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Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
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OCR for page 27
Appendix B
Automated Assembly Fixture Drilling
The Automated Assembly Fixture Drilling System was conceived as a
way to automate drilling of such large contoured structures as wings
that would otherwise have to be drilled manually. Like other types of
automated assembly tasks it became feasible only when mini-computers
became available that could operate in a shop floor environment. The
system's task is to scan the piece to be drilled, storing the
information in its computer memory, locate and check the bole
coordinates, and then drill and countersink holes in a wing skin and
understructure, or other large component, mounted In a fixture. The
system consists of a CNC drill unit mounted on a vertical gantry
capable of f ive-axis movement, a scanning camera to guide and check the
work, and a modif fed f ixture to accommodate the automated drilling.
Certain conditions related to the technical and market environment
for this system need to be understood as background to the case of
technology transfer. A discussion of these conditions follows.
Technical Conditions
1. Grumman holds a basic patent in Automated Assembly Fixture
Or illing because the only developmental work on the device was funded
by internal R&D money.
2. Much of the drilling in aircraft manufacture (250, 000-400, 000
holes per average fighter, three times as many per average bomber)
could be automated by other means, but existing methods were not
adequate for drilling large contoured places that had to be mounted in
fixtures.
3. The distinctive concept of the Grumman system was its use of a
scanning technique to locate and correct the holes prior to drilling.
The embodiment introduced other equipment features as issues--for
example, the ruggedness and cost of the system as it was configured by
GO unman .
4. The drilling task varies along several dimensions. The needed
accuracy and measurement capability of the equipment depends on such
f actors as wing conf figuration , structure, and whether holes are tb`rough
sk in only or into substructure . The ruggedness of the equipment needed
in terms of force delivered, durability, and reliability depends on the
volume of shipsets assembled and the type of material (e.g. , aluminum
or titanium versus composites) to be drilled.
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5. The main drivers for automating the drilling task have beer
increasingly tighter tolerances, the expense of templates, and the time
and cost involved in manual wor k when pilot drilling and back drilling
are required. Another driver is the need for consistency to reduce the
danger of major scrappage. A human driller becomes progressively less
accurate during an eight-hour shift.
6. Other automated alternatives to Grumman's device bave been
explored in the industry. One has been the location of holes using a
laser beam, locater, or some other form of sensor that can look through
the wing skin at its substructure. Another alternative is a robotic
driller (see below in General Dynamics).
Market Conditions
1. Aircraft manufacturers beve a variety of cooperative
manufacturing arrangements. Contractors act as prime contractors for
some programs and subcontractors for others. Major structural parts
are often subcontracted to other firms. In this case, Grumman was to
have the subcontract, under Rockwell ' s pr ime contract, for the B-1
Bomber horizontal stabili zer .
2. A number of traditional divisions have existed in the industry
that tend to affect relationships among contractors. One is the
traditional identif ication with a particular branch of military
service. General Dynamics has historically worked primarily for the
Air Force whereas Grumman teas historically worked more for the Navy.
These historical relationships do not prevent companies from designing
planes for either service, but the differences in the ways the two
services have dealt with their contractors and the somewhat different
design traditions have some effect on company development and
manufacturing philosophies.
3. Shortages of skilled labor and large f fluctuations in company
workforces between major programs have been driving factors towards
automation of airframe assembly, particularly during the 1970s.
General Dynamics' Fort Worth division, for instance, has fluctuated
between 35,000 workers at the height of the F-lll program and 6,000
workers before the F-16 program began to build up production.
4. Because of the nature of Air Force contracting procedures,
major new capital equipment is rarely purchased by an airframe
manufacturer outside the time when the company is tooling up for a
major new program. Most companies monitor developments in tooling
routinely, but the cost of shifting equipment in the middle of a
program is generally prohibitive.
In 1969 and 1970, the Air Force Materials Laboratory began to call
for proposals for new ways to automate assembly. The Sagamore and
French Lick Conferences both emphasized the Air Force's interest in
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acquisition cost reduction, a shif t from its traditional emphasis on
manufacturing for Estate of the art. performance. Programs that were
seen as appropriate for Air Force funding would, according to
regulations, have to be technically feasible as demonstrated in the
company laboratory, generic (applicable to other Air Force programs
with a clear indication of payback I, and beyond the normal risk of
industry. Programs should promise cost reduction, materials
conservation , or shorter lead times.
