Tolerances in Engineering Design

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Tolerances in Engineering Design

• STEP Lesson 2
• 2/7/08
• STEP Fellow Mr. Herfat
• STEP Teacher Mrs. Truesdell

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Tolerances Review

• No two manufactured objects are identical in
  every way. Some degree of variation will exist.
• Engineers apply tolerances to part dimensions to
  reduce the amount of variation that occurs.
• A tolerance is an acceptable amount of
  dimensional variation that will still allow an
  object to function correctly.

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Medical Devices

• Medical device - covers a wide range of health or
  medical instruments used in the treatment,
  control, diagnosis or prevention of a disease or
  abnormal physical condition.
• Prosthesis - a device, either external or
  implanted, that substitutes for a missing or
  defective part of the body.

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Tolerances in the Nati
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Tolerances in the Nati
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Tolerances in Medical Design

• Total Knee Reconstruction (DePuy Orthopaedics,
  IN)
• checked with laser scanning
• complex sculptured contours required for proper
  functioning
• Very precise tolerances are needed
• abnormal motion (additional range of motion)
• additional loading on other structures
• wear on the implant
• too little movement will not restore full range
  of motion.