The Almen Strip: An 80+ Year Journey of Setting a Standard

Author:  Erik Waelchli | Industry Advisor | IBD Connection, Inc.
Source:  The Shot Peener magazine, Vol 40, Issue 3, Summer 2026
Doc ID:  2026051
Year of Publication:  2026
Abstract:  
INTRODUCTION After intense work, shot-peening engine valve springs for durability, John O. Almen filed for the “Shot Blasting Test”- Patent in 1942. On June 6th 1944 the patent was granted under the number #2,350,440 with its inventor John O. Almen and assignor General Motor Corporation, Detroit MI. With this event GM and John Almen laid the foundation for the industry to follow and challenge, a foundation becoming the basis for the SAE J-442 industry standard. Throughout many years of evolution and refinements of the Almen strip, strip holder, and Almen gauge, the basic principle remained: Peening a standardized strip and measuring its stress-induced deflection. This Almen strip “peen-sensor” has no knobs turn, no electronic circuits to adjust, no calibration is required, yet it responds to all peening parameters, from media velocity, -size, -hardness, -flowrate, nozzle type or size, set-up geometry, exposure time, etc. Exposed to any peening process, the Almen strip’s response is unconditional and without prejudice, truly setting an industry standard. This Almen strip peen process-performance test is standardized and adopted worldwide across a variety of industries. Industries that manufacture critical components and products we all rely on throughout our daily lives. On millions of technical drawings and technical documents the Almen strip response is “the qualifier” for the peen process. Over the years, processes and their machine control technologies have evolved, demanding more accuracy from Almen strips and its support devices. The following is about the 80+ year journey of the Almen strip.