Tool Steel

Round Tool Steel

Round tool steel refers to tool steel that is manufactured in a round bar form. It is commonly used in machining, tool and die making, and industrial applications where high-strength, wear resistance, and toughness are required.

Common Types of Round Tool Steel:

  • O1 (Oil-Hardening Tool Steel) – Good wear resistance, easy to machine.
  • A2 (Air-Hardening Tool Steel) – Higher toughness than O1, better dimensional stability.
  • D2 (High-Carbon, High-Chromium Tool Steel) – Excellent wear resistance, moderate toughness.
  • M2 (High-Speed Tool Steel) – Used for cutting tools due to its heat resistance.
  • H13 (Hot-Work Tool Steel) – Good heat resistance, used for dies and molds.

Uses:

  • Dies and punches
  • Cutting tools (e.g., drill bits, end mills)
  • Shafts and spindles
  • Molds and stamping tools

Precision Ground Tool Steel

Precision ground tool steel is tool steel that has been ground to a precise tolerance, usually with a smooth surface finish and exact dimensions. This makes it ideal for applications requiring high accuracy and minimal machining.

Key Features:

  • Tight tolerances (e.g., ±0.001" or better)
  • Smooth surface finish (reduces friction and wear)
  • Available in various shapes (flat, round, square)
  • Improved dimensional stability compared to standard tool steel

Common Grades:

  • A2 Precision Ground – Excellent for wear resistance and toughness.
  • D2 Precision Ground – Superior hardness and edge retention.
  • O1 Precision Ground – Easy to machine, good for general-purpose applications.
  • M2 Precision Ground – High-speed tool steel, great for cutting applications.

Uses:

  • Precision dies and gauges
  • Punches and stamping dies
  • High-accuracy machine components
  • Molds and wear-resistant parts

Round Tool Steel vs. Precision Ground Tool Steel - Comparison

FeatureRound Tool SteelPrecision Ground Tool Steel
ShapeRound barsGround to exact dimensions (flat, round, etc.)
Surface FinishStandardVery smooth, precise
ToleranceStandard manufacturing toleranceTight tolerances (±0.001" or better)
ApplicationsGeneral machining, toolingHigh-precision components, dies, and molds
Round tool steel comes in various grades, each designed for specific applications based on hardness, toughness, wear resistance, and machinability. Here’s a breakdown of common tool steel grades used for round bar stock:

Water-Hardening Tool Steel (W-Grades)

  • W1, W2
    • High carbon, water-quenched tool steels.
    • Good hardness and wear resistance but lower toughness.
    • Used for cutting tools, knives, and woodworking tools.

Oil-Hardening Tool Steel (O-Grades)

  • O1, O2
    • Medium alloy, oil-quenched steels with high wear resistance.
    • Good machinability and dimensional stability.
    • Common for dies, punches, and knives.

Air-Hardening Tool Steel (A-Grades)

  • A2, A6, A8
    • Medium alloy content, air-quenched for reduced distortion.
    • Good toughness and wear resistance.
    • Used for blanking dies, punches, and gauges.

High-Speed Tool Steel (M & T Grades)

  • M2, M4 (Molybdenum-based)
  • T1, T15 (Tungsten-based)
    • High wear resistance and heat resistance, maintains hardness at high temperatures.
    • Used for cutting tools, drills, milling cutters, and lathe tools.

Shock-Resisting Tool Steel (S-Grades)

  • S1, S5, S7
    • High toughness, impact resistance, and moderate hardness.
    • Used for chisels, hammers, and impact tools.

Hot-Work Tool Steel (H-Grades)

  • H11, H13, H21
    • Good heat resistance, retains hardness at high temperatures.
    • Used for die-casting molds, forging dies, and extrusion tools.

Cold-Work Tool Steel (D-Grades)

  • D2, D3, D5
    • High wear resistance and hardness but lower toughness.
    • Used for punches, dies, and shear blades.

Plastic Mold Tool Steel (P-Grades)

  • P20, P21
    • Good machinability and polishability, used for plastic molds and die casting.