Capability or Gage R&R Study for Leak Tester?

#1
I have a really hard trouble making an analysis of my leak tester

We put the pipe plugged into the device (leak tester)with the opposite side blocked, then 150 psi air pressure fill the interior of pipe in order to verify any possible leak.
Once this device has completed the test, It displays a leak value which It should not be greater than the leak value specified in the print. If the value is greater, the part has failed because It has a leak.

Logically, this is not a replicable test, because same part never will show same values. We can not control the value, we can only control if the part is going to leak or not by checking all joints where It could be a leak. That is the most important thing here.

The problem is that a normal capability study does not represent anything here since we do not control the distribution of the data and I do not care if I have a CPK 1.33 in this case.

Someone recommended me a Gage R&R study Nested. I have already done that in Minitab but I can not find how that can help this.

Does anybody of you guys know something about how to conduct a kind of capability or Gage R&R Study for this type of situations? I really need some help.

Thanks in advance.
 
Elsmar Forum Sponsor

Ronen E

Problem Solver
Staff member
Moderator
#4
It doesn't get more specific than that. An honest GR&R study lets you know whether the problem is in the testing equipment, or with the testers (operators), or the actual product. If that can't help, I don't know what can.
 

Marc

Hunkered Down for the Duration
Staff member
Admin
#5
I was just asking if someone who has actually worked with leak tests could help. Don't take my reply here personally. I was a lab manager in a lab that did leak tests, but that was in the 1980s and I don't remember much other than the operational aspects. Not to mention I'm not a GR&R guru nor am I a math/statistics wiz. The original poster probably isn't either. More specific help from a statistician with or without hands on experience would be appreciated.
 

Ronen E

Problem Solver
Staff member
Moderator
#6
I have some of both - experience with leak testers and with GR&R. I don't consider myself an expert/guru on either, and of course additional input from one would be great. However, I think what can really help here is a clarification from the OP what exactly is the issue. It is my impression something is wrong with the test set-up or the test method, because the results can't be replicated to a satisfactory level. IMHO a straightforward GR&R study should go a long way in this case, but maybe there's something important I don't know / don't understand here.
 
Last edited:

optomist1

A Sea of Statistics
Trusted Information Resource
#7
sometimes, sharing the specifics of the test process can shed some light....Equipment Setup, Specifics air as the pressurized gas, device being tested...etc., etc.,
 

William55401

Involved In Discussions
#8
Think about this from a test method validation standpoint. Do you have a known bad part? Hopefully, you have several representative of the defects you are trying to prevent in your process. Does the tester reject these parts? Can you translate the leak rate of known bad into a leak rate that your tester can detect? Is your test method providing protection to your customer? There are both variable and attribute approaches to TMV. The capability studies and the GRR will help you understand inherent variation. However, IMHO, the goal is to ensure that known good (and bad) parts are accurately detected. Your leak test may have ability to analyze variation in measured pressures during Charge, Settle, and Test times. Enough rambling. Have fun.
 

Miner

Forum Moderator
Staff member
Admin
#9
Logically, this is not a replicable test, because same part never will show same values. We can not control the value, we can only control if the part is going to leak or not by checking all joints where It could be a leak. That is the most important thing here.
Are you expecting a measurement device to always provide identical results? This only happens when the measurement device has low resolution. A measurement device with sufficient resolution will always show variable results.

Do your results vary randomly around an average value? Do they trend in a particular direction? What specifically do you find illogical about it?

Note: I do have some experience with leak testing using Helium and a mass spec.
 
