An Unlikely Combination: How Wire EDM Opens Up New Possibilities in Grinding 2016-08-29 Michael Klotz 2
founded 1912 2015 Employees Fritz Studer AG ~ 770 Apprentices included in total 77 Sales CHF 210 Mio. 2016-08-29 Michael Klotz 3
Chapters Technical Properties Economic Potentials 2016-08-29 Michael Klotz 4
Grinding is Dressing 2016-08-29 Michael Klotz 5
Approach Machine Equipment Grinding Process Material of Workpiece Grinding Tool 2016-08-29 Michael Klotz 6
Technological approach Grinding External cylindrical grinding Ceramics Tungsten carbide Hardened steel Superabrasives CBN Diamond Resin Ceramic Metal Metal Bonds Large potential 2016-08-29 Michael Klotz 7
Starting position Characteristics of the bond systems Cutting performance Dimensional stability Thermal stability Thermal conductivity Dressability Resin Metal Ceramic Metalceramic STUDER-WireDress Very good Good Unsatisfactory Source: Diametal 2016-08-29 Michael Klotz 8
2016-08-29 Michael Klotz 9
Experience of basic research on the product 2007 2010 2014 2016 applied research, swiss industry + ETH Zürich Agie Progress V4 Wire EDM machine ETH Zürich Prototyp 1 For internal wheels on S31-1000 ETH Zürich Prototyp 2 For external wheels Ø500mm on S12 + S22 STUDER STUDER-WireDress Source: IWF ETHZ, Inspire 2016-08-29 Michael Klotz 10
Principles of EDM, WEDD process Electro Discharge Machining (EDM) / Wire Electro Discharge Dressing (WEDD) z x D91 Source: IWF, Martin Schöpf, Dissertation ETH Nr. 14120 2016-08-29 Michael Klotz 11
Principles of EDM, WEDD process non-contact method only bond becomes dissolved abrasive grain drops out abrasive grain stays sharp arbitrary geometries dressable (radii, chamfer, ) grain protrusion on wheel after WireDress -dressing 2016-08-29 Michael Klotz 12
Example: dressing system integrated in S22 grinding wheel WireDress wire cutter with collecting container workhead oil supply wire guide wire power supply WireDress unit tailstock 2016-08-29 Michael Klotz 13
Performance characteristics 2016-08-29 Michael Klotz 14
Dressing of metal bonds with diamond or CBN up to D126 / B126 D64 only with grinding oil B91 D46 D126 B91 GAP 2016-08-29 Michael Klotz 15
High grain protrusion producible Maximum cutting performance approx. 30μm (0.0012 ) grain protrusion blunt dressed 2016-08-29 Michael Klotz 16
Fine geometries possible on the workpiece R internal 0.05 mm (0.0019 ) R external 0.2 mm (0.0078 ) R0.0499 2016-08-29 Michael Klotz 17
No wear on the dressing tool Rotary dressing STUDER-WireDress No compensation necessary Continuously renewed tool Maximum precision Fewer influences, greater reliability 2016-08-29 Michael Klotz 18
Quick dressing Removal rate on the wheel approx. 80 mm 3 /min (depending on bond composition) STUDER-WireDress Wheel speed 50 120m/s possible during dressing (9,840 23,600 ft/min) Same conditions for profiling from solid and sharpening 0.010 (0.39") 20 (0.79") WireDress Example: Dressing a Diametal D64 M263 C100 Ø400 D64 Dressing Time : 8.3min 2016-08-29 Michael Klotz 19
Simple handling Fully integrated in StuderWIN control system surface Usual procedure for machine set-up in StuderWIN Generation of path optimized programs in StuderDRESS Simple handling of dressing unit 2016-08-29 Michael Klotz 20
2016-08-29 Michael Klotz 21
Chapters Technical Properties Economic Potentials 2016-08-29 Michael Klotz 22
Economic Potentials Abilities of Grinding Wheel Operation / Handling Dressing Tool Costs Energy Requirement 2016-08-29 Michael Klotz 23
Higher productivity WireDress Cutting performance Dimensional stability Thermal conductivity +30% grinding power Source: IWF ETHZ, Inspire 2016-08-29 Michael Klotz 24
Less wear at grinding wheel with metal bond Tungsten carbide, finishing, HSG peel grinding D46 0.05mm Ceramic bond Metal bond + wear 80μm (0.003 ) after 100 pieces -75% wear wear 20μm (0.00079 ) after 100 pieces WireDress D16 0.05mm after dressing after 100 strokes with Ø50μm infeed (0.0019 ) after 100 strokes with Ø50μm infeed plus 50 strokes with Ø100μm infeed Process data: Vc=120m/s (23,600ft/min) f z =200mm/min 7.8In/min f R =30mm/min A 1 = Ø0.05mm 2016-08-29 Michael Klotz 25
