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Glue layer minimum ??
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stevej.g.


Jul 14, 2012, 12:44 PM
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Glue layer minimum ??
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Are there any tests / knowledge about this ?

For Glue-ins , the manufacturers normally recommend 1 mm layer thickness

(10 mm bolt : 12 mm hole or 12 mm bolt: 14 mm hole )

I think i read somewhere about 12 mm bolts and 13 mm holes beeing sufficent ?

Would it be possible to drill smaller ?


somewhere it was mentioned, that the glue needs a minimum thickness / mass to cure / harden.
( I think the reason was said to be something with self-heating during reaction of the components)

Beeing a chemist myself, i cant ( first quick thought about it) find a reason, why a glue would not cure at all. ( it just should take longer)

Any hard facts out there ??

Thanks,
steve


patto


Jul 14, 2012, 3:53 PM
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Re: [stevej.g.] Glue layer minimum ?? [In reply to]
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Read the manufacturers specifications! But normally it is bolt size +2mm. I'm not sure why you would want to deviate.

Example for ramset studs:


Code
Part No.	 Thread Size  	 Length 	 Drill Size 	 Drill Depth 	 Type 	 Environment 	 Box Quantity 	Add to toolbox	View Related 
CS08110GH M8 110 mm 10 mm 80 mm Grade 5.8 Outdoor 10
CS10130GH M10 130 mm 12 mm 90 mm Grade 5.8 Outdoor 10
CS12160GH M12 160 mm 14 mm 110 mm Grade 5.8 Outdoor 10
CS16190GH M16 190 mm 18 mm 125 mm Grade 5.8 Outdoor 10
CS20260GH M20 260 mm 24 mm 150 mm Grade 5.8 Outdoor 6
CS24300GH M24 300 mm 26 mm 160 mm Grade 5.8 Outdoor 6


Here is a nice picture:



(This post was edited by patto on Jul 14, 2012, 3:56 PM)


JimTitt


Jul 14, 2012, 3:59 PM
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Re: [stevej.g.] Glue layer minimum ?? [In reply to]
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The glues we use (correctly called chemical morter) are exothermic and cure by heat which is generated by the catalyst and accelerator. You need a certain mass of glue to generate more heat than is lost to the surroundings and provide a cure. This is called the critical glue mass. The commonly used products need about 1mm thickness but there are thin crack glues and thick crack ones as well. For most bolts and threaded bar either 1 or 2mm larger diameter is nescessary but some designs you can drill the same size hole as the glue mass is concentrated in other areas than around the shaft itself for example to the sides.
The anchor manufacturer will tell you which diameter is correct, larger is acceptable and normally just as strong, smaller is not acceptable.
There are other methods of hardening the resins such as UV but they are for industrial processes and not suitable for us.
There is more information out there on the hardening process of organic resins than you could probably read in a lifetime!


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