An assumption behind the funding that was not necessarily reflected
in specific contracts was that a technology would be reported in such a
way that it could transfer readily. Anyone skilled in the art should
be able to practice. Theoretically, only lead-time and experience
would separate the originator from the adopters. Transfer was
desirable to provide a second source for all forms of manufacture.
Although spreading the new cost reduction concepts was recognized as
valuable, the one sure evidence of successful payback for Air Force
funding would be the physical replication of a system in another
company's manufacturing facility. In most cases, then, the AFML
considers a transfer successful if the embodiment as well as the
concept is transferred.
Both Grumman and General Dynamics took up the AFML challenge to
apply automation to drilling in the early 1970s. General Dynamics
began to pursue the concept in conjunction with its F-16 program, for
which the first prototype was produced in 1974. Grumman was not in the
early stages of a major new program; its F-14 was already too advanced
in 1974. Nevertheless it pursued the concept in anticipation of later
programs. Both companies submitted contract proposals for their
systems as part of the Air Force Manufacturing Methods Program in 1975.
The AFML Manufacturing Technology Group selected Grumman's approach
to fund because it was judged technically superior. Assessors at the
AFML did not believe that General Dynamics' tripod locating approach
was technically feasible. Further, Grumman's proposal to include a
scanning device as part of the system was attractive. Since Grumman
did not itself have a major airplane program coming up to which the new
system could be applied, the ANAL suggested that Grumman should
cooperate with General Dynamics and demonstrate its system on an F-16
part . Grumman thus became the originator of this automated wing
drilling system and General Dynamics became, in the AFML's view, the
designated adopter.
Grumman
Grumman Aerospace had roughly $1. 2 billion in sales in the
mid-1970s, of which all but 3100 million was aerospace business. The
company was attempting to diversify to lessen its dependence on the
volatile defense industries by producing mass transit vehicles and by
subcontracting for commercial aviation houses. Nevertheless it still
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relied on military business, mostly from the Navy. Because it had no
prime contracts for major new weapons systems, Grumman was seeking
major subcontracting business.
Grumman was non-unionized, and it tried to stabilize its work
levels as much as possible to avoid laying off skilled workers and
engineers. Any new process technologies that it might develop were
regarded as potential sources of income and possible opportunities to
gain significant subcontracts on a fluid Pro Duo basis. Upper
management made known its expectation that any other company that
adopted Grumman's technology should be prepared to provide Grumman with
a reasonable return on its investment in one form or another. Such a
return should not only cover Grumman's development cost but also offset
the potential cost and risk to Grumman in transferring its
development. The additional costs of transfer included extraordinary
amounts of documentation and potential legal liability.
Grumman's Advanced Development Group was located in a separate
facility, Plant Twelve on Bethpage, Long Island. Its staff consisted
of a core of 35 permanent employees and a number of others borrowed
from the different divisions that the group served. Advanced
Development had a standing mandate to f ind opportunities in high cost
areas of production, to anticipate production processes needed for
major new programs, and to formulate responses to critical material
shortages if they arise. The automated wing drilling device was
pursued not only because it was expected to offer savings in direct
labor cost, throughput time, and f ixture fabr ~cation, but also because
i t would enable Grumman to drill wings with improved consistency.
Grumman takes pr ide in its reputation for quality and consistency in
i ts production processes. As a result the f irm sought equipment
designed for a high degree of accuracy. Grumman's stated objectives
for the automated assembly wing drilling system were first to reduce
production labor with a minimum of capital investment and, second, to
improve hole quality .
Grumman demonstrated an early prototype version of its device to
representatives from General Dynamics and Fairchild in 1975 before its
contract with the ANAL began in May 1975. The Grumman representatives
indicated their intention to bold the capital equipment cost to
$100,000. They also said that the company planned to charge a royalty
as a 1 icensing fee . A f igure of f ive cents per hole was suggested .
Shortly after the demonstration, Grumman requested drawings of the
F-16 wing from General Dynamics. It received a few documents in
response, but the flow of information soon ceased. When it was clear
to Grumman that General Dynamics did not intend to cooperate further,
the Advanced Development Group shifted to demonstrating the wing
drilling system on Grumman's own A-6 program. The results of their
evaluation on the A-6 part ~ rated at about one shipset per months
showed savings of 40 percent with potential further improvement through
the learning curve effect if a larger volume of components were drilled.
