Development of kinematic coupling preload guidelines through design and testing of an adjustable micromanufacturing fixture

• Main Author: Evans, Brandon A. (Brandon Adam)
• Other Authors: Martin L. Culpepper.
• Format: Others
• Language: English
• Published: Massachusetts Institute of Technology 2014
• Subjects: Mechanical Engineering.
• Online Access: http://hdl.handle.net/1721.1/92063

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014. === This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. === Cataloged from student-submitted PDF version of thesis. === Includes bibliographical references (pages 111-117). === In the growing field of non-lithographic micromanufacturing, the ability to properly align a workpiece to a machine limits the attainable tolerances in micro-electro-mechanical-systems (MEMS) prototyping. This limit has created the need for a standard adjustable base for implementation into multiple precision machines, allowing for six-axis adjustment and alignment of workpiece stages that are moved between these machines. Such a fixture--a hybrid positioning fixture (HPF)--has been designed, fabricated, and tested. This HPF has demonstrated <50 nm and <1.5 [mu]rad 2[sigma] (95% confidence) static positional repeatability over 1000 separation-engagement cycles and equivalent 2[sigma] (95% confidence) path-following accuracy when used as a dynamic nano-stage. The HPF has also demonstrated adequate stiffness to ensure <50 nm positional accuracy over an adjustment range of ±5 [mu]m and ±100 [mu]rad in response to 2 N normal and lateral forces during micro-milling operations. The HPF is based upon a kinematic coupling concept, and experiments have been completed that show highly repeatability coupling can be obtained by loading the Hertzian kinematic contacts of the HPF past the fully plastic half-groove material limit. This is a novel result that allows for stiffness increases of ~2.5 and load capacity increases of ~15.5 over conventional kinematic couplings, which are typically loaded to the sub-surface elastic limit. === by Brandon A. Evans. === S.M.