How to Select Materials and Estimate Costs: Comparing the Advantages and Disadvantages of Stainless Steel, Aluminum, and Brass for CNC Turning

When planning a CNC turning project, material selection is more than just a technical decision—it directly impacts machining efficiency, production cost, and final product performance. Many engineers and buyers ask: Should I choose stainless steel, aluminum, or brass for CNC turning?

In this guide, we’ll share real-world machining insights, cost estimation tips, and performance comparisons to help you make the right choice.

Why Material Selection Matters in CNC Turning

From my own factory’s experience, choosing the wrong material can increase machining time by 30–50% and lead to unnecessary tool wear. On the other hand, selecting the right alloy ensures:

• Faster machining cycles

• Better surface finish with less polishing required

• Lower cost per part due to reduced scrap and tool replacement

• Improved durability in the final application

Let’s break down stainless steel, aluminum, and brass from both a technical and cost perspective.

Stainless Steel: Strength with Higher Machining Costs

Advantages:

• Excellent corrosion resistance, suitable for medical, food processing, and marine applications

• High strength and durability under mechanical stress

• Long service life in harsh environments

Disadvantages:

• Harder to machine: cutting speeds are slower, tool wear is faster

• Higher overall machining cost compared to softer alloys

• Requires coolant management to avoid heat-related deformation

Case Example:
In one of our projects producing stainless steel valve components, cycle times were nearly 40% longer than with aluminum due to the need for slower feeds. However, the parts were able to withstand pressures above 200 bar, which justified the higher cost.

Cost Range: Stainless steel CNC turning typically costs 25–35% more than aluminum, depending on grade (304, 316, 17-4PH).

Aluminum: Lightweight and Cost-Efficient

Advantages:

• Excellent machinability—cutting speeds up to 3x faster than stainless steel

• Lightweight yet strong enough for aerospace and automotive components

• Lower material cost and faster cycle times

• Anodizing available for enhanced surface protection and aesthetics

Disadvantages:

• Lower strength compared to stainless steel, not ideal for heavy load applications

• Surface scratches easily if not anodized

• Lower temperature resistance

Case Example:
For a recent batch of motorcycle hubs, switching from stainless steel to aluminum cut machining time by 45% and reduced total project cost by 28%, while still meeting performance requirements.

Cost Range: Aluminum is generally the most cost-effective of the three, especially for large production runs.

Brass: Precision and Premium Machinability

Advantages:

• Exceptional machinability—short chips and low tool wear

• Naturally corrosion-resistant without additional coating

• Provides excellent dimensional accuracy, ideal for fittings, gears, and decorative components

• Attractive gold-like finish for visible parts

Disadvantages:

• Material cost is higher than aluminum

• Softer than stainless steel—less suitable for high-stress mechanical parts

• Limited heat resistance

Case Example:
When producing custom CNC-turned connectors for an electronics client, brass allowed us to achieve tolerances of ±0.005 mm consistently. The machining time was 30% faster than stainless steel, which offset the higher raw material cost.

Cost Range: Brass parts typically fall 10–20% higher than aluminum, but lower than stainless steel when machining complexity is factored in.

Cost Estimation Factors Beyond Material

When estimating CNC turning costs, material is only one part of the equation. From our quoting experience, the following also affect the final price:

• Part complexity: Deep grooves or thin walls increase machining time.

• Batch size: Larger runs reduce cost per unit due to setup efficiency.

• Tolerances required: ±0.01 mm precision may increase cost by 15–20%.

• Surface treatment: Anodizing, polishing, or coating adds to the final price.

Quick Comparison Table: Stainless Steel vs. Aluminum vs. Brass