CNC Machining Metal Materials

CNC Machining Metal materials 

Pictures	Materials		Details
	Aluminum	Aluminum  6061	Our aluminum alloy. With good strength-to-weight ratio, excellent machinability and natural corrosion resistance.
		Aluminum 7075	The aerospace-grade material with excellent strength-to-weight ratio and high strength and hardness.
		Aluminum 5052	The strain hardening aluminum alloy with excellent corrosion resistance. Suitable for marine applications. Can be welded.
	Stainless  Steel	Stainless steel 304	The most common stainless steel. It is non-magnetic steel.
		Stainless steel 316/316L	SS316 has superior corrosion resistance in chloride containing environments, with good elevated temperature strength.
		Stainless steel 303	SS303 has excellent toughness, but lower corrosion resistance than 304
		Stainless steel 430	SS430 is a non-hardenable steel containing straight chromium, and belongs to the ferritic group of steels.
		Stainless steel 201	High density, with certain acid and alkali resistance, no bubbles, no pinholes.
	Brass	Brass C360	Good tensile strength and natural corrosion resistance, ideal for parts with low friction.
	Copper	Copper	Good electrical conductivity, thermal conductivity, ductility, deep drawing and corrosion resistance.
	Titanium	Titanium	lightweight, high-strength, low-corrosion structural metal and is used in alloy form for parts in high-speed aircraft.
	Mild steel	Mild steel 1018	Good machinability, weldability, toughness, strength, but it’s susceptible to corrosion on the surface.
		Mild steel 1045	Medium tensile carbon steel with good strength and impact properties.
		Mild steel A36	The most commonly used mild and hot-rolled steel.
	Alloy steel	Alloy stee  4140	The heat treatable and low alloy steel containing chromium, nickel and molybdenum.
		Alloy steel 4340	heat treatable and low alloy steel containing chromium, nickel and molybdenum.
	Spring  steel	Spring steel	Is used prominently in automotive and industrial suspension applications.

How to Choose the Right Metal for CNC Machining

The table above lists what we stock and machine every week. Choosing between those grades comes down to five questions, and answering them honestly usually narrows the list to one or two candidates.

1. Strength and stiffness. Do you need yield strength (a bracket carrying load) or stiffness against deflection (a long shaft, a thin plate)? Aluminium is light but flexes; steel is stiff but heavy.
2. Machinability. Some grades cut cleanly and cheaply, others fight the tool. Free-cutting brass and 6061 aluminium are at the easy end; titanium and hardened tool steel sit at the difficult end.
3. Corrosion resistance. Indoors and dry, almost anything works. Outdoors, near salt water, or in a wash-down environment, the choice matters — 316 stainless, 5052 aluminium or an anodised finish.
4. Weight. Every kilogram removed from a moving part pays back for years. This is the single biggest reason aluminium and titanium win in automation and aerospace work.
5. Finishing compatibility. Not every finish suits every alloy. Anodising is an aluminium process; passivation is a stainless one; powder coating and plating are more universal but add thickness.

Machinability at a Glance

Machinability is a relative number, not a fixed property — it depends on the tool, the speed and the setup. As a practical ranking for turning and milling on standard carbide tooling:

A "moderate" rating does not mean a part is unmakeable — it means slower cutting speeds, more tool wear and a higher price. That is worth knowing before the quote arrives.

Tolerance Capability by Material

The tolerance you can hold depends as much on the material as on the machine. Stiff, stable metals hold tight numbers easily; soft or gummy ones move under clamping and cutting forces.

For numeric guidance on a specific alloy, see our aluminium tolerances guide, which explains ISO 2768 limits and how tightening a tolerance affects price.

Common Specification Mistakes

• Specifying "stainless" without a grade. 303, 304 and 316 machine completely differently and resist corrosion to different degrees. The grade changes the price.
• Asking for the tightest tolerance everywhere. A single tight feature among loose ones is cheap; a drawing covered in ±0.01 mm is not. Apply tolerance only where the function demands it.
• Ignoring material condition. T6, T651, annealed, cold-drawn — the same alloy in a different temper behaves differently on the machine and in service.
• Forgetting lead time. Exotic grades are often not in stock and add days before the first chip is cut.

Frequently Asked Questions

Which metal is best for a strong, lightweight part?

Aluminium 7075-T6 offers the best strength-to-weight ratio of the common alloys. Where corrosion resistance matters more than peak strength, 6061-T6 is usually the better balance of price, finish quality and availability.

Is stainless steel worth the extra cost?

Only when you genuinely need corrosion resistance, hygiene or elevated-temperature strength. For a dry indoor bracket, painted carbon steel does the same job for less.

Can you supply the material yourself, or should I?

We buy from certified Chinese mills and can supply mill certificates on request. If you have an approved grade or a customer-specified source, we will machine material you supply — just confirm it is cut to a workable size.

Do you machine titanium and tool steel?

Yes. Both are routine work for us, though they carry longer lead times and higher prices because of slower cutting speeds and faster tool wear.

Related Reading

• CNC Machining Service
• CNC Turning vs CNC Milling: Which Process Do You Need?
• CNC Machining Cost: 7 Factors That Drive Your Per-Part Price
• Anodizing vs Powder Coating: Which Finish to Choose?

Not sure which grade suits your application? Send us the drawing and the operating conditions — our engineers will recommend a material that meets the requirement without over-specifying the price.

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