Page 1 of 1

Very Good Magnet Bonding Epoxy

Posted: Apr 23 2011 8:27pm
by bigmoose
Here is the best magnet bonding epoxy out there that I know of: Hysol EA9394 177 deg C rated capability based on maintaining 1Ksi Shear Strength.

NASA reference for Hysol EA9394 use bonding magnets in space flight generators (Page 264, marked 252-3 in report) ... ual-Report

Data sheet (with loads of good info): ... 209394.pdf

Independent Sandia test report: ... 950229.pdf

Where to buy it for $16 bucks through KR Anderson: ... 0ML-SEMPAK

This stuff is amazing. It has been tested in JP4 and hydraulic oil and held up fine per the data sheet. The data sheet also shows 600psi shear strength up to 400 degF!!!

A hint that makes the bond even stronger (applicable to all epoxies): Be very careful mixing to have as little air entrained as possible. Entrained air makes it weaker, but not to a failure level. I am talking about getting the last 15% out of this material with respect to bond strength. Also note the cure kinetics in the first NASA article and the data sheet. This material likes a higher than room temperature cure after one day at room temperature. Like 150 deg F for an hour or so after a day at room temperature.

PS:If anyone is using epoxy in a production environment, just buy the THINKY mixer that meets your specifications and that you can afford. These centrifugal, planetary mixers (some with vacuum capability) are just the finest for preparing epoxies and epoxy compounds. It doesn't get any better!

A few hints from Fechter from the thread where I discussed this epoxy:
"Also make sure the surfaces are clean and have no traces of oil. I think when they manufacture the steel parts they are coated with oil and they don't always do a good job of getting all the oil off.

After mixing epoxy, a good way to get the air out is to pull a vacuum on the mixuture. I like to load the mixed epoxy into a large syringe, then push as much air out as possible, block off the tip and pull the plunger back. This expands all the air bubbles and allows them to float to the surface. The syringe makes it handy for applying the epoxy afterwards.

You can get some flavors of the Hysol stuff from McMaster-Carr."

Re: Very Good Magnet Bonding Epoxy

Posted: Apr 23 2011 8:38pm
by liveforphysics
Excellent to know for all of us tinkers.

Thank you Moose!

Re: Very Good Magnet Bonding Epoxy

Posted: Apr 24 2011 4:13pm
by Kingfish
Bookmarked, KF :)

Re: Very Good Magnet Bonding Epoxy

Posted: May 30 2011 6:12pm
by spinningmagnets
A thread about adding hall sensors, turns into discussion on popular epoxies used: ... 1&p=411378
We are using 3M DP 490 epoxy, workable potting time about 1 - 1.5 hrs, sets in about 8 hrs to a workable / usable condition, then cures during the next few days. Incredible stuff, high temp & age resistant, also ideal to stick neodym magnets to surfaces or fix small holes. Is hard, tough, expensive but really good. Look at the spec sheet and you'll know what I mean.
The DP420 is the same stuff, but the work life is only 20 minutes.. just enough to place the hall sensor. Then, put that in an oven at 170F for 30 minutes and than leave them to cool down during 2-3 hours.. the epoxy will become as hard as metal! Ebay often offer the DP460 and DP420.

I know alot these DP epoxy from 3M I used them nearly once a week at my job. My torque arms ( the two on my giant DH) are glued with the DP420, and with 20kW burst on that motor they never failed ! DP scotchweld from 3M are some of the best!... also to fix magnets to the metal parts.

Re: Very Good Magnet Bonding Epoxy

Posted: Aug 31 2011 8:52am
by Doctorbass
3M DP-460 or DP-460 scotchweld products are also excellent products!

They are also recommanded by the manufacture for bounding magnet material.

4600psi shear strengh at ambiant with great derating

I "weld" my torque arms to the frame with it and it is MORE than enough.

4 of my ebikes are now equiped with that technic, two use regen at up to 6kW and run 20kW burst and one towed two time a schoolbus and the T-A is bonding is still intact and no sing of failure.

they also endured -30 during winter as well as 30 celsius during summer + the heat o fthe motor thru the axel.. and never had any problem.

I have a friend who had his X5 magnets that unstick during cold winter and hard power demand. ( magnet was rotating inside the hub!!! but no wheel spining... just like a friction clutch!!! he repaired them with the DP460 and that is still perfect

At work we use it in many aerospace project since many years

100% satisfied

cost around 40$ for a 43ml tube with the plunger