Loctite 330 problems

East Branch Knives

East Branch Knives

Joined
Feb 5, 2014
Messages
169
I tried using Loctite 330 (plus the 7387 activator) for gluing liners together (G10 and micarta). After 24 hours (the recommended cure time) I could peel the liners apart, as though the adhesive had failed completely. I figured maybe my stuff was expired, so I ordered more and got the same results w/ the brand new supply.

I clamp the liners together in a woodworking vise lined with aluminum plates to allow them to setup for a few minutes (the instructions say 1 minute), then take them out and leave them overnight.

I don't think it's a starved joint because: (1) the recommended bond gap is .05mm (.002"), and the bond strength decreases as bond gap increases; and (2) I can see a thin layer of yellowish residue coating the liner faces, so it looks like the adhesive is there, it just didn't stick.

I keep the temp in my shop at 55 - 60 degrees F during the winter, and this stuff is "room temperature cure," so the only other thing I can think of is that perhaps my shop was too cold for the adhesive to cure?

Has anyone else ever had this issue w/ Loctite 330? Any guesses as to what went wrong?

Thanks very much!

Mike
 
Sometimes some instructions say moisten the area you glue. ???

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Do the instructions with the activator say to wait 3 minutes after you spray the activator on before putting the parts together?

It is very important to wait as the instructions say.

It acts as if the activator isn't ready to be used until after the volatiles have evaporated.
 
woodwrkr221 said:
Do the instructions with the activator say to wait 3 minutes after you spray the activator on before putting the parts together?

It is very important to wait as the instructions say.

It acts as if the activator isn't ready to be used until after the volatiles have evaporated.
Click to expand...

It says the parts must be assembled within 15 min, but it does not mention letting the activator sit for any period of time before assembling. I could try it and see if it helps.
 
DevinT said:
I think it only works with metal to handle material bond.

Hoss
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I think it should work w/ plastic to plastic, although the data sheet shows testing data for steel and aluminum bonds. There are a few specific materials it's not recommended for, but G10 and micarta aren't among them.
 
Another problem with bond failure is glue joint starvation. If a glue joint is clamped hard, all the glue can be squeezed out leaving barely and resin in the bond. This fails easily. Clamping pressure for joints should only be the minimum to assure the surfaces are together. This leaves a thin layer of resin in the joint.
 
Stacy E. Apelt - Bladesmith said:
Another problem with bond failure is glue joint starvation. If a glue joint is clamped hard, all the glue can be squeezed out leaving barely and resin in the bond. This fails easily. Clamping pressure for joints should only be the minimum to assure the surfaces are together. This leaves a thin layer of resin in the joint.
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Stacy, thanks very much for your response. I'd thought that joint starvation wasn't an issue b/c the datasheet shows the highest performance at a bond gap of .05mm, roughly three thousandths of an inch. I figured that even with squeezing the liners in a vise with medium pressure, there would still be a .003" gap, although I can't really conceptualize that distance so I'm not sure--maybe it's larger than I'm thinking. I've used the vise method w/ liners and CA glue and haven't had problems.

Do you think clamping in a vise would really reduce the bond gap past .003" all the way down to zero and squeeze everything out? I'll try just light pressure and see where that gets me, then report back.

For others who use Loctite 330, how do you clamp your pieces when using two pieces of relatively thin liner material? I feel like using a couple spring clamps wouldn't work very well because the liners are thin enough to be flexible, and thus there would be an uneven bond gap.
 
I have been using 324 with 7075 activator all weekend, but have very little experience with it before now. I hope it works on g10 to g10! It says to let the activator "dry" 2-5 minutes until solvent smell is gone.

Like I said, I don't have much experience with this, and it is a different ## so ymmv
 
Surface preparation is as important, if not more important, than the adhesive. Make sure you're following the manufacturer's instructions. If you don't know them, call the manufacturer. Don't trust clowns like me on an internets forum -trust the guys that engineered the adhesive!
 
330 does expire and so does the activator. It's normally very good stuff and works well. It's related to the Speedbonder 324,325,326 stuff but the activators are not interchangeable. The activator matters and should be sprayed on the side that is roughest and doesn't absorb the chemical. Make sure you have the right activator. Give it time to dry.

A couple spring clamps are enough. 5 spring clamps will squeeze everything out.

By far, good surface prep will make a lessor epoxy outperform a better grade. Sandblasting is what the manufactures use for testing because it gives the best surface prep. Lacking that a heavy scratch pattern with 36 or 40 grit really makes a difference. Using acetone to clean parts leaves an oily film that contributes to joint failure. Try using 90% rubbing alcohol for cleaning before bonding.
t
 
Micarta is absorbing fluid far more then G10 ............maybe this is problem ? I mind activator on micarta ... adhesive on G10 .Actvator is very liquid /never used loctite 330 I just look some tube video / and if you spray actvator on micarta probably will soak deep in micarta ...and that is problem ? I just guessing ??
 
