I need help with joint rate simulators everyone is used to using just the power tool key on the CDI torque transducer. I need all the information I can get about these. How they work, how to change the stacks, I am a newer guy at the lab and I wanted to figure the concept and understanding of these. Thank you
I am not a Torque expert. But let me add some possibly contentious input on this. First, I am presuming we are discussing electric torque screwdrivers, or possible pneumatic somehow motorized drivers. The term sometimes used is "dynamic torque." Here is where I may get some disagreement (but I firmly stand by my following comments).
So-called "Dynamic Torque" is not a proper traceable calibration. This is because there is not traceability for the higher speed operation of torque calibrators. I worked in a highly regulated lab and walked into a circumstance where one company had used one brand of torque calibrator on many hundreds of Mounts/Hios electric torque screwdrivers set to 3 month intervals. I worked for the next company who took over the calibrations on these and used another brand of torque calibrator. When you did a static torque test between these two brands of calibrator of the same setting (can't remember actual setting, but lets say we did 12 in. lbs), you would get very good statistical matches on repetitive tests. But when you did the same match (numerous iterations of warm ups, and numerous actual readings), there was a very repeatable difference. I even contacted some national standards lab for background info. What I found was that so-called "dynamic torque" is not truly torque (because torque is only an angular force times distance - only). When you add a speed component, it is no longer torque. Problem is many in industry incorrectly attempt to calibrate non-torque with a torque standard. The addition of speed is more or less the addition of risetime (which is not spec'd or designed in by any OEM - I even got an OEM sales rep mad at me about this - which I stand by) is not in the specs or design considerations as far as I know (unless it has been recently added in). If you think of screwing a screw in at X rpm, and all of a sudden, spiking the transducer when you hit bottom, there is a force pulse at a given speed, with a risetime. I even got I believe Japan and Germany's national labs, a few years ago to tell me they were experimenting with this and how to create national traceability on this. If someone has more up-to-date info on this traceability, I'd love to hear about it.
So as long as you remain with the same brand of torque calibrator you will get good repeatability. The run-down adapter is designed to provide a soft landing so that torque standard will more closely resemble the device being torqued.
I was even a little disturbed by an otherwise very high quality company regulated by a particular federal agency (which I won't mention out of respect for them) chose to continue to "calibrate" these electric torque screwdrivers. They chose that since they changed OEM's for the torque calibrators, and virtually every single one of their hundreds of Mountz/Hios electric torque drivers went out of tolerance, to do up a special justification report and include it with the out of tolerance reports (played politics with the whole thing).
USE OF RUN DOWN ADAPTERS: I don't know off the top of my head specs for the run down adapters. I believe there are instruction sheets on what range you are calibrating, and how many washers, and what spring to use. The only important consideration I think is that you pick one that reasonably simulates your production use. When we selected run down adapters, we looked (as I think I recall) at the ranges for each and intuitively selected which one to use. I would recommend buying a set of them, and experimenting. I don't know a definitive answer for exactly which one to use with what range (and it has been about four years).
I also have a lot of problems/questions with the run down adapters. Another problem I havce seen is where they try to purchase the cheaper handheld screwdrivers and then ask me to calibrate them. I know there are some nicer ones out there but most companies do not want to spend 3,000 to $4,000 to get a good repeatable screwdriver manufactured for the purpose of repeatable measurements. Have you had any luck with the torque "guns" themselves? Any recomendations for me?
Thanks for the help
USMCPMEL - the most popular brand I see a lot of is Mountz/Hios electric torque screwdrivers. I worked at a large factory that had many hundreds of them and they seem to be a good, robust method. I believe if you want to do some google searching, try looking for HIOS CL6000 to start with.