Mass media finishing large aircraft components final


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Mass media finishing large aircraft components final

  1. 1. Mass Media Finishing Large Aircraftand Aircraft Engine Components David A. Davidson 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 improveFigure 1 -- This large aluminum component shown in the composite photo above their edge and surface finishingwas previously deburred with hand tools. Implementing a vibratory finishing operations. In his Deburring andprocesses with a tub shaped chamber reduced processing time from hours to Edge Finishing Handbook, (1999minutes, 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 athe part with a part and feature consistency and uniformity not possible with comparative table which pointed outmanually directed or single point of contact abrasive methods. PHOTO courtesy that in some mechanical finishingRobert 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 ofwith the Turbo-Finish method. This dry abrasive finishing method has Manufacturing Engineers in essay entitledbeen successful in bringing mass media finish economies to large “Boeing Issues an Invitation” referenced acomplex rotationally oriented parts. In addition to the uniform and situation that is still all too common. That isconsistent edge contours developed, the method also produces highly that many manufacturers, after spending vastsophisticated isotropic surface finishes by radically altering thecharacter of the as- machined or as-ground surface finish. PHOTO sums on CNC machining equipment tocourtesy Dr. Michael L. Massarsky, Turbo-Finish Corporation
  2. 2. produce parts to very precise tolerances and specifications consistently, in the end, hand off these expensiveparts 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 finishingprocesses have been adopted, put into service, and the parts involved have developed a working track record, anunanticipated development has taken place. Their parts are better—and not just in the sense that they no longerhave burrs, sharp edges or that they have smoother surfaces. Depending on the application: they last longer inservice, are less prone to metal fatigue failure, exhibit better tribological properties (translation: less friction andbetter wear resistance) and from a quality assurance perspective are much more predictably consistent anduniform. The question that comes up is why do commonly used mass media finishing techniques produce thiseffect? There are several reasons. The methods typically are non-selective in nature. Edge and surface featuresof the part are processed identically and simultaneously. These methods also produce isotropic surfaces with
  3. 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 farFigure 5 -- Centrifugal barrel machines such as these can produce outweigh the substantial cost-reductionexceptional edge and surface finishes in very short cycle times. Accelerated benefits that were the driving forceprocess effects can be developed because of the high speed interaction behind the initial processbetween abrasive media and part surfaces, and because media interaction withparts are characterized by high pressure by virtue of the high centrifugal implementation.forces developed in the processes. Smaller turbine blades can be processed inthe 5 x 8 inch compartments in the 12-liter capacity machine shown to the This assertion has been affirmed by bothright. Larger centrifugal machines such as the 220 liter or 330 liter capacity practical production experience andmachine shown to the left can handle much larger parts as the barrel validation by experiment in laboratorycompartments are as much as 42 inches in length. Larger parts processed inthis type of machinery can be processed one at a time within the barrel settings. David Gane and his colleaguescompartment suspended within the media mass or be fixtured. Barrel at Boeing have been studying the effectscompartments can be divided into processing segments to accommodate more of using a combination of fixtured-partthan 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 studyutilizing 6-axis machining technology. Centrifugal barrel finishing was that the practicality and economictechnology was used to clear and blend in the milling cutter paths and feasibility of the vibro-deburring and burnishingthen develop very refined and burnished isotropic surfaces in the foil method increased with part size and complexity.area.
  4. 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 onturbine disk components processed with the method showed an improved cycle life of 13090 ± 450 cycles whencompared to the test results for conventionally hand deburred disks of 5685 ± 335 cycles, a potential service lifeincrease 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 fatigueresistance. 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 cyclesa 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 arenot the result of poor planning or poor engineering. They are a natural result of machining and blankingprocesses. Large burrs, however, may be the result of poor planning.” A similar axiom could be said to existregarding surface finishes. “Rough, non-isotropic surface finishes with undesirable stress conditions are notthe result of poor planning or poor engineering. They are a natural result of almost all common machining,
  5. 5. grinding, fabrication and abrasive methods. These results can be exacerbated by abusive machining andgrinding, and improved or reversed with mass media finishing techniques.”Mass media finishing techniques improve part performance and service life, and these processes can be tailoredor modified to amplify this effect. Although the ability of these processes to drive down deburring and surfacefinishing costs when compared to manual procedures is well known and documented, their ability todramatically effect part performance and service life are not. This facet of edge and surface finishing deservescloser 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.orgACKNOWLEDGEMENTS: The author wishes to acknowledge the technical assistance of the followingmembers 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. 6. technical session concerning deburring and surface finishing methods for aircraft frame components sponsoredby the Society of Manufacturing Engineers at WESTEC, April 6, 2005 in Los Angeles, CaliforniaFURTHER READING: Aircraft Related Deburring Technical Papers/Articles – does not include aircraft enginecomponent partsTaken from: Deburring a 70-Year Bibliography, edited by LaRoux K. Gillespie and Elena Repnikova, Deburring TechnologyInternational, 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. 7. 21. Anonymous, “Teamwork Develops Breakthrough in Manufacturing Technology,” Boeing Vertol Company News, Philadelphia, 1979. (3M Scotchbrite finishing machine deburrs clad soft aluminum aircraft components22. 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 Lockheeds 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, addendum40. 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).