This document discusses how mass finishing processes can be used to process large aircraft components and aircraft engine parts. It describes how vibratory finishing and centrifugal barrel finishing are being used to deburr and surface finish large complex parts more efficiently than manual methods. Mass finishing produces uniform, consistent edges and surfaces and can impart beneficial compressive stresses that improve part performance and fatigue life. The document provides examples of how processes like vibratory finishing and turbo-abrasive machining have been used to finish large aircraft turbine disks and blades. It also discusses research showing how vibratory deburring and burnishing can enhance fatigue resistance comparable to conventional peening while maintaining a smoother surface finish.

1. Mass Media Finishing Large Aircraft
and Aircraft Engine Components
David A. Davidson
ddavidson@deburringsolutions.com
Chair: [DESC] Deburring, Edge
Finish, Surface Conditioning
Technical Group
SOCIETY OF
MANUFACTURING ENGINEERS
Mass finishing processes have long
been widely adopted throughout
industry as a preferred method for
producing advanced edge and surface
finish effects on many types of
machined and fabricated components.
American industry has long been in
the forefront in aggressively
deploying these methods to improve
Figure 1 -- This large aluminum component shown in the composite photo above their edge and surface finishing
was previously deburred with hand tools. Implementing a vibratory finishing operations. In his Deburring and
processes with a tub shaped chamber reduced processing time from hours to Edge Finishing Handbook, (1999
minutes, and reduced direct manual deburring labor to nil. More importantly,
surface finish and edge contour effects have been produced on all critical areas of
edition) Laroux Gillespie developed a
the part with a part and feature consistency and uniformity not possible with comparative table which pointed out
manually directed or single point of contact abrasive methods. PHOTO courtesy that in some mechanical finishing
Robert M. Kramer, KRAMER INDUSTRIES. equipment categories such as rotary
barrels, vibratory finishing and centrifugal
barrel finishing equipment American industry
leads the world in terms of the number of
equipment installations. Despite this, all too
often, situations still exist where archaic, even
primitive hand or manual finishing methods
are used to produce edge and surface finishing
effects. This is not to say that some industrial
part applications are not going to require a
manual deburring approach – some do. In
many cases, however, hand or manual
methods are still being utilized because more
automated or mechanized methods have not
been considered or adequately investigated.
Commenting on an often observed dichotomy
in precision manufacturing operations,
Figure 2 - This large aircraft engine turbine disk has been processed Rodney Grover of the Society of
with the Turbo-Finish method. This dry abrasive finishing method has Manufacturing Engineers in essay entitled
been successful in bringing mass media finish economies to large “Boeing Issues an Invitation” referenced a
complex rotationally oriented parts. In addition to the uniform and situation that is still all too common. That is
consistent edge contours developed, the method also produces highly
that many manufacturers, after spending vast
sophisticated isotropic surface finishes by radically altering the
character of the as- machined or as-ground surface finish. PHOTO sums on CNC machining equipment to
courtesy Dr. Michael L. Massarsky, Turbo-Finish Corporation

2. produce parts to very precise tolerances and specifications consistently, in the end, hand off these expensive
parts to a deburring and finishing department that utilizes hand methods, with all the inconsistency, non-
uniformity, rework and worker injury potential that implies. Even when manual methods cannot be completely
eliminated, mass media finish techniques can
and should be used to produce an edge and
surface finish continuity that simply cannot be
duplicated with manual or single-point-of-
contact methods. Developing an overall edge
and surface finish continuity and equilibrium
can have an significant effect on the
performance and service life of critical
components as well.
In the past, mass finishing methods have been
thought to be limited to uniformly processing
large numbers of small to moderately sized
Figure 3 - These titanium test coupons show a before and after example components to precise edge and surface finish
of mass finishing processes being used to blend in milling cutter paths. specifications. Increasingly, this type of
Transforming the positively skewed surface profiles of machined parts processing is being investigated by
into parts with isotropic and negatively skewed surface characteristics manufacturers of large and very large
can be an important element in any program where surface
improvements are being developed to improve wear resistance and components to drive down the high costs
metal fatigue resistance on critical parts. associated with utilizing hand tools or hand-
held power tools to abrasively modify part edges and
surfaces. Machinery capable of processing very large
components can now be built. Equipment with chamber
capacities as large as 200 cubic feet have been designed to
accommodate individual parts. In some cases the parts are
fixtured within the processing chamber to amplify
processing effects on specified areas or prevent edge damage
on extremely heavy parts. In other cases or circumstances,
parts are suspended in the media mass for more equalized
surfacing and stress equilibrium effects.
