Does anyone what what proceedures spring manuf. use to obtain spring rates?
I'm testing springs and while I'm somewhat close to their test results I'd like to know what technique is manufacturer approved or standardized (if any) for testing spring rates. As of now, I'm using my jig to test at each 1/2" and 1" compression 3 times averaging the results. To compensate for variances in spring height I start each spring at 1oz of preload and then subtract that from the final scale display.
IE, I put a spring in my jig, I set my fixture to 1 oz. of preload and then zero my caliper. I then will move my jig 1.000" down and record the measurement minus 1g. Then divide that by 16 to get lb/in. if at 1" compression. If at .500" I'll divide that by 8, etc. My results are very repeatable so I can at least compare all of my springs but I'm very curious as to the spring manufacturers test proceedures.
Do they measure at only 1", average rate through 2 points, 4 points, 18 points up to 1 inch, 2 inches? Until coil bind?
Any input is appreciated.
Dave