1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2014 SAE International All rights reserved. No part of this p
3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J3020_201405 SURFACE VEHICLE RECOMMENDED PRACTICE J3020 MAY2014 Issued 2014-05 Me
5、dical Device Shot Peening RATIONALE The intent of this document is to establish an industry standard for the shot peening of a medical device. The focus of this standard is to address the undefined requirements needed for shot peening in the medical device industry that are not included in current s
6、hot peening standards used by other industries. 1. SCOPE This SAE Standard and its supplementary detail specifications cover the engineering requirements for the controlled shot peening of a medical device where shot peening is required for enhancement of a materials mechanical properties through th
7、e intentional creation of compressive residual stress. 1.1 Purpose This SAE Standard covers the engineering requirements for peening of medical device surfaces by impingement of stainless steel, glass beads, or ceramic media. 2. REFERENCES 2.1 Applicable Documents The following publications form a p
8、art of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-497
9、0 (outside USA), www.sae.org. AMS 2431 Peening Media General Requirements AMS 2431/4 Peening Media, Conditioned Stainless Steel Cut Wire Shot AMS 2431/6 Peening Media, Glass Shot AMS 2431/7 Peening Media, Ceramic Shot SAE J442 Test Strip, Holder, and Gage for Shot Peening SAE J443 Procedures for Usi
10、ng Standard Shot Peening Almen Strip SAE J2277 Shot Peening Coverage Determination SAE INTERNATIONAL J3020 Issued MAY2014 Page 2 of 11 SAE J2597 Computer Generated Shot Peening Curves AMS 2430 Shot Peening, Automatic 2.1.2 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P
11、.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM E 18 Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials ASTM E 11 Standard Specification for Wire Cloth and Sieves for Testing Purposes 3. DEFINITIONS 3.1 MEDICAL DEVICE A medical device is a
12、 product which is used for medical purposes in patients, in diagnosis, therapy or surgery. 3.2 SHOT PEENING Shot peening is a cold working process used to produce a compressive residual stress layer and modify mechanical properties of metals. It entails impacting a surface with shot (round metallic,
13、 glass, or ceramic particles) with force sufficient to create plastic deformation. 3.3 COGNIZANT ENGINEERING ORGANIZATION Cognizant Engineering Organization is a term applied to the engineering organization responsible for the design of the part or a designee of that organization. 4. GENERAL REQUIRE
14、MENTS 4.1 Peening Area Designation 4.1.1 All surfaces designated by the engineering drawing to be peened shall be peened and exhibit full coverage unless otherwise specified. 4.1.2 Areas designated not to be peened, shall be masked or otherwise protected from the peening stream to prevent overspray
15、into prohibited areas. Masking shall be removed after the peening operation and parts shall be free of peening overspray and damage due to the masking method. 4.1.3 Sections under 1mm (.040 inch.) in nominal thickness shall not be peened unless specifically required on the engineering drawing. 4.1.4
16、 Areas where peening is designated as optional, may remain unpeened, peened with full coverage, partially peened, or exhibit peening overspray that does not achieve full coverage. 4.1.5 Peening is optional in areas where peening is neither specified nor prohibited. In areas of optional peening, cove
17、rage verification is not required. When the masking tolerance is not indicated on the drawing, and a peening required zone is adjacent to a peening prohibited zone, the area of peening tolerance shall encroach into the peening required areas to a maximum of 3.2mm, while the peening prohibited area s
18、hall remain free from peening indentations and overspray. If the peening required zone is adjacent to a peening optional zone no tolerance is required and the peening required zone shall receive required coverage with no allotment for peening tolerance permitted. SAE INTERNATIONAL J3020 Issued MAY20
19、14 Page 3 of 11 4.2 Intensity Verification 4.2.1 Intensity verification locations shall be as indicated on the drawing; when not specified on the drawing, locations shall be established by the cognizant engineering organization and shall represent locations of critical importance. 4.2.2 Verification
