Fiber Glass Yarn Forming Tube Study

         Advanced Glassfiber Yarns (AGY) is the largest global supplier of glass yarns.  These yarns are a critical material used in a variety of electronic, industrial, construction, and specialty applications.  In order to increase the product performance at AGY, the team must determine the specific characteristics of the plastic forming tubes that prevent the uniform movement of glassfiber yarn over them and develop a method to measure these characteristics.  Advanced Glassfiber Yarns has presented the team with several requests, which include:

        · Examine and analyze the tube samples using the following characteristics:
            length, width, weight, friction, inside diameter, surface roughness, and tensile
            strength.
        · Develop and document a standard measuring system to quantify the
            characteristics of the tubes.
        · “Fix” AGY’s tube measuring machine.

    The team has developed a Gantt chart that shows the twelve steps that must be taken to meet the requests made by AGY.  These steps include – gather preliminary data; determine relevant tube characteristics; develop and complete length, wall thickness, weight, friction, inside diameter, surface roughness, and elastic modulus tests; statistical analysis; and document testing procedures and tools.  The team completed all the measurement tests, documented the procedures, and conducted statistical analysis to determine repeatability of the testing methods and significant differences between good and bad tubes.  Several conclusion were formed from the results of the statistical analysis:

        · The methods of conducting the length, wall thickness, weight, friction, and inside
            diameter measurement tests were determined to be repeatable.
        · The elastic modulus measurement test was determined to be not repeatable
            because of the non-circular shape of the tubes and the dependence on
            length, wall thickness, and inside diameter measurements.
        · The wall thickness, weight, and surface roughness measurements were
            determined to be statistically different between good and bad tubes.
        · Good tubes have a wall thickness between 0.00004 and 0.00448 inches greater
            than that of bad tubes.
        · Bad tubes weigh between 8.594 and 5.557 grams more than good tubes.
        · Bad tubes have a roughness between 85.10 and 56.53 micro-inches greater than
            that of good tubes.

The team then formed several recommendations for AGY:

        · Further measurement testing should be done.
            o Investigate the possibility of redesigning the elastic modulus measurement
                test in order to obtain more accurate and repeatable results.  This could
                possibly be done with a capable compressive machine or a tensile testing
                machine with a strain gage.
            o Conduct all the measurement tests on a wider variety and number of tubes.
                 Complete the tests on the tubes when they are brand new and then again
                when they have reached their service life in order to analyze changes of the
                tubes over time and use.
        · Surface roughness of the forming tubes should be more closely monitored.
            o Machine the outside layer of a batch of tubes to provide a smoother finish,
                and then test for improved production efficiency.
            o Provide surface roughness specifications to the tube vendor.  Check the
                surface roughness when the tubes are delivered to see if they comply, and
                return the tubes if they do not.
            o Research other tube vendors that may provide better surface roughness
                tolerances.