc [m/min] Feed rate per tooth fz [mm] n Studies show: Optimum results can be realized in a very little process window n Little process changes lead to significant losses in terms of economical efficiency n To realize complex parts you need to use five-axis motion control to fulfill the demand Tool: Torus D3R0,5, CBN; Material: 1.2343, 55HRC© WZL/Fraunhofer IPT Page 18
  20. 20. Technological core aspects in milling Milling tools & Coatings Technological orintated Machine & Controling NC-Programming Source: Hembrugn Abrasions-resistance n Harmonic tool path n Precision and repetition exactnessn Geometrical variety n Stock allowance n No vibrationsn Precision n Easy and quick operation n Harmonic motion controln Stability and process reliability n Implementation of technological background concerning motion n Low wearn Technological knowledge control n Reliable automation© WZL/Fraunhofer IPT Page 19
  21. 21. Outline of the presentation 1 What is the motivation for advanced milling technologies 2 What is required to realize a successfull implementation of HSC? 3 Advanced roughing possibilities 4 Improved finishing results due to intelligent CAM-Systems and tool adaption 5 Conclusion© WZL/Fraunhofer IPT Page 20
  22. 22. Technological optimized process planning – process modelingMulti-axial roughing of cavities 0,04 Chip thicknesshsp [mm]Tool geometrie 0,03 f z(increasing)n Diameter, twist, 0,02 number of teeth,n cutting blade geometrie 0,01 Asp hsp 0Process parameter 110 120 130 140 150 160 170 180 Wrap angle j [°]n Feed rate per tooth, cutting speed Fc WZ- Kont akt - Werkzeug n+1-t e n-t e Rot at ion zonen- Hüllkurve erzeugt erzeugt 0,03 Chip thicknesshsp [mm] w inkel Fc Kont ur Kont ur Werkzeug- a e (increasing)Track geometrie mit t elpunkt Zust ellung je 0,02 Kreisbahn aen circle, ellipse, spline, …n track radius, infeed 0,01n Epizykloids, hypozykloids 0 Rückw ärt ige Kreisbahn des 100 120 140 160 180 Bew egung Werkzeug- Wrap angle j [°] mit t elpunkt es© WZL/Fraunhofer IPT Page 21
  23. 23. Technological optimized process planning – ImplementationRoughing of hard materialsA maximum uniformity is given by a minimum Optimal depth of cut forvariation of the cross section. tool diameter = 12mm Helix angle l [°] Number of teeth z [-] 15 30 45 60 4 35,2 16,3 9,4 5,4 70,3 32,6 18,8 10,9 28,1 13,1 7,5 4,4 5 56,3 26,1 15,1 8,7 uniformity [-] 23,4 10,9 6,3 3,6 6 46,9 21,8 12,6 7,3 Depending on material L/D relations of maximum 1,5 – 2 were reached. As a consequence there are limitations for the choice of the geometry of the optimal tool.Wrap angle [°] ap [mm]© WZL/Fraunhofer IPT Page 22
  24. 24. Technological optimized process planning – ImplementationRoughing of hard materialsn Tool JH170 Tool life volume [cm³] Material removal rate [cm³/min]n vc = 90 m/min Tool life volumen ae = 0,25/ Fc = 30° Material removal rate The metal removal rate is proportional to the cut depth, but there is no linear behavior of the cutting volume concerning cutting depth.© WZL/Fraunhofer IPT Page 23
  25. 25. Technological optimized process planning – ImplementationRoughing of hard materials Fxy [N] 240 µm tool flank wear land (VB) 1800 1600 1400 200 * Slot milling 1200 1000 160 800 600 120 400 200 80 fz [mm] 0,06 0,06 0,03 0,03 0,03 0,02 U/ae [°/mm] 30° 10mm 40 vc [m/min] 100 100 60 50 50 20 ap [mm] 10 1 1 3 10 20 30 40 50 60 Material S600 S790 S290 S600 S790 S290 Machined volume [cm³] V‘ [cm3/min] 1,9 1,9 0,58 1,9 1,9 1,53 JH120 JH120 JH120 JH170 240 µm tool flank wear land (VB) Tool Jabro Tools Material 1.2379 200 Circular milling VHM JH120 / *JH170 S 600 Diameter D=10mm S 790 PM 160 Teeth Z=4 S 290 PM 120 80 Slot milling Circular milling U=30° 40 Slot width 10 mm Slot width 13 mm V‘ = 1,9 cm³/min V‘ = 2 cm³/min ap = 1 mm ap = 10 mm 10 20 30 40 50 60 Machined volume [cm³]© WZL/Fraunhofer IPT Page 24
  26. 26. Further research and OutlookProcess verification on different workpiecesn The circular milling was successfully applied on the complex slot geometries of a Blisk workpiece made of Ti-6Al-2Sn-4Zr-6Mo (b-processed) – Large increase of tool life – Different algorithms for the optimization of the tool paths – Nearly constant engagement angle of ΦC = 41°© WZL/Fraunhofer IPT Page 25
  27. 27. Outline of the presentation 1 What is the motivation for advanced milling technologies 2 What is required to realize a successfull implementation of HSC? 3 Advanced roughing possibilities 4 Improved finishing results due to intelligent CAM-Systems and tool adaption 5 Conclusion© WZL/Fraunhofer IPT Page 26
