6-sigma,Cp,Cpk,Pp,Pk calculation for SPC Analysis in MII

[Former Member]

Hi,

1) Are there any built in functions or calculations available in MII to get the 6-sigma,Cp,Cpk,Pp,Pk for SPC/SQC Analysis?

2) Is it possible to enable the periodic calculation of control limits?

In past if anybody implimented the above scenarios in MII, please let me know.

I'm using MII 12.1.4.

Thanks in advance.

-Suresh

Edited by: Suresh Hiremath on Feb 17, 2010 8:17 AM

[former_member201407]

Hi dude

I think there is an action called SPC/SQC Analysis under Charts option in the BLS which provides u all the required data for a SPC/SQC Analysis. In that action, u'll find a set of property nodes like Cp, Cpk, Cr and others which will return the values of them based on ur inputs (Query Template and Display Template [SPC Chart]).

Otherwise, u may need to have build ur own defined calculation formula for the same.

Regards

Som

[Former Member]

Som,

I've used the below builtin method to get the Cp in SPC Chart but I'm getting infinity for Cp.

var Cp=document.SPCAPP.ChartObject.getStatasticsItem("Cp");

Here I gave LSL=73.98 and USL =74.02,but couldn't help. Let me know I need to pass any other values to get the good Cp.

If I go for calcultaion seperately I have to use 6-sigma.To get 6-sigma I've to do hell lot of things.Is there any otherway buddy?

-Suresh

Edited by: Suresh Hiremath on Feb 17, 2010 8:39 AM

[former_member201407]

Hey i think u need to use following code (EST_CP instead of Cp)

var Cp=document.SPCAPP.ChartObject.getStatasticsItem("EST_CP");

Alternate way as follows

First u can get all standard params like mean, standard, lsl and usl using following codes

var x= document.SPCAPP.getChartObject().getStatisticsItem("MEAN");

var sigma = document.SPCAPP.getChartObject().getStatisticsItem("STANDARDDEVIATION");

var lsl= document.SPCAPP.getChartObject().getStatisticsItem("EFFECTIVE_LSL");

var usl= document.SPCAPP.getChartObject().getStatisticsItem("EFFECTIVE_USL");

then

	if(usl=="" && lsl!="")
		{
                                          var Cp = "NA";
		var Cpl  = Math.round(((x - lsl)/(3*sigma))*100)/100;
		var Cpu = "NA";
		var Cpk = Math.round(((x - lsl)/(3*sigma))*100)/100;
		var Cpm = "NA";
		var Cr = "NA";
		}
		if(usl!="" && lsl=="")
		{
		var Cp = "NA";
		var Cpl ="NA";
		var Cpu = Math.round(((usl - x)/(3*sigma))*100)/100;
		var Cpk = Math.round(((usl - x)/(3*sigma))*100)/100;
		var Cpm = "NA";
		var Cr = "NA";
		}
		if(usl!="" && lsl !="" )
		{
		var Cp = Math.round(((usl - lsl)/(6*sigma))*100)/100;
		var Cpl = Math.round(((x - lsl)/(3*sigma))*100)/100;
		var Cpu = Math.round(((usl - x)/(3*sigma))*100)/100;
		var Cpk = Math.min(Cpl,Cpu);
		var Cpm = Math.round(((usl - lsl)/(6*Math.sqrt((Math.pow(sigma,2) + Math.pow(x-((parseFloat(usl)+parseFloat(lsl))/2),2)))))*100)/100;
		var Cr = Math.round(((6*sigma)/(usl - lsl))*100)/100;
		}

Regards

Som

[Former Member]

Som,

Thanx a lot buddy.... i will check the above and get back to you.

-Suresh

[jcgood25]

I assume you have a valid Target to go along with the USL and LSL.

You're getting infinity because there is no sigma (if you enable the control limits auto calc you should get a CP and CPK number)

Otherwise the EST ones should work.