Six Sigma for the Apparel Industry

By Richard AtwellManager of Education and Engineering

Textile Clothing Tech. Corp. [TC]²

The trade agreements are passing, the buzzwords are flying, and every manufacturer is looking for the nextcertification to use as a badge of honor. And so enters “Six Sigma” to the rescue. The Superhero is really the mildmannered Clark Kent in Guatemalan manufactured tights and cape. The “supercharge” comes from computer softwarethat allows the average apparel engineer or quality manager to perform analyses that previously were done only bycollege educated statisticians. Take away the computer and there is a solid basis of statistical methods that have beenin the “bag of tools” for decades.

The prevailing motto for Six Sigma is “Perfection is Possible”. The subtitle would be “Even when things go wrong, theproduct is still good”. There are two major qualifiers to the concept of perfection. The major concept is that perfectionspecifically means that the product meets the customer's accurately determined specification. Therefore perfectproduction of a size “large” shirt, which has a specification of 42 inches +/- ¾ inch, does not mean that all shirtsproduced measure 42” but rather that all shirts measure between 41 ¼ inches and 42 ¾ inches. The second majorconcept of Six Sigma is that the variation of the output is very slight. Thus, when size “large” shirts are produced themeasurements of multiple shirts will be so closely gathered around 42 inches that when something goes wrong, such asbad cutting or a gauge being misadjusted, the end result is that shirts still measure within the tolerance.

The rest of the Six Sigma process is understanding the statistics behind the charts and controls, learning the methods todetermine what is working properly, and how to identify and fix problems that do occur. The concept as a statisticalterm has been frequently used since the 1930's and gained popularity in Japan and the USA beginning in the 1950'swith Crosby, Deming, and Juran. However, Motorola is credited, by most, for bringing the term to the general publicin the 1980's. Oh yes, the statistical term. Six Sigma manufacturing says that the variation in the product is so slightthat 99.73 % of the output falls within the tolerances. Actually, the quality is so good, and multiple measurements soclosely centered around the specified number, that even when the measurement is off by three times the standarddeviation, in either direction, it is still within tolerance. Thus the measurements fall within Six Sigma or six standarddeviations of the mean and the quality yield is 99.73%.

Because many companies are seeking badges or medals to show to prospective clients, frequently the managers aredisturbed that Six Sigma certification is for individual people rather than companies. The green belt and black beltdesignations are awards for proficiency in using the tools of the program. The Six Sigma methodology is a structuredprogram for improving quality through a process with the acronym of DMAIC. Define, Measure, Analyze, Improve,and Control. Portions of each of these steps can be performed using manual techniques that are found in any statisticstextbook. The computer programs included in many of the certification classes provide much more powerful tools andthe capability of calculating in minutes what might take days to calculate manually.

Convincing apparel executives to accept the process, other than as a selling tool, has been a difficult task. About theonly agreement reached is that every garment can NOT be manufactured to the perfect specification. However, thetypical manufacturing plant is producing apparel at about a 3 sigma level with 2.5 to 4 % defects. That is 4 defects per100 not the 3.4 defects per 1,000,000 produced by a Six Sigma manufacturer. The gap is wide enough that significantimprovement can be made in any such plant. Two financial facts are important to note. Historical studies have shownoverall savings in the $10,000 to $20,000 range for an improvement of just one Sigma. Apparel managers are generallyastounded by the “True Cost of Quality” in their manufacturing facility. Typically, these costs are hidden in overheadbut include inspection and marking, sorting, transport, reinspection, supervisor time, downstream operator repair,cleaning, and irregulars. Therefore, any improvement in quality has a triple effect of reducing indirect labor, loweringtotal fabric cost, and improving customer satisfaction. Direct Labor Productivity will normally show a 10 to 15%improvement due to less repair time, correction of imbalances, and higher throughput.

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Within the DMAIC process, the management team must Determine the actual quality requirement through discussionswith the end customer. Such determination must eliminate the “Give them an inch- they will take a mile” attitude.Record the needed result, train both operators and auditors, and then hold the appropriate people accountable.

The measurement and analytical processes use tools and charts that are already available in many plants. Theseinclude some capabilities within basic spreadsheet computer programs such as Check Sheets, Histograms, ParetoCharts, and Scatter Diagrams. Flowcharts and Fishbone diagrams are easily drawn by hand.

The actual analysis and improvements come through human interpretation of the information and a logical thoughtprocess. There are two areas within this section that can be greatly assisted by the newer computer programs available.The first item is the determination of whether changes observed are statistically relevant, thus avoiding unnecessaryadjustments to a existing process. The second area, with less use in the apparel industry, is the Design of Experimentscapability to see what combination of changes will give the best end result. Experienced and motivated people giventhe time for thought and experimentation are the critical resource for analysis and improvement.

Controlling the change is often a matter of “What gets Measured and Posted is What Improves”. While computerprograms can calculate the control limits required to know when a process is out of control, the limits have less valuein an environment utilizing human operators. Manual calculations and charting will allow quick recognition of changesin the average apparel plant.

Should a company have people certified as Green Belts or Black Belts? The answer is “YES, IF”. If the companyneeds the computer program, needs a show of management support for Quality Improvement, or lacks personnel withEngineering or Quality Management training.

However, any company can reap significant financial benefits from a focused quality program utilizing the statisticaltools that have been available for years. The requirement is to provide a motivated team of people with a structuredprocess, an agreed upon set of standards, an expectation of continuous improvement, and then hold them accountable.

August 2005

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