ME324 Precision Engineering

Students learn concepts and technology that enable precision measurements for application areas including applied physics, diamond-turning equipment, integrated circuit manufacturing, and manufacturing metrology systems. Final projects include design and manufacture emphasizing principles of precision engineering.

Spring 2024

Project #3: one degree of freedom stage (translation or rotation)

1. Overall learning objective:
   1. In this project students will design and build a one DOF (translation or rotation) stage to minimize error motion and variation of error motion from run to run (unrepeatability).  The purpose of this project is to give students hands-on experience with: bearings (in particular air bearings), guides, actuators, measuring error motion and reversal techniques.  Some students may also wish to explore lapping and surface metrology. 
2. Requirements:
   1. Translation or “linear” stage with a minimum travel of 100 mm or a rotation stage with “infinite” rotation.  
   2. Actuator to drive the stage through its travel and hold it in position.
   3. Designated sensor interface(s) for measuring stage position and error motion.  For example if using the CMM a “trap” for the CMM probe.
   4. Actuation force sufficient to support chosen measurement tool.
3. Students will (on their own time, outside of class):
   1. Choose either a translation or rotation
   2. Set a goal for how small the error motion of their stage will be in terms of position error and repeatability. 
   3. Design and build the stage using air bearings.
   4. Verify whether the goal above was reached by characterizing the stage by measuring the error and repeatability of the motion.  The error motion measurement can be of one or more degree of freedom.  
      1. For a rotational stage, it is interesting to measure the radial displacement of the rotation axis ‘r’ as a function of angular position ‘theta.’  How to instrument the stage to collect this data is left to the student, though one low-tech combination could be made from a dial indicator and a wheel with angular tick marks.
      2. For a translational stage, if the translation axis is ‘z’ it is interesting to measure the displacement in one (or more) of the orthogonal cartesian axes ‘x’ and ‘y’ as a function of ‘z’. This could be done with the CMM.  Angular (pitch, yaw, roll) error motion could be measured optically using a laser beam projected onto a distant surface.