“You must first design quality-in.” In this, the great quality pundits admitted that their quality management theories were based on the premise that the engineering requirements exhibited on drawings were assumed to be valid data for statistical use. Yet, neither the pundits nor any contemporary intellection on quality assurance covered the subject of design quality as part of a quality assurance “system.”
The great ones’ contributions in adding statistics into the qualification processes were enormous but they were not design engineers. And they, unfortunately, had no idea of the magnitude of deficiencies within our nation’s design engineering departments. It makes no sense to inspect parts to the requirements of engineering drawings that are basically bad. And then, to compound the folly, perform statistical process control or even Six Sigma methodologies.
How can quality be truly ensured if their statistical data is not likewise ensured to be based on good engineering drawings? Assumptions are not sufficient in design any more than in manufacturing. Hold design engineers accountable to a design inspection much in the same way as manufacturers are held accountable to a mechanical inspection.
This article is intended to complete the intellections on contemporary quality management by bringing design into the quality assurance system. For, unless design is included somewhere in the quality process, true quality assurance will be unattainable.
The Two CrisesIn 1986, Dr. W. Edwards Deming authored the book, “Out of the Crisis,” wherein he offered his contributions to the solving of America’s quality dilemma. He established the core concept for implementing Total Quality Management (TQM) through his 14 key principles or set of managerial practices to help companies increase their quality and productivity.
But while this book was being recognized by such notables as Secretary of Defense Caspar Weinberger, as the panacea to our nation’s competitive problems, another crisis raised its ugly head.
In October 1987, representing the National Standards Educators Association, I presented a paper to the ASQC Western Regional Conference in Sacramento. Entitled, “The Metrology Crisis,” it exposed a deficiency deep within our American industrial complex that was not recognized by management, the military customer or the great quality pundits. Virtually our nation’s entire industrial complex did not know how to control the shape of their manufactured parts-this was the crisis.
The resulting impact of this revelation was augmented a hundredfold the following August with a Government Industry Data Exchange Program (GIDEP) alert issued out of a Westinghouse facility in Sunnyvale, CA. It reported, “Certain algorithms that on many coordinate measuring machines (CMMs) are advertised as measuring according to ANSI Y14.5 are calculated incorrectly.“
The combination of the metrology crisis and this GIDEP alert sent shock waves throughout the government, military and industrial sectors of our nation. These events led to a review and revamping of all ASME measurement standards. It would take seven years to develop the technology to solve the metrology crisis.
In 1988, a new subcommittee, ASME Y14.5.1, was formed to create the algorithms for measurements. That same year another new subcommittee, ASME Y14.5.2, was formed to create a two-tiered certification program on ASME Y14.5 named Geometric Dimensioning and Tolerancing Professional (GDTP). The first tier is the technologist level and is aimed primarily at the drawing reader. The second tier is the senior level and is aimed primarily at the designer.
Necessity of Geometric DimensioningConventions, designed to deliver industry from its dimensional metrological morasses experienced during World War II with the terrible weapons failures that threatened to turn the tide of the war, began to be developed immediately following the war and subsequently established as standards.
These practices are embodied today within the American National Standards Institute (ANSI) B46, B89 and Y14 series of standards, sponsored and written by our nation’s largest accredited standards making body, the American Society of Mechanical Engineers (ASME). The root of these conventions is established in ASME Y14.5.
Why is this standard essential to the proper dimensioning and tolerancing of mechanical hardware?
First, it defines the orientation of the part for measurement. It must be understood that when a part is improperly oriented for measurement, the nominal dimension is wrong. The elimination of variation cannot correct this. The quality pundits were not aware of this.
Second, it defines all lines associated with the measurement. For example, center lines do not exist on parts. The standard offers conventions that can define the meaning of those lines.
Third, it totally defines the shape of the part. This standard is the only criterion that addresses all of the means necessary for an engineer to control the fit, function and economy of his designed hardware, including:
Profile tolerancing for controlling irregular shapes
Virtual condition for controlling a maximum interface envelope
Bonus tolerances for reducing the cost of manufacture
The Taylor Principle for reducing the cost of gaging
Free-state variation for controlling the shape of non-rigid parts
Projected tolerance zones for controlling the exposed portions of press-fitted pins.
