Search the Elsmar Cove!
**Search ALL of Elsmar.com** with DuckDuckGo Especially for content not in the forum
Such as files in the Cove "Members" Directory

Gauge R and R - Product - Conveyor belt with threads that goes on Sprocket

#1
Hello Everyone,
Product - Conveyor belt with threads that goes on Sprocket
I have to find best way to measure pitch of the threads on the conveyor belt.( By using Variable Gauges or attribute gauges)
And also prepare plan for Gauge R and R for that Measurement method.
Could you please share your ideas.
It would be very helpful.
Thanks in advance.
 

Miner

Forum Moderator
Staff member
Admin
#2
I am not familiar with that product, but in general, a variable R&R study will require fewer measurements than an attribute study and provide more precise information identifying the source of any measurement problems. How do you currently measure it? If you find a better measurement method, do you intend to change to the new method?
 
#3
They are measuring pitch (39mm) of the threads on back of timing belt.
Currently they are using calipers with customized fixtures.
But they want to find a better measurement for consistency.
 
#5
Thanks Miner!!
This is my first task
I want to give them as many options as possible
1)
They have smaller ones too
Like belts with thread tolerances of 0.039+_0.04
Any other option?
2) And they are performing Gage R and R with only good parts(threads)
I am concerned that it will be biased
Will it be a problem?
 

John Predmore

Quite Involved in Discussions
#6
they want to find a better measurement for consistency
Can you share a portion of the engineering drawing of the feature you want to measure? A drawing or sketch with dimensions would give people an idea of the scale and geometry you are working with. In your first post you said conveyor belt, in the second you said timing belt. I have a different mental picture of those two belts, and my advice might not be helpful if your belt is very different in size or configuration.

The selection of a method will depend on a lot of things, like how many of these you measure in a day or how much money you are willing to spend.
What exactly is the difficulty with the current method (calipers with custom fixturing)? Maybe the design locates the dimension on a virtual feature, like a pitch diameter, and finding a virtual point consistently with handheld tools may not be practical. Taking measurements on elastomer features can also be a challenge because contact forces deform the rubber. So perhaps you should consider non-contact methods. There are many optical technology methods, staring with a comparator. If the belt is molded you may be dealing with flash, parting lines or other molding variation which is a different complication.
 

Miner

Forum Moderator
Staff member
Admin
#7
You could improve the results by measuring the pitch across more threads and dividing by the number of threads.

Regarding using only good parts: It depends on whether you are interested in %Tolerance or %Process Variation. If you are measure to a specification to determine whether parts are good or bad, use % Tolerance, and don't worry about part selection. If you use the gage to control the process (i.e., SPC), use %process variation and select parts that represent the typical variation from the process.
 
#8
Thank you so much sir!
Sorry for the confusion
1) Attached image is one of the type. It is extruded ones.

2) They are measuring it with calipers with fixtures that goes on two threads which gives pitch distance
problem: Fixtures are not sitting on the teeth when they are measuring ( gap between teeth and fixture)
I have to redesign it or suggest new method which will be consistent.
If i have to redesign could you please suggest some material which can help.
or could you sugest some new methods

3) Gage R and R
How to plan Gage R and R on this type of product. How to take samples ( Teeth of belt).
They did Gage R and R with caliper with fixtures.
but they did not take bad parts.
If I am thinking wrong about this could you please let me know
 

Attachments

John Predmore

Quite Involved in Discussions
#9
I suggest an optical comparator. From the drawing it looks like you are able to lay the belt flat so the pitch dimension is horizontal and a linear length, not a curved distance (maybe using weights to hold the circular belt in a flat plane). I commented earlier that virtual features can be difficult to measure consistently with handheld tools. The center of the tooth (maybe you call it a thread), which is the start and stop of the dimension, has no physical feature on the part to align the caliper blade against. The centerline of the tooth can be located on a comparator with some arithmetic; if you have an optical measuring device with software the centerpoint of a edge can be identified automatically. If your customer or design team is willing to consider an print change, it is the outside surface of the tooth not the centerline which is the functional feature. If the teeth are symmetrical and uniform in shape, the distance from the corner of the first tooth to the same corner of the second tooth is equal to the distance on centers. Using an optical system you could also measure the distance along the pitch plane, which is truly the functional dimension of a spline or gear-form.

If you still want to use calipers, maybe you can measure the distance from fillet at the root of one tooth to the opposite fillet on the next tooth. That would be pitch distance plus one tooth width, but it would be easier to measure with calipers than a corner which is not a right angle, and therefore more consistent. Subtract the tooth width, measured the same way, if you must have the pitch dimension.
 
Last edited:

GRP

Involved In Discussions
#10
Thank you so much sir!
Sorry for the confusion
1) Attached image is one of the type. It is extruded ones.

2) They are measuring it with calipers with fixtures that goes on two threads which gives pitch distance
problem: Fixtures are not sitting on the teeth when they are measuring ( gap between teeth and fixture)
I have to redesign it or suggest new method which will be consistent.
If i have to redesign could you please suggest some material which can help.
or could you sugest some new methods

3) Gage R and R
How to plan Gage R and R on this type of product. How to take samples ( Teeth of belt).
They did Gage R and R with caliper with fixtures.
but they did not take bad parts.
If I am thinking wrong about this could you please let me know
The characteristic is 1.956 +/- 0.005 what? If the units you are using are mm, forget about it.

Kindly share if the units are mm for further comments.
 
Top Bottom