Common Materials for CNC Machining
CNC machining plays a vital role in modern manufacturing, shaping the parts and products that power industries worldwide. From aerospace and automotive to healthcare and electronics, Computer Numerical Control (CNC) technology makes it possible to produce complex, high-precision components with consistency and speed.
But no matter how advanced CNC technology becomes, the quality of the final product ultimately depends on the machinist’s expertise and the materials they choose.
In this guide, you’ll learn about the most common metals and plastics used in CNC machining, how each performs, and why understanding material properties is essential for anyone training to become a CNC machinist.
What Is CNC Machining?
CNC machines use computer-guided tools—such as mills, lathes, and drills—to cut, shape, and form raw materials with exceptional accuracy. Each movement follows computer-programmed instructions, allowing machinists to produce consistent results at large volumes.
Common CNC processes include:
- Milling: Removes material using rotating cutting tools.
- Turning: Spins the workpiece to cut cylindrical shapes.
- Drilling: Creates precise holes or channels.
- Grinding: Refines surfaces for smooth finishes and tight tolerances.
CNC machining services play a vital role across various industries such as aerospace, automotive, medical device manufacturing, and consumer products. They offer repeatable precision and can be used with a range of materials, including metals, plastics, and composites. By combining automation with craftsmanship, CNC machining has redefined what’s possible in large-scale design and production.
Factors to Consider When Choosing a CNC Material
Selecting the right CNC material affects the performance, durability, and cost of the finished product. Before starting a project, machinists evaluate several key factors:
- Mechanical Strength and Durability – Will the material hold up under stress or load?
- Machinability – How easily can it be cut, drilled, or milled without tool wear?
- Surface Finish Quality – Does it achieve the required polish or texture?
- Thermal and Corrosion Resistance – Can it withstand heat, moisture, or chemical exposure?
- Cost and Volume – What’s the budget and production scale?
- Environmental Conditions – Will it withstand vibrations, impact, or exposure to extreme elements?
The right choice balances function, form, and financial feasibility, a crucial skill every machinist learns through experience.
Common Metals Used in CNC Machining
Aluminum
Lightweight yet strong, aluminum is one of the most popular materials in CNC machining. It’s highly machinable and naturally corrosion-resistant, making it ideal for industries that require precision and reliability.
Common Uses: Aerospace parts, automotive components, consumer electronics.
Benefits:
- Excellent strength-to-weight ratio
- Smooth, polished surface finish
- Good electrical and thermal conductivity
- Affordable and recyclable
Steel
Steel is both durable and versatile. It’s often chosen for its wear resistance and ability to be heat-treated for extra hardness.
Common Uses: Tools, machinery components, structural parts.
Benefits:
- High wear and impact resistance
- Long-lasting under heavy loads
- Adaptable through heat treatment
- Suitable for both prototypes and production runs
Stainless Steel
Known for strength and corrosion resistance, stainless steel is a top choice for environments that require durability and cleanliness.
Common Uses: Medical instruments, food processing equipment, marine components.
Benefits:
- Resists rust and oxidation
- Withstands high temperatures
- Easy to sterilize and maintain
- Delivers a sleek, professional finish
Brass
Brass machines smoothly and provides a bright, polished appearance. It’s often used for decorative or precision parts that require low friction.
Common Uses: Valves, fittings, connectors, electrical components.
Benefits:
- Excellent machinability
- Naturally corrosion-resistant
- Non-magnetic and low-friction
- Great for tight tolerances and aesthetic parts
Titanium
Titanium combines light weight with extreme strength and corrosion resistance. It’s used where performance and durability are critical.
Common Uses: Aerospace structures, implants, high-performance equipment.
Benefits:
- Outstanding strength-to-weight ratio
- Resistant to heat, corrosion, and fatigue
- Biocompatible for medical use
- Maintains stability under extreme conditions
Common Plastics Used in CNC Machining
ABS (Acrylonitrile Butadiene Styrene)
ABS is a durable, affordable plastic that’s easy to machine and ideal for prototypes and consumer products.
Common Uses: Enclosures, housings, testing models.
Benefits:
- Strong and impact-resistant
- Lightweight and versatile
- Cost-effective for iterative design
Nylon
Flexible and durable, nylon performs well in moving parts and mechanical assemblies.
Common Uses: Gears, bearings, bushings.
Benefits:
- Low friction for smooth motion
- High wear and fatigue resistance
- Absorbs impact and vibration
Acrylic (PMMA)
Known for clarity and polish, acrylic is a lightweight substitute for glass.
Common Uses: Displays, lenses, lighting fixtures.
Benefits:
- Exceptional optical clarity
- Shatter-resistant
- Easy to shape and polish
Delrin (Acetal)
Delrin (also called acetal) offers precision, rigidity, and low friction for mechanical and electrical parts.
Common Uses: Automotive components, fixtures, and electronic connectors.
Benefits:
- Excellent machinability
- Maintains tight tolerances
- Resistant to moisture and chemicals
PTFE (Teflon)
PTFE (commonly known as Teflon) is known for its extreme resistance to heat and chemicals, making it indispensable for specialized applications.
Common Uses: Gaskets, seals, insulators.
Benefits:
- Non-stick, low-friction surface
- Performs in high-temperature environments
- Chemically inert and durable
Metal vs. Plastic — Which Is Right for Your CNC Project?
| Material Type | Best For | Advantages | Considerations |
| Metals | Heavy-duty, structural components | High strength, excellent durability | Higher cost, heavier weight |
| Plastics | Prototypes, lightweight parts | Easy machining, cost-effective | Lower strength, less heat resistance |
Key Takeaway:
Use metals when performance and load-bearing capacity are top priorities. Choose plastics when you need flexibility, low weight, or budget efficiency.
How to Choose the Right CNC Material
Selecting your CNC machining material is all about matching performance to purpose.
Follow these steps:
- Define part requirements. Consider strength, flexibility, and appearance.
- Evaluate the environment. Think about exposure to heat, moisture, or chemicals.
- Set your budget. Cost and quantity directly affect material choice.
- Test multiple materials. Prototyping helps determine the best fit.
- Consult an expert. Machinists and engineers can help balance cost, quality, and efficiency.
CNC Machining Applications Across Industries
CNC machining is used across nearly every manufacturing sector:
- Aerospace: Lightweight aluminum and titanium components for engines and airframes.
- Automotive: Steel, brass, and nylon for gears, fittings, and performance parts.
- Medical: Stainless steel and titanium for surgical instruments and implants.
- Electronics: ABS and acrylic for device housings and optical components.
- Industrial Manufacturing: A mix of metals and plastics for tools, jigs, and fixtures.
Why Learn About CNC Machining at EIT
At the Erie Institute of Technology (EIT), students don’t just read about machining—they practice it. EIT’s CNC Machinist Training Program teaches students to program, set up, and operate real CNC machines using many of the materials overviewed in this guide.
Program highlights include:
- Hands-on training with industry-grade equipment
- Small class sizes and individualized instruction
- Guidance from experienced professionals
- Job placement assistance with local manufacturers in Erie, PA
- Flexible scheduling and financial aid options
Whether you’re a first-time job seeker or an experienced professional looking to explore a new trade, EIT’s vocational training programs offer short-term practice and certification to help you succeed in a variety of high-demand industries.
Start Your CNC Machining Career with EIT
Ready to turn your interest in precision manufacturing into a rewarding career? EIT gives you the skills, tools, and confidence to succeed in today’s competitive job market.
Learn how to operate advanced CNC machines, work with a variety of materials, and gain real-world experience employers value.
Get started today. Contact EIT to apply, request information, or schedule a campus tour.