1. The Goal of the Workshop
The purpose of this NIST-initiated workshop was to provide an opportunity for U.S.
discrete-part manufacturing companies which see potential benefit from improved NIST
research and services in areas of interest to them to make needs known such that NIST
can address them, in particular to identify specific needed measurement-and-standards
support from NIST which is not currently being provided or is being provided in forms
or with accuracies insufficient to those needs.
2. The Motivation of the Workshop
When Congress changed the name of this Federal agency from NBS—the National Bureau
of Standards—to NIST, it kept the NBS measurement-and standards function and added
a new, principal mission: to assist U.S. industry to develop and deploy the new technology
it deems it requires to achieve international competitiveness. Pursuing this mandate,
the Director of NIST—who came to NBS from industry—is focusing on support which will
assist U.S. manufacturers to achieve higher quality, lower costs, and increased speed
to market. The Precision Engineering Division further focuses on providing to U.S.
manufacturing industries practical access to national and international standards
of length at levels of accuracy which they need.
The basis for the workshop—that is, its motivation, content, and structure—was the
recent report by the Precision Engineering Division, entitled Challenges to NIST in
Dimensional Metrology: The Impact of Tightening Tolerances in the U.S. Discrete-Part
Manufacturing Industry, which identified a variety of industry needs within its mission
area [1].
This report showed an on-going trend to tighter dimensional tolerances in manufactured
parts with: 1) the dimensions and tolerances of state-of-the-art precision-tolerance
products shown in Fig. 1; 2) the decrease in the size of such tolerances an average
of a factor of three every 10 years shown in Fig. 2; 3) the multiples by which accuracies
of industry’s production control measurements are expected to be better than tolerances
and the multiples by which accuracies of NIST measurements are expected by industry
to be better than those of their production control shown in Table 1; and 4) the lag
of NIST laboratory capabilities behind these changes in industry needs shown in Table
2.
3. The Scope of the Workshop
Manufacturing industries served by this workshop included those with products whose
function, quality, cost and availability depend on parts or part features specified
in terms of length-based tolerances.
Invited industry participants included those from firms in industries such as automotive,
aerospace, farm-and-construction equipment, machine tool, electronics, semiconductor
equipment, computers and instrumentation which have measurement problems associated
with assuring that dimensional features of the product as made conform to those of
the product as designed.
Attendees were company, industry, or agency representatives able to address specifics
of measurement needs in terms of design tolerances, manufacturing deviations, production-control
measurement accuracies, and required reference standards and in the context of their
business or mission goals and needs. Among the 80 industry attendees were representatives
of, for example, AT&T, Boeing, Caterpillar, Cummins Engine, Eastman Kodak, Ford, General
Motors, Hewlett Packard, IBM, Ingersoll Milling, Northrup, Texas Instrument, the machine
tool and gear manufacturers associations, and an array of instrument and gage manufacturers.
A complete list of firms represented at the workshop is shown in Appendix A.
4. The Structure of the Workshop
The 2 day workshop included plenary and parallel working sessions organized to address
the range of industries, measurement technologies and problems suggested by the “Challenges”
report which defined the three tolerance regimes shown in Table 3.
Following welcoming remarks by Dr. John W. Lyons, Director of NIST, were three theme-setting
presentations by representatives of Boeing commercial aircraft company (illustrating
issues of close-tolerance manufacturing of large-scale discrete-parts in the aerospace
industry), Cummins Engine company (illustrating issues of the close-tolerance manufacturing
of medium-scale discrete-parts in the automotive industry), and IBM (illustrating
issues of close-tolerance manufacturing of small-scale discrete-parts in the advanced
microelectronics industry). Similar plenary-session presentations on the metrological
issues in discrete-part manufacturing in their lines of business were made by representatives
of 11 other firms.
