// RESOURCE — MATERIAL SELECTION
Material Selection for CNC Machining
Aluminum, titanium, Inconel, stainless, and engineering plastics compared — strength, weight, corrosion and heat resistance, machinability, and cost — so you can spec the right material the first time.
Material choice is the first and most consequential decision in any machined part. It sets the performance envelope, drives much of the cost, and determines how the part will behave in service. Over-specifying a premium alloy where a common one would do wastes money; under-specifying invites failure. This guide compares the materials we machine most and links to detailed pages for each, so you can make a defensible choice and confirm it with a DFM review.
How to choose
Start from the application, not the material. Define the loads, operating temperature, corrosive or chemical exposure, weight limits, electrical or magnetic requirements, regulatory constraints (biocompatibility, flammability), and budget. Then choose the lowest-cost material that comfortably meets every requirement. A licensed engineering firm can help weigh these trade-offs — that is the value of engineering plus machining under one roof.
- Mechanical: strength, stiffness, fatigue, and hardness needed.
- Environment: temperature, corrosion, chemical, and wear exposure.
- Weight: strength-to-weight matters for flight and motion.
- Compliance: biocompatibility, traceability, flammability, ITAR.
- Cost: raw stock price plus machinability (tougher = slower = pricier).
Aluminum
Aluminum is the everyday workhorse: light, corrosion-resistant, an excellent thermal and electrical conductor, and fast to cut. 6061 is the versatile general-purpose default; 7075 offers near-steel strength for aerospace structure; cast plate such as MIC-6 stays flat and stable for tooling. It anodizes beautifully for cosmetics or wear. See aluminum machining.
Titanium
Titanium delivers an outstanding strength-to-weight ratio, excellent corrosion resistance, and biocompatibility, which is why it dominates aerospace structure and medical implants. Ti-6Al-4V (Grade 5) is the workhorse. It is more expensive to buy and to machine — its strength and low thermal conductivity demand controlled speeds and rigid setups — but for flight-critical and implantable parts it is often the only right answer. See titanium machining.
Inconel & superalloys
Nickel-based superalloys such as Inconel 625 and 718 hold their strength at extreme temperatures and resist aggressive corrosion, making them the choice for turbine, energy, and high-temperature parts. They work-harden rapidly and are hard on tooling, so many shops decline them — but that is exactly the hard-part work we specialize in. See Inconel machining.
Stainless steel
Stainless steels balance corrosion resistance, strength, and cost. 303 machines freely; 304 is the general-purpose corrosion-resistant grade; 316 adds marine and medical corrosion resistance; 17-4 PH is heat-treatable for high strength. They are heavier than aluminum and titanium but far less expensive than superalloys. See stainless steel machining.
Engineering plastics
Engineering polymers shine where you need light weight, electrical insulation, chemical resistance, or low friction. PEEK offers high temperature and chemical resistance and is biocompatible; Delrin (acetal) machines cleanly with good stiffness and wear resistance; Ultem and PTFE serve specialized thermal and chemical needs. They cut quickly but require attention to fixturing and heat to hold tolerance. See engineering plastics machining.
At-a-glance comparison
| Aluminum 6061/7075 | Light, conductive, low cost, fast-cutting; general-purpose. |
|---|---|
| Titanium Ti-6Al-4V | Best strength-to-weight, biocompatible; costly to buy & cut. |
| Inconel 625/718 | Extreme heat & corrosion resistance; hard to machine. |
| Stainless 304/316/17-4 | Corrosion resistance & strength; moderate cost. |
| PEEK / Delrin | Light, insulating, chemical-resistant; lower strength than metals. |
Not sure which to pick? Send your part for a free DFM review and we will recommend a material and process for your application, or request a quote directly.
// FAQ
Frequently asked questions
Aluminum — especially 6061 — is the most common because it is light, corrosion-resistant, inexpensive, and fast to machine. 7075 is used when higher strength is needed, such as aerospace structure.
Choose titanium when you need a much higher strength-to-weight ratio, biocompatibility for medical implants, or better corrosion and high-temperature resistance than aluminum provides. It costs more to buy and machine, so reserve it for parts that genuinely need it.
Inconel work-hardens quickly, retains its strength at high temperature, and is abrasive on tooling. It requires controlled parameters, rigid fixturing, and the right inserts — which is why many shops avoid it and why experienced superalloy machining matters.
Yes. As a licensed engineering firm we review your application, loads, environment, and budget and recommend the lowest-cost material that meets every requirement. A free DFM review is the easiest way to start.
Send us the hard one.
Upload your drawing or STEP file and we'll come back with pricing and lead time — from a single high-mix part to full production runs, held to exacting tolerances.