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

Feature Round Tool Steel Precision Ground Tool Steel
Shape Round bars Ground to exact dimensions (flat, round, etc.)
Surface Finish Standard Very smooth, precise
Tolerance Standard manufacturing tolerance Tight tolerances (±0.001" or better)
Applications General machining, tooling High-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.