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Torque Wrench Gage RR

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  • #39098

    keyes
    Participant

    I am seeking a method for conducting a Gage R&R study on a torque wrench.

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    #118176

    Anonymous
    Guest

    Greg,
    One of the problems with torque measurements, in general, is a difference between torque-up and torque-down values: but one has to torque down to measure the amount of torque-set.
    You may be able to overcome this problem by recognising the role of stiction and making an allowance for it. It depends on whether or not you’re convinced by the ‘stiction’ argument!
    You might be interested to know that I came across a company in the UK that fastened an LCD to a hospital bedside unit without the use of a torque driver and destroyed just about every single ground plane. When I pointed it out they denied it, got quite angry, started shouting, but were very happy when I told them that I would them a set of  torque drivers of the correct value.
    (Later, a friend of mine joined a German company where they program magnetic domains into a spindle and can measure torque directly via an induction loop.
    Regards,
    Andy

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    #118196

    Dayton
    Member

    Andy,
    where they program magnetic domains into a spindle and can measure torque directly via an induction loop
    It’s not clear to me how that works.  Can you explain what is done and how the torque readings are picked up via an induction loop or give me the name of the German company?   I did a less than satisfactory google search on the topic.   Vinny 

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    #118198

    Dayton
    Member

    Andy,
     
    Never mind.   Thinking it over, I believe you are just talking about using induction relays and probably induction cup or double induction loop structures.   It just didn’t connect at first.
     Vinny

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    #118201

    Anonymous
    Guest

    Vinny,
    The company my friend worked for was called Fast Technology. They were bought out about a year ago by a Chicago based company. http://www.fastechnology.com/
    My friend now does other work using this technology – mainly for transmission torque control.
    My understanding is they use a machine to align magetic domains within a spindle, and then detect ‘misalignment’ of the domains under torque using an induction loop operating in saturation mode. I’m afraid that’s all I know about it, but I found the patent once and scanned it and it does describe the technology in detail. If you really interested I can put you in touch with my friend in Munich.
    Something else you might find interesting about this technology is that it uses Principle Components Least Squares in real time to detect the torquing end-point, which involves some interesting signal processing!
    Best regards,
    Andy

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    #118203

    Dayton
    Member

    Thanks Andy.  
     
    Poking around their website they describe the closed loop application that stops the torque driver’s rotational action at preset torque thresholds as you described in your comment on torque endpoint identification and response and that’s one of the things I was curious about – in addition to the overall technology and programming.
     
    I’m also real curious as to who did the algorithm work needed to make usable principle components least squares in constructing their torque endpoint detection slopes, thresholds and signal processing.   It all smoothly ties together in a seamless application – or doesn’t.  
     
    As you are well aware, it’s one thing to understand the math and quite another to effectively apply it in engineered resolutions.  
     
    I’m going to give them a call and talk to their technical folks to get a better understanding.  There could be all sorts of additional robotics implications at many macro and micro levels.  Cool stuff.   There’s so much out there, some already done but much yet to do.    
     Vinny

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    #118209

    Anonymous
    Guest

    Vinny,
    The software was prepared under contract, before my time, and did suffer some problems, mainly due to covariance between parts of the signal, but my friend ironed most of them out using a heustic approach. In other words, he tweaked parameters in the covariance matric. He now enjoys poking around in high speed cars! (One of their torque drills was made for Sears)
    Regards,
    Andy
     

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    #175182

    Craig
    Participant

    Did the initial question ever get answered? We are embarking on a similar endeavor.
    The plan at this point is to try an abbreviated version with 5 parts, 3 operators, and 3 replicates. “Parts” in this case are 5 different torque wrenches. The objective is to study our torque analyzer, not the torque wrenches themselves. If the torque wrench has a specification of 16 +/- 2, we will calculate the precision to tolerance ratio with a tolerance of 4 units.
    Insights? This was a little tricky to plan. The torque analyzer has its own spec, the torque wrenches have theirs, and the product that the wrenches are used on also has a specification on the degree of torquing required.

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