Complex rotating parts such as power generation turbine
disks as large as four feet in diameter have been edge-
contoured and surface conditioned with spindle-fixtured
processes such as the Turbo-Finish method.
Figure 4 - This shafted gear utilized in helicopter Mass media finishing processes have gained widespread
turbine applications has been processed in centrifugalacceptance in many industries primarily as a technology for
barrel finishing equipment to produce very specific reducing the costs of producing edge and surface finishes.
isotropic finishes with very high load bearing ratios to
This is particularly true when manual deburring and
improve gear tooth life and overall performance
finishing procedures can be minimized or eliminated. Many
efficiency.
manufacturers have discovered that as mass finishing
processes have been adopted, put into service, and the parts involved have developed a working track record, an
unanticipated development has taken place. Their parts are better—and not just in the sense that they no longer
have burrs, sharp edges or that they have smoother surfaces. Depending on the application: they last longer in
service, are less prone to metal fatigue failure, exhibit better tribological properties (translation: less friction and
better wear resistance) and from a quality assurance perspective are much more predictably consistent and
uniform. The question that comes up is why do commonly used mass media finishing techniques produce this
effect? There are several reasons. The methods typically are non-selective in nature. Edge and surface features
of the part are processed identically and simultaneously. These methods also produce isotropic surfaces with

3. negative or neutral surface profile skews.
Additionally, they consistently develop
beneficial compressive stress
equilibriums. These alterations in
surface characteristics often improve part
performance, service life and
functionality in ways not clearly
understood when the processes were
adopted. In many applications, the
uniformity and equilibrium of the edge
and surface effects obtained have
produced quality and performance
advantages for critical parts that can far
Figure 5 -- Centrifugal barrel machines such as these can produce outweigh the substantial cost-reduction
exceptional edge and surface finishes in very short cycle times. Accelerated benefits that were the driving force
process effects can be developed because of the high speed interaction behind the initial process
between abrasive media and part surfaces, and because media interaction with
parts are characterized by high pressure by virtue of the high centrifugal implementation.
forces developed in the processes. Smaller turbine blades can be processed in
the 5 x 8 inch compartments in the 12-liter capacity machine shown to the This assertion has been affirmed by both
right. Larger centrifugal machines such as the 220 liter or 330 liter capacity practical production experience and
machine shown to the left can handle much larger parts as the barrel validation by experiment in laboratory
compartments are as much as 42 inches in length. Larger parts processed in
this type of machinery can be processed one at a time within the barrel settings. David Gane and his colleagues
compartment suspended within the media mass or be fixtured. Barrel at Boeing have been studying the effects
compartments can be divided into processing segments to accommodate more of using a combination of fixtured-part
than one part. vibratory deburring and vibratory
burnishing (referred to by them as
“Vibro-peening” or “Vibro-strengthening”)
processes to produce (1) sophisticated edge and
surface finish values and (2) beneficial
compressive stress to enhance metal fatigue
resistance. In life cycle fatigue testing on
titanium test coupons it was determined that the
vibro-deburring/burnishing method produced
metal fatigue resistance that was comparable to
high intensity peening that measured 17A with
Almen strip measurements. The striking
difference between the two methods however, is
that the vibratory burnishing method produced
the effect while retaining an overall surface
roughness average of 1 µm (Ra), while surface
finish values on the test coupon that had been
processed with the 17A high intensity peening
had climbed to values between 5-7 µm (Ra).
Figure 6 - This large power generation turbine blade was made
The conclusion the authors reached in the study
utilizing 6-axis machining technology. Centrifugal barrel finishing was that the practicality and economic
technology was used to clear and blend in the milling cutter paths and feasibility of the vibro-deburring and burnishing
then develop very refined and burnished isotropic surfaces in the foil method increased with part size and complexity.
area.

