Choosing the Right Material for Your Project: A Practical Guide

Over recent decades, we have manufactured numerous unique projects and components. While many decisions—from design nuances to custom tooling—shape a part’s performance, the most fundamental choice made during manufacturing is the material.

Every metal offers distinct strengths and limitations, making it suited to specific applications. Achieving optimal results in a machining project begins with a careful assessment and selection of the most appropriate material. Below are five key material choices for custom machining.

Copper

Copper boasts the highest electrical conductivity of any common metal—100% relative to silver—making it the go‑to choice for high‑performance electrical components. It also resists corrosion in mechanical, aqueous, and saline environments. Although it forms a thin, stable oxide layer when exposed to air, this patina protects the underlying metal from further degradation. Copper’s excellent ductility and machinability make it ideal for automotive and electrical applications.

Phosphor Bronze

Phosphor bronze—a copper alloy with up to 10 % tin and 1 % phosphorus—offers excellent oxidation resistance during heat treatment. Although its conductivity is only about 15 % that of pure copper, it delivers reliable electrical performance in cryogenic conditions thanks to its balanced conductivity and low thermal conductivity.

It is highly resistant to fatigue cracking and provides superior corrosion protection in marine and industrial settings. Renowned for its strength, fatigue resistance, and low wear rate, phosphor bronze is a popular choice for springs, gears, and high‑strength components. Typical automotive and electrical parts use thicknesses from 0.008 ″ to 0.050 ″.

Brass

Brass is often the most economical choice for electrical components, offering good ductility, hardness, and corrosion resistance at a lower cost than pure copper. Combining copper and zinc yields a material that is more ductile than either element alone. Approximately 90 % of brass is recycled, making it an environmentally friendly option.

It resists corrosion in freshwater, neutral or alkaline salt solutions, and typical atmospheric conditions, both marine and inland. Alloying with aluminum enhances corrosion resistance, while a small amount of lead improves machinability.

Aluminum

Aluminum is a widely used material prized for its high strength‑to‑weight ratio, making it ideal for lightweight structural parts in isolation or as a composite with other metals.

Aluminum also offers excellent corrosion resistance in humid and many chemical environments. With a conductivity of 61 % relative to copper, it is suitable for both mechanical and electrical applications.

Its combination of toughness, lightness, and malleability makes aluminum a standard choice for automotive and mechanical parts with thicknesses ranging from 0.012 ″ to 0.120 ″.

Steel

Steel comes in countless grades, each engineered to meet specific industry requirements. By adjusting carbon content and adding alloying elements, manufacturers tailor strength, conductivity, and corrosion resistance. Heat treatments—such as quenching, tempering, and hardening—further modify a steel’s final properties.

Steel is typically corrosion‑resistant, offers conductivity up to 15 % of copper, and delivers exceptional formability and toughness. While it provides reliable ductility and yield strength, variations in composition and heat treatment create a broad spectrum of options, allowing engineers to select the optimal grade for a particular application.