Issues to be aware of when CNC machining hard and soft metals
- Issues to be aware of when CNC machining hard and soft metals
- What are the characteristics of hard and soft metals that can be machined by CNC?
- What are cemented carbide materials : issues and solutions during machining ?
- What are soft alloy materials ? Machining considerations and solutions.
- How to Choose the Right Materials for Your CNC Machining Project
- How do you determine whether your machining project is better suited to cemented carbide or soft carbide?
- What are the strategies for successfully performing CNC machining of hard and soft metals?
- Choose a suitable CNC machined parts manufacturer
- in conclusion
Generally, metals can be divided into “hard metals” (such as stainless steel, titanium, and nickel-chromium alloys) and “soft metals” (such as aluminum, copper, and brass). Each type of metal presents unique challenges during CNC machining. Understanding the differences between machining hard and soft metals is crucial for achieving optimal part quality and maintaining efficient production processes.
In this blog post, we’ll discuss the specific challenges of CNC machining hard and soft metals, highlighting the unique problems that need to be addressed for each material type. As an industry professional, you need to understand these distinctions to make informed decisions and achieve better results in your CNC machining operations.
What are the characteristics of hard and soft metals that can be machined by CNC?
The following is a representative classification of common hard and soft metals used in CNC machining projects. This classification reflects the actual machinability, hardness, and cutting characteristics encountered in CNC milling, turning, and Swiss-type machine tooling.
| Category | Metal Type | Typical Examples | Common CNC Applications |
| Hard Metals | Carbon Steel | AISI 1045, AISI 1060 | Shafts, structural parts, mechanical components |
| Hard Metals | Alloy Steel | 4140, 4340, 8620 | Gears, molds, high-load machine parts |
| Hard Metals | Tool Steel | D2, H13, A2 | Injection molds, dies, punches |
| Hard Metals | Stainless Steel | 304, 316, 17-4PH | Medical parts, valves, aerospace components |
| Hard Metals | Titanium Alloys | Ti-6Al-4V | Aerospace parts, implants, high-strength components |
| Hard Metals | Nickel-Based Alloys | Inconel 625, Inconel 718, Hastelloy | Turbine parts, high-temperature components |
| Hard Metals | Cobalt Alloys | Stellite, Co-Cr alloys | Wear-resistant and medical components |
| Hard Metals | Hardened Steel | HRC 45–60 steels | Precision molds, hardened mechanical parts |
| Soft Metals | Aluminum Alloys | 6061, 7075, 2024 | Housings, brackets, aerospace structures |
| Soft Metals | Copper | C110, C101 | Electrical connectors, heat sinks |
| Soft Metals | Brass | C360, C260 | Fittings, valves, decorative parts |
| Soft Metals | Bronze | C932, C954 | Bearings, bushings, wear components |
| Soft Metals | Magnesium Alloys | AZ31, AZ91 | Lightweight structural parts |
| Soft Metals | Zinc Alloys | Zamak 3, Zamak 5 | Housings, small precision components |
| Soft Metals | Lead Alloys | Lead-tin alloys | Counterweights, shielding components |
What are cemented carbide materials : issues and solutions during machining ?
When CNC machining hard metals such as alloy steel, stainless steel, tool steel, titanium alloys, and nickel-based superalloys, the main considerations focus on cutting forces, heat generation, and tool life. These materials have high hardness and strength, increasing cutting resistance and accelerating tool wear. Therefore, machining strategies must prioritize process stability, rigid fixtures, and optimized toolpaths to avoid chatter and tool failure. Cutting speeds are typically low, and careful control of depth of cut and feed rate is required to manage thermal load. Advanced cutting tools, such as coated carbide, ceramic, or CBN inserts, are often necessary, along with high-pressure or directional coolant delivery for heat dissipation and chip removal. In many cases, achieving tight tolerances and fine surface finishes on hard metals may require secondary machining, such as grinding or polishing, especially for hardened parts.
What are soft alloy materials ? Machining considerations and solutions.
Compared to machining hard materials, CNC machining of soft metals such as aluminum, copper, brass, bronze, magnesium, and zinc alloys prioritizes efficiency, chip control, and surface finish. These materials typically allow for higher spindle speeds, greater depths of cut, and faster feed rates, resulting in higher material removal rates and shorter cycle times. Tool wear is generally lower, allowing the use of standard carbide or even high-speed steel tools. However, soft metals are more prone to problems such as built-up edge, burr formation, and material adhesion, which can affect surface finish and dimensional accuracy. Appropriate tool geometry, a sharp cutting edge, and suitable lubrication or minimal cooling strategies are crucial for maintaining part quality and consistency, especially for thin-walled or high-precision parts.
