Analysis of Continuous Diameter Measurements

[NickMechE]

Hello all! This is my first post to this forum, so here it goes...

I recently came on a new project involving the design and manufacture of complex cable assemblies. I've never worked with cables or other long continuous parts before.
[ul]
[li]Each cable goes through multiple manufacturing processes, including many different insulation extrusions of various materials and thicknesses.[/li]
[li]Each Manufacturing step has a desired final OD with tolerances.[/li]
[li]During each process, the diameter of the cable as it's spooled onto the take-up reel is measured, with a measurement taken every foot or so.[/li]
[li]

For my current project we're working with cables between 1000 and 10000 ft in length​

[/li]
[/ul]

My question is: How do I best analyze this measurement data throughout the entire build of the cable? What should I be looking for? What are my red flags?
I have access to matlab so I can create histograms and find any measurement you care to name, but it's been a while since college and my statistics classes.

E.G. What kind of histogram? How many bins? How should they be spaced? How should they be normalized?​

Before I can onto the project, the engineer was simply finding the average diameter and noting where along the length the diameter varied from the average by arbitrary amounts (like, "green" measurements were within .010" of average, "yellow" were between .010" and .015", "red" was more than .015"), but I don't feel like that's a very useful system.

Do you guys have any thoughts?

 

[aap2]

You could do a perimeter measurement. An additional thing to look for are exposed wires.

The histogram function in Matlab will automatically create a histogram with 10 bins: histogram(x).
If that is not appropriate, then you can adjust the plot with histogram(x,nbins) to specifiy the number of bins and their spacing.

As a refresher, the histogram will show the frequency of each bin, with the bins as the diameter.

 

[granQC]

In my opinion,
Based on your information below, you will be the one to design and manufacture the cable assemblies THEN also given the prerogative to judge if the cables are acceptable; therefore you should also be the one to indicate the acceptance criteria and test required for these cable based on project specification and minimum as required by International Standards (e.g. visual-no exposed wire,every 100ft of wire : ± 0.01" tolerance of OD Diameter, or every 100ft of insulation (2pts check): minimum thickness is every 100ft of cable 2.2mm or or every 100ft of cable (incl. insulation) : ± 0.02" tolerance of OD Diameter, etc. or voltage test of 0.6 kV for 5 minutes or Resistance test @ 20deg C of 4.7 for 0.25 in2, etc.).
Remarks: OD Check is I believe only one of the criteria for acceptance.

As long as these criteria were met, cables can be deemed as ACCEPTABLE.

Just my thought.
Ciao!