CNC Machining Materials: Complete Guide to Metals and Plastics

1. Introduction to CNC Machining Materials

Selecting the right material is crucial for CNC machining success. The material affects machinability, cost, strength, weight, and final part performance. This guide covers the most common CNC machining materials.

2. Aluminum Alloys

Aluminum is the most popular CNC machining material due to excellent machinability and strength-to-weight ratio:

6061 Aluminum

• Properties: Good strength, excellent corrosion resistance, weldable
• Machinability: Excellent (rating: 70%)
• Applications: Aerospace, automotive, consumer products
• Typical Uses: Brackets, frames, housings, prototypes

7075 Aluminum

• Properties: Very high strength, good fatigue resistance
• Machinability: Good (rating: 70%)
• Applications: Aerospace, military, high-stress parts
• Typical Uses: Aircraft fittings, gears, shafts

2024 Aluminum

• Properties: High strength, good fatigue resistance
• Machinability: Good (rating: 70%)
• Applications: Aerospace structures, truck wheels

3. Steel Alloys

Mild Steel (1018, 1020)

• Properties: Good strength, ductile, weldable
• Machinability: Good (rating: 78%)
• Applications: General purpose, shafts, pins

Medium Carbon Steel (1045, 4140)

• Properties: Higher strength, can be heat treated
• Machinability: Fair (rating: 65-70%)
• Applications: Gears, shafts, connecting rods

Alloy Steel (4340, 8620)

• Properties: Very high strength, tough
• Machinability: Fair (rating: 60-65%)
• Applications: Heavy-duty gears, axles, landing gear

4. Stainless Steel

304 Stainless

• Properties: Excellent corrosion resistance, non-magnetic
• Machinability: Fair (rating: 60%)
• Applications: Food processing, medical, marine

316 Stainless

• Properties: Superior corrosion resistance (molybdenum added)
• Machinability: Fair (rating: 60%)
• Applications: Chemical processing, marine, medical implants

416 Stainless

• Properties: Free-machining stainless
• Machinability: Excellent (rating: 85%)
• Applications: Screws, nuts, bolts, fittings

5. Brass

• Properties: Excellent machinability, corrosion resistant, decorative
• Machinability: Excellent (rating: 100% - benchmark)
• Applications: Valves, fittings, electrical components, decorative
• Common Alloys: C36000 (free-cutting), C26000 (cartridge brass)

6. Titanium

• Properties: High strength-to-weight, biocompatible, corrosion resistant
• Machinability: Poor (rating: 20-30%)
• Applications: Aerospace, medical implants, racing
• Common Alloys: Grade 2 (pure), Ti6Al4V (Grade 5)
• Machining Tips: Low cutting speed, high feed, generous coolant

7. Engineering Plastics

ABS

• Properties: Tough, impact resistant, easy to machine
• Machinability: Excellent
• Applications: Prototypes, enclosures, automotive trim

Nylon (PA6, PA66)

• Properties: Strong, wear resistant, self-lubricating
• Machinability: Good
• Applications: Gears, bearings, bushings

Delrin (POM)

• Properties: Stiff, low friction, dimensionally stable
• Machinability: Excellent
• Applications: Precision parts, gears, bearings

PTFE (Teflon)

• Properties: Lowest friction, chemical resistant, high temp
• Machinability: Good (but soft, requires sharp tools)
• Applications: Seals, gaskets, chemical processing

PEEK

• Properties: High performance, biocompatible, high temp
• Machinability: Good
• Applications: Medical, aerospace, semiconductor

8. Material Selection Guide

9. Corgi Capacity Network Material Expertise

Corgi Capacity Network works with all major CNC machining materials:

• Access to suppliers specializing in various materials
• Cost Optimizationstrategies
• AI Smart Quote - Get quotes for any material