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 MPa = 300 – 600 range that formed to a surface layer of metal to a depth of 20 – 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 and fabrication 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 and this is also true of larger and more complex parts – only more so.
(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