4. Dr. Michael
Massarsky of
the Turbo-
Finish
Corporation
was able to
supply
comparative
measurements
on parts
processed by
his method for
edge and
surface finish
improvement.
Utilizing this
spindle
oriented
deburr and
finish method
it is possible to
produce
compressive
stresses in the
Figure 7 - Mass finishing methods are usually thought of in terms of facilitating the surface finishing of large numbers of
MPa = 300 -
smaller parts. As can be seen from this illustration, very large structural components such as this titanium airframe 600 range that
bulkhead can be processed also. When coupled with both fixtured and sequential finish techniques these kinds of formed to a
processes can not only be used to replace costly manual deburr operations, but also produce significant compressive
stress and work-hardening effects that can dramatically increase metal fatigue resistance properties. Studies have shown
surface layer
that as part size grows, the more economical and practical vibratory deburring and vibratory peening/burnishing of metal to a
processes become as potential replacements for hand deburring and conventional shot peening process combinations. depth of 20 -
Photo courtesy of Giant Finishing, Inc. 40 µm. Spin
pit tests on
turbine disk components processed with the method showed an improved cycle life of 13090 ± 450 cycles when
compared to the test results for conventionally hand deburred disks of 5685 ± 335 cycles, a potential service life
increase of 2 – 2.25 times, while reducing the dispersion range of cycles at which actual failure occurred.
Vibratory tests on steel test coupons were also performed to determine improvements in metal fatigue
resistance. The plate specimens were tested with vibratory amplitude of 0.52 mm, and load stress of 90 MPa.
The destruction of specimens that had surface finishes developed by the Turbo-Finish method took place after:
(3 - 3.75)*104 cycles
a significant improvement over tests performed on conventionally ground plates that started to fail after:
(1.1 - 1.5)*104 cycles.
In his Deburring and Edge-Finishing Handbook, Gillespie makes a very astute observation: “Typical burrs are
not the result of poor planning or poor engineering. They are a natural result of machining and blanking
processes. Large burrs, however, may be the result of poor planning.” A similar axiom could be said to exist
regarding surface finishes. “Rough, non-isotropic surface finishes with undesirable stress conditions are not
the result of poor planning or poor engineering. They are a natural result of almost all common machining,

5. grinding, fabrication and abrasive methods. These results can be exacerbated by abusive machining and
grinding, and improved or reversed with mass media finishing techniques.”
Mass media finishing techniques improve part performance and service life, and these processes can be tailored
or modified to amplify this effect. Although the ability of these processes to drive down deburring and surface
finishing costs when compared to manual procedures is well known and documented, their ability to
dramatically effect part performance and service life are not. This facet of edge and surface finishing deserves
closer scrutiny. This is also true with larger and more complex parts – only more so. ?
REFERENCES:
(1) Gane, David H., Rumyantsev, H.T., Diep, Bakow, L. "Evaluation of Vibrostrengthening for Fatigue
Enhancement of Titanium Structural Components on Commercial Aircraft". Ti-2003 Science and Technology;
Proceedings of the 10th World Conference on Titanium, Hamburg Germany, 13-18 July 2003, Edited by G.