  28. 28. Five-Axis-Finishing with torus milling tools:technological basics Example for the optimal coordination of angle and lead angle Zb,a Z a b degree 1 Contour radius r 24 (simple curved) 50 mm 100 mm 200 mm Lead angle b a 500 mm Yb,a q cos(b) 12 a r cos(a) b b z Xb,a= Xß Yß=Y 6 z Z X 0Aims 0 6 12 degree 24 Y Tool radius RF = 20 mmn Economic process due to Cutting plate radius rp = 5 mm Tilt angle a high axial depth of cutn High surface quality Theoretical roughness normal to feed rate directionn Optimum process é æ a ö 2 ù conditions Rth ,n = reff × sin b × ê1 - 1 - ç e ÷ ú ê ç 2×r ÷ ú – Contact length ê ë è eff ø ú û – Cutting speed Source: Zander, Altmüller© WZL/Fraunhofer IPT Page 27
  29. 29. Process exampleUse of torus mill in the Five-Axis-FinishingMachining task Conventional Five-axisn Rotating slider for a injection n Three-Axis-Process with ball-end n Simultaneous Five-Axis-Process mould mill, ae = 0,1 mm with torus mill, ae = 1 mmn Surface has to be polished n Process time ca. 120 min n Process time of the surface ca. 25 after process min n Reached surface quality ca.n Material: 1.2379, 62 HRC Ra = 1 µm n Reached surface quality ca. Ra = 0,25 µm© WZL/Fraunhofer IPT Page 28
  30. 30. Development of process technology for hard millingIdentification of optimum milling parameters for the systematic orientation of coating systems Motivation n Complex and challenging material profiles require specific, concrete and stable process parameters n Variation of cutting parameters with numeric analysis of cutting to affiliate mechanic and thermal applied load of the cutting edges and with it abrasion, impact and temperature resistance Aim n Raising of chip thickness Asp(φ) , max. cutting thickness hsp(φ), cutting width bsp(φ) and reduction of cutting length lsp(k) to reduce abrasive wear n Necessary condition φ → min Solution n Systematic identification of optimum process windows with numeric analysis n Implementation of analog surveys with identified parameter window bsp(φ)© WZL/Fraunhofer IPT Page 29
  31. 31. Development of process technology for hard millingIdentification of optimum milling parameters for the systematic optimization of coating systems Hypothesis n Coatings protect the substrate from thermal but not from mechanical applied loads n A minimum applied load on the cutting edges comes along with… - the most possible cross section area Asp(φ)1, which distributes the normal pressure 1 towards the edge with an even cutting force amplitude and a minimized total load on the tool while reaching a high productivity due to high material removal rate [3] 2 bsp(φ) - the most possible unformed chip thickness hsp(φ) and width of undeformed chip thickness bsp(φ), to ensure a high cross section area [2] - And the smallest possible chip length lsp(k) or wrap angle φ, to reduce the impact time and therefore minimize the abrasion impact on the cutting edge 3 bsp(φ)© WZL/Fraunhofer IPT Seite 30
  32. 32. Development of process technology for hard millingIdentification of optimum milling parameters for the systematic orientation of coating systems Modification of parameters n Integration of tilt angle Theta (QFB) and Psi (YB) which become additional degrees of freedom due of the five-axis- process n …only with five-axis-process the optimum cutting parameters can be defined and configured n Variation of… - Feed rate per tooth fz = 0,01 … 0.1 [mm] - Cutting depth ap,n= 0.01 … 0.1 mm - Axial depth of cut ae,n = 0.01 … 0.1 [mm] - Theta QFB = 25 … 50 [°] - Psi YB = 0 … 90 [°] n Constant Parameters… bsp(φ) - Cutting speed vc,eff= 90 [m/min] - Tool diameter D = 6 [mm] - Number of teeth z = 2 [-]© WZL/Fraunhofer IPT Page 31
  33. 33. Five-axis-process in tool manufacturing Challenges n ball end mill tools can machine nearly every component geometry n Due to ever-changing machining situation is this essential for the finishing process Problem n Different contact conditions in chip formation of three-axis-cutting with ball mill tool n »Freedom of geometry« can lead to unfavorable contact conditions Source: IPT in terms of process technology Solution n Five-axis-processes allow to influence the process parameters actively, even with complex geometries n To use additional degrees of freedom »favorable« and »unfavorable« process parameters need to be known!© WZL/Fraunhofer IPT Page 32
  34. 34. ProcessexampleStamp for colt forming operations 10 µm 10 µm 10 µm 10 µm Quelle: IPT© WZL/Fraunhofer IPT Page 33
