Elsmar Cove Forum Header Graphic The Elsmar Cove Wiki More Free Files The Elsmar Cove Forums Discussion Thread Index Post Attachments Listing Failure Modes Services and Solutions to Problems Elsmar cove Forums Main Page Elsmar Cove Home Page
Miner's MSA (Measurement Systems Analysis) Blog 
Go Back   The Elsmar Cove Forum > Common Quality Assurance Processes and Tools > Inspection, Prints (Drawings), Testing, Sampling and Related Topics
Forum Username

Wooden Line

Significant digits when reporting measurements

Wooden Line
Search the Elsmar Cove
Search Elsmar
Monitor the Elsmar Forum
Follow Marc & Elsmar
Elsmar Cove Forum RSS Feed  Marc Smith's Google+ Page  Marc Smith's Linked In Page   Marc Smith's Elsmar Cove YouTube Page  Marc Smith's Facebook Page  Elsmar Cove Twitter Feed
Elsmar Cove Groups
Elsmar Cove Google+ Group  Elsmar Cove LinkedIn Group  Elsmar Cove Facebook Group
Donate and $ Contributor Forum Access
Courtesy Quick Links

Links that Elsmar Cove visitors will find useful in your quest for knowledge:

Howard's
International Quality Services
Marcelo Antunes'
SQR Consulting
Bob Doering's
Correct SPC - Precision Machining

NIST's Engineering Statistics Handbook
IRCA - International Register of Certified Auditors
SAE - Society of Automotive Engineers
Quality Digest Portal
IEST - Institute of Environmental Sciences and Technology
ASQ - American Society for Quality
Reply
 
Thread Tools Search this Thread Rate Thread Content Display Modes
  #1  
Old 4th March 2004, 11:05 AM
vforge

 
 
Posts: 6
Please Help! Significant digits when reporting measurements

What is the accepted practice when reporting dimensional results with regard to significant digits and rounding?

For example, if a feature is toleranced as 5.00 +/- 0.25, should we report to 3 places (measurement is 5.252 = out of spec) or do we round down to 2 places and report 5.25 = in spec?

I'm new to quality, so trying to grasp the basics. Thanks.

Sponsored Links
  #2  
Old 4th March 2004, 01:21 PM
Bill Ryan - 2007's Avatar
Bill Ryan - 2007

 
 
Posts: 978
Welcome to the Cove

Our normal "practice" is to report one digit further than the callout. We don't have that documented internally but I seem to remember seeing it as a "should" somewhere (I require it for any documentation I may be sending to our customer). You may be, momentarily, "fooling" the customer (and yourself) but if you take variability into account, you could end up shipping product which will cause a "no build" or loss of functionality.

Good luck!!

Bill
Sponsored Links

  #3  
Old 4th March 2004, 01:58 PM
Wes Bucey's Avatar
Wes Bucey

 
 
Posts: 10,959
Quote:
In Reply to Parent Post by Bill Ryan

Welcome to the Cove

Our normal "practice" is to report one digit further than the callout. We don't have that documented internally but I seem to remember seeing it as a "should" somewhere (I require it for any documentation I may be sending to our customer). You may be, momentarily, "fooling" the customer (and yourself) but if you take variability into account, you could end up shipping product which will cause a "no build" or loss of functionality.

Good luck!!

Bill
When I was in the high tech aerospace/medical machining business, we made it a policy to cover this issue in Contract Review with the customer before we ever cut metal.

As an aside, we always discussed the form, fit, and function aspects of a component we made for customers (everything custom to customer's design.)

We found it helpful to request tolerances as either
(+0.000 / -0.xxx) or (+0.xxx / -0.000),
instead of (+/-0.yyy),
depending on the mating part. We had a nice little set of toys to illustrate our point (male mating parts with dimension at maximum material condition and female mating parts the opposite.)

Sometimes the customer's design engineers would have an epiphany and modify ALL their drawings to show tolerances in our suggested method.
  #4  
Old 4th March 2004, 02:09 PM
Sam's Avatar
Sam

 
 
Posts: 1,446
Normally you use an instrument that has a discrimination of ten times the tolerance or as Bill stated "one more place than the callout", which means you report the result to 3 places. Based on this I would say no you cannot round down.
  #5  
Old 22nd March 2004, 09:57 AM
Graeme's Avatar
Graeme

 
 
Posts: 428
I Say... The standard that applies is ...

Quote:
In Reply to Parent Post by vforge

What is the accepted practice when reporting dimensional results with regard to significant digits and rounding?
Practices vary, of course, and should conform to your customer's requirements. However, the applicable standard is:

ASTM E 29, Using Significant Digits in Test Data to Determine Conformance With Specifications.

Thist can be purchased (paper or electronic) from ASTM (www.astm.org).

According to the footnotes, this standard was first published in 1940 and reaffirmed in 1999.
Reply

Lower Navigation Bar
Go Back   The Elsmar Cove Forum > Common Quality Assurance Processes and Tools > Inspection, Prints (Drawings), Testing, Sampling and Related Topics

Do you find this discussion thread helpful and informational?


Bookmarks


Visitors Currently Viewing this Thread: 1 (0 Registered Visitors (Members) and 1 Unregistered Guest Visitors)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Forum Search
Display Modes Rate Thread Content
Rate Thread Content:

Forum Posting Settings
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Discussion Threads
Discussion Thread Title Thread Starter Forum Replies Last Post or Poll Vote
Supplier Measurements vs. Incoming (Receiving) Measurements freddie1997 Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 16 4th August 2011 10:01 PM
Explanation of Rule of Thumb (10:1) - Tolerance Zone or Digits Number Gabiddon Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3 15th March 2011 01:12 PM
Drafting Conventions per ASME Y14.5m - Three significant digits rule Dr. Electron Various Other Specifications, Standards, and related Requirements 12 4th January 2010 08:26 AM
How many digits should be used when measuring density? LTobiasL Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 5 12th March 2007 05:23 PM
Customer Satisfaction Reporting Metrics - Reporting to upper management? Scania22 - 2011 Documentation Control Systems, Procedures, Forms and Templates 3 9th December 2006 08:03 AM



The time now is 10:31 AM. All times are GMT -4.
Your time zone can be changed in your UserCP --> Options.


   


Marc Timothy Smith - Elsmar.com
8466 LeSourdsville-West Chester Road, Olde West Chester, Ohio 45069-1929
513 341-6272
NOTE: This forum uses "cookies".