Lutejering and J Albrecht.WILEY-VCH Vol 2. pp 1053-1058
(2) Massarsky, M. L., Davidson, D. A., “Turbo-Abrasive Machining, CODEF PROCEEDINGS, 7th International
Deburring Conference, Berkeley, CA.: CODEF [Consortium on Deburring and Edge Finishing], University of
California at Berkeley, June 2004
(3) Massarsky, M. L., Davidson, D. A.., “Turbo-Abrasive Machining - A New Technology for Metal and Non-
Metal Part Finishing”, THE FINISHING LINE, Vol. 18 No. 4, Dearborn MI: Association of Finishing Processes,
Society of Manufacturing Engineers, Oct. 30, 2002
(4) Massarsky, M. L., Davidson, D. A., “Turbo-Abrasive Machining and Turbo-Polishing in the Continuous Flow
Manufacturing Environment”, SME Technical Paper MR99-264, CONFERENCE PROCEEDINGS: 3rd
International Machining and Grinding Conference, Cincinnati, OH, Oct 4-7, 1999, Dearborn, MI: Society of
Manufacturing Engineers, 1999
(5) Gillespie, LaRoux, Deburring and Edge Finishing Handbook, Dearborn, MI: Society of Manufacturing Engineers,
1999
(6) Davidson, D. A., “Mass Finishing Processes”, 2002 METAL FINISHIING GUIDE BOOK AND DIRECTORY,
White Plains, NY: Elsevier Science, 2002
(7) Davidson, D. A., “Micro-Finishing and Surface Textures”, METAL FINISHING”, (White Plains, NY: Elseveir)
July, 2002
(8) Massarsky, M. L., Davidson, D. A., “Turbo-Abrasive Machining and Turbo-Polishing in the Continuous Flow
Manufacturing Environment”, SME Technical Paper MR99-264, CONFERENCE PROCEEDINGS: 3rd
International Machining and Grinding Conference, Cincinnati, OH, Oct 4-7, 1999, Dearborn, MI: Society of
Manufacturing Engineers, 1999
(9) Rossman, Edward F., [Boeing], “Collected Thoughts On High Speed Machining Of Titanium” SME
Technical Paper, Dearborn MI: Society of Manufacturing Engineers, 2004
(10) Grover, Rodney, “Boeing Issues an Invitation” Dearborn, MI: Society of Manufacturing Engineers, 2004,
http://www.sme.org
ACKNOWLEDGEMENTS: The author wishes to acknowledge the technical assistance of the following
members of the newly formed Society of Manufacturing Engineers DESC Technical Group [Deburring, Edge-
Finish, Surface Conditioning]. Dr. Michael Massarsky, Turbo-Finish Corporation; David H. Gane, Boeing;
Edward F. Rossman Ph. D., Boeing; Jack Clark, ZYGO Corporation; LaRoux Gillespie, PE, CmfgE,
Honeywell. Rodney Grover, Society of Manufacturing Engineers. Many of these colleagues will be present at a

6. technical session concerning deburring and surface finishing methods for aircraft frame components sponsored
by the Society of Manufacturing Engineers at WESTEC, April 6, 2005 in Los Angeles, California
FURTHER READING: Aircraft Related Deburring Technical Papers/Articles – does not include aircraft engine
component parts
Taken from: Deburring a 70-Year Bibliography, edited by LaRoux K. Gillespie and Elena Repnikova, Deburring Technology
International, Kansas City, MO, 2001.
1. Linsley, H. E., “High Production Requires Ingenious Methods of Deburring Aircraft Sheets,” American Machinist,
Vol. 95, June 25, 1951, pp. 99-101. (Inclined tables combines with drum sanders deburr sheet metal cutouts. Steel wool and
beeswax on high speed spindle provide finish required. Hand deburring equipment is also shown. On some sheets burrs are rolled
over rather than removed.)
2. Anonymous, “Tumbling Big Parts Speeds Finishing,” Iron Age, Vol. 180, Aug. 1, 1957, pp. 118-119. (Barrel tumbling
unit is 6 feet long and 4 feet in diameter. This is used to deburr and finish aircraft shroud rigs.)
3. Furgeson, Ray, and John H. Eggum, “Vapor Blasting Deburrs and Blends Machined Surfaces,” Machinery, Vol. 63,
July 1957, pp. 180-183.
4. Woolf, James E., Electrochemical Deburring of Molybdenum, Aluminum, and Stainless Steel (rev. ed.), McDonnell
Aircraft Corp. report N A478, 1964 (available from NTIS under accession number AD 431602) (ref. R.Z.M., 1966,
5b231K). (This report presents the results of a study using several electropolish solutions for deburring and edge radiusing. The
initial burr was produced by chemical machining and chemical milling. This «burr» was actually more of a sharp edge than a
burr. Electrogleam 55 produced a 0.002 — 0.006 inch edge radius, but a 25% by weight solution of nitric acid produced a more
uniform edge leveling in molybdenum. Electrogleam BS was the most effective solution used on 321 stainless steel.)
