TROUBLE SHOOTING EPOXY AND URETHANE CURING/GELLATION PROBLEMS
It is worthwhile to conduct some general
tests before getting involved with detailed trouble shooting. The
majority of the difficulties encountered are related to mix ratio,
defective or unclean equipment or not following supplier
instructions.
The following cursory tests will
confirm the integrity of a compound:
Make certain that the correct mix ratio is
being utilized ( by weight or by volume)
Manually weigh 100grams of material, using
the correct ratio by weight and thoroughly mix in a small clean cup.
Scrape the sides of the container to insure that everything is mixed
thoroughly.
If possible de-air the mix under 29" of
vacuum.
Leave the mixed material or place into an
oven, according to the suppliers recommended cure schedule until it
solidifies.
Check the sample for correct gel time and
if possible the hardness expected for the material.
Check the sample for uniform
gellation, after the recommended time interval.
If this sample is uniformly gelled and firm,
then the material is fine and the problem is elsewhere. Soft spots
within the sample indicate that the material was not mixed thoroughly
enough and the test should be repeated with more care. If the sample is
totally soft or does not gel, re-check the mix ratio used and repeat the
test. If the ratio is correct and the sample still does not gel, there
is a good chance that something is wrong with the product or the wrong
resin/hardener combination is being used.
Additional tests when utilizing a
dispense machine:
The above tests will confirm basic material
integrity. To confirm that the material is correctly and thoroughly
mixed by the dispense machine, it is highly advisable to conduct a "Bead
Test" as follows;
Take a good size sheet of Aluminium foil and
form into a tray, by forming small edges on each side, to prevent the
material from flowing off the sheet. Dispense a long bead of material
through the machine, onto the sheet. This should be done to include at
least one re-cycle by the machine.
Carefully note the beginning and the end of
the bead. If this is a heat cured product, place into an oven at the
recommended gellation temperature, otherwise leave at room temperature
to gel. After the recommended gel time, carefully check along the length
of the bead for soft spots. Any soft spots indicate improper mix from
the dispense equipment and provides a rough reference as to when the
problem occurs within the machine cycle. Uniform hardness along the bead
indicates that the machine worked well within that cycle. For a more
thorough test, repeat the "bead test" through several cycles.
It is extremely important
to maintain the exact mix ratio recommended by the material supplier.
 Disclaimer:
The above information is general in nature and is based solely on experiences by Crosslink Technology Inc. The recommendations provided herein may not be applicable in all situations. They are provided to the recipient as part of our customer service and the user must determine the relevance of the information to his/her application, considering any limitations that may be applicable thereto. Crosslink technology Inc. does not accept any liability for direct or consequential damages resulting from the the implementations of these recommendations or the use of this information.
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