High Wheel lifetime with Metal Bond + WireDress Wheel Setup once + balancing No external Dressing no Downtime for Wheel Change Wheel stays in Machine until end of tool life e.g. up to 15,000 parts (pending on process) Increase in OEE (Overall Equipment Effectiveness) 2016-08-29 Michael Klotz 26
Low costs for dressing tool 0.02 Rotary dressing STUDER-WireDress Dressing roll Purchase + Regrinding of roll -66% Dressing tool costs 1 wire coil ( 16h dressing) Tool costs example: Peel grinding with high requirement to profile accuracy, dressing tool costs for whole grinding wheel lifetime (5mm, 0.2 layer) 2016-08-29 Michael Klotz 27
Convenient rated break point at handling mistake Dressing roll -83% Tool costs Wire guide 2 cavities remaining 2016-08-29 Michael Klotz 28
Low energy costs Rotary dressing STUDER-WireDress 500W 0.5 1.5kW Sealing air 120 l/min 1kW (26 gal./min) in) -53% energy required operation -94% energy required standby standby after 5min no dressing 2016-08-29 Michael Klotz 29
Simple Economic Calculation 2016-08-29 Michael Klotz 30
Involved in Calculation Increases wheel lifetime Higher feed rate Less wear stable bond Abilities of Grinding Wheel Low Costs for damaged Wire Guide Operation / Handling No wheel change for dressing Increased OEE Long lasting wear parts Low dressing Wire costs Now wear at dressing Wire Dressing Tool Costs Energy Requirement Low energy use in operation Low standby energy use 2016-08-29 Michael Klotz 31
Previous Grinding Process Grinding with WireDress and Metal Bond Operation Hours per Shift 8h = 480min 8h = 480min Non productive auxilary time (wheel change, dressing) -5%, because no wheel change, longer dressing 15% interval 10% Real productive Machine operation per Day 408 min 432 min Grinding Time per part 6:00 min -30% Grinding Time 4:00 min Parts per Shift 68 pc. +58% output per shift 108 pc. Machine hour rate 100 $ 100 $ Machine Cost of Operation per Part (due to grinding time) 10 $ -3.33$ per part 6.66 $ Parts in 240 Workdays per Year, 1 Shift 16 320 +58% output per year, 1 Shift 25 920 Savings of Machine Operation Costs per Year 0$ 86 572$ 2016-08-29 Michael Klotz 32
2016-08-29 Michael Klotz 33
Examples 2016-08-29 Michael Klotz 34
Sample Part (example for grinding performance + complex profile) 23,600 ft/min 2016-08-29 Michael Klotz 35
Process (example for grinding performance + complex profile) OP 1) Peel grinding OP 2) Plunging v c 120 m/s v fa 350 mm/min a e 0.5 mm 23,600 ft/min 13.8 In/min 0.02 In D91 Ø400 Ø15.75 In M267 C150 D25 Ø400 Ø15.75 In M263 C150 v c 120 m/s depht 0.7 mm v fr 1.6 mm/min 23,600 ft/min 0.028 In 0.06 In/min Grinding time 3:35min Grinding time 0:35min resulting Surface R a 0.22μm 8.66 R a Total Grinding Time 4:05min 2016-08-29 Michael Klotz 36
Sample workpiece over 3.2mm section W t 1.18 μm 0.00007 2016-08-29 Michael Klotz 37
Tungsten Carbide Thread Cutter 2016-08-29 Michael Klotz 38
Thread Cutter Profile of Thread Wheel HSG 120 m/s 23,600 ft/min Peel Grinding Roughing D126 + Finishing D9 From solid, ØTolerance within 1μm 0.000039 In (with Measurement control) Shaft Rough+Finish 5:00 min Total Grinding Time R z Shaft 0.5 μm 19.6 R z R z Thread 0.6 μm 23.6 R z Thread 4:00 min 9:00 min 2016-08-29 Michael Klotz 39
Tungsten Carbide Tool, Pre Form 2016-08-29 Michael Klotz 42
Workpiece 2016-08-29 Michael Klotz 43
Grinding Process Roughing Finishing D91 D10 HSG 120 m/s Peel Grinding Grinding time 4:24 min R z 0.47 μm 0.000019 In R ONt Corner Radius (repeatable) 0.54 μm 0.12 mm 0.00047 In 2016-08-29 Michael Klotz 44
Summary 2016-08-29 Michael Klotz 52
Product Dressing hardware Dressing technology Software StuderWin integrated Dressing module Electric cabinet Wire cutter 2016-08-29 Michael Klotz 53
WireDress as Enabeling Technology to overcome with Metall Bond In running processes Increase Dressing Intervall Decrease Grinding Time Until today, not producible Small Radii High constancy of profiles 2016-08-29 Michael Klotz 54
2016-08-29 Michael Klotz 55