SAE J442 pdf download
SAE J442 pdf download.(R)Test Strip, Holder, and Gage for Shot Peening.
1. This SAE Standard defines requirements for equipment/supplies to be used in measuring shot peening intensity. Guidelines for the use of these articles (test strip, holding fixture, and gage) are also included.
2. References
I2.1 Related Publications—The following publications are provided for information purposes Only and are not a required part of this specification, The latest issue of SAE publications shall apply.
2,1.1 SAE PuBLIcATION—Available Iron, SAE. 400 Commonwealth Drive, Warrendale, PA 15096-0001.
SAE J443—Procedures for Using Standard Shot Peening Test Strip
• SAE AMS-S-13165—Shot Peening of Metal Parts
2.1.2 ASTM PuBLICA noN—Available from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.
ASTME 18—Standard Test Method for Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials
3. Outline of Method of Control—The control of a peening machine operation is primanly a matter of the control of the properties of a stream of shot in relation to the work being peened. The basis of measurement of these properties is as follows:
If a flat piece of steel (the test strip) is clamped to a sobd block (the test strip holder) and then exposed to a stream of shot it will be curved upon removal from the block, The curvature is due to residual compressive stresses induced by the shot impacts, causing the peened face to be convex. The curvature serves as a means of measuring the effect of the shol stream. The degree of the curvature depends upon the properties of the shot stream, the properties and mounting of the test strip, and the exposure condition.
3.1 PropertIes
3.1.1 SHOT STREAM—The properties of the shot stream are: shot material (inciues chemical and physical characteristics), size, shape, velocity, directional consistency. and shot flow rate.
3.1.2 TEST STRIP—The properties of the test strip are: material (Includes chemical and physical properties). hardness, physical dimensions, and the extent of any internal stresses. The properties of the test strip mounting are flatness, rigidity, and the location and force of the holding means.
3.1.3 EXP0SLsE—The properties of exposure to the blast stream are length of time, angle of impact, and the degree of uniformity and consistency of the geometric relationship between the shot stream and test strip.
3.2 Standards—Based on these principles, the SAE has adopted the following standards: test strips, holding block, and gage. Specifications for these parts, the method of use, and a standard designation are presented herein.
4. SpecifIcations of Intensity Measuring Equipment
4.1 Test Strips and Holding Fixture—Standard test strips, N, A, and C are shown in Figure 1 and test strip holder is shown in Figure 2. The approximate relationships between readings of test strips N, A. and C (for conditions of identical blast and exposure) are as follows:
C strip reading x 3.5 = A strip reading
A strip reading x 3.0 — N strip reading
4.2 Gage—The gage (Almen gage) for determining the curvature of the test strip must incorporate the elements shown in Figure 3. Curvature of the test strip is determined by a measurement of the height of the comblned longitudinal and transverse arc across standard chords. This arc height is obtained by measuring the displacement of a central point on the nonpeened surface from the plane of four balls forming the corners of a particular rectangle To use this gage, the test strip is located so that the indicator spindle bears against the center of the NONPEENED surface, one long edge of the strip bearing against the two back stops. The test strip Is then centered by placing the ends even with the edges of the base. or by resting the ends against built- in end stop(s).
5. Designation Standard of Intensity Measurement
5.1 PrImary Standard—The standard designation of intensity measurement includes the gage reading and the test strip used. It may be explained by the example shown in Figure 4:
5.2 TransItion Standard—Gages utilizing the inch.pound system (English units) may be encountered during the period of transition to SI. The designation of intensity measurement In this temporary alternate is explained in the example shown in Figure 5:
6. Maintenance, Calibration and Use
6.1 Test Strips—After removal from the test strip holder, lest strips should not be replaced. re-used, or shot peened for any additional time.
6.2 HoldIng Fixture-The test strip contact area of the holding fixture shall be checked for flatness on a periodic basis. Flatness of the test strip contact area shall not exceed 0.1 mm, In addition to a dirnensioial check for flatness, holding fixtures shall be checked visually for the following characteristics:
a. Burrs or raised material that can be caused by damage or excessive peening (particularty on the holding fixture end faces).
b. Particles of shot or beads that could become trapped under the test strip during installation.
c. Damage to threads that may prevent one or more screws from adequately holding the test strip in place
6.3 Gage—Locating balls and indicator tip shall be checked periodically for wear. Any visual signs of wear shall be cause for repair of the gage such that new round surfaces are in contact with the test strip. The indicator shall be calibrated periodically over the range used for measuring test strips. The calibration tolerance for the indicator shall not exceed 0005 mm. The use of calibration blocks, either flat, curved, or equipped with steps. is recommended.
