I often receive this question “ what’s the life of this metal dome? We require 1million times?” from customers, it’s very easy to tell you the answer, but I think you maybe want to know how to test and get the result.
Hereby I will tell you how to test the life of metal dome, but firstly, I should let you know, we don’t have a unified test method in the market. And right now, a lot of people use ASTM F15780-07: Contact closure cycling generally testing conditions. And the standard we used was more higher in most of areas.
1) Testing probe: Often use rubber probe & tungsten steel probe, probe size from 1.5 mm to 3.0 mm or more bigger, normally it’s 30% of diameter of metal dome.
2) Test force: We use two times active force of metal dome, but in USA and EU, most of customers only use 1.1 times, so our testing force is higher, so that the final life cycle result will be smaller than others, but that also means customer can get a more longer life cycles if using their own standard.
3) Test Frequency: 2-3 times per second (120 times -180 times per minutes), 72,000~10,800 times/hour.
Before testing, should pre-press the dome 5-10 times, then put this dome under the test probe, set the test condition and begin life testing, until metal dome broken.
We will record various parameters of metal dome after each 100,000 times testing. (normally take 10 hours to go through 100,000 times). These parameters will includes:
CP: Compression Peak Force;
CL: Compression Low Force;
RL: Release Low Force;
RP: Compression Peak Force
CC: Click Feeling:
(CC(%)=(CP-CL)/CP x 100%, it is normally between 35% and 60%.)
For other parameters, please refer to another article: http://www.metal-domes.com/blog/2006/11/11/metal-dome-tech-and-parameter/
It will take 4-5 days to finish this metal dome life cycle testing, if your target was 1 million times. And for some metal domes, life cycles can be 2M or 3M times. And we are also developing new metal dome to achieve 5M and 10M times.
Also if your testing condition was different from us, the final result will be different. As mentioned above, most of customers in USA or EU will have longer life cycles than us, because different testing probe, force, or frequency. So maybe you can tell us what your testing parameters are so that we can simulate your metal dome life cycle testing condition to get a more closed result as yours.
Now are you clear how to test the life of metal dome? Below photo is the life testing machine. (metal dome life tester)