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  1. 1 Background Downsizing of machine tools can improve space utilization factor, and reduce the price and energy consumption including air conditioning and facility investment. The agility in reconfiguring the manufacturing lines in the factories will be elevated. Furthermore, location of the machines can be spread off the factory floor, to the design office, classrooms and distributed to small manufacturing laboratories, even in residential areas. As technical aspects, the downsizing makes it easier to achieve high-speed machining and high-precision/rigidity motion control due to reduce inertia, and in turn, it leads to higher precision, quality and productivity. With these objectives, a desktop NC milling machine has been developed, using a miniature high-speed spindle. The purpose of the development is to evaluate the technical possibility of extremely downsized machine tools in practice. Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST)

  2. 2 Compact: 450x300 (base)x380(H) Ultra-high speed spindle: 200krpm XY+Z slides: 0.2G, 50mm/s max. feed Rugged: “Housing” construction Custom NC: Full-closed 0.1µm resolution/DNC compatible Low power consumption: 120W Mechanical design Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST)

  3. 3 Z-axis drive mechanism • Spindle unit • High-frequency AC motor up to 200krpm • 2 ceramic-ball bearings • Collet chuck at the spindle end (1mm dia.) • Mist-air coolant for both spindle and cutting point Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST)

  4. Video monitor Notebook PC Milling machine CAD/CAM system NC with console Spindle drive 4 NC System overview Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST)

  5. 5 Step response Ruling law changes depending on the step size! 2m/s2 Max. velocity Max. Acceleration Servo gain Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST)

  6. Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST) 6 Surface finish Sa=0.255µm, Pt=1.35µm Sa=0.106µm, Pt=0.61µm NAK55 d = 0.05mm F = 50mm/s Pf= 0.05mm N = 200,000rpm R0.2 WC Downcut A7075 d = 0.05mm F = 12.5mm/s Pf= 0.05mm N = 200,000rpm R0.2 diamond Reciprocating cut

  7. feed feed pickfeed Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST) 7 Surface texture depends on cutting direction Surface finish UpcutSa=0.211, Pt=1.22 Reciprocating cut Sa=0.214, Pt=1.26 A7075 Pf = 0.05mm d = 0.05mm F = 50mm/s N = 200krpm

  8. 0.5 φ0.5 Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST) 8 High-aspect ratio machining 200 krpm 50 krpm  (Inclined! Higher rpm for less damage) Fin thickness: 80µm x 2mm x 6mm Work material：A7075, Tool: Square end mill Φ0.5, Depth of cut: 0.02mm×100 times=2mm Feedrate: 50mm/s Work material: A7075Tool: Square End mill Φ 0.5 Feedrate: 50mm/s, Depth: 0.02mm x 100times=2mm Alternatively machined on both sides 50µm20µm

  9. 0.1 4 9 Machined examples Workpiece: A7075 (20x20mm) Tool: Ball end mill, R0.2 Max. feedrate: 50mm/s Pick feed: 0.1mm Cutting depth: 0.1mm x 2times Duration: 130 seconds Helical milling Φ150µm x 2mm Work material: A7075, Tool:Tapered ball end mill R0.2mm，5deg Feed rate:50mm/s Pick feed:0.1mm,0.025mm Depth: 0.05mm x 40 times = 2mm Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST)

  10. 10 Conclusions Taking advantages of downsized machine tool, the developed milling machine features high acceleration due to the reduced moving mass even using small actuators, and minimized power consumption, Furthermore, ultra-high speed spindle enables high speed milling on hard materials. High aspect ratio machining was also performed. Fine Manufacturing System Research Group http://unit.aist.go.jp/imse/finemfg/ (former Mechanical Engineering Laboratory, AIST,Tsukuba) Institute of Mechanical Systems Engineering (IMSE), National Institute of Advanced Science and Technology (AIST)

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