The Standard Mini Mill Stiffness Calculations By Roger

The Standard Mini. Mill™ Stiffness Calculations By: Roger Cortesi rcortesi@mit. edu http: //pergatory. mit. edu/rcortesi/ Precision Engineering Research Group Massachusetts Institute of Technology, Mechanical Engineering Department Room 3 -470 77 Massachusetts Ave. Cambridge, MA 02139 Phone: (617) 253 -1953 Fax: (617) 258 -6427 http: //pergatory. mit. edu/ Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.

Types of Stiffness Calculations • • Ball Screw Stiffness Servo Stiffness Carriage Translation Stiffness Carriage Roll Stiffness Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.

Standard Mini. Mill™ Ball Screw Stiffness Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.

Standard Mini. Mill™ Servo Stiffness The ball screw is really a wedge Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.

Standard Mini. Mill™ Carriage Translation Stiffness The carriage stiffness in the UP DOWN and SIDE directions in 4 times the truck stiffness in each of these directions. Star Linear™ Steel Truck Short (left) and Standard Truck (right) Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.

Standard Mini. Mill™ Carriage Roll Stiffness Lb 2 Trucks Lt Center of Stiffness Tool Force 2 Trucks Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.

Carriage Stiffness Comparison Between The Standard and Modified Mini. Mill™ Axial Stiffness 1 is the servo stiffness. Use if a linear encoder is used Axial Stiffness 2 is the stiffness of the ball screw, use if a rotary encoder is used See the Modified Mini. Mill™ Stiffness Presentation for the calculation of the its stiffness values Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.

Overall Machine Stiffness Estimates Between The Standard and Modified Mini. Mill™ The Standard Mini. Mill™ has an estimated Machine Stiffness of: 10 N/micron (57, 000 lbf/inch) This can be doubled by upgrading from short trucks (0. 02 C Preload) to Standard Trucks (0. 08 C Preload) The Modified Mini. Mill™ has an estimated Machine Stiffness of: 5 N/micron (27, 000 lbf/inch) The machine stiffness was estimated from the deflection due to the rolling of Y Carriage and Deflection of the Z Axis. See the Modified Mini. Mill™ Stiffness Presentation for the calculation of the its stiffness values Property of Roger Cortesi, MIT Precision Engineering Research Group. DO NOT COPY or TRANSMIT without written permission.