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Plastic Mold Steels



  • Welding
    Due to low carbon content, age hardening, and the availability of NAK weld rod, hardness is lowered in the heat-affected zone during the welding process. NAK55 can be re-aged to 40 HRc with no distortion or stress put into the mold. Polish, texture and wear in the weld are indistinguishable from adjoining "parent steel" on the finished product.
  • Machining
    Machines up to 50% faster than P20 to a superior surface with negligible dimensional change. Positive rake cutters with concave, chip breaking inserts work best, and last up to twice as long as with P20 mold steels.
  • EDM
    The soft recast layer (approximately 32 HRc) is much thinner and is easier to remove than steels with a recast layer that is equivalent to their "as quenched" hardness. With NAK55, no post EDM stress relieving is ever needed.
  • Stability
    Age hardening eliminates the stresses inherent in quenched and tempered steels. NAK55 is dimensionally stable and predictable over many years of heating and cooling cycles.
  • Surface Enhancements
    VAR processing with uniform grain structure facilitates superior nickel, chrome, titanium, and other coatings. Unique chemistry responds extremely well to ion-nitriding.

  • Texturing and Polishing
    Exceptionally clean steel with uniform grain structure polishes beautifully allowing superior texturing and photo etching.
  • Wear
    Higher hardness ensures molds have a longer life than those made from P20, particularly in gate, runner, and parting line areas.

    The uniform, refined grain structure of NAK55

All technical and engineering data and suggested procedures, specifications and applications contained in this publication are for general information only. Daido Steel, International Mold Steel and/or their distributors disclaim any and all express or implied warranties of merchantability, suitability for any particular purpose or use, or freedom from infringement of any patent, trademark or copyright. NAK80 is a registered trademark of International Mold Steel, Inc. and Daido Steel Limited.



Recommended Reading

Unique Characteristics


Typical Chemistry

Mechanical Properties

Physical Properties

General Design Guidelines

Processing Guidelines

Welding Guidelines

Technical Center


  International Mold Steel, Inc. 
1155 Victory Place
Hebron, KY 41048 USA 
Tel: 859.342.6000
Fax: 859.342.6006
Sales E-mail: [email protected]
Literature E-mail: [email protected]