When I first started working with custom machined parts, I quickly realized that choosing the right material wasn’t just a technical decision—it was a strategic one. Whether you’re building a prototype, optimizing a product for long-term use, or managing production costs, the material you select for your machined part has a direct impact on performance, durability, and price.
Over the years, I’ve seen firsthand how the right—or wrong—material can make or break a project. In this blog post, I’ll walk you through how I approach material selection, what factors you need to consider, and share a few insights from real-world experience that might help you avoid common pitfalls.
Why Material Selection Matters
Let’s start with the obvious: different materials behave differently. Some are stronger, others lighter. Some conduct electricity or heat, others resist it. Some cost a lot more than others. But beyond the basic material properties, each choice comes with trade-offs that can affect machining time, tooling requirements, surface finish, and even long-term product reliability.
Whether you’re building aerospace components, medical devices, or custom enclosures for electronics, you need to match the material to the job—not just in theory, but in the real-world context of how the part will be used.
The Big Questions to Ask
Here are the key questions I always ask before choosing a material for a custom machined part:
What will this part actually do?
Consider the part’s function. Will it carry a load? Will it be exposed to friction, vibration, high temperatures, or chemicals? Does it need to be flexible or rigid?
What kind of environment will it live in?
A part used outdoors in harsh weather will need different properties than one used in a clean, temperature-controlled lab. Consider exposure to moisture, salt, UV, heat, and cold.
What are the mechanical performance needs?
Think tensile strength, hardness, impact resistance, fatigue life, and so on. Do you need something that can bend without breaking, or resist deformation over time?
Are there regulatory or industry standards involved?
If you’re in aerospace, medical, or food-grade applications, certain materials may be required or restricted by regulation.
What’s the budget—and does it scale?
Some exotic materials offer amazing performance, but if you’re making hundreds or thousands of parts, costs can escalate quickly. Think about how scalable your material choice is.
How easy is it to machine?
Some materials are notoriously difficult to work with, requiring slower machining speeds, special tools, or post-processing steps. This affects both cost and lead time.
A Quick Breakdown of Common Materials I Use
Let’s dive into some of the most common materials I work with, and when I choose to use them.
Aluminum: The All-Purpose Workhorse
Aluminum is my go-to material for many custom machined parts. It’s lightweight, corrosion-resistant, and fairly strong for its weight. It machines beautifully, which means lower production costs and faster turnaround times.
I often recommend aluminum for:
Enclosures and housings
Brackets and mounts
Prototype parts
Heat sinks (with the right alloy)
The most popular grades I use are 6061 (great balance of strength and machinability) and 7075 (stronger but slightly more expensive and less corrosion-resistant).
Stainless Steel: For Strength and Corrosion Resistance
When strength and durability are critical—and corrosion is a concern—I usually turn to stainless steel. It’s harder to machine than aluminum, but the trade-off is worth it in high-performance applications.
Ideal for:
Medical devices
Marine components
Structural parts
High-wear components
I’ve had great success with 304 for general corrosion resistance and 316 for more demanding environments like saltwater exposure.
Brass and Copper: For Electrical and Thermal Conductivity
I don’t use brass and copper every day, but when I need excellent electrical or thermal conductivity, they’re indispensable. Brass also has a unique aesthetic quality, which makes it a popular choice for visible or decorative parts.
Common uses:
Electrical connectors
Plumbing components
Custom heat sinks
Decorative hardware
Copper is softer and trickier to machine, but it’s unmatched in conductivity. Brass is easier to work with and still performs well in low-friction and decorative roles.
Plastics: Lightweight and Cost-Effective
Plastics are incredibly versatile—and not just for cost savings. I often recommend materials like Delrin (acetal), Nylon, PTFE (Teflon), or PEEK for applications where weight, chemical resistance, or low friction are more important than raw strength.
Great for:
Bearings and bushings
Fluid system parts
Lightweight mechanical components
Electrical insulation parts
Plastics also absorb vibrations well and are often easier to machine at high speeds, making them a smart option for lower-load applications.
Titanium: High-Performance, High-Stakes
Titanium is the superstar of custom machining—lightweight, incredibly strong, and corrosion-resistant. But it’s expensive and difficult to machine. I usually reserve it for aerospace, medical, or high-performance industrial parts where the benefits outweigh the cost.
When to consider titanium:
Surgical instruments or implants
Aerospace brackets and frames
High-performance automotive components
It requires special tooling, slower feeds and speeds, and a good understanding of heat management during machining.
Balancing Performance and Cost
One thing I always emphasize with clients is that material choice is a balancing act. You don’t want to over-engineer a part if a simpler material will do the job just as well. But you also don’t want to cheap out on materials and pay for it later in failures or rework.
Here’s an example: I once worked on a project that originally spec’d out stainless steel for a sensor housing, purely out of an abundance of caution. After reviewing the use case, we realized the housing would never be exposed to moisture or abrasion—so we switched to anodized aluminum and cut both the cost and machining time in half, without compromising performance.
That kind of insight can only come from asking the right questions up front.
Working With a Machining Partner
If you’re unsure about what material to use, my best advice is: talk to your machining partner. We see these decisions play out every day across dozens of projects. A good partner won’t just take your order—they’ll help you optimize your design for the best combination of performance, manufacturability, and cost.
When clients come to me early in the design process, we often save them thousands of dollars (and weeks of headaches) just by adjusting the material spec or making small tweaks to the geometry.
Final Thoughts
Choosing the right material for your custom machined part is more than just picking from a list—it’s about understanding how each material performs under real-world conditions. You need to think through the environment, the function, the scale of production, and yes, the budget.
The good news? You don’t have to do it alone.
I love helping customers find the right balance between strength, cost, and performance. If you’re working on a new part or trying to optimize an existing one, don’t hesitate to reach out. I’d be happy to walk through your options and help you make the most informed decision possible.
Because in machining—as in life—it’s not just about having the best material. It’s about having the right material, for the right job.
