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TLS™
420 MQ |
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| Stainless |
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| Plastic
Mold Steel |
TLS™ 420 MQ |
is
a highly-refined, Mold Quality stainless steel exhibiting excellent |
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polishability, good corrosion
resistance, and good wear resistance.
The material is melted using |
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an
electric-arc furnace, is refined by the argon-oxygen-decarburation (AOD)
process, and is |
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further enhanced to aerospace
quality levels using Vacuum -Arc or Electro-Slag Remelting. |
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These
special melting and forging practices result in ultra-high microcleanliness
and a |
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homogeneous microstructure. |
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TLS™ 420 MQ is a superior
material for the manufacture of plastic molds |
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that require high hardness for good
parting line retention and sealing between colored resins. |
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The corrosion resistance also
enhances extended tool storage in humid environments. The high |
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cleanliness and homogeneity make
this material a superb choice for mold cavities that require |
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photoetching/texturing or the
highest, lens-quality polished finishes. |
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| Typical
Chemistry |
Carbon |
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0.38 |
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Molybdenum |
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0.20 |
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Manganese |
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0.50 |
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Sulfur |
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.003 Max |
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Silicon |
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0.50 |
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Phosphurus |
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.015 Max |
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Chromium |
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13.60 |
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Oxygen |
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20 ppm Max |
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Vanadium |
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0.30 |
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Hydrogen |
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2 ppm Max |
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| Applications |
TLS™ 420 MQ is suitable for use
in plastic injection, compression and transfer molding |
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where rusting or pitting of the mold
may be a problem, and molds for abrasive filled plastics |
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requiring improved wear resistance
compared to other mold steels. |
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| Annealing |
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Performed after hot working and
before rehardening. Heat at a rate
not exceeding 400 F per hour |
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to 1525-1625 F and hold at
temperature for I hour per inch of maximum thickness; 2 hours min. |
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Cool
slowly with furnace at a rate not exceeding 40 F per hour to 1000F. Continue cooling in |
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ambient temperature in the furnace
or in air. Resultant hardness should
be 235 BHN max. |
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| Stress
Relieving |
To improve dimensional stability in
hardening, it is recommended to stress releive tools after |
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rough machining and prior to heat
treating. Stress relieve annealed
tools at 1200-1250 F, |
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equalize, hold for 2 hours and air
cool. |
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After
EDM machining, it is important to stress relieve at 50 F per minute below
final tempering |
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temperature. Likewise, finished tools may be stress
relieved after final fitting, polishing, etc…, |
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50 F below the final tempering
temperature. |
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| Heat
Treating |
To
minimize distortion, double preheat complex tools. Heat at a rate not exceeding 400 F per |
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hour
to 1150-1250 F, equalize, then raise to 1400-1500 F and equalize. Normal tools should use |
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second temperature range as a single preheating treatment. Heat rapidly from preheat to a |
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HH range between 1850 - 1920 F. Hardness needed will determine HH
temperature used. |
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Soak at temperature for 30 minutes
min. for sections up to 5" thick.
Add an additional 10 minutes |
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of soak time for each additional
inch of thickness. Quench in air,
pressurized gas or warm oil. |
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Typically
sections up to 5" thick will fully harden with air. Sections greater then 5" will
require |
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excellerated cooling using forced
air, pressurized gas, or an interrupted oil quench to obtain |
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maximum hardness, corrosion
resistance and toughness. |
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Pressurized Gas - min. quench rate
of 30 F per minute down to 1000 F. |
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Oil - quench until black, about 900
F then cool in still air to 150-125 F. |
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| Tempering |
Double temper the tool at once upon
cooling to hand-warm. 550-750 F is
recommended for best |
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results. Hold at temperature 1 hour per inch of thickness, but not less
than 4 hours. |
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Hardened From: |
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Tempered |
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1850 F |
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1880 F |
1920 F |
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550 F |
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49.5 |
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51 |
52 |
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650 F |
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49.5 |
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51 |
52 |
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750 F |
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50.5 |
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51.5 |
53.5 |
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800 F |
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51 |
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52 |
53 |
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Note: |
Variations in section size, heating
rate, soak time, quench rate and tempering will |
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cause
deviations from the above values.
Gateway Metals should be consulted for specific |
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applications. |
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