5. Anonymous, “Automatic Vibratory Finishing System for Aircraft Stringers Finishes High Costs, Tool” Production,
July 1966, pp. 101-102. (Aircraft stringers, 8 feet long, are vibratory deburred in special equipment.)
6. Anonymous, “New Deburring Machines Cut Costs on Aircraft Parts,” Western Machinery & Steel World, April, 1967.
(Spindle finishing and vibratory units deburr aircraft parts. Control of radii can be maintained within 0.0001 inch.)
7. Anonymous, “Long Machine Ready for Shakedown,” Iron Age, Dec. 19, 1968, Vol. 202, p. 63. (Wing spars 14 ft. log are
vibratory deburred by Roto—Finish equipment)
8. Hurst, Tommy, “Vibratory Deburring 24 Foot Wing Spars,” Industrial Finishing, April 1970, pp. 38-41. (Wing spans, 24
ft. long, are vibratory deburred).
9. Fleming, C. M., Precision Hole Generation Methods, McDonnell Aircraft Co., Technical Report AFML-TR-73-135,
Volumes I and II, March, 1973. (An evaluation of drill and reamer geometry on hole quality. Burr height could not be corrected
to hole quality or wearland at the drill or reamer corners. A drill with dubbed corners performed better than other drills).
10. Phillips, Joseph L., “Multi-Layer Fastener Systems,” Boeing Commercial Airplane Company, Report IR-752-4(I), July,
1974.
11. Phillips, Joseph L., Multi-Layer Fastener Systems, Boeing Commercial Airplane Company Report IR-752-4(II),
October, 1974.
12. Phillips, Joseph L., “Sleeve Coldworking Fastener Holes,” Volumes I and II, Boeing Commercial Airplane Company
Report AFML-TR-74-10, February, 1974.
13. Phillips, Joseph L., Multi-Layer Fastener Systems, Boeing Commercial Airplane Company Report IR-752-4(III),
January, 1975.
14. Phllips, Joseph L., Multi-Layer Fastener Systems, Interim Report IR-752-4 (IV), Boeing Commercial Airplane
Company, Seattle, Washington, April, 1975.
15. Phllips, Joseph L., Multi-Layer Fastener Systems, Interim Report IR-752-4 (V), Boeing Commercial Airplane
Company, Seattle, Washngton, July, 1975.
16. Phllips, Joseph L., Multi-Layer Fastener Systems, Interim Report, IR-752-4 (VI), Boeing Commercial Airplane
Company, Seattle, Washington, September, 1975.
17. Phillips, Joseph L., Multi-Layer Fastener Systems, Final Report, AFML TR-76-76, Vol. I, II, III and IV, June 1976
(Boeing Commercial Airplane Company).
18. Anonymous, “New Record for ROI,” Finishing Highlights, September/ October, 1975, p. 32 (Vibratory deburring unit
is 45 feet long. Wing spars are deburred by Boeing at a savings of $100,000 a year. It can produce edge radii up to
0.030 inch.)
19. Anonymous, Advanced Multilayer Drilling, Rockwell International Los Angeles Division Report AFML-TR-77-124,
Part I, published July, 1977, for Air Force Materials Laboratory.
20. Kerr, Gordon, Phase I Report - AIAC Deburring Program, Canadair Limited, Report #RAM-000-121, Montreal,
Canada, April, 1977. (Available from Technical Information Service, National Research Council of Canada, Ottawa,
Canada, KiA 033).

7. 21. Anonymous, “Teamwork Develops Breakthrough in Manufacturing Technology,” Boeing Vertol Company News,
Philadelphia, 1979. (3M Scotchbrite finishing machine deburrs clad soft aluminum aircraft components
22. Blount, Ezra A., “Edge Finishing Standards in Aerospace -Possibilities for Improvement,” SME paper MR79-753, 1979.
23. Lambert, Brian, “Prediction of Thrust Force, Torque and Burr Height in Drilling Titanium,” SME paper MR79-363,
1979.
24. Rowlson, Peter C., “Deburring and Finishing of Airplane Parts--Present and Future Requirements,” SME paper
MR79-749, 1979.
