NAVISTAR MPAPS P-39-2017 Shot Peening of Metal Parts.pdf

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1、 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2017 by Navistar, Inc. APRIL 2017 Page 1 of 10 NAVISTAR, INC. Material, Parts, and Process Specification

2、s (MPAPS) NUMBER: MPAPS P-39 Former Designation: CEMS A-39 or 5% of the “A” intensity arc height for parts RC 45 and greater. Convert “N” or “C” intensities to equivalent “A” value. 4.6.3 Unless otherwise specified, heating after shot peening such as to bake or cure paint will be limited to: 230C (4

3、50F) max for steel; 135C (275F) max for aluminum. 4.6.4 Treated surfaces will be suitably cleaned and protected with a rust inhibiting coating before shipping or storage. 4.7 Method of Test 4.7.1 Test Strip Intensity Support the appropriate tests strips so that their exposure simulates that of each

4、specified area. Follow the procedure outlined in SAE J443 to generate an “Intensity Determination Curve.” Saturation of the test strip is defined as the “Shortest time” point on the curve from which doubling that time will result in no more than a 10% increase in arc height. Full or 100% coverage of

5、 the test strip or complete denting of the surface will correspond very closely to saturation. Use a fresh test strip for each exposure; no strip may be reused. 4.7.2 Piece Part Intensity All variables, except time, determined above must be maintained. The time to get saturation or 100% coverage of

6、the piece part will vary with the base hardness. This time will be determined visually. A 150% of 1.5 coverage specification refers to 1-1/2 times the piece part saturation time. 4.7.3 Coverage Piece part coverage will be determined visually using a 10 power magnifying glass. Full or 100% coverage w

7、ill be uniform with complete denting or obliteration of the original surface. NUMBER: MPAPS P-39 TITLE: Shot Peening of Metal Parts REVISION: 1704 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are

8、 required to assume all patent liability. 2017 by Navistar, Inc. APRIL 2017 Page 4 of 10 5.0 QUALITY All product supplied shall be clean and free from dirt, oils, or defects harmful to product performance. The supplier should be capable of providing statistical evidence that parts have been processe

9、d with process control limits established by the supplier for this product and that the process is capable of meeting all requirements of this specification. 6.0 QUALIFICATION Engineering qualification of sources is required in advance of production shipments. Samples shall be accompanied by test da

10、ta certifying that all requirements of the specification have been met. 6.1 Quality Control Plan A Quality Control Plan for products supplied to the requirements of this specification will be established by mutual agreement between NAVISTAR and the supplier. Unless specific exception is noted, the f

11、ollowing characteristics, where applicable*, shall be included in the plan as features for management by statistical process control.* * Other characteristics for inclusion in the control plan may be specified on the engineering drawing and/or purchase order. * See NAVISTAR Engineering Design Standa

12、rd A-16 7.0 SOURCE APPROVAL AND QUALITY CONTROL 7.1 Supplier Requirements All suppliers to NAVISTAR are required to be registered to ISO 9001 Quality System Requirements. NAVISTAR will also accept TS-16949 registration as long as the supplier can also fulfill all AIAG PPAP (Production Part Approval

13、Process) documentation and approval requirements. Suppliers must maintain their certification with an accredited registrar and must furnish copies of registration certificates to their Corporate Buyer upon request. 7.2 Approval Parts supplied against contracts or purchase orders citing this specific

14、ation shall be equivalent in all respects to those samples which were approved by the purchaser. No changes in formulation or processing practices are permitted without approval. In the event that changes in material, properties, processing practices, construction, color, or labeling of the product

15、are required, the supplier shall notify NAVISTAR Materials Engineering and Purchasing and Supplier Development of the proposed change(s). Test data indicating conformance to all requirements of this specification, test samples, and new or amended or updated Material Safety Data Sheet(s) (MSDS), in a

16、ccordance with CFR Title 29, Part 1910 shall be submitted with the request for change. 7.3 Process Control The supplier shall either, perform and report results of tests on specific lots of parts produced using ISO 9001 or TS-16949 guidelines, or provide statistical evidence of the lot having been p

17、roduced in a state of statistical control and with a process capable of providing all required properties. The part supplier NUMBER: MPAPS P-39 TITLE: Shot Peening of Metal Parts REVISION: 1704 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission fr