During the course of the workshop, participants received briefings on NIST laboratory
capabilities, the research and services it provides, and the new means by which it
aims to support domestic manufacturing industries, including: Cooperative Research
and Development Agreements (CRDAs), under which NIST can work jointly with industry
on problems of mutual interest; Regional Manufacturing Technology Centers, the system
of technology-transfer centers being funded and administered by NIST; and the Advanced
Technology Program (ATP), the new grants program to help high-tech companies or consortia
of companies improve their competitiveness. Attendees were also asked what effect
on their operations NIST’s proposed adoption of the BIPM-recommended means of expressing
measurement uncertainty would have (Appendix B).
Individual firm’s needs were presented to NIST in the form of worksheets. For developing
common points of view on industry needs, attendees self-selected into one or more
of five working groups topically devoted to:
Larger-Scale Parts, Coordinate Measuring Machines and Theodolites;
Complex-Shape Parts, Including Gears and Screw Threads;
Medium-Sized Parts, Including Small-Bore Features (such as microwave airlines);
Figure/Finish, Including Diamond Machining; and
Ultrasmail Features, Microelectronic Lithographies, and Scanning-Probe Microscopies.
5. Specific Working-Group Recommendations
The following is a summary of the industry needs and desired NIST actions related
to those needs which the working groups produced and industry spokespersons presented
in plenary sessions.
5.1 Working Group on Larger-Scale Features
This working group included a large contingent of users of coordinate measuring machines
and their summary-report statement of needs consisted of: 1) improved NIST calibration
accuracy, especially of meter-size standards, with a base calibration by NIST or DoE;
2) standards-committee support by NIST, especially ISO, where NIST should lead the
U.S. delegation; 3) development of a long-term strategy to learn the accuracy achieved
on real workpieces on 3D coordinate measuring systems; 4) for probing, provision of
application documents on performance characterization and calibration methodology,
covering also thermal properties and especially long-stylus properties; and 5) calibrations
of thermal-expansion coefficients of CMM calibration artifacts to accuracies of one
to three percent. For emphasis, this group concluded its presentation of needs by
reading a letter from a Vice President of the Caterpillar Company to NIST, quoted
in the “Challenges” report, saying:
“Five years ago our company embarked on a major factory modernization program with
the purpose of maintaining, if not increasing the competitive edge that has historically
been ours. A vital component of our overall program was modernization of our metrological
equipment. Central to the metrology upgrade was increased use of coordinate measuring
machines (CMMs) on our factory floor. Obtaining length standards of adequate accuracy,
certified by NIST, for use in certification and ongoing verification of our new CMMs
is a problem of ongoing concern. For the past three years we have been unable to obtain
certification of step gages from NIST… Our current solution is to use PTB (German
Standards Bureau) for certification of step gages … The current situation is unacceptable.
We cannot afford the cost and time of continuing to send reference artifacts to Europe
for certification. For both competitive and strategic reasons, we must have a metrologically
strong partner at NIST…”
5.2 Working Group on Complex-Shape Parts
This working group included a large contingent of manufacturers of gears and gear-measuring
equipment and their summary-report statement of needs consisted of: 1) establishing
a calibration service for gear involute/lead masters for which none now exists, potentially
including a round-robin measurement exercise coordinated by NIST; 2) publishing a
report addressing the propagation of uncertainties down through the “hierarchies”
of measurement/calibration processes; 3) doing something about the problem that “calibration”
is a vague term with different meanings in different applications; 4) conducting round-robins,
correlating data, and working with industry in developing measurement techniques because
methods are needed to correlate measurement techniques for complex shapes; 5) with
small manufacturers needing certification of outside measurement services, address
the accreditation of organizations providing measurements of complex shape; and 6)
step up research, including cooperative research with industry, in the area of on-line
measurement techniques for processes producing parts of complex shape.
5.3 Working Group on Mid-Scale Features
This working group included representatives of a number of companies and groups within
a single company who indicated measurement issues for part and feature sizes “below
what can be reliably measured on a CMM,” a region which they showed graphically by
amending Fig. 1, originally of the NIST “Challenges” report, to produce Fig. 3. The
figure so presented illustrates three points: 1) state-of-the-art tolerances for manufacturing
processes used by Hewlett-Packard Santa Rosa — from sheet-metal radio-frequency enclosures
through diamond-turned microwave parts to e-beam and molecular-beam-epitaxy fabricated
features — agree with those shown in the NIST “Challenges” report; 2) there is a region
of industrial demand below that delivered by coordinate measuring machines and above
that achieved in research; and 3) the trend of this industry’s needs lies in this
region which is bounded by dimensions from sub-millimeter to above one meter and tolerances
from about 20–50 nm to about 2 μm.
