Cold Drawn Bar｜Smooth Surface, High Dimensional Accuracy for Machining and Mechanical Components

Key Industry ChallengesIn machining, mechanical parts, and mold industries, manufacturers often face issues such as rough shaft surfaces (high surface roughness), out-of-tolerance dimensions, and inconsistent hardness between production batches. Hot rolled bars are generally unsuitable for precision work due to surface oxide scales and potential warping from rolling processes. These issues require additional grinding or finishing before use, increasing time and production costs unnecessarily.

Root Cause of the Problem

Hot rolled steel typically exhibits high dimensional deviation and may warp during transport. In contrast, precision machining requires materials with tolerances tighter than ±0.01 mm, smooth surfaces, and straight bars. Therefore, materials that undergo cold drawing or fine grinding are ideal for high-precision industrial production.

Solution

Yamaichi Special Steel (Thailand) offers Japanese-standard cold drawn bars, produced with cold drawing and fine grinding technologies to achieve smooth, scale-free surfaces, high dimensional accuracy, and excellent straightness. Each bar is ready for immediate use without the need for additional grinding. All grades are tested for mechanical and chemical properties under JIS G4051 / JIS G4105 / JIS G3123 / JIS G3505 standards and certified under ISO 9001:2015 to ensure consistent quality and precision throughout the manufacturing process.

Specifications of YAMAICHI Cold Drawn Bar

1. SS400 (SGD3) — Mild Steel Bar

• Tensile strength: ~400–510 MPa
• Easy to form, bend, and weld
• Smooth shaft surface, ready for use without further grinding
• Ideal for: Shafts, general structures, and non-hardened components

2. SUM22 — Free Cutting Steel

• Sulfur added for easier machining and smoother finish
• Hardness: approx. HB 160–200
• Reduces tool wear and increases tool life and productivity
• Ideal for: Nuts, screws, rotating shafts, and high-speed CNC work

3. S15C – S45C — Medium Carbon Steel

• Carbon content: 0.15–0.45%
• Can be surface hardened for increased hardness
• Balanced hardness and toughness
• Suitable for: Shafts, pins, bushings, and impact-loaded parts

4. SCM415 — Cr–Mo Alloy Steel for Carburizing

• Alloyed with chromium (Cr) and molybdenum (Mo)
• Ideal for components requiring hard surfaces with tough cores, e.g., gears, shafts, pins
• Well-suited for carburizing + quenching + tempering
• Surface hardness after hardening: approx. HRC 55

5. SCM435 — High Tensile Alloy Steel

• Higher carbon than SCM415 (~0.35–0.38%)
• Tensile strength: 930–1080 MPa
• Excellent resistance to torsion and repeated loads
• Ideal for: Machine parts, drive shafts, high-tensile bolts, and mold components
• Normalized and suitable for localized hardening

Key Advantages of Yamaichi Cold Drawn Bars

• Manufactured to Japanese standards
• ISO 9001:2015 certified quality
• Smooth bright finish and precise dimensions
• Reduces machining time and production costs
• Cut-to-length service available per customer requirements

※ For more information, please contact us or download the brochure.

Glossary

• Bright Bar – Cold drawn or precision ground bar with a smooth, ready-to-use surface
• Centerless Grinding – Precision grinding process to achieve round bar dimensional and surface accuracy
• Carburizing – A heat treatment to enrich the outer surface of steel with carbon for increased hardness
• Tolerance – The allowable dimensional deviation in machining

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