The use of these and a multitude of other conventions enable an engineer to design a part within true worst case conditions, thereby assuring that any part manufactured to his documentation cannot possibly fail as the result of its geometric form. Without these conventions, no such assurances are possible.
Intent & Assessment of the Metrology CrisisThe chief deficiency in today’s design engineering rooms lies in the fact that many of those who manage them lack the fundamental skills and knowledge of the standards of their trade. They do not understand the language of drawings and they lack the high degree of geometric perception necessary to control the dimensional requirements of sophisticated mechanical hardware. Because of these shortfalls, they turned design departments into towers of Babel.
Before the trade agreements took effect, the Department of Defense required document checkers on most military programs. It was expected that they would require GDTP oversight not just for design, but also for manufacturing and inspection operations particularly for those involving critical, complex hardware.
Government policies changed this outlook in that once the tariff structures broke down, they removed such requirements in order to reduce costs. This was because we were now competing with countries whose wages were considerably less than ours for the same work. Thus the trade agreements turned many of our companies into sweat shops.
Life in American industry lost much of its joy as people worried about their jobs.
The Y14.5 certification program became a hard sell because of the costs and burden of training and effectively implementing the changes necessary in design, manufacturing, and quality assurance. In short, the revelation of the metrology crisis and the Y14.5 certification program came at a bad time in our nation’s economic history arguably perhaps as a result of bad trade agreements.
Document Integrity AssuranceA concept I called Design Quality Management (DQM) was first introduced in my paper, “The Addendum,” in April 2010, to an ASQ conference in New Jersey. Raytheon SAS division in El Segundo, CA, a major defense plant at which I am employed, has essentially adopted this idea under their title of Document Integrity Assurance. Its primary purpose, as in DQM, is to integrate design in some manner into their quality assurance system.
In essence the only products generated by an engineering department are documents. Document quality traditionally has been the responsibility of check departments, while the Engineering Drawing and Related Documentation Practices standards for document quality was and continues to be the responsibility of the ASME Y14 standards committees. Thus, design quality should be centered about the check function and the ASME Y14 standards. Included could be the corporation’s in-house design and drafting manuals and standards provided they are free of error. Some of our nation’s corporate in-house measurement standards are flawed.
The concept I proposed included many of the following action items, some of which were already in effect when I joined the organization in 2008:
The return of the check departments and perhaps renaming the Check Department to Product Integrity Center, which ensures design quality. It’s not about checking.
The technical certification of checkers based on the standards common to their work. The renaming of checkers also may be considered to better reflect their true function, such as design check engineers.
Moving the design check function into a new directorate for the purpose of avoiding conflicts of interest.
The creation of a crack dimensional metrology unit staffed with various SMEs and certified GDTPs for planning complex dimensioning schemes, performing complex tolerance checks and worst-case analysis of critical components and assemblies.
The creation of a more effective multi-tiered training program for certifying designers, checkers, producibility and manufacturing engineers, and inspectors for their knowledge in the ASME Y14.5 standard. There is too much content in conventional training materials to recall much, if any, in a mere one-week course.
The creation of a training program for selected individuals in preparation for the ASME GDTP exams for national certification in the Y14.5 standard.
The creation of a training program for certifying designers and checkers for their knowledge of the ASME Y14.100 standard and its ancillary standards.
Heart of the MatterThe significance of “The Metrology Crisis” report was underscored in a letter days after my presentation by the moderator of that Western Regional Conference session whereat I first addressed it in 1987. In it, William L. Newman, stated: “The Metrology Crisis, like so many factors in the current economy, is so enormous in its implication that it is much easier on the short term to simply duck it. In my work in creating quality management systems, it is at the heart of the matter of effective process control.”
This article on document integrity assurance shares a theory of management for American industry intended to confront again the quality community with a 24-year-old issue and to fill-in the missing link in contemporary quality assurance. If its concepts are implemented and proven effective, they will surly qualify someday to be admitted into the family of organizational functions associated with total quality management.Q
Tech TipsWhy is ASME Y14.5 essential to the proper dimensioning and tolerancing of mechanical hardware?
It defines the orientation of the part for measurement.
It defines all lines associated with the measurement.
It totally defines the shape of the part.
Geometric Characteristic SymbolsCharacteristic Symbol
Profile of line k
Profile of surface d
Circular runout h
Total runout t
Maximum material condition m
Least material condition l
Projected tolerance zone p
Report Abusive Comment