Lower Manufacturing Costs

Precision Fabrics Group, Inc. supplies parachute fabric to the U.S. military. In 2001, the company was experiencing quality issues with this fabric regarding porosity. This was the company's highest priority quality issue. LSS methodology was used to identify the cause of the problem and correct it; saving the company $350,000 in the first year.

Problem

Precision Fabrics Group, Inc. is a supplier of finished woven and nonwoven fabrics to food, medical, clothing, and military customers.  The company is a high volume producer of materials, and ships to customers around the world.  For the military, Precision Fabric’s woven business unit provides finished fabric for various parachute applications.  In 2001, Precision Fabrics was experiencing high rework of finished parachute fabrics for porosity issues.  Porosity is the amount of air that is allowed to pass through the fabric.  It was found that about 30 percent of the material had to be reworked due to high porosity readings.  The porosity requirements were specified per formal military specifications.  The Plant Manager assembled an employee team led by a Lean Six Sigma (LSS) Black Belt to work with the R&D and Technical Departments to correct this problem. 

Approach

The assigned Black Belt conducted a traditional LSS project in a four-month time frame to resolve this issue.  The Black Belt started with a process map to understand the steps the fabric passed through to obtain not only the required porosity characteristics, but also all the other required traits that enabled it to function as an individual soldier parachute.  Through an analysis of each step and piece of processing equipment, the Black Belt identified the piece of equipment with the greatest impact on fabric porosity.  That piece provided a special finish to the fabric by passing it through two rollers to tighten the fabric and give it a particular texture.  This piece of equipment also had a sensor unit to provide an “at the moment” reading of fabric porosity as it passed through the “calendar” rolls.  The Black Belt collected data from multiple rolls of fabric across multiple shifts utilizing the team and data collection sheets.

The team found that the data, when placed in a control chart format, showed that the process used to make the material was not in control, and the process produced many errors.  The process was not capable of producing the required porosity finish the first time the fabric passed through the piece of equipment. Further, in many cases the rolls of fabric that would pass through came out with the required porosity, but other rolls would pass through with readings out of specification.

Through discussion with R&D and the equipment operators utilizing a cause and effect diagram, it was determined the material utilized for “calendar” rolls was the cause of the issue.  The Black Belt researched multiple suppliers that made this type of roll and identified a new type of roll for the process.  This new roll was purchased and installed.  A design of experiment (DOE) was completed to establish the new process settings for the piece of equipment and a two-week pilot run was completed.  The pilot did not produce any porosity defects and operators were very happy with the improved process.  The new process settings were recorded in procedures at the machine and in quality control documents.

Results

Reworking the parachute fabric due to porosity issues was eliminated and the company realized a $350,000 cost savings in the first year. This represented a 25 percent reduction in parachute fabric finishing cost and was in alignment with projected costs.  Follow-up evaluation of the process using the porosity sensors on the machine found the process to be in control and repeatable from one roll of material to the next.  The new piece of equipment paid for itself in just over a month and the highest priority quality issue within the business unit was eliminated.