P.O.S.T.L.U.D.E.S: Selection Criteria

There are many factors to consider when selecting the correct linear motion system for your specific application. P.O.S.T.L.U.D.E.S is an acronym which will quickly guide you to asking the right questions to determine the best product for the job.

P — Precision

  • What is more important, accuracy or repeatability?
  • What is the accuracy/repeatability requirement?
  • Are these values realistic, based upon the desired motion profile?

O — Orientation

  • How will the system be mounted? (“normal”, on its side, inverted, vertical, at an angle, etc.)
  • How will this affect the load requirements?

S — Speed

  • What is the maximum speed and acceleration required?
  • What is the maximum jerk allowable?
  • What motion profile (shape) is desired?

T — Travel

  • What is the required travel (stroke)?
  • What is the overall envelope allowed?
  • How much over-travel (safety zone) is required?

L — Load

  • What is End of Arm Tooling (EOAT) and where is it located?
  • What additional forces are seen by the system during use (e.g., cutting or pushing forces)?
  • What do the static and dynamic free body diagrams look like? Have all loads been accounted for?
  • What is expected of the system after an impact?

U — Unknown

  • What are the known unknowns? What is a reasonable value for these unknowns?
  • How will someone misuse this system?
  • What could possibly go wrong?
  • What else could go wrong? (Repeat this question until you can’t think of anything else!)

D — Duty Cycle

  • What is the actual duty cycle for the system?
  • What is the expected lifetime?

E — Environment

  • In what environment will the system be installed?
  • Are there any hazards in the environment?
  • What is the maintenance schedule, and is the system accessible for maintenance/lubrication?
  • Are there contaminants in the environment which can damage the motion system?
  • Will the system disburse contaminants into the environment that could damage other equipment or products

S — Safety

  • Are there any safety standards to which this system needs to conform?
  • What could happen if the system fails?
  • Are there safeguards that need to be installed for a system failure?
  • Could people be injured by this system? If so, how will the system be protected?