Thread starter Similar threads Forum Replies Date
O Capability or Gage R&R Study for Leak Tester Reliability Analysis - Predictions, Testing and Standards 11
D AIAG 4th Edition Capability Study and Gage R&R Requirements Document Control Systems, Procedures, Forms and Templates 8
B MSA (Gage R&R) vs. Capability Cpk Study - Helium Leak Check Station Statistical Analysis Tools, Techniques and SPC 2
T Machine GR&R (Gage R&R) - Capability Study Capability, Accuracy and Stability - Processes, Machines, etc. 5
V Supplier Capability and 100% Sort causing Gage Wear APQP and PPAP 1
E Capability of Gage (Cg & Cgk) for New and Repaired Gages Capability, Accuracy and Stability - Processes, Machines, etc. 10
F Process Capability on go / no-go gage? Capability, Accuracy and Stability - Processes, Machines, etc. 1
S Operator Capability - Gage R&R Poor Repeatability Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 8
Y Product Stability (Machine Capability) vs. Equipment Repeatability (Gage R&R) Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 7
I What is Gauge Capability? Dial Thickness Gage and Digital Vernier Calipers Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 17
M Gage R&R and Capability - Between 10% and 30% and cannot be improved Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
Q Capability - CPk comparison values Capability, Accuracy and Stability - Processes, Machines, etc. 8
R Capability analysis - What is going on this chart? Manufacturing and Related Processes 15
H Capability Data for Paint Thickness on Painted Parts Statistical Analysis Tools, Techniques and SPC 10
N Is capability applicable for a destructive test? Capability, Accuracy and Stability - Processes, Machines, etc. 9
D Pre-Production Capability Assesment Reliability Analysis - Predictions, Testing and Standards 5
T Iec 60601 Impedance and current-carrying capability IEC 60601 - Medical Electrical Equipment Safety Standards Series 1
S Machine Setup for a CNC Machine Capability Study Capability, Accuracy and Stability - Processes, Machines, etc. 1
D O Ring capability and measurement - What is the automotive 'norm' for capability studies on O Rings? General Measurement Device and Calibration Topics 3
M Measuring Capability of Process with Multiple Specifications Capability, Accuracy and Stability - Processes, Machines, etc. 6
G Capability Study for Tapped Hole Reliability Analysis - Predictions, Testing and Standards 3
E Sampling for capability studies for variables and attributes Capability, Accuracy and Stability - Processes, Machines, etc. 4
L How to evaluate the process capability of a data set that is non-normal (cannot be transformed and does not fit any known distribution)? Capability, Accuracy and Stability - Processes, Machines, etc. 12
T Final process capability results - What I am supposed to present? Cp and CpK? APQP and PPAP 11
G Plotting capability study data - I have a bimodular data distribution Capability, Accuracy and Stability - Processes, Machines, etc. 4
A Statistic Tools to Know Capability of Sealing Machine for Seal Width Capability, Accuracy and Stability - Processes, Machines, etc. 3
Q How to perform Process Capability for true position Statistical Analysis Tools, Techniques and SPC 10
V Generic requirements regarding capability study in automotive Capability, Accuracy and Stability - Processes, Machines, etc. 1
A Capability Analysis for Packaging Seal Strength with spec. >0.1 Kgf using Minitab Using Minitab Software 6
J Initial capability for injection molding part Capability, Accuracy and Stability - Processes, Machines, etc. 6
Ron Rompen Ford Method - Position Capability with MMC Modifier Capability, Accuracy and Stability - Processes, Machines, etc. 14
S Understanding control chart and measurement capability Statistical Analysis Tools, Techniques and SPC 2
L IATF 16949 Cl. 8.3.3.2 Manufacturing process design input - Process capability IATF 16949 - Automotive Quality Systems Standard 1
B Short term vs Long term Capability - We ship millions of parts in a year Capability, Accuracy and Stability - Processes, Machines, etc. 7
M IATF 16949 - Capability study on non critical dimensions? Statistical Analysis Tools, Techniques and SPC 4
J Are Capability Requirement(s) Valid for All Characteristics? Capability, Accuracy and Stability - Processes, Machines, etc. 6
Y Process Capability for Non-Normal Data - Philosophical Questions Capability, Accuracy and Stability - Processes, Machines, etc. 6
M Process Capability in a High Precision Environment Capability, Accuracy and Stability - Processes, Machines, etc. 7
M CAAC-145 Manuals - Looking for examples of MOM's, MMM's Capability Lists, etc. Federal Aviation Administration (FAA) Standards and Requirements 13
J Powdercoating Capability Employing a Robotic Arm Manufacturing and Related Processes 1
L Excel Template for Cgk Study wanted (Capability Gauges Study) Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 12
V Product Development - When to start calculating Process Capability Capability, Accuracy and Stability - Processes, Machines, etc. 3
V Capability for Correlated Charteristics Capability, Accuracy and Stability - Processes, Machines, etc. 2
S Proving Process Capability of a Packing Machine Capability, Accuracy and Stability - Processes, Machines, etc. 6
R Visual Attribute Inspector Capability and KAPPA Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
ncwalker Process Capability Study - Aggregate vs. Individual Processes Statistical Analysis Tools, Techniques and SPC 24
KyloDen Capability Study and Qualifying a Supplier Capability, Accuracy and Stability - Processes, Machines, etc. 5
V Process Capability for parameters with non-normal distribution. Capability, Accuracy and Stability - Processes, Machines, etc. 16
J Process Capability - How much percentage of tolerance? VDA Standards - Germany's Automotive Standards 3
bobdoering Unilateral Tolerance Capability Calculations Capability, Accuracy and Stability - Processes, Machines, etc. 1
Similar threads


















































Top Bottom