18、om Corporate Technical Standards. Suppliers are required to assume all patent liability. 2017 by Navistar, Inc. APRIL 2017 Page 5 of 10 and the quality control manager of the using NAVISTAR plant may determine testing and reporting requirements on specific products. 8.0 SHIPPING AND HANDLING Shippin

19、g and identification shall be in accordance with NAVISTAR Supplier Packing and Shipping Standard D-13. Parts shall be packaged so as to avoid any damage in shipment detrimental to the appearance of the part. 9.0 DESIGNATION ON DRAWINGS The class, suffixes and other required information will be speci

20、fied as follows: Shot Peen, Class 8CH, Coverage 150% min, MPAPS P-39 Shot Peen, Class 12A, MPAPS P-39 Shot Peen, Class IND, 12-20 AH, MPAPS P-39 Shot Peen, Class IND, 10C, min, MPAPS P-39 10.0 TECHNICAL INFORMATION For further information related to the technical content of this specification, conta

21、ct: Suppliers may purchase controlled copies of this specification by contacting: Materials Engineering and Technology Dept. 10400 W. North Avenue Melrose Park, IL 60160 E-mail: MaterialsEngineeringN IHS Markit Inc. 15 Inverness Way East Englewood CO 80112-5776 Phone: 1-800-854-7179 E-mail: Automoti

22、veIHS.com Website: http:/ NUMBER: MPAPS P-39 TITLE: Shot Peening of Metal Parts REVISION: 1704 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2017 by Na

23、vistar, Inc. APRIL 2017 Page 6 of 10 A.0 GENERAL INFORMATION Not a Requirement A.1 INTRODUCTION Shot peening is the process of exposing a metal surface to bombardment by a high velocity stream of solid particles. This treatment creates a compressively stressed layer on that surface which will reduce

24、 the effect of a tensile stress from an applied load and thereby increase the load carrying capacity in fatigue. Fatigue strength, for high cycle applications, can be improved significantly. Depending on the application, this can vary from 20% to well over 100%. The percent improvement decreases as

25、higher overloads are reached. Resistance to stress corrosion cracking can also be increased. A.2 EQUIPMENT The acceleration of the particles is usually accomplished in one of two ways, centrifugal force or air pressure. The centrifugal force method employs a rotating wheel and the shot velocity is d

26、etermined by the peripheral speed of that wheel. Usually, the wheel diameter and speed are controlled to produce a shot velocity about equal to that delivered by a direct pressure gun operating at 80 psi. The volume of shot delivered is quite high, but since the stream tends to diverge, a portion of

27、 it never reaches the part. The power consumed is only a fraction of that required for a compressor to drive a direct pressure gun. Air pressure guns employ either induction or gravity to feed shot into the air stream. The induction gun uses an air jet to introduce the shot into the stream; mixing o

28、ccurs at the nozzle. The shot volume is about the same as a direct pressure gun of same size as the air jet, but the velocity is reduced due to the energy consumed to create the vacuum used for shot induction. The direct pressure gun is supplied with shot fed by gravity from a pressurized reservoir.

29、 A single line delivers both shot and the propelling air to the nozzle. Shot velocity is proportional to air pressure. A.3 SHOT The shot used for peening must be essentially free from sharp edges or corners, as they can damage the surface by creating stress risers which may detract from the availabl

30、e improvement and actually abrade the surface. To reduce the chances of this occurring, the shot should be conditioned to removed edges and promote the breakdown of cracked or defective shot. The fragments can then be removed prior to use. For cut wire, conditioning is essential. Some specifications

31、 list the degree and extent of cracked or porous shot allowable, as well as shape requirements. This is mainly for manufacturing control. It may be advantageous to order preconditioned shot which is more expensive, but better since shot breakdown during the peening operation and, therefore, replacem

32、ent costs are reduced. NUMBER: MPAPS P-39 TITLE: Shot Peening of Metal Parts REVISION: 1704 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2017 by Navis

33、tar, Inc. APRIL 2017 Page 7 of 10 A.4 INTENSITY When discussing intensity only saturation intensity or the intensity produced when there is 100% coverage and complete overlapping of dimples on the surface is considered. “Intensity” at any other point on the curve should be referred to as “arc height

