Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. The Mighty Spindle™ Precision Engineering Research Group Massachusetts Institute of Technology, Mechanical Engineering Department Phone: (617) Fax: (617) Room Massachusetts Ave. Cambridge, MA By: Roger Cortesi

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. The Mighty Spindle™

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. Mighty Spindle™ Design Goals Low Cost High Stiffness 10,000 to 15,000 RPM Automatic Tool Changer Option New Features

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. Mighty Spindle™ Parameters 1.5 to 2.2 kW Max Speed of 15,000 RPM Radial Stiffness at Nose of 87 N/micron Critical Speed of 23,000 RPM

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. Mighty Spindle™ Components GE/Fanuc Motor Porous Graphite Air Bushing Spindle Sensor Duplex Nose Bearings No. 30 Taper Tool Holder

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. Why A Air Bushing in the Tail? Thermally Forgiving: Allows thermal expansion of spindle shaft. No Additional Seal Needed: The air flow provides a positive pressure air seal.

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. The Tail Support Assembly The Bushing is replicated in place to ensure good shaft alignment. The Tail Assembly is Kinematically aligned to housing. Allowing it to be removed for service and replaced WITHOUT messing up the alignment.

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. Assembly Steps Core Assembly Housing and Stator Assembly Tail Support Assembly Drawbar End Cap Nose Cap Tool Holder After the Core is inserted an Nose Cap screwed in the Tail Assembly (w/ Bushing Loose) is mated. The Bushing is pressurized and replicated in place. Ensuring good shaft alignment.

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. Tail Support End Cap Tail Support Assembly Air Bushing Kinematic Grooves O-Ring

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. Front Air Seal Labyrinth Seal is integral to the Nose Cap and Shaft Seal Air In Nose Bearing Air Exit Spindle Shaft Tool Holder Nose Cap

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. The Hot Swappable Spindle Small High Speed SpindleHeavy Duty Low Speed Spindle Kinematic Alignment Grooves

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. The Hot Swappable Spindle No need to recalibrate machine after swap Kinematic interface is repeatable to sub microns

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. Cooling the Mighty Spindle Helical Cooling Groove Cooling Water In Cooling Water Out Aluminum Housing Jacket

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. Cooling the Mighty Spindle Small Cross Section Groove = Better Heat Transfer Coolant enters at tail to pre-warm it before Nose Bearing Section Volume Flow Rate of 3 Gal per Hour No Closed Loop Chiller Needed Faucet to Drain

Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission. The Thermal Model The Dominant Thermal resistance is: The contact resistance between the motor/bearings and the housing The convection resistance between the groove walls and coolant To Dissipate 200 Watts of Heat: Tap Water at 10 C 3 Gallons per Hour