Strain gauge adhesive subsitute?

[Wond3rboy]

Hi i know this is the wrong question on the wrong forum.. but i am totally out of options right now.I cant import adhesive since it makes the shipment charges to USD 500!!!..

I want to know whether there is any locally available (like super glue)substitute to strain gauge adhesive?or not?

 

[dknguyen]

This

**broken link removed**

makes it sound like it's some kind of superglue (cyanoacrylate)? Maybe that rubber-toughened super glue that's more flexible than normal? From Loctite (craft shops and tool stores) or Mercury Adhesives (at hobby shops).

 

[jpanhalt]

1) Which adhesives do you have available? Of those adhesives, are there modified versions available, such as the neoprene modified cyanoacrylics or epoxies? Is Pliobond available (it is a solvent-based, neoprene contact cement)?
2) What are the materials you are trying to attach? That is, the best adhesive for metal to metal is different than for plastic to plastic, rubber to plastic, etc. There are even good ways to attach Teflon to steel, but you need to know what the materials are that you are trying to attach to each other.
3) Do you need a flexible bond, a bond that is shock resistant, etc. Does the bond need to be water resistant or waterproof?

John

 

[Wond3rboy]

This

**broken link removed**

makes it sound like it's some kind of superglue (cyanoacrylate)? Maybe that rubber-toughened super glue that's more flexible than normal? From Loctite (craft shops and tool stores) or Mercury Adhesives (at hobby shops).

Vishay They were charging USD 550 for S&H and USD 125 for processing even when i told them that i was a student and offered them proof!

1) Which adhesives do you have available? Of those adhesives, are there modified versions available, such as the neoprene modified cyanoacrylics or epoxies? Is Pliobond available (it is a solvent-based, neoprene contact cement)?
2) What are the materials you are trying to attach? That is, the best adhesive for metal to metal is different than for plastic to plastic, rubber to plastic, etc. There are even good ways to attach Teflon to steel, but you need to know what the materials are that you are trying to attach to each other.
3) Do you need a flexible bond, a bond that is shock resistant, etc. Does the bond need to be water resistant or waterproof?

John

I want to bond a strain gauge on to a stainless steel bar.I 2.5 to 3mm in diameter.A video said that it was similar to superglue(http://www.elfy.com/epoxies.htm) This is a company that produces superglue over here.I can mange to get their products.

A flexible bond since i will bend the steel bar not completely but to some extent.

 

[jpanhalt]

I want to bond a strain gauge on to a stainless steel bar.I 2.5 to 3mm in diameter.A video said that it was similar to superglue(http://www.elfy.com/epoxies.htm).This is a company that produces superglue over here.I can mange to get their products.

A flexible bond since i will bend the steel bar not completely but to some extent.

The "This" is to a missing URL. Elfy products on the linked page are all epoxies. The first few appear to be 1:1 mix and are fast setting. The last may or may not be 1:1 ratio, but is at least slow setting.

As a rule of thumb, the stronger epoxies are not 1:1 and are usually 1:2 to 1:4 ratios of hardener to resin. If you see ratios of 1:10 or greater, it's a chance that the adhesive is acrylic or polyester, not epoxy, and the catalyst is a peroxide. The biggest drawback from some epoxies is that they tend to be brittle compared to, say, polyurethanes.

For your application and with the Efly products that you show as available, I would recommend using the slow setting epoxy. If it is too brittle and you are into experimentation, you can make epoxies a little more flexible by adding a small amount of neoprene rubber. This will remove some of the brittleness, but not make them truly flexible like rubber. That is why I asked about Pliobond or similar "contact" adhesives you may also have available. You can mix Pliobond with the resin (not hardener). Then, mix the epoxy as usual and apply. I have used up to abut 10% vol/vol Pliobond. The solvent in Pliobond (or other neoprene-based contact adhesive) will delay final curing, as it must evaporate. If the joint construction is such that evaporation cannot occur (e.g., a large sealed surface), then allow the solvent to evaporate from the resin before mixing with hardener. Last time I did this was about 10 years ago. Since then, I have been able to get modified epoxies that are slightly flexible.

