Equipment Utilization Inefficiencies – Not using all the equipment in the universal test station
One of the side effects of having a universal test station with all the hardware you will ever need is underutilized equipment. If you are not using equipment in the station for most of the test of your product, then it might not be the most effective approach for manufacturing test.
- Adding equipment for the “just in case” scenario
Universal test stations end up in this situation when the developer tries to plan for the unknown. They think, well we might have this capability in the future so we should add this piece of equipment to test for it. Sounds like a good idea, but then that scenario never occurs or occurs infrequently. Now money has been spent on a piece of equipment that isn’t used to its full potential. Because that equipment is part of the standard hardware in the universal test station, money spent on underutilized equipment is multiplied by the number of universal test stations containing it.
For example, you have a device with a LVDT, RVDT, and power output interface. A universal test station is built to test these three interfaces necessitating two pieces of equipment, an active load for the motor output and a power supply and DMM for the LVDT and RVDT. You start testing and realize that the active load and DMM are only used for half of the test. The rest of that time the equipment is sitting idle, wasting time and money. The device or station may not allow for the ability to test using both pieces of equipment at the same time, and making the station a multiple unit tester increases complexity and cost. Maybe it would have been better to make two stations at this point. One for the LVDT and RVDT testing, and one for motor output testing. This way the equipment is being used 100% on both stations while testing two different units, without adding hardware or software complexity. It may not always be possible to get 100% utilization out of all equipment during test, but striving for it should be a goal.
- Use test carriers to reduce test connection times
One could argue that the time it takes to connect the unit under test justifies having a universal test station. Your device may have connections that take a long time to make or have low insertion counts. A counter argument to that is that you create test carriers for each product you have. The carrier just takes the signals from the device and routes them to a common connector back plane that could be used on multiple stations. There would just need to be a unique carrier for each unique product interface. Carriers can save test time if the connection to the station is quick and simple.
A further benefit is if the products can be designed with a standardized test connection. This requires less unique test carriers, which saves time and money on the development of new carriers to connect the product to the test station.
- More station equipment and paths, more things to validate
Another consideration when having lots of different equipment in a station is validation. Even though only a fraction of the test system is being utilized to test any one product, the entire system needs to be validated and verified. This can be very time-consuming depending on the number of interfaces there are, and how they need to be tested. Keeping the station streamlined to the function it is testing will help avoid these issues.