20、 locations shall be positioned to embody shot peen standoff distance and angle of impingement that correlates to the conditions that are to be practiced in the peening process of the part. 4.2.3 In areas of optional peening, intensity verification is not required. 4.2.4 Intensity and coverage shall
21、be specified on the engineering drawing. 4.3 Media 4.4 As Received Shot Peen Media 4.4.1 Conditioned Cut Wire, Glass Bead, and Ceramic as received media shall conform to AMS 2431. 4.4.2 Use of carbon Steel peening media is prohibited. 4.5 Media in Machine 4.5.1 In machine media size uniformity shall
22、 be in accordance with AMS 2430. 4.5.2 Media size uniformity shall be determined using the sampling and sieving procedures defined in 7.3.7.4. 4.5.3 Glass bead and ceramic media shall be sampled, in accordance with Table 2, and inspected to ensure that not more than 10 percent (by number) of the bea
23、ds or shot are broken. 4.6 Measuring Instruments 4.6.1 Almen gages, scales, air pressure gages, tachometers, and other applicable instruments, used for controlling shot peening, shall be calibrated against instruments whose calibration is traceable to National Institute of Standards and Technology (
24、NIST) or other national accredited standards organization acceptable to the cognizant engineering organization. 4.6.2 Almen strips shall conform to SAE J442, except thickness and pre-bow tolerances shall be 0.013mm (.0005 inch). Compensation for pre-bow of the Almen strip shall be performed in accor
25、dance with 4.10.5. Mechanically deforming strips to meet the pre-bow requirements is not permitted. Hardness of strip shall be 73.0 to 74.5 HRA for N strips and 45 to 48 HRC, or equivalent, for all other strips. 4.6.3 Gages for determining pre-bow and arc height of Almen strips shall conform to the
26、requirements of SAE J442 with end stops, except that the gages shall have digital readouts and have a minimum resolution of 0.001mm (0.00005 inch). Almen gages shall be zeroed before each period of use, and at a minimum, once every 8 hours. Zeroing of the Almen gage shall be performed using a block
27、that is flat within 0.005mm (0.0002 inch). 4.7 Almen Strip Holding Fixture 4.7.1 A representative non-adjustable fixture used to hold Almen strips shall be used to hold strips for the purpose of establishing or verifying a specified peening intensity. Almen strip holding fixtures shall conform to SA
28、E J442 and shall be oriented to the peening shot stream and rotated or translated in the same manner and equipment as for peening the part. The design of the Almen strip fixturing shall be approved by the cognizant engineering organization and shall be recorded in process documentation and used for
29、all subsequent Almen intensity verifications. SAE INTERNATIONAL J3020 Issued MAY2014 Page 4 of 11 4.8 Shaded Strips or Sub-size Strips 4.8.1 In locations where standard Almen strips cannot be placed to accurately reflect the peening intensity, shaded or sub-size strips (as defined in SAE J442) shall
30、 be used. The relationship between the peening intensity on the shaded or sub-size strip and that on the standard strip shall be established. The intensity thus established for the shaded or sub-size strip shall be used for control of the peening intensity. 4.9 Process Monitoring 4.9.1 Peening machi
31、nes shall provide means for continuously monitoring and recording the parameters shown in Table 1 within the tolerance indicated. Monitoring and recording of process parameters shall be performed with the use of computerized controls or any other system that is approved by cognizant engineering orga
32、nization. TABLE 1 - PROCESS MONITORING PARAMETERS Parameter Units Process Tolerance Shutdown Limits Plus or Minus Media Flow (each nozzle) pounds / minute 10% of full scale Air Pressure (each nozzle) Psi 20 psi 10%, 20 psi 20% Wheel Speed (each wheel) Rpm 2000 rpm 1% 2000rpm 20 rpm Translation Speed
33、 mm/minute (Inches/minute) 10% Deflector Speed mm/minute (Inches/minute) 10% Rotary Speed Rpm 10% Part Speed rpm mm/minute (inch/minute) 10% Conveyor Speed mm/minute (Inches/minute) 10% Peening Cycle Time Seconds 1 Nozzle/Wheel Position mm/degree (Inch/degree) 1.57mm (0.062 inch) /5 degrees Table/Pa
34、rt Indexing mm/degree (Inch/degree) 1.57mm (0.062 inch) /5 degrees * Calibration of measuring devices used in the peening system shall be performed in accordance with ISO-10012-1. 4.9.2 The peening system shall be capable of interrupting the cycle within one second, when excursions outside set toler
