Tools used for measuring (New to metrology)

Rvija

Registered
Hi,my work is creating inspection plans for drawings/part spec/label using Inspection xpert in a medical device manufacturing company. I am very new to this. I don't get to actually use the tools to measure it (funny ha?), but I have to just look at the cad /solidworks dwg and understand which method to put in the inspection form, along with the Inspection code. I am lost but trying to learn very hard. What I do gets inspected by am experienced inspector who doesn't really encourage learning (he thinks I do t have the ability to learn). I appreciate his help but not the discouraging words when I ask him to explain something. Does anyone have a discussion thread here or an appropriate source to help me? For eg: If a diameter is shown, how do I know,if a vernier or vision system or micrometer is better ? I get the idea about gage (why is it gage and not Gauge??) pin usage lately. And certain other stuff which I am learning every day. Thank you in advance
 

Johnny Quality

Quite Involved in Discussions
Rvija,

Welcome.

Your best bet would be to throw your questions here or here.

It's good that you're engaging with the people who perform the work you are planning.

For a start, the correct tool depends on the type of measurement, material, criticality of the dimension, what you'll use with the information, access of measurement, manufacturing method, expected variance, tolerance and many other factors that I've missed.

If we take your diameter example, it might suffice to use a Vernier if it's say...less than 250mm in diameter otherwise you'll have a hard time keeping the Vernier parallel. If it's machined on a lathe from stainless steel with a tolerance of +/- 5mm then it stays feasible, if the tolerance is only +/-0.05mm then you'd consider precision gages or using a CMM. If the diameter is internal instead of external then it'd be unwise to use a Vernier as you'll be measuring from chords in the circle instead of a points. Your best bet then would be a CMM or vision system. If the material is carboard you'd almost certainly want a non contact solution.

I hope this helps somewhat.
 

Rvija

Registered
Rvija,

Welcome.

Your best bet would be to throw your questions or

It's good that you're engaging with the people who perform the work you are planning.

For a start, the correct tool depends on the type of measurement, material, criticality of the dimension, what you'll use with the information, access of measurement, manufacturing method, expected variance, tolerance and many other factors that I've missed.

If we take your diameter example, it might suffice to use a Vernier if it's say...less than 250mm in diameter otherwise you'll have a hard time keeping the Vernier parallel. If it's machined on a lathe from stainless steel with a tolerance of +/- 5mm then it stays feasible, if the tolerance is only +/-0.05mm then you'd consider precision gages or using a CMM. If the diameter is internal instead of external then it'd be unwise to use a Vernier as you'll be measuring from chords in the circle instead of a points. Your best bet then would be a CMM or vision system. If the material is carboard you'd almost certainly want a non contact solution.

I hope this helps somewhat.
Thank you for your guidance I am so glad to have found this forum. I am breathing a sigh of relief since I wasnt getting anywhere other than the self taught comparison lessons I have been doing between different inspection plans. I hope to learn a great deal of information through discussions here.
 

Johnny Quality

Quite Involved in Discussions
That's exactly how I felt three years ago when I was tasked to revise our management systems. It's a cosy place with very wise people.
 

Miner

Forum Moderator
Leader
Admin
You can find some good reference material on the websites of the gage manufacturers, such as this reference. This article lists six basic questions you should ask. While the author obviously wrote with expensive devices in mind, the questions are still relevant for hand gages.
 

Rvija

Registered
Thank you !! Is this the asq book? I bought one called "the beginners guide to Quality Manufacturing" do you any thoughts on that?
 

David-D

Involved In Discussions
It is a bit dated, but i find a great resource on gaging techniques, particularly for new hires is MIL-HDBK-204, Design of Inspection Equipment for Dimensional Characteristics. It is available free from the USG here:

https://quicksearch.dla.mil/qaDocDetails.aspx?ident_number=53932

Its last update was 1990, so it isn't well focused on newer methods (CMMs, vision systems, etc) but on classic techniques it is great.

David
 
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