Failures – Identifying the Root Cause

Carbon Fibre BowsBow failures are almost always due to external factors. Reasons may include:

  • Wire breaks.
  • Improper balancing after attaching the retaining hardware and wear strip.
  • Foreign objects accidently left inside the machine picked during winding can break the bow on contact.
  • Fluctuating wire tension either upon entry or exit, causing the bow to flex in or bow out, and hit a stationary machine part.
  • Quick start-up or shutdown of the machine can cause the bow to twist and break.
  • A change in the product being processed may require a change in bow.
  • Clamps in some machines can slip out of alignment, which can cause undue stress.
  • Centrifugal force may carry the bow out. If the outer edge of the clamp is sharp, it may cause bow failure at the clamp.
  • Insufficient preventive machine maintenance (bearing wear, vibrations, etc.) may contribute to bow failure.
  • Human error relating to inexperience with machine operation.

Failures can also result from the use of substandard materials, poor design, incorrect material selection, and inferior manufacturing methods.

The following 2 lists related to the bow and the machine should help you increase bow life and overall productivity.

5 Bow ‘C’s

  1. Correct profile
  2. Correct composite (i.e,, uni/bi/triaxial carbon fiber; fiber glass; or GKC)
  3. Correct size
  4. Correct hardware
  5. Correct fit

5 Machine ‘P’s

  1. Proper preventive maintenance with check sheets to verify
  2. Properly trained operators with up-to-date standardized work
  3. Properly certified suppliers providing built-in quality
  4. Proper equipment set-up based on the control plan with check sheets to verify
  5. Proper 5S* environment with equipment, tools & inventory management

*A workplace organization method based on a list of five Japanese words, which describe a process for creating and maintaining new order. There are 5 primary phases that can be translated into 5 English ‘S’ words – sorting, straightening, systematic cleaning, standardizing, and sustaining. Sometimes, the process includes 3 other phases – safety, security, and satisfaction.