Introduction

The intrinsic friction of the Nanomotion motor offers an interesting solution for Z applications, where gravity functions as a permanent load. Nevertheless, some considerations must be taken into account to ensure safe and reliable system operation. This report highlights these considerations and shows that in order to achieve successful implementation in Z direction the load should not exceed 1/3 of the nominal static holding force.

Design Margins

Figure 1 above shows the correct installation of the Nanomotion motor as stipulated in the motor manuals.

While operating Nanomotion motors in the Z direction, the following points should be considered:

In a preloaded condition, the bearing should yield a stiffness of 50N/µm. Acceptable bearing designs are:

• Intrinsic friction.
• Shearing of the double sided tape and the epoxy.
• Vibrations

The analysis in the attached appendix yields the following conclusions regarding the Design Margins for vertical operation.

• Stiffness Without epoxy drops, stiffness is low. Each drop gives stiffness of 12.5 N/µ . For multiple motors on a small ceramic strip, more drops should be used to achieve high stiffness and high accuracy.
• Holding force Taking into consideration the friction coefficient change with time and standard industrial vibrations, a vertical set up would hold 117 gr/motor element. For a higher mass/motor element counter balance provisions must be used.

Summary

Considerations for the motor operation in the Z direction overcoming gravity were described. It is clear that with proper system design, the unique feature of the intrinsic holding force can be utilized maintaining precise position with no power.

This report did not consider close loop functions, but position can be better maintained under close loop, overcoming vibration.