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LOW TEMPERATURE DIFFUSED COATINGS FOR STAMPING APPLICATIONS
-Product information-
The new hard coatings developed by
Sputtek are a combination of nitriding and hard coating technology. The
coatings are applied in one cycle and are based on Ti-Al or Cr metalo-ceramics
with high hardness and good ductility.
• Advantages of the low temperature
diffused coatings:
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Forming HSLA steels
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High volume programs
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No distortions/Tight tolerances
maintained
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Quick turnaround -Unlimited number of
re-coatings
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Will not develop fatigue cracks in
the base metal.
• Recommended applications:
SP-5.1 (duplex Ti-Al): for steel
stamping (including stainless steel);
SP-5.2 (duplex Cr): for copper-based alloys and mild steels stamping.
• Description:
The high hardness and thickness (up to 15
microns) of the coating provides the capacity to withstand the normal loads
developed at radii, while the fine nano-structure of the coating increases
the shear stress capacity. Due to the low coefficient of friction the flow
of the blank material is eased and the abrasion wear of the tool as well as
galling (pick-up) are delayed. The mechanical properties of the substrate
and the coating (toughness, hardness and ductility) are matched through the
nitrided layer. The dense and thick structure that is created will decrease
the plastic deformation of the tool under the effect of the concentrated
load.
• Technical data:
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-Deposition temperature |
: 350 - 450 oC (660 – 840 °F)
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-Thickness of the coating |
: up to 15 microns (6 tenths) |
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-Depth of the nitrided layer |
: > 50 microns (.002”) |
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-Oxidation temperature |
: > 800 oC (1,470 °F) |
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-Hardness |
: up to 3000 HV020 - diffused TiAl (Sp5.1) |
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: up to 2500 HV020 - diffused Cr (Sp5.2) |
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-Coefficient of friction |
: 0.20 – diffused TiAl (SP-5.1) |
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(Steel on steel conditions) |
0.25-0.30 – diffused Cr (SP-5.2) |
-Case study-
• Data:
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forming HSLA steel (60 KSI)
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thickness of the stock: 4 mm (5/32 “)
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depth of draw: 38 mm (1 ½ “)
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material of tool: D2 (58-60 HRC)
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number of sections in the tool: 4
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program: 1.2 mil. parts/year
• Problem:
When using TD coating it has been noticed
that the pick-up on the sections started after aprox.35,000 parts and after
another 15,000 parts the quality of the formed parts became unacceptable.
Below the build-up it has been seen that cracks were developing at the
radii. The tool had to be repaired (cut and welded) with a 6 days
turnaround. After two coatings the tool could no longer be used due to the
cracks and decarburization of the steel structure. Therefore new sections
had to be built with other 5 days turnaround. In total 12 sets of dies were
used.
• Sputtek solution:
The longevity of the tool has been
preserved (50,000 hits), but no fatigue cracks developed on the surface. The
tools have been recoated and turned back to the customer in 2 days. The
sections were re-used 11 times up to now and are still in use. No signs of
catastrophic damage have been determined.
• Benefits for the customer:
1. The yearly tool maintenance cost has
been cut by 61 % ($ 61,280);
2. The waiting time/year for tool recoating and rebuilds has been reduced by
68 % (from 151 days cumulated for two sets of tools in use to 48 days/year).
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