35、ances are detected for media flow, air pressure, wheel speed, nozzle or wheel translation speed, turntable speed, part speed, or conveyor speed. Excursions outside the limits in Table 1 shall cause an aborted cycle and the computer system shall record the time and abort details for the parameters li
36、sted in Table 1. Notation of root cause and corrective action shall be documented. After the out-of-tolerance condition has been corrected, the peening system shall be able to resume operation to complete the balance of the process cycle from the position of shut-down, or restart program from the be
37、ginning. Restarting of the machine shall only be done by authorized personnel. Parts processed during an aborted cycle shall be so identified on the peening certification of conformance, computer print-out, or both. Reprocessing of parts processed during a cycle abort is only permitted at the discre
38、tion of the cognizant engineering organization. 4.10 Process Intensity 4.10.1 Conditioned Stainless Steel Cut Wire peening media may be used for peening to intensities requiring use of “N”, “A”, and “C” Almen strips. 4.10.2 Glass bead peening media may be used for peening to intensities requiring us
39、e of the “N” Almen strip. 4.10.3 Ceramic peening media may be used for peening to intensities requiring either “A” and “N” Almen strips. SAE INTERNATIONAL J3020 Issued MAY2014 Page 5 of 11 4.10.4 Process intensity shall be established in the same machine to be used in production peening and shall be
40、 in accordance with SAE J443. 4.10.5 Pre-bow compensation of Almen test strips is required. Pre-bow Compensation: For example, a positive pre-bow value is subtracted from the gross arc height measurement to provide the net arc height measurement. A negative pre-bow value is added to the gross arc he
41、ight measurement to provide the net arc height measurement. 4.11 Equipment 4.11.1 Peening Machine 4.11.1.1 Media propulsion shall be accomplished by way of either pneumatic or centrifugal force. 4.11.1.2 Air pressure or wheel speed shall be adjustable. 4.11.1.3 Tumble peening, barrel peening, and pe
42、ening processes that allow part-to-part contact are prohibited. 4.11.1.4 The peening machine shall provide closed loop control of the following parameters: Air pressure, wheel speed, media flow rate, nozzle/part movement limits as applicable. 4.11.1.5 Machine shut down limits shall be in accordance
43、with (Table 1). 4.11.1.6 The peening machine shall provide means of uniformly moving the media stream across the work piece or the work piece through the media stream in either translation, rotation, or both as required. 4.11.1.7 The peening machine nozzles, the work, or both shall be held and moved
44、 mechanically. Manual movements and uncontrolled movements shall be prohibited. 4.11.1.8 Peening equipment shall include an integrated media separator to continuously control media size with size and uniformity confirmations made in accordance with (Table 2). 4.11.1.9 Peening machine shall include e
45、quipment to extract dust and fine particle contaminants from the in-process media. 4.12 Almen Test Strip, Holder and Gage 4.12.1 Almen Test Strips, Holders, and Gages shall conform to SAE J442 and be utilized per SAE J443. 4.12.2 Gages used with “A”, “C”, and “N” strips shall conform to SAE J442 wit
46、h end stops. 4.13 Media Size Sampling Equipment 4.13.1 A rotating and tapping type of testing machine shall be used. 4.13.2 The shaking speed shall be 275 to 295 rpm. 4.13.3 The taps per minute shall be 145 to 160. 4.14 Sieves 4.14.1 The test sieve shall be in accordance with ASTM E 11. They shall b
47、e of the 203mm (8 inch) diameter series, of either 25mm (1 inch) or 51 mm (2 inch) height. SAE INTERNATIONAL J3020 Issued MAY2014 Page 6 of 11 4.15 Preparation of Parts 4.15.1 Parts shall be free of grease, dirt, oil, corrosion-preventive coatings such as anodic coatings, plating, and paint. 4.15.2
48、Areas of the part or work piece, which are designated to be free from any shot peening marks, shall be masked or otherwise handled to protect such surfaces from the peening stream or subsequent damage. 4.15.3 The following items are not necessarily the responsibility of the peening source, but shall
49、 be completed prior to peening: 4.15.3.1 All machining and forming of areas to be peened shall be completed, all fillets shall be formed, all burrs shall be removed, and edges and corners shall be rounded. 4.15.3.2 Parts shall be inspected and confirmed to be free from the presents of edge rollover or bulging. 4.15.3.3 When non-destructive inspection is required, parts shall be subjected to such inspections before being pee