Finally, the aircraft industry is heavy into metal bonding. Many of the processes that have been developed are proprietary or only available by license (e.g., Boeing's method for preparing aluminum). However, you can find similar methods for phosphate priming that are "open source." The most important thing in bonding something like stainless is to be sure the surface is suitably abraded and cleaned. Degrease, media blast, then degrease again is a typical sequence. You may also find specific references on the Internet to chemical etchants or other surface preps that will enhance bonding.

John

 

[Wond3rboy]

Samad Bond Super(P4) - Samad Rubber Works (PVT) Ltd.(P4) - Samad Rubber Works (PVT) Ltd.)
This is also available here.Made of neoprene rubber.But personally having used this i dont think this will do.

 

[jpanhalt]

Samad Bond looks like it is very similar to Pliobond. My point was not to use it by itself. It is used in small quantity to modify the epoxy and make it less brittle . Use it only if the epoxy you chose is too brittle and snaps off the SS when it is deformed. Follow the mixing directions I gave. BTW, you can try it in CA adhesives too.

If you want to reference use of neoprene as a modifier, see: Handbook of Adhesives, 3rd ed., Irving Skeist, ed., Van Nostrand Reinhold, New York, 1990.

As stated in my post, it was a "make do" solution before I had ready access to flexible epoxies.

John

 

[Wond3rboy]

Hi i got this from an application engineer at Vishay's:

es the M-Bond 200 is a Cyanoacrylate which is also what “super glue” is. Our adhesive is selected and tested by our Engineering department to qualify as a strain gage bonding adhesive. I recognize your problem but I cannot recommend an alternative. When people are forced to use other than up to date or qualified materials I usually advise testing them to prove them out. But then that my require some extra gages to accomplish.

So if i take his word...this will do right?


Elfy Adhesives and Sealents

When you click on the cyanoacrylate link you get SUPERGLUE!.

I can use it then right?.

Thanks.

 

[kinarfi]

I used super glue and it works great, Do you have the preparation instructions? What type strain gauge are you using and for what, if you don't mind me asking.
Kinarfi
On mine, squareness with the shaft was very critical, after a few, this is the method I used,
Place the strain on a clean surface and put a piece of scotch tape on it as squarely as you can.
Put some tape on the bar you're going mount this on to insulate the leads from the bar.
Place the taped strain gauge on the bar and look at the squareness and do it over until you think it's perfect, not just good enough, Stick one side of tape good and lift the other side using the stuck side as a hinge. Put a drop of super glue on the bar and lay the taped strain gauge back down and hold in place with a piece of plastic bag between it and your thumb with pressure for about 30 to 60 seconds to make sure it bonds, then leave it alone for an hour. My strain gauges had a resistance of 350 ohms per leg and max variation was less than .7 ohms, you will be dealing with Δ voltages in 100 µvolt range, so don't expect even the best VDM read it.
Hope this helps
kinarfi

After you get your strain gauge mounted, read this thread,https://www.electro-tech-online.com/threads/wheatstone-op-amp.95124/#post763452, in short get an INA128 instrument amplifier.

 

[Wond3rboy]

Hi Kinarfi, thanks(and others too) for your reply.I am going to use the elfy super glue.Also thanks for the installation pdf.I found a video(in 2 parts) that do exactly what is written.

YouTube - Strain Gage Installation (Part 1)

YouTube - Strain Gage Installation (Part 2)

PS: I also called Omega inc a week ago and they said that they do not ship to Pakistan.And i am having to pay the same money to buy some crap from China which i hope works.


Sorry didnt answer you question...just read it.I am using a 3.4mmx6.6mm (backing dimension widthxlength) with a grid dimension of 2.44mmx3mm(widthxlength) on a steel bar to determine its bending.The steel bar 2.5 mm in diameter.Adhesives are not available here and neither are strain gauges.Any pointers?

My strain gauge will also be of 350 ohms.