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Natlek said:
Micarta is absorbing fluid far more then G10 ............maybe this is problem ? I mind activator on micarta ... adhesive on G10 .Actvator is very liquid /never used loctite 330 I just look some tube video / and if you spray actvator on micarta probably will soak deep in micarta ...and that is problem ? I just guessing ??
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That sounds like a good guess.
 
tmickley said:
That sounds like a good guess.
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Well , now I re-read that you already mentioned that :thumbup: BW , sandblasting increases surface contact .More surface more strenght of glued parts ..............

tmickley said:
330 does expire and so does the activator. It's normally very good stuff and works well. It's related to the Speedbonder 324,325,326 stuff but the activators are not interchangeable. The activator matters and should be sprayed on the side that is roughest and doesn't absorb the chemical. Make sure you have the right activator. Give it time to dry.

A couple spring clamps are enough. 5 spring clamps will squeeze everything out.

By far, good surface prep will make a lessor epoxy outperform a better grade. Sandblasting is what the manufactures use for testing because it gives the best surface prep. Lacking that a heavy scratch pattern with 36 or 40 grit really makes a difference. Using acetone to clean parts leaves an oily film that contributes to joint failure. Try using 90% rubbing alcohol for cleaning before bonding.
t
Click to expand...
 
Not familiar with these adhesives, always used epoxy for bonding this sort of thing together.

From the instructions it sounds like you are doing all the right things. Maybe the glue gap would be better at 0.1 rather than the 0.05 shown in their chart, :confused: but if you are getting a thin joint the 15 minute assemby applies.
2014 version. https://tds.us.henkel.com/NA/UT/HNAUTTDS.nsf/web/65B0DB8566343883882571870000D66C/$File/AA%20330-EN.pdf
Directions for use:
  1. For best performance bond surfaces should be clean and free from grease.
  2. To ensure a fast and reliable cure, Activator 7387™ or 7386™ should be applied to one of the bond surfaces and the adhesive to the other surface. Parts should be assembled within 15 minutes.
  3. The recommended bondline gap is 0.1 mm. Where bond gaps are large (up to a maximum of 0.5 mm), or faster cure speed is required, Activator 7387™ or 7386™ should be applied to both surfaces. Parts should be assembled immediately (within 1 minute).
  4. Excess adhesive can be wiped away with organic solvent.
  5. Bond should be held clamped until adhesive has fixtured.
  6. Product should be allowed to develop full strength before subjecting to any service loads (typically 24 to 72 hours after assembly, depending on bond gap, materials and ambient conditions).

Found this interesting document:
http://na.henkel-adhesives.com/us/content_data/397189_LT2197_Plastic_Guide_v6_LR.pdf
Page 37 shows Loctite 330, on a scale of 1 - 28 for strength on Phenolic, as being 6.2. Page 27 for G-10 doesn't look much better at 6.9.


There is also this one for bonding metals which as data on 324 etc
http://na.henkel-adhesives.com/us/content_data/LT3771_Metal_Bonding_Guide_v5_LR404796.pdf



Is the adhesive residue adhering equally to both materials when the joint is broken? Are the parts really flat to begin with? I often find that micarta is not flat in its sheet form and requires lapping flat on glass and glued down abrasive paper. If there is any spring in the parts, they could be pulling away from each other when you release the clamping pressure. The gap might not be bigger than the adhesive can deal with, but if it was clamped, and then released before full cure, the joint could be either starved, or it could be stressed before the adhesive has reached full strength.

Just throwing ideas in the pot. Am sure that you will figure out a way to get it to work!

Chris
 
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Matthew Gregory said:
Surface preparation is as important, if not more important, than the adhesive. Make sure you're following the manufacturer's instructions. If you don't know them, call the manufacturer. Don't trust clowns like me on an internets forum -trust the guys that engineered the adhesive!
Click to expand...

tmickley said:
...By far, good surface prep will make a lessor epoxy outperform a better grade. Sandblasting is what the manufactures use for testing because it gives the best surface prep. Lacking that a heavy scratch pattern with 36 or 40 grit really makes a difference. Using acetone to clean parts leaves an oily film that contributes to joint failure. Try using 90% rubbing alcohol for cleaning before bonding.
t
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Matthew and Tracy, your point re surface prep is well taken. I've been using alcohol on a cotton makeup pad to wipe the surface, then fresh sand paper to rough it up. After roughing up the surface, there's newly created dust that needs to be removed, so I again wipe w/ the alcohol. However, sometimes the scratches will tear away fibers off the pad, which contaminate the surface. Maybe this is part of the problem? In the past to avoid this I've used canned air to blow the dust away instead of re-wiping w/ alcohol, but this always risks contaminating the surface with the bitterant. Ironically, loctite makes a point of saying that surface prep isn't even that big a deal with 330, which seems kind of baffling to me.
 
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