Case Study - Machining Defect ReductionMajor Pipe Manufacturer - NSW, Australia

A manufacturer of large diameter Oil & Gas Pipe was experiencing excessive rejected pipe and work in progress rates due to machining errors at each end of a pipe while creating a bevel and landing.

The standard for the manufacture of pipe to be used in the oil and gas industry requires that the end of each length of pipe be finished with a bevel suitable for joining by manual field welding.  This bevel has comparatively tight tolerances.

Customer feedback, competitor capability and high rework rates required the capability of the end-machining units to be dramatically improved.

The equipment in use was originally designed and built when the plant opened in 1966.  While it had been maintained well, it had not been upgraded since commissioning. 

Analysis of the capability of equipment showed that, even at its best performance, the defect rate was unacceptable.

High-speed photography, and tools from the Lean Six Sigma toolkit such as multivariate regression analysis, and Failure Modes and Effects Analysis (FMEA) were used to address the problem.

The project team also called on the expertise of external metal cutting specialists to understand metal cutting characteristics and recommend possible solutions from the results of the analysis.

The outcome of this was a complete ‘back to the drawing board’ re-design.  The re-design incorporated the latest CNC cutting tool positioning technology to remove the most significant sources of variation in the process. 

The underlying philosophy for the solution was to reduce the defects by eliminating the sources of variation and reducing complexity.