25. Anonymous, “Automatic Deburring of Long, Slender Parts,” Tooling and Production, December, 1980, p. 61.( Aircraft
wing spars are deburred and radiused on straight line equipment. Parts range in length up to 105 feet and weigh up to 400
pounds. Edge breaks of 0.020 to 0.060 inch are required. Soft three-dimensional abrasive wheels are used for deburring.)
26. Behringer, Brian J., “Automated Deburring of Flat Sheet Metal,” SME Technical Paper, SME, MR81-387, 1981. (A user
presents an analysis of three—dimensional abrasive deburring on aluminum aircraft parts. Photomicrographs of part
edges are shown and test procedures are described.)
27. Saberton, Roger, Industry, “Trade and Commerce Sponsored Deburring Program,” SME Technical Paper, SME,
MR81-216, 1981.
28. Blanton, Albert Glenn, “Ultra-Long String Abrasive Brush Deburring,” SME Technical Paper, SME, MR83-691, 1983.
29. Barto, J. J., JR. “Robotics in Aircraft Manufacturing” (United Technologies Corp., Sikorsky Aircraft Div., Stratford, CT)
in: Proceedings American Helicopter Society, Annual Forum, 41st, Fort Worth, TX, May 15-17, 1985, Proceedings
(A86-35601 16-01). Alexandria, VA, American Helicopter Society, 1985, p. 793-800. (Documents available from AIAA
Technical Library).
30. Harbert, G. K.; Sams, R. A.“Case History of FMS Introduction in Aerospace Aircraft Sheet Metal Detail Manufacture -
'a Time for Change',” Publ by IFS (Publ) Ltd, Kempston, Engl, pp. 379-396, 1985.
31. Harrison, William M., Jerney, Thomas D., Langer, “A New Automated Work Cell for Manufacturing Aircraft Parts,”
SME Technical Paper, SME, MS85-202, 1985. Stoewer, Udo-H.“Development Stages in the Automation of Rivet
Assembly in Aircraft Manufacture in Germany” Tech Pap Soc Manuf Eng 1985 AD85-1030.
32. Kartak, Jeff, “$1.2 Million Robot System Aids Lockheed's C-5 Program,” Production, 1987, February, p. 15.
33. Dawson, B.L., Hennies, R.C., Robotic Long String Brush Deburring System, Robots and Vision Conference, SME,
MR88-297, 1988, June.
34. Thistlethwaite, P. H., “Flexible Manufacturing System (FMS) for Aircraft Components ,” Sheet Metal Industries, v 65,
n 3, Mar 1988, p. 118.
35. Warren, Jeffrey H.; Ellis, and L. Donald, “Design of a Semi-automatic Drilling Machine for the Outer Wing Beam of a
C-130 Aircraft,” American Society of Mechanical Engineers (Paper). Publ by ASME, New York, NY, USA. WA/DE11,
1988.
36. Bump, Thomas T., Deburring and Finishing Processes at General Dynamics, SME Technical Paper, SME, MR91-125,
1991, February.
37. Miyabe, Tomohiko and Hitoshi Fukagawa, “Automated Finishing for Machined Parts,” Proceedings of the Aircraft
Symposium, 29th, Gifu, Japan, Oct. 7-9, 1991, Proceedings (A92-56001 24-01). Tokyo, Japan Society for Aeronautical
and Space Sciences, 1991, pp. 478-481. (In Japanese.) (available from AIAA Technical Library).
38. Coulter, R. W., and D.S. MacKenzie, “Classification of Aerospace Fatigue Failures at Skin-substructure Fastener
Holes,” Proceedings International Non-Ferrous Processing and Technology Conference, 1st, Saint Louis, MO, Mar. 10-
12, 1997, (A98-10526 01-37), Materials Park, OH, ASM International, 1997, pp. 391-404, (available from AIAA
Technical Library).
39. Chodakauskas, Stanislaus, “Titanium Deburring Process Improvements, Proceedings 5th International Conference on
Precision Surface Finishing and Burr Technology, San Francisco, 1998, addendum
40. Hartman, John, and Peter Zieve, “Wing Manufacturing - Next Generation,” AIAA Paper 98-5601; SAE Paper 985601,
1998 World Aviation Conference, Anaheim, CA, Sept. 28-30, 1998, p.16. (available from AIAA Technical Library).