| SAE J445 | |
|---|---|
| Metallic Shot and Grit Mechanical Testing | |
| Abbreviation | SAE J445 |
| Status | Published |
| First published | 1984 |
| Latest version | 2022 |
| Organization | SAE International |
| Domain | Shot peening, abrasive blasting |
J445 is an SAE standard that specifies laboratory methods for characterising metallic blast media, principally shot and grit, used in shot peening and blast cleaning. The methods are used to compare media durability (sometimes referred to as "Ervin Life") and the energy transmitted during impact with standardised bench equipment, and the report is applied alongside material and size specifications within the wider family of peening standards. Because it prescribes comparative tests rather than production settings, J445 is used for quality control of incoming media and for benchmarking suppliers in the automotive, aerospace and general manufacturing sectors. [1]
The report was first issued in 1984 under the title Metallic Shot and Grit Mechanical Testing, as recorded in the Shot Peener Library index. [2] Later editions followed, including a 1996 revision that is widely circulated in training materials and vendor archives, and a current edition issued in 2022 by national standards distributors. Across these editions the stated purpose remains to describe reproducible laboratory tests for metallic shot and grit. [3] [4]
J445 defines laboratory procedures that quantify two parameters important in selecting peening media, namely service life and the effectiveness of impact. Aerospace peening practice documents cite the report for comparing media quality, describing durability as the number of machine cycles required to replace the tested sample and transmitted energy as inferred from the arc height induced on a standard Almen strip after a prescribed exposure in the test machine. The document is framed for comparing shipments and manufacturers rather than calculating operating conditions for specific blast rooms or wheel machines. [5]
In industrial laboratories the J445 procedures are implemented with compact wheel-type bench machines derived from the Ervin Test Machine. A weighed and sieved sample of metallic shot or grit is propelled repeatedly against a hardened target and then re-sieved at fixed intervals to measure breakdown and loss. The report recognises several durability determinations, including an average life calculated from the breakdown curve, a stabilised loss-rate method, and a 100 percent replacement method that runs the machine in fixed increments, replaces the fraction lost each increment with new media, and determines the number of passes required for complete replacement of the original sample. Transmitted energy is evaluated by using a peening attachment that holds a standard Almen A strip and measuring the resulting arc height after a set number of cycles. [6] [7]
Trade and training articles that reproduce the report's cautions advise that average life figures are best used for shipment uniformity checks and for comparing abrasives when test sieves and machine settings reasonably match production conditions, and they discourage treating bench data as a direct proxy for field economics where part hardness, wheel maintenance and reclaim streams differ. [8]
Although written for SAE users, the approach aligns with international practice. ISO 11125-9 defines laboratory wear testing and performance methods for metallic blast-cleaning abrasives, addressing service life and cleaning performance, and equipment makers describe their test machines as supporting both SAE J445 and ISO 11125-9 procedures. [9] [10]