34、.” Shot peening intensity is indicated by the amount of curvature that is produced in a steel test strip by exposure to the stream. The curvature is measured in 0.025 mm units on a dial indicator. When necessary, a dial indicator with 0.001 inch (0.0254 mm) graduations may be used. A.4.1 There are t

35、hree standard (Almen) test strips of different thickness currently in common use. This permits specifications, measurement and control in three intensity ranges, light (N), average (A) and heavy (C). The “A” strip is usually used as a general purpose range. To extend the range in either direction, t

36、he “N” strip (reading about three times “A” heights) and the “C” strip (readings about 0.3 times “A” heights) are available. A.4.2 To calibrate the peening operation, a series of test strips are exposed to the shot stream; all variables except exposure time are held constant so that a time-arc heigh

37、t curve can be generated. Saturation of 100% coverage is defined as the point at which doubling the exposure time increases the arc height by less than 10%. Reaching this point completes the calibration curve which then serves as a guide in the operation of the equipment. If the specified arc height

38、 does not coincide with the saturation point, the machine variables must be changed and another curve generated. The time required to saturate the test strip is not necessarily the same as that required for the part; harder parts require more time while softer ones require less. For example, at a pi

39、ece part hardness of RC 55, the time will be about twice that for RC 45. This is due to the fact that for a harder material each peening particle will make a smaller impression. A.4.3 To determine the time required to saturate the surface of the part, several methods have been proposed; some of thes

40、e are in use. They all have in common the attempt to quantify the portion of the surface affected after some exposure and then to use one or more of these observations to determine a saturation time. One relatively straight forward way involves the use of a fluorescent type coating which is removed

41、by the peening operation; the minimum time required to completely remove the “Coating” is the saturation of 100% coverage time for that intensity for that part at that hardness. A.5 SHOT SIZE VERSUS INTENSITY The maximum intensity actually attainable using any particular size shot will vary dependin

42、g on part geometry and condition as well as machine operating variables which affect shot velocity, shot volume and stream pattern. Following is a list of maximum intensity versus shot size. For intensities higher than those shown in the white pages, the vendor may have to be consulted. The presence

43、 of fillets or apertures may limit the shot size usable, but by increasing pressure or wheel speed, the desired intensity may be achievable. NUMBER: MPAPS P-39 TITLE: Shot Peening of Metal Parts REVISION: 1704 This document is restricted and may not be sent outside Navistar, Inc. or reproduced witho

44、ut permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2017 by Navistar, Inc. APRIL 2017 Page 8 of 10 A.6 SHOT HARDNESS VERSUS INTENSITY TABLE I SHOT SIZE VERSUS INTENSITY Shot Size Maximum Intensity Cast Steel Cut Wire S110 S170 S230 S280 S330 S460

45、S660 - - CW23 CW28 CW35 CW47 - 12A 16A 22A 26A 28A 10C 14C A.6.1 Figure 1 illustrates the next step, that is, relating intensity to depth of compressive stress layer. Figure 2 goes on to show the relationship of maximum attainable compressive stress to tensile strength of the base material. While pe

46、ening the hardened steel test strip, various combinations of shot size and shot velocity may be used to produce the same arc height; these intensities are considered equivalent. However, when peening softer materials such as aluminum, the larger the shot size the deeper the effected layer. NUMBER: M

47、PAPS P-39 TITLE: Shot Peening of Metal Parts REVISION: 1704 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2017 by Navistar, Inc. APRIL 2017 Page 9 of 1

48、0 A.6.2 When peening harder material, harder shot should be used; the shot should be at least as hard as the part. If the shot is too soft, it will deform and absorb the energy that should be delivered to the parts surface; this would result in little or no benefit to the part. Figure 3 shows the “T

49、rend” for shot hardness versus piece part hardness as related to surface compressive stress. TREND ONLY H a r d ness 200 100 R C 45 R C 60 Sho t H a r d ness R C 60 InducedCompressiveStressX10-3Piece Part Hardness Figure 3 Compressive Stress as Related to Shot and Part Hardness A.7 MATERIAL THICKNESS AND INTENSITY The following limits should be considered if relatively thin sections are to be peened. To exceed these intensi