ultrasonic thickness measurment

I have not the foggiest. Think I would start talking with people who may know something about this - the makers of sensors just may be a good place to start.

Ultrasonic may be a good place to start - they use it for checking brazed joint quality and if I recall paint thickness.

Dan Bentler

I looked at a similar problem only I didn't always have a metal inner to be able to detect. I couldn't find a sensor to measure the thickness of plastic directly if I only had access to one surface of the material.

Ultrasonics are fine but you have to have good surface to surface contact between the sensor and the plastic, i.e. no air gaps, and then a fluid to give perfect transmission. If you have seen a woman have an ultrasound to 'see' an unborn baby you will have noticed that they don't just put the sensor on to the belly, they use a jelly type transmission fluid.

Types of measurement:

The simplest is if you can make physical contact with the Fibre layer. You know the spacial position of the inner core, you touch the Fibre to know its spacial position and subtract one from the other to get the material thickness.

Or you can use a non contact sensor to give the spacial position of the outside of the fibre and again subtract one from the other.

Or you can use a non contact sensor with two measurement systems, one measures the distance to the surface of the plastic, another measures the distance to the metal liner. The combined sensor gives a single output of plastic thickness.

I have been in contact with this company in the UK:
http://www.micro-epsilon.co.uk/index.html
They deal with exactly the type of thing you are trying to do.

Bryan

fever16 said:

this is just an idea that i had in mind.is this gonna work?

Click to expand...

Yes.... I have done a lot of measurement applications, never with ultrasonic but laser and mechanical

I did have issues finding the way to connect them to the PLC, the first one did was setup as a two piece application.... the operator set the tolerance inside the ( http://www.mitutoyo.com/ ) controller, I wired in a optical relay and had that relay give the PLC a GO or NO-GO signal

There are a lot of measurement companies out there and they love to work with people on their application

One question... is either the inside or the outside in a fix location when you are wanting the measurement? if the ID will always be in location X then you just need to look at the location of the OD and compare the two, not knowing the mechanical application its hard to figure out what can be done

One of mine was to measure a thin circuit board, so I used vacuum to pull it down to a fix position, also used another cylinder to push the laminate down, then measured the change from zero with a plunger style micrometer

Yes it is possible but you will need to do your home work

when i discussed this with pepperl+fuches people.
they gave me quote for below sensor.

http://www.pepperl-fuchs.com/cps/rd...id=39282&cid=2&rdsessid=SID-44793724-96F1A6F0

as per spec,0-70mm is dead band and 70-1000mm is working(sensing area).and this gives 0-10V analog output.
so i was planning to mount the sensor around 150mm and get the 0-10v for that minimal rage.which gives me better and accurate result.
this is just an idea.as i never worked on ultrasonics i need some experts opinion.

thanks

Fever16, my two cents, I worked 15 years for a pipe plant, i was involved in designing controls for the FBE (fusion bond epoxy) and polyethilene cover for pipes. If your process is polyethilene be careful with ultrasonc transducer, normally the work inmerse in water, mechanical support for the ultrasonc transducers has to be well designed otherwise you`re going to have problems when the pipe is rotating (if that the case) and you get the polyethilene spiral causing noise. There is a company in canada that design excellent support for ultrasonic transducers, though they design equipment for testing welded pipe mainly, maybe they can help you, here is the link, I used to work with their equipment.
http://www.inspectech.ca/Content05/Products/index.htm