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General Dynamics
General Dynamics was one of the largest defense contractors in tbe
country in the mid-1970s. It" Fort Worth Division bad produced bombers
for the Air Force for a long time. The F-lll had been its first
f ighter program. The F-lll program had encountered such serious cost
overruns that the Fort Worth division had mounted a thorough cost
reduction effort in order to sell its F-16 programe The F-16 was
designed to be smaller, lighter, and simpler than earlier f ighter
designs. Its low cost was partly responsible for its successful sales.
said to be the largest single buy in history. At peak rate, production
would reach 20 shipsets per month, an unusually high volume that
required General Dynamics to rethink its approach to manufacturing in
many areas.
One of the main ways General Dynamics chose to reduce cost was by
reducing direct labor, which had the added advantage of moderating the
workforce fluctuation that the Fort Worth Division had typically
experienced from one airframe program to the next. As a result the
General Dynamics Manufactur ing Technology group was seeking to automate
such labor-intensive operations as wing drilling.
General Dynamics had strained relations with Grumman in the early
1970s because of a bad experience with the F-lll program. In the early
stages of the F-lll the two companies had been partners, with General
Dynamics taking the design lead for the Air Force version, and Grumman
the design lead for the Navy version. Then the Navy had pulled out of
the F-lll program in favor of Grumman ' s F-14 which began in 1968-69,
and relations between the two companies were damaged. When Grumman
showed interest in subcontracting in the composite production area for
the F-16, General Dynamics refused to do business.
General Dynamics' loss of the automated wing drilling contract to
Grumman did nothing to improve its predisposition to cooperate on its
further development, especially when Grumman indicated its intent to
charge a royalty for use of its system in what General Dynamics
interpreted as a violation of the spirit of Air Force sponsorship.
Nevertheless, when Grumman demonstrated its system for the industry in
1976, General Dynamics evaluated the system for use on the F-16.
General Dynamics had already abandoned its own former approach to
automated wing drilling. Grumman continued to request a royalty for
i ts propr ietary interest in the system. The Air Force contract had
funded the f ixture and the software development, but it had not
compensated the company for its prior investment. The AEML left
negotiation of licensing arrangements strictly up to the parties
involved unless and until an impasse was reached.
General Dynamics manufacturing technology personnel who went to
i nvestigate the Gru~Tunan system reported that the equipment had now been
designed for the A-6 and would consequently require considerable
adaptation for use on the F-16. The following problems were cited:
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1) General Dynamics questioned the ruggedness (structural
rigidity) of the Grumman prototype for use on the much higher volume
F-16. The 60 pounds of force that the Grumman drill delivered was also
lower than General Dynamics needed for its wing application.
2) Grumman had tried unsuccessfully to interest Cincinnati
Milacron in building the machine, and General Dynamics was
uncomfortable purchasing for use in production what amounted to nothing
more than a set of drawings, because the system would still be only a
prototype when they had replicated it in Fort Worth. Poor
communications with Grumman only increased the anticipated difficulty
of getting all the necessary information.
3) Because the F-16 had been designed to be easily manufactured,
the Grumman system was designed to be more accurate than was necessary
for the General Dynamics application. Taking into consideration the
original cost of the equipment and the royalty (;ru~Tenan was ask ing, the
General Dynamics evaluation showed that the cost of adopting the
Grumman system would be roughly comparable to the cost of designing and
developing a wing drilling system using a robot. The General Dynamics
organization had been look ing for suitable robotics applications in
which to gain experience, and the wing was such an application. A
robot would be less accurate than the Grumman system but would have the
advantages of lower capital cost and flexibility for use on other tasks.
Taking all these factors into account, General Dynamics rejected
the Grumman system in favor of developing its own robot driller.
Because the economic evaluation was indecisive, the risk caused by the
poor relations between the two companies, as well as the existence of
attractive alternatives, added up to non-adoption of the Grumman
automated assembly fixture drilling system.
Fa irchild (not interviewed ~
When General Dynamics rejected the Grumman system in 1976,
Fairchild, which was also in the early production stages of a new
program, the A-10, agreed to cooperate in evaluating the Grumman
system. Fairchild signed an agreement to lease the system and
indicated its intention to adopt if the economics proved attractive.
Tbe AFRO supported this further demonstration of the system with a new
contract. Tooling had already been completed for the A-10 program, but
it seemed possible that the savings from the Grumman system would be
sufficient to justify the unusual step of changing in mid-program.
Grumman was no longer demanding a royalty for use of its concepts; the
AFML had involved itself in the discussions at the beginning of the
cooperative demonstration program, and licensing terms agreeable to
both parties had been stipulated in the demonstration contract. In
early 1979 Fairchild rejected the Grumman system, saying that the
savings that could be expected two years into the program were not
sufficient to warrant changeover. Timing was clearly the decisive
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factor in the non-adoption since the AEML had funded the reduction of
uncertainty .
