Measurement of extra-small distances

[Vianney]

Hello,

I am currently working on seats for the automotive industry and I would like to detect the presence of a small plastic joint automatically. When this small joint is not present, another part of the mechanism is able to move a few millimeters. I thought of using a proximity sensor with contact to measure the position of this part with the joint and set it as a reference. Then, for each test, the part can be pushed from the opposite side of the sensor by a spring and the difference between the measure and the reference can be calculated.

Do such sensors exist? Is there another solution?

Thanks.

Vianney

 

[IRstuff]

There are lots of options; it's just a question of what accuracy do you actually need, and how much are you willing to pay. One option is a laser rangefinder:

https://www.mysick.com/eCat.aspx?go...D=380&Category=Produktfinder&Selections=44127

This has the advantage of being tolerant of most material or surface properties.

TTFN
faq731-376

 

[Vianney]

Actually, I would like something really precise (to measure about 1mm), the probleme is that the object that moves is really thin (cf picture). Do you think a laser rangefinder could work? I also thought of a microswitch.

And I would prefer something not too expensive but that is not the most important.

Thanks.

 

[GregLocock]

No, don't use a microswitch unless robustness issues force you there.

I strongly suggest you get a sample into a lab and measure the force vs deflection curve with and without the missing part. Then decide on an appropriate pass fail criteria.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[IRstuff]

Laser is light, so if it reflects, and is not transparent, there is no issue.

The Sick laser has resolution down to 0.05 mm

TTFN
faq731-376