# US 5,704,239 A · Method for ceramic peening of orthopaedic titanium alloy implants > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,704,239 A - Document ID: US5704239A - Status: Granted - Kind: A - Application number: 08/583,924 - Filed: 1996-01-11 - Granted: 1998-01-06 - Earliest claimed: 1996-01-11 - Assignees: Smith & Nephew, Inc. - Inventors: Neil B. Beals; Willard L. Sauer - Web page: https://patentgrep.com/patent/US5704239A ## CPC - A61F 2/30767: {Special external or bone-contacting surface, e.g. coating for improving bone ingrowth} - B24C 1/10: for compacting surfaces, e.g. shot-peening (for deforming sheet metal, tubes or profiles B21D31/06; as a metallurgical treatment C21D7/00, C22F1/00) - B24C 11/00: Selection of abrasive materials {or additives} for abrasive blasts (polishing compositions C09G) - A61F 2/3094: {Designing or manufacturing processes} - A61F 2/32: for the hip - A61F 2/38: for elbows or knees - A61F 2/44: for the spine, e.g. vertebrae or spinal discs - A61F 2002/30685: {Means for reducing or preventing the generation of wear particulates} - A61F 2002/30922: {Hardened surfaces} - A61F 2002/30934: {Special articulating surfaces} - A61F 2310/00023: Titanium or titanium-based alloys, e.g. Ti-Ni alloys - Y10T 29/479: by shot peening or blasting - A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C) - B24C: ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A method of preparing fretting wear resistant titaniumbase alloy orthopaedic implants includes the steps of shot peening the surface of the implant with spherical ceramic beads of a selected size and density, and with selected intensity such that the fretting wear resistance of the implant is increased and wherein the implant surface is uniformly peened to create a compressively-stressed region within the surface of approximately 100-300 microns depth. ## Claims ### Claim 1 A method of preparing fretting wear resistant titanium alloy orthopaedic implants, comprising the steps of: a) shot peening the surface of the titanium alloy implant with ceramic beads of a selected shot size, shape, and with selected intensity and coverage uniformity so that the fretting wear resistance of the implant is increased; and b) wherein the implant surface area is peened such that a compressively-stressed region of approximately one hundred to three hundred (100-300) microns in depth is achieved. ### Claim 2 (depends on 1) The method of claim 1 wherein the titanium implant is subjected to cyclical loading conditions during use by a patient. ### Claim 3 (depends on 1) The method of claim 1 wherein the titanium implant has a first surface that is subjected to oscillatory relative motion with a second surface. ### Claim 4 (depends on 1) The method of claim 1 wherein there are two adjacent contacting surfaces of the implant which experience oscillatory relative motion of small amplitude. ### Claim 5 (depends on 1) The method of claim 1 wherein in step "a" the surface is compressively-stressed by ceramic shot peening. ### Claim 6 (depends on 1) The method of claim 1 wherein the fretting wear debris generation is minimized. ### Claim 7 (depends on 1) The method of claim 1 further comprising the step of producing residual compressive stresses of at least one hundred (100) Kpsi within the surface area of the titanium implant. ### Claim 8 (depends on 1) The method of claim 1 wherein step "a" includes shot peening with shot of a sized between about one hundred twenty and twelve hundred (120-1200) microns diameter. ### Claim 9 (depends on 1) The method of claim 1 wherein step "a" includes shot peening with spherical shot. ### Claim 10 (depends on 1) The method of claim 1 wherein step "a" includes shot peening with ceramic shot of a material having a density (specific gravity) of between about 2.2 and 10.0 g/cm.sup.3. ### Claim 11 (depends on 1) The method of claim 1 wherein step "a" includes shotpeening with shot material of oxide ceramic. ### Claim 12 (depends on 1) The method of claim 1 wherein step "a" includes shotpeening with Almen intensity between about 2.5 A and 18 A. ### Claim 13 (depends on 1) The method of claim 1 further comprising the step of filtering the shot to remove any non-spherical shot material prior to the shotpeening step "a". ### Claim 14 A method of preparing a controlled surface roughness of titanium orthopaedic implants, comprising the steps of: a) shot peening the surface of the implant with generally selected spherically shaped ceramic shot of a size, density, and selected Almen intensity so that the fretting wear resistance of the implant surface area is increased. ### Claim 15 (depends on 14) The method of claim 14 wherein the surface of the implant is titanium-base alloy. ### Claim 16 (depends on 14) The method of claim 14 further comprising the step of subjecting the titanium implant to cyclical loading conditions. ### Claim 17 (depends on 14) The method of claim 14 wherein the titanium implant has a first surface and a second surface and further comprising the step of subjecting the first surface to oscillatory relative motion with the second surface. ### Claim 18 (depends on 14) The method of claim 14 wherein there are two adjacent contacting surfaces of the implant and further comprising the step of subjecting the contacting surfaces oscillatory relative motion of small amplitude. ### Claim 19 (depends on 14) The method of claim 14 wherein the peening almen intensity is between 2.5 A and 18 A. ### Claim 20 (depends on 14) The method of claim 14 wherein a compressively-stressed region within the surface of approximately 100-300 microns in depth is created. ### Claim 21 (depends on 14) The method of claim 14 where, prior to peening, the shot is filtered to remove non-spherical shot such that the number fraction of such shot is less than 5.0%. ### Claim 22 (depends on 14) The method of claim 14 wherein an automated peening process is utilized to ensure a uniform, pre-selected peening coverage of 100-200%. ### Claim 23 (depends on 14) The method of claim 14 further comprising the step of producing residual compressive stresses of at least one hundred (100) Kpsi within the surface area of the titanium implant. ### Claim 24 (depends on 14) The method of claim 14 wherein step "a" includes shot peening with shot of a sized between about one hundred twenty and twelve hundred (120-1200) microns diameter. ### Claim 25 (depends on 14) The method of claim 14 wherein step "a" includes shot peening with spherical shot. ### Claim 26 (depends on 14) The method of claim 14 wherein step "a" includes shot peening with shot of a material having a density (specific gravity) of between about 2.2 and 10.0 g/cm.sup.3. ### Claim 27 (depends on 14) The method of claim 14 wherein step "a" includes shotpeening with shot material of oxide ceramic. ### Claim 28 (depends on 14) The method of claim 14 wherein step "a" includes shotpeening with almen intensity between about 2.5 A and 18 A. ### Claim 29 (depends on 14) The method of claim 14 further comprising the step of filtering the shot to remove any non-spherical shot material prior to the shotpeening step "a".