A summary of 18 specific types of artifact standards needed to support unique or non-general
purpose measurement solutions for particular types and sizes of manufactured part
features which was presented is shown as Table 4. In addition to those artifact standards,
this working group also indicated industry need for educational/training information
from NIST, including NIST-lead development of industry-useable calibration procedures,
for precision-tolerance applications when production tolerances are less than 16 times
NIST capabilities, i.e., measurement accuracies, including better documentation of
NIST procedures.
5.4 Working Group on Figure/Finish
This working group included representatives of manufacturing companies with principal
interests in characterization of surface roughness, surface figure (e.g., curvature
of aspherical forms), and specialized production processes associated with them, such
as single-point diamond machining and ductile regime grinding.
In the area of surface finish, the major concerns were that NIST should: 1) send NIST
technical staff to participate in development of international (ISO) and national
(ANSI) documentary standards dealing with surface roughness; 2) develop a set of artifacts
and standard protocols for instrument evaluation, for example, sinsuoidals with spatial
wavelengths from 200 mm on down and “realistic” (e.g., quasi-random) surfaces; 3)
provide standard data sets for software evaluation; and develop better step-height
standards. A specific surface-finish standard needed is one with standard data sets
for known sinusoidal, triangular, and square-wave forms (for instrument adjustment)
plus a random wave form with an RMS roughness of less than 10 nm (for instrument correlation).
In the area of figure, the present NIST program should be encouraged, with its good
approach of progressing from successively developing state-of-the-art capabilities
to measure first flat, then sphere, then asphere forms. In the area of ductile regime
grinding, NIST needs to develop the means for measurement of sub-surface damage, including
determination of the transfer function between instruments, and developing definitions
and standard tests, all supported by educational services including tutorials and
giving of hands-on experience.
5.5 Working Group on Ultrasmall-Scale Features
This working group included representatives of manufacturing firms that either use
or produce scanning-probe-microscope instruments for the characterization of ultrasmall
features of discrete-part manufactured goods such as nanoelectronic devices. The principal
needs from NIST identified were those for: 1) Standard Reference Materials—with certification
of sub-micrometer artifacts in all the dimensions (2D plus height) and 2D in distance
(with field characterization and pattern placement); 2) Technology Development — especially
STM probe tip development, which is a key enabling technology for small high-tech
companies facing heavy foreign competition but having difficulty getting support from
the NIST Advanced Technology Program; and 3) Road Maps—with a 5 year plan from NIST
in response to the workshop’s requests, indicating what is feasible and how it will
conform to other roadmaps in industry, e.g., Sematech.
6. Principal Findings of the Workshop
The principal recurring theme of needs, broadly shared among the industry representatives
— whether from commercial aircraft, heavy equipment, automobiles, engines, computers,
instrumentation or microelectronics was an urgent request that NIST provide new or
improved accuracy physical artifact dimensional standards applicable to industry specific
needs, including those for coordinate measuring machines, involute gears, small bore
microwave devices, x ray optical surfaces and nanometer scale microelectronics.
The most frequently stated basis of the need of companies for more high-accuracy artifact
standards from NIST is the “new traceability” required to meet ISO-9000-type quality
requirements for products to be sold both in the European Economic Community and Pacific-rim
nations. The next most frequently stated basis is the need for fixed reference points
to support development of innovative products being strongly competed by Japan.
Finally, the sense of the closing plenary session was that this group of representatives
of U.S. discrete-part manufacturing urged NIST to immediately respond to these stated
needs for higher-accuracy artifact standards across the range of applications indicated
in this workshop, including developing a documented operational plan spelling out
how over the next few years it will do so.