A Guide to Choosing Materials for Your CNC Project
At ETG, we supply cutting-edge CNC machines from industry-leading brands like Chiron, Axile, bavius and Nakamura Tome. CNC machines deliver a world of possibilities.
But even with the most advanced CNC technology at your fingertips, the success of your project also hinges on the properties and quality of the material you choose to work with.
A machinist is only as good as the material he uses.
This guide aims to demystify the process of choosing a material, providing insights into the factors to consider and the benefits of various materials for CNC machining.
Benefits of Different Materials
1. Brass –
Advantages: Excellent electrical conductivity, good machinability, and low friction make brass suitable for components requiring conductivity and smooth movement such as locks, gears, and bearings.
Disadvantages: Brass can be expensive when compared to other common metals. It also has a tendency to work-harden making it brittle when exposed to repeated stress or deformation.
Applications: Consumer goods, electronics, medical equipment.
Variants: Brass C36000 offers high corrosion resistance and tensile strength, ideal for high-volume production.
All of our milling and turning machines are capable of machining brass.
2. Aluminium –
Advantages: Lightweight, strong, and corrosion-resistant with good thermal and electrical conductivity, aluminium is also recyclable, meaning you can reclaim costs on any waste material.
Disadvantages: Its low melting temperature can cause aluminium to soften during machining, making it difficult to cut and occasionally causing it to fuse to tools. Furthermore, its oxide coating can also cause damage to your tooling
Applications: automotive parts and aerospace.
3. Copper –
Advantages: Copper has excellent electrical conductivity, corrosion resistance, and malleability. Like aluminium, copper is also 100 percent recyclable making it economically efficient and environmentally friendly. Its inherent antimicrobial properties are what makes copper pipe ideal for use with consumables like drinking water, medical gas – and gin during distillation! From copper pipe manufacturing to medical instruments, copper caters to a wide range of applications.
Disadvantages: Its high ductility, plasticity, and toughness can make copper tricky to machine if you are inexperienced working with it. Copper is also susceptible to certain chemicals.
Applications: Valves, electrical connectors, radiators.
Popular Grades: Aluminium 6061 and Aluminium 6082.
4. Stainless Steel –
Advantages: Stainless steel boasts high strength, corrosion resistance, durability, and good ductility. It can be further strengthened with the use of heat treatments. Stainless steel is also resistant to chemical deterioration
Disadvantages: The same properties that make stainless steel perfect for manufacturing long-lasting parts can make it difficult to machine. The use of sharp tooling, proper geometry, and appropriate feed rates improve CNC machining of stainless steel.
Applications: Aerospace components, surgical tools, hardware.
Popular Grade: Stainless Steel 304.
5. Mild Steel –
Advantages: Good mechanical properties, high machinability, and weldability. Mild steel is easy to cut, drill, and shape to exact specifications. It also has good impact resistance. Mild steel offers a wide range of finishes and is more affordable than some other common metals.
Disadvantages: Mild steel isn’t inherently corrosion resistant and therefore relies on the proper application of a rust-resistant coating to protect it from the elements. It’s also not as strong as stainless steel.
Applications: General-purpose parts, jigs, fixtures.
Popular Grade: Mild Steel 1018.
6. Plastics (PVC, Delrin, Nylon) –
PVC: Boasting excellent chemical and flame-resistant properties, PVC is also cost-effective.
Disadvantages: PVC is not environmentally friendly nor recyclable. It can be difficult to machine as it’s prone to cracking, warping and burring.
Delrin: Precise dimensional stability, ideal for accurate parts.
Nylon: Strong, abrasion-resistant, and suitable for various engineering applications.
Factors to Consider When Choosing Your Material
1. Application requirement –
The first step is to understand the specific needs for your component. CNC machining can be used for a wide variety of applications. Is it a structural component, an electrical connector, or a decorative piece
Different applications demand different material properties.
For example, aerospace components require corrosion resistance and high strength, while electrical connectors need good electrical conductivity. Certain materials would work optimally for each of these two materials.
Think about the application.
2. Mechanical properties –
Next, consider the mechanical attributes your part needs, such as tensile strength, hardness, and flexibility. For instance, parts subjected to heavy loads might require high tensile strength, while flexible parts demand materials with good ductility.
3. Consider the environmental conditions your component will be subject to –
Will it be exposed to extreme temperatures, outdoor elements or chemicals? Choosing materials with appropriate resistance will ensure the longevity of your part.
Choosing materials with appropriate resistance will ensure the longevity of your part.
4. Cost constraints –
Budget considerations are another important factor to keep in mind. While certain materials offer exceptional properties, they might be overly expensive. Balance the material’s benefits with your project’s financial limitations.
5. Machinability –
Different materials have varying levels of ease when it comes to machining. Consider the complexity of your design and whether the material can be accurately machined to meet those specifications.
6. Finishing Requirements –
Some materials are better suited for specific surface finishes, coatings, or treatments. Ensure your chosen material aligns with your desired surface finish.
7. Industry Standards –
Some industries have regulations that dictate material choices for safety and compliance. Ensure your selected material meets these standards.
Once you’ve considered the various factors affecting choice of material, it’s time to look at the materials themselves to see which best meets the requirements for your part.
Choosing the right material for CNC machining is a crucial step in ensuring the success of your project.
By considering factors such as application requirements, mechanical properties, and environmental conditions, you can narrow down your options effectively. Each material comes with its own unique benefits, making it important to match the material’s properties with your project’s needs. Armed with this knowledge, you can confidently make informed decisions that result in high-quality, efficient, and precise CNC machining outcomes.