McDonnell
McDonnell was approaching the S2 billion mark in revenues from
military aircraft, mostly for Navy use, in the mid-1970s. It was known
as a design house, dominated by engineering and highly conservative in
manufacturing matters. No separate manufacturing technology group
existed at McDonnell to anticipate future production processes. New
equipment was adopted when it constituted a low-risk investment that
promised to pay of f in the short term. McDonnell paid attention to the
reports issued by the AFML concerning new processes. It rarely
competed for development contracts, however, in part because it lacked
a separate manufacturing technology organization to focus on such
matters.
The 1976 Grumman demonstration spurred McDonnell's manufacturing
process engineers to pursue the automated wing drilling concept. Until
the F-18 program, manual drilling had seemed the most economical
approach for wings. But the F-18, McDonnell's first significant
composite airplane, required more tooling than previous planes.
Ordinary numerically controlled equipment would not be adequate for
F-18 wings because the presence of seal grooves on their edges made the
boles harder to locate through simple edge distance measurement.
Grumman's scanning approach seemed to provide the solution to this
unusual measurement problem.
After careful evaluation of the Grumman system for their F-18
application, the McDonnell process engineers chose to develop their own
system. The Grumman equipment fell short of their needs in several
ways. The F-18 wing was a heavier machining task than the A-10,
requiring 80-250 pounds of force delivered instead of Grumman's 60.
Moreover the complexity of the drilling task on the F-18's graphite and
titanium skin was much greater than the aluminum drilling task on the
A-6, requiring many more tool changes. Changing the Grumman tool took
10 to 15 minutes, which posed a serious obstacle to adoption.
McDonnell's device was to be heavier duty, rated for 12 shipsets
per month. As of 1980, the McDonnell device has yet to be adopted in
production, in part because McDonnell teas yet to f ind a machine tool
builder to build it. This is unusual because McDonnell, operator of
the largest numerically controlled machine shop In the Free World,
r arely has trouble ga in ing the attention of mach ine tool compan ies when
it wants something.
Nor throp
Northrop Aviation was one of the smaller military aircraft
producers in the late 1970s. It was traditionally a Navy contractor,
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and in the late 1970s it was planning for its F-18 subcontract under
McDonnell's prime contract. Northrop had a longstanding reputation as
a low-cost producer characterized by innovative manufacturing. Lacking
the organizational resources to do much researob, it followed a policy
of seeking innovative process equipment from a variety of sources and
adapting it for use in airframe production. Upper management
encouraged this receptivity by not insisting on 'strictly abort-term
payback s .
Engineers in the manufacturing process organization at Northrop
became aware of the Grumman device by reading the interim reports of
the A-10 contract. The Grumman scanning approach was attractive to
them for use on the vertical stabilizer. In 1978 they began a
feasibility study on the Grumman system applied to the F-18 component,
assuming a capital cost of S250, 000 for the automated fixture drilling
system. Since they were proposing to do 10 shipsets per month there
were some doubts about the system's structural rigidity, but they
estimated that it would not be too complicated to adapt to their
purposes. They calculated expected savings of about 28 percent,
yielding a modest but acceptable payback period of nearly four years.
Towards the end of the feasibility study, however, Grumman raised the
capital figure to $1.2 million. At that point Northrop rejected the
Grumman system on financial grounds and turned to less expensive
alternatives, such as a laser locater device with a calculated cost of
S15,000. No alternative has yet been adopted because the F-18
stabilizer has undergone some design changes.
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Automated Fixture Drilling Chronology
1969-73 Series of Air Force-sponsored acquisition cost reduction
conferences.
1974
1975
1976
1977
Automated fixture developed at Grumman and first production
panels drilled a year later.
Grumman demonstrates Automated Assembly Fixture Drilling to
General Dynamics and Fairchild.
Grumman performs the Air Force contract evaluating 5-axis
operation on A-6 parts, using the f ixture on the A-6 assembly
line.
Fairchild signs a lease agreement for the Grumman system;
General Dynamics rejects the system and opts for its own
robotics approach .
AEON contract supports application of the Automated Fixture
Drilling System to Fairchild's A-10 stabilizer.
1978-79 Discussions between Northrop and Grumman result in rejection
by Northrop because of increased capital cost.
1979 Fairchild re jects the system and cites timing as sole reason
for re j ect ion .
35
Representative terms from entire chapter:
fixture drilling
