Choosing the Right Material for CNC Machining

Because CNC machining does not cause any changes to the molecular integrity of a part’s material, the selection of metals, alloys, and plastics that can be cut using the technology is broad and varied. The only property a material needs in order to be machined is the right level of hardness. In metals, this includes everything from titanium and steel to aluminum or copper. In plastics, high-performance polymers like PEEK can be machined, as well as more common thermoplastics like ABS.

So, which material is right for your purpose? Here is a list of some popular CNC machining materials, the predominant characteristics and some common applications for each one. Tip: If you can’t find your requirement below, see Xometry’s full CNC machine materials list or contact us for custom alloys.

Aluminum

Aluminum

Key properties: Aluminum is highly regarded for its strength-to-weight ratio and corrosion resistance. It also exhibits good thermal and electrical conductivity.

  • Aluminum 6061-T6: 6061 is one of the most commonly used varieties of aluminum, finding universal application. T6 designation gives the material an ultimate tensile strength 276 MPa. Common applications: general
  • Aluminum 7075: 7075 has an ultimate tensile strength of 572 MPa, which is comparable to steel. Useful for high-stress applications, its use is somewhat limited by high cost. Common applications: aerospace, automotive, marine
  • Aluminum 2024-T3: A 2000 series alloy, 2024-T3 has a high strength-to-weight ratio with a tensile strength of 400–430 MPa and yield strength of at least 270–280 MPa. Through T3 designation it has been solution heat treated and cold worked. Common applications: industrial, aerospace, medical, electronics
  • Aluminum 5052: At 117 MPa, the fatigue strength of this variety is higher than most aluminium alloys. It also has exceptional resistance against seawater and salt spray. Common applications: marine, aerospace, electronics
  • Aluminum MIC-6: Similar to the 7000 series of aluminum alloys, MIC-6 is a cast plate material commonly used in tooling and base plates. Common applications: aerospace, electronics, gears

Brass, Bronze and Copper

Copper Element

Key properties: Pure copper is a soft and malleable metal with very high thermal and electrical conductivity. Both brass and bronze are alloys of copper. Brass is a combination of copper and zinc, and bronze is mainly copper with tin. In general, brass is valued for its machinability and high strength retention. Bronze has low-friction properties with high resistance to corrosion. Brass, bronze and copper are all often selected for their aesthetic appearance.

  • Brass C360: A highly machinable material, C360 is the lowest cost of all brass alloys. Sectors: industrial, commercial
  • Brass 260: The most ductile brass alloy, 260 is used in greater quantity than others of this variety. Sectors: industrial, commercial
  • C932 M07 Bearing Bronze: Used for light-duty applications, this alloy is easy to machine and corrosion resistant. Sectors: general
  • ETP Copper C110: This alloy has the highest electrical conductivity (100% IACS) of any metal except silver (105% IACS). Sectors: electric, building, medical
  • Copper 101: The base material for many brasses and bronzes, Copper 101 has high ductility (5% to 50% elongation) and impact strength. Sectors: electronics, automotive, commercial

Steel

Carbon Iron Elements

Key properties: Arguably offering the widest variety of CNC machining materials, steel is available as stainless, alloy, tool and mild varieties. Generally speaking, steels have good mechanical properties and are easy to machine.

  • Steel 1018: This low-carbon, general-purpose steel is ductile and suitable for forming and welding. Sectors: general, gears, screws, nuts
  • ASTM A36: An example of mild steel, A36 is a low-cost alloy with good mechanical properties, including an ultimate tensile strength of 400–550 MPa and 20% elongation at break. Sectors: gears, construction
  • Alloy Steel 4130: This versatile steel alloy is optimized in composition for strength (670 MPa ultimate), toughness (435 MPa tensile strength at yield) and machinability. Sectors: aerospace, oil & gas, automotive
  • Stainless Steel 304: The most common variety of stainless steel and exemplary of the base qualities of steel, this alloy has a higher corrosion resistance than most other steels, with lower conductivity. It is not suitable for applications that require welding. Sectors: food, screws, automotive
  • Stainless Steel 17-4: This precipitation hardened stainless steel is known for its high strength and mechanical properties which can be further developed through heat treatment. With good mechanical properties even in operating temperatures of 600 Fahrenheit and high corrosion resistance, this material works very well in demanding environments. Sectors: Nuclear, marine, food, and medical.

Titanium

Titanium Element

Key properties: Although heavier than aluminum (but still lighter than steel), titanium is also known for its exceptional weight-to-strength ratio. Due to its hardness, many varieties of titanium are deemed difficult to machine.

  • Titanium Grade 2: An unalloyed variety of titanium, Grade 2 is a common form of this metal, with high strength (344 MPa ultimate) and exceptional corrosion resistance. It is often used to make heat exchangers. Sectors: aerospace, automotive, chemical
  • Titanium 6Al-4V: Another commonly used titanium variety, this alloy is best used when low density (4.429–4.512 g/cm3) and excellent corrosion resistance are required. Sectors: medical, aerospace, marine, gas

Zinc

Zinc Element

Key properties: Zinc is not commonly used in CNC machining because most varieties are too brittle for the process. In some particular forms, the material becomes easy to work and is readily treatable.

  • Zinc Sheet Alloy 500: A continuous-cast alloy, this machinable zinc has good electrical conductivity and is highly resistant to corrosion. Sectors: construction

Plastics

Key properties: Lightweight and strong, some industrial plastics can be considered as low-cost replacements for metal parts. Incredibly versatile, plastics have wide-reaching applications across all industries.

  • ABS: This common, high-strength thermoplastic with electrical insulation properties is good for low-cost, lightweight tooling and for prototypes. Sectors: general, medical, automotive, electronics
  • Acetal: Branded as Delrin, this material is arguably the easiest plastic to machine. It has excellent stiffness (flexural strength 82.7 MPa), low friction and good resistance to moisture. Sectors: general, gears, electronics, medical, construction
  • Nylon 6/6: A common polyamide, Nylon 6/6 — or simply 66 — has high mechanical strength (66 MPa), rigidity and good stability under heat and chemical exposure. Sectors: automotive, electronics, gears, pipes
  • PEEK: This high-grade thermoplastic is used in a variety of mechanically demanding situations. Sectors: medical, aerospace, automotive, electronics
  • Polycarbonate: Commonly referred to as PC, this clear plastic has excellent optical properties. It is durable, lightweight and strong, with high impact resistance (600–850 J/m). Sectors: general, electronics, aerospace, automotive, pipes

Xometry offers all materials listed above and more for CNC machining, as well as other capabilities in 3D printing, sheet metal fabrication, injection molding, and urethane casting.

Contact our Applications Engineering Team for more help and guidance when selecting the perfect material and process.

With material, process and model in mind, access Xometry's Instant Quoting Engine™ for immediate pricing, design feedback and expected delivery date.

About Xometry

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