  35. 35. Process- and CAM development –Machining example: cold massive forging die Application n Cold massive forming: great significance of surface quality for the lifetime of the tools n Continuous and fast process chains are demanded Hart milling processing n 5-axis machining offers technological advantages n Optimal availability and stable process management Objectives n Transfer and establishment of research results in hard milling in practice n Exclusively through the use of simultaneously 5-axis hard milling machining a holistic process stability can be guaranteed. + = n Component spectrum –Complex component geometry –Bad quality of the CAD-data n Economic aspects –Maximum process performance and robust processes –Optimized component- and clamping devices –Intuitive CAM- ProgrammingSource: IPT & ModuleWorks GmbH, Aachen© WZL/Fraunhofer IPT Page 34
  36. 36. Hard milling: Net based tool path calculation»automatic programming: Three axis – five axis «Programmingn Net-based conversion of 3-axis tool path into 5-axis path motionn Reduction of programming effortn Bo support structure is requiredn Less dependent on the CAD quality + = Quelle: ModuleWorks GmbH, Aachen© WZL/Fraunhofer IPT Page 35
  37. 37. Hard milling: Net based tool path calculationCold massive forming die Result n Enhanced surface quality n Harmonic tool path motion reduces visual defects caused by the axis n Ra < 0,15 µm conventional Net-based Source: IPT© WZL/Fraunhofer IPT Page 36
  38. 38. Hard milling: Net based tool path calculationCold massive forming die n Ra,quer = 0,16 µm n Ra, längs = 0,12 µm n Ra,quer = 0,25 µm n Ra, längs = 0,25 µm n Ra,quer = 0,14 µm n Ra, längs = 0,07 µm n Ra,quer = 0,2 µm n Ra, längs = 0,15 µm Source: IPT© WZL/Fraunhofer IPT Page 37
  39. 39. Geometry adaptive milling tools Ball end mill Questions Flexibility n What measures can increase the productivity of hard milling processing Barell tool significantly? n How can the required flexibility be retained? n How is the machining mechanism influenced by the form of the operation zone? Productivity End mill n Maximum adaption of tool geometry for surface properties Productivity n Use of big line width to reduce the required process time n Large ration of rv/rh, for end mill rh/rv à ¥ Geometric flexibility n Use of milling tools with „universal“ geometry n Low ratio of rv/rh, for ball head milling cutter rv/rh à 1 rh rv source: IPT© WZL/Fraunhofer IPT Page 38
  40. 40. Geometry adaptive milling tools Milling tool technology: geometric flexibility vs. productivity 1 Ball end mill 1 Ball end mill Flexibility § Maximum flexibility and least productivity Barrel tool § Fast programming due to simple geometry 2 2 Geometry adaptive milling tool ››barrel tool‹‹ § High process flexibility while simultaneously high productivity § Production of complex free form surfaces and ruled geometries 3 3 Torus-/End mill workpiece Torus § High productivity with severely limited flexibility § Only simple curved surfaces can be machined Source: Productivity IPT Solution - combining both characteristics of ball end mill and end mill© WZL/Fraunhofer IPT Page 39
  41. 41. Outline of the presentation 1 What is the motivation for advanced milling technologies 2 What is required to realize a successfull implementation of HSC? 3 Advanced roughing possibilities 4 Improved finishing results due to intelligent CAM-Systems and tool adaption 5 Conclusion© WZL/Fraunhofer IPT Page 40
  42. 42. End of the journey?Hard milling Summary n Due to simultaneous 5-axis processes - reduction of critical time-to- market lead times n Utilization of latest machine equipment and milling tools for the optimization of the holistic process performance n Further simplification of the CAM-programming n Addressing the correct process windows and ensuring constant processes is essential for the further introduction of simultaneous 5-axis processes Outlook n Further implementation tool contact situations and process forces into the tool motion planning n Optimized process planning via CAM integrated simulation and Source: IPT & ModuleWorks GmbH, Aachen implementation of specific process knowledge© WZL/Fraunhofer IPT Page 41
  43. 43. Your contact to Fraunhofer IPT Dipl.-Ing. Benedikt Gellissen Fraunhofer Institute for Production Technology IPT Steinbachstraße 17, 52074 Aachen Phone: +49 241 89 04-256 Fax: +49 241 89 04-6256 Mail: benedikt.gellissen@ipt.fraunhofer.de© WZL/Fraunhofer IPT Page 42
  44. 44. : © WZL/Fraunhofer IPT Page 43

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