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How Does Corrosion Resistance Affect CNC Machining Material Selection? Corrosion resistance is an important factor when selecting materials for CNC

How Does Material Density Affect CNC Machined Parts? Material density is a critical factor when selecting materials for CNC-machined parts.

How Does Material Ductility Affect CNC Machining? When a CNC cutting tool removes material from a workpiece, the material does

How Do Thermal Properties Affect CNC Machining? Heat is inevitably generated during the CNC machining of materials. As the cutting

How Does Material Strength Affect CNC Machining? When a CNC machine cuts metal, the cutting tool must penetrate the material

In CNC machining, material hardness influences cutting forces, tool wear, heat generation, feasible cutting speeds and feed rates, surface finish, and dimensional accuracy. Machining harder materials typically requires more rigid workholding, appropriate tooling, and stricter process control, often resulting in longer machining cycles and increased costs. However, material machinability is not determined solely by hardness; factors such as work hardening, thermal conductivity, ductility, microstructure, and heat treatment condition all alter a material’s behavior during the cutting process.

This article outlines the practical differences between AISI, ASTM, EN, and ISO material standards and explains why they should not be considered interchangeable. While AISI primarily deals with the designation of steel grades, ASTM and EN specify detailed technical requirements, and ISO provides international standards covering materials, products, testing, and processes.

For purchasers of CNC machining services, this article recommends considering factors beyond just the material grade itself. In particular, when a supplier proposes using an “equivalent” grade, the purchaser should verify the applicable product standards, material condition, certification requirements, and documentation such as MTRs (Material Test Reports) or material certificates.

This article focuses on common errors and solutions regarding material selection, emphasizing that decisions should not be based solely on purchase price. Instead, a comprehensive assessment must consider factors such as the actual operating environment, specific material grades, machinability, dimensional stability, material compatibility, fatigue and aging characteristics, supply chain dynamics, and certification documentation. The article advocates for integrating material evaluation early into the design and production processes through a collaborative approach involving engineering, manufacturing, quality, and procurement teams; this strategy helps mitigate risks related to processing costs, quality, delivery schedules, and product failure. Xtmade assists clients with material evaluations by addressing aspects such as engineering reviews, grade verification, machinability, tolerances, surface treatments, procurement, and production feasibility.

Hard-to-machine metals—such as titanium alloys, nickel-based alloys, hardened steels, specific stainless steels, tungsten, and molybdenum—offer excellent mechanical, thermal, and corrosion-resistant properties but present numerous challenges during CNC machining. Their high strength, high hardness, low thermal conductivity, work-hardening tendencies, and high cutting resistance often lead to accelerated tool wear, heat accumulation, vibration, chip evacuation difficulties, surface quality issues, and dimensional deviations. Machining becomes even more difficult when dealing with thin walls, deep cavities, tiny internal features, deep holes, complex 3D surfaces, and high-precision geometries.