Which control chart to use for SPC control for torque moment which value is min 15 Nm

[igor_zdraveski]

Hallo !
I have problem. I need to make SPC control for torque moment which value is min 15 Nm. Please help me which control chart I need to use and if someone have example please send me.

Best Regards.
:mg::mg::mg::mg:

 

[Miner]

Re: Whitch control chart I need to use

Please provide additional information on your process.

At this point all I can tell you is that you will need some type of variables control chart. To tell you whether an IMR, Xbar-R or other type will depend greatly on the type of processing that occurs.

 

[Steve Prevette]

Re: Which control chart to use for SPC control for torque moment which value is min 1

Hallo !
I have problem. I need to make SPC control for torque moment which value is min 15 Nm. Please help me which control chart I need to use and if someone have example please send me.

Please do realize that the control chart itself has nothing to do with the specification (min 15 Nm). So whether the specification is one sided or two sided, we still make the same chart. I would agree, that likely this is either xbar-R, or x-sigma.

I do have some control charting materials (with example charts) at Trending Primer and Trending Training - Performance Measures and Statistics Course Number 7885 Fluor Hanford.

 

[bobdoering]

Re: Whitch control chart I need to use

Please provide additional information on your process.

At this point all I can tell you is that you will need some type of variables control chart. To tell you whether an IMR, Xbar-R or other type will depend greatly on the type of processing that occurs.

I agree - the distribution of torque is likely a normal distribution, and the choice of I-MR or X-bar-R really depends on whether the variation found within a sample is representative of the variation of the population - except for special causes.

 

[Kales Veggie]

Re: Which control chart to use for SPC control for torque moment which value is min 1

Hallo !
I have problem. I need to make SPC control for torque moment which value is min 15 Nm. Please help me which control chart I need to use and if someone have example please send me.

Best Regards.
:mg::mg::mg::mg:

I agree with the other posters (XBar-R).

How are you planning to measure torque? Are you verifying the torque as part of the process or "off line"?

 

[igor_zdraveski]

Re: Which control chart to use for SPC control for torque moment which value is min 1

Hallo to everyone.

My part is metal plate on which are riveted two screws (clinch studs) . At the drawing is specified min push-out force and min torque moment. For torque moment is not specified the tolerances only min torque moment 15Nm (I don't have Upper limit). This characteristic we are measuring whit torque wrench out of line. I don't now does we need to go to the maximum torque and scrap measured parts or we need to make measure only pass no pass and use again measured parts, and use attributive charts.
I have tried to make x-r but the result was wrong.

Thank in advance for your help.

 

[Kales Veggie]

Re: Which control chart to use for SPC control for torque moment which value is min 1

Hallo to everyone.

My part is metal plate on which are riveted two screws (clinch studs) . At the drawing is specified min push-out force and min torque moment. For torque moment is not specified the tolerances only min torque moment 15Nm (I don't have Upper limit). This characteristic we are measuring whit torque wrench out of line. I don't now does we need to go to the maximum torque and scrap measured parts or we need to make measure only pass no pass and use again measured parts, and use attributive charts.
I have tried to make x-r but the result was wrong.

Thank in advance for your help.

I think it is a destructive test and probably should not use for process control and SPC (measuring the wrong thing and very costly!).

Checking the torque and force on the finished part is too late in the process. You must control the process upstream.

You should look at your PFMEA and determine what process controls (for example: hole size control, surface finish, hardness, taper, material thickness, clinch nut capability on size and material) are in place to control the failure mode.

Start looking at process characteristics and control those with SPC.

I have seen similar situation where only one piece is tested per shift to verify the process. The push out force / break away torque is recorded on a run chart (not for SPC or process control, verification of the process only).

 

[bobdoering]

Re: Which control chart to use for SPC control for torque moment which value is min 1

I think it is a destructive test and probably should not use for process control and SPC (measuring the wrong thing and very costly!).

Checking the torque and force on the finished part is too late in the process. You must control the process upstream.

You should look at your PFMEA and determine what process controls (for example: hole size control, surface finish, hardness, taper, material thickness, clinch nut capability on size and material) are in place to control the failure mode.

Start looking at process characteristics and control those with SPC.

I agree - destructive testing verus simple torque or torque falloff - is a different animal. Controlling upstream (if possible) would be a control rather than a report card chart.

But, I am curious as to the "wrong result" you had with an X bar-R chart? What did you see, and what did you thing was wrong about it?