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Topic |
Response |
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| How sensitive is the compound surface
layer to cleaning? |
It is recommended that the TherMaLL ifeÒ
surface be cleaned so as not to disturb the compound layer. No more than a
20psi glass bead, or Scotch-BriteÒ should be used. If more aggressive
cleaning is required, we recommend reapplication. |
| Can you weld over the process?
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You may have heard that welding over a nitrided surface is difficult. This is because of the sputtering from the diffused nitrogen in the steel. When heated the nitrogen expands and "pops". Nitrocarburzing also
has some nitrogen in the surface so sometimes, it can sputter, but welding can be
done without significant problems. |
| Can it be done to used tooling?
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Once a tool has developed thermal heat checking,
TherMaLLifeÒ
does not have the ability to close heat checks as does
MetaLL ifeÒ. |
| Is there a need to be concerned about distortion?
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TherMaLLifeÒ is performed at a safe temperature that is not only well below the austenitizing temperature of the steel but well below (at least 50 degrees F) the last temper temperature. Consequently, no distortion occurs during heating or quenching, which is also done in a
controlled atmosphere to maintain the size, shape, and tolerance of the original tool.
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| What is the difference between the TL** processes?
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Many recipes are possible depending on the tool steel being treated. In addition to time, there are also temperature, velocity, pressures, and gases that enter into each recipe. Basically each of these "TL" processes can contain many other criteria besides the time that the tool is in the
controlled atmosphere. Beyond the time factor, we do not disclose the specifics of the
processes, however, each recipe is tailored for the application. Does Mrs. Fields tell you what goes into her cookies?
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| What criteria do you use to choose one "TL" process v/s another?
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When deciding on which recipe to use, we consider size, weight, steel composition, application, and configuration of the tooling. As a rule, smaller tooling require less time in the bed to reach saturation, however, the configuration of the tool also must be considered.
Each recipe will generate specific compound layers on the surface and varying
diffusion depths. Thicker diffusion lends itself to soldering, washout,
and wear resistance. Thinner diffusion is better suited for solder,
washout, and heat checking resistance. |
| Will H-13 w/ TL out perform Anviloy?
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Anivloy
because it does not contain iron is very resistant to the intermetallic
attraction of the molten aluminum in die casting. Recent 2002 tests at
Case Western have shown that Anviloy outperformed all of the test steels
without any diffusion process applied. One must consider cost,
machining, and brittleness of Anviloy steel when deciding on this
material. TherMaLLifeÒ when tested on H-13 material showed similar positive benefits
for solder resistance. |
| Does it chip or peel?
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Decarburization or "bluing" such as that which occurs when a tool has been abused during machining or grinding will have a tendency to flake off at the area of decarb. This is due to the total loss of carbon at the surface of the tool by overheating the steel when grinding or machining it. Sharp edges that
have not been properly machined are usually the most likely regions for this to occur.
It is possible to apply
MetaLL ifeÒ after
TherMaLLifeÒ to NEW tooling that has been properly machined without spalling the compound layer. It is important to combine the two processes properly.
When doing this there are special recipes that need to be utilized.
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| Applying over PVD coatings
back to index
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Prior to application of
it is required that any previous coatings be completely stripped or removed.
Without this being done, it is not possible to have the proper interaction
between the gases and tool steel that provides the diffusion and compound layer characteristics. |
| How often do I need to apply?
back to index
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Normally the tool is processed once with the
TherMaLLifeÒ
process when it is new and after final approval. Some customers apply it
again at the normal half life of the tool with a prior application of
MetaLL ifeÒ
to close up minor existing heat checks. |
Applying PVD coatings over
TherMaLLifeÒ
back to index
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With the exception of CrC, all common commercially available
PVD coatings (including
TiAlN, CrN, TiN) showed excellent adhesion characteristics when applied over
either a
TherMaLLifeÒ
or MetaLL ifeÒ
surface. |
| What about Lubricity?
back to index
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The TherMaLLifeÒ
surface is extremely hard and smooth. Because of this there is an added
lubricity factor, similar to that obtained when doing standard gas nitriding.
If MetaLL ifeÒ
has been performed prior to TherMaLL ifeÒ,
the micro pockets formed add an additional means to retain applied lubricant. |
| Is there any type of hot work
steel that cannot be treated?
back to index
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For
a proper TherMaLLifeÒ
diffusion process, the desired temperature has to be at least 900 degrees F
minimum with a preferred minimum of 1000 or better. Any type of hot work
steel, such as maraging, that does not have a high last temper at this point
would not be a candidate. Maraging is aged at about 950 degrees F or less and
could possibly be put at risk if TherMaLLifeÒ
is done at a higher temperature. We are currently evaluating this
situation and doing some testing on both maraging and maraging weld done to
H-13 material. As the results are available, we will post the information here
and possibly in one of our email newsletters. |
| What about doing the process to
Uddeholm's DievarÒ
or 2367 material?
back to index
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There are some steels for die casting which diffuse more quickly. A special recipe
for TherMaLLifeÒ
has been developed for these steels that will assure a proper compound zone
thickness and diffusion depth.
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What assurance is there at this treatment will perform as
advertised?
back to index
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TherMaLLifeÒ
is not a panacea for all die soldering or failure problems, however, references
by NADCA in their Die
Care Maintenance User Guide (E501) and
MetaLL ifeÒ
in the Relieving Stresses in Die Casting Dies (#531)
support the fact that these are both viable
processes. In addition customer testimonies
continue to show the successes the processes are having in the field.
One major US Japanese die caster has all of their new tooling
TherMaLLifeÒ
processed to extend the die life and improve performance of automotive dies. |
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If a Stress Temper of the die after
TherMaLLifeÒ
is performed, what effect does this have on the process? |
The diffusion process is
done at a higher temperature than normal stress tempering (1000 degrees F) so it
does not affect the process. A stress relieve at a higher temperature or a
sustained temperature close to the processing temperature will dissolve the
diffused layer.
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