How to Choose the Right Materials for Your CNC Machining Project
To successfully select materials for your CNC machining project , you can follow these basic steps:
| Determine the material requirements for the project | Consider the required properties of materials, such as functionality, electrical properties, strength, and hardness, to determine the most suitable candidate materials for the project. In addition, the operating environment and exposure conditions of the parts should also be taken into account. |
| Identify potential material options | Compile all suitable materials according to your requirements (including design specifications). |
| Choose more suitable materials | Choose materials that meet more requirements. Sometimes trade-offs are necessary; for example, to ensure part quality, choose materials with good machinability rather than those with lower costs. |
How do you determine whether your machining project is better suited to cemented carbide or soft carbide?
When choosing between hard and soft metals for CNC machining projects, the decision should be based on factors such as functional requirements, manufacturability, cost objectives, and life cycle, not just hardness. From an engineering and production perspective, the following factors are crucial:
Functional and mechanical performance requirements
If parts must withstand high loads, wear, impacts, or high temperatures, hard metals such as alloy steel, tool steel, stainless steel, titanium alloys, or nickel-based alloys are typically required. These materials offer excellent strength, fatigue resistance, and long-term dimensional stability. For parts requiring reduced weight, corrosion resistance, good electrical or thermal conductivity, or only moderate strength, softer metals such as aluminum, brass, copper, or magnesium are generally more suitable.
Manufacturability and Design Complexity
Because of their excellent machinability and lower cutting forces, soft metals are generally better suited for complex geometries, thin walls, deep cavities, and demanding machining cycle requirements. Hard metals, on the other hand, increase the risk of tool wear, vibration, and thermal deformation, which may limit design freedom or require more conservative toolpaths and additional finishing steps.
Cost and production volume
Soft metals typically have lower overall manufacturing costs due to their faster machining speeds, longer tool lives, and shorter machining times. They are well-suited for prototyping and mass production. Hard metals, on the other hand, increase the cost per part due to their lower cutting parameters, higher tool costs, and more stringent process control; however, their use is justifiable if performance and durability are more important than cost.
Surface finish and tolerance requirements
If excellent surface finish and tight tolerances are required directly through CNC machining, soft metals are generally easier to control. Hard metals may require post-processing techniques such as heat treatment, grinding, or coating, which should be considered when selecting materials.
Work environment and life cycle
The intended use environment of a part typically dictates the choice of material , such as exposure to high temperatures, corrosion, friction, or chemicals. Hard metals are suitable for harsh or highly abrasive environments, while soft metals perform well in non-abrasive, weight-sensitive, or corrosive applications.
What are the strategies for successfully performing CNC machining of hard and soft metals?
Whether you’re focusing on hard or soft metal machining, the key to success lies in implementing comprehensive process planning and optimization. This includes effectively using CAM software and simulation tools to model the machining process, identify potential problems, and optimize toolpaths and machining parameters. Equally important is operator training and skills development. The CNC machine operators at the manufacturers you choose to partner with must have a deep understanding of the unique characteristics and requirements of hard and soft metal machining to make informed decisions, solve problems, and ensure the continuous production of high-quality parts. Furthermore, CNC component manufacturers must also possess the ability to achieve continuous improvement through data collection and analysis . Only by continuously monitoring and analyzing the performance of CNC machining operations can opportunities for optimization be identified and targeted process improvements implemented.
Choose a suitable CNC machined parts manufacturer
At Elimold, we offer a wide range of hard and soft materials and related tailored CNC machining services, including CNC milling, turning, Swiss-system machining, and multi-axis machining. Our team’s experience and in-house manufacturing capabilities enable us to provide our clients with unparalleled quality and precision.
Furthermore, we are committed to providing you with the best customer service, helping you achieve your goals and reduce expenses. Our technicians can help you select the best materials for your project and provide free professional advice. Whether you have a specific project or need custom CNC machined parts, we can assist you at every stage. Price consultations start now.
in conclusion
CNC machining of different metal materials presents unique challenges. Understanding these challenges and adopting targeted machining strategies is crucial for improving machining efficiency and quality. By selecting appropriate tool materials, adjusting cutting parameters, effectively controlling cutting temperature, and using coolant appropriately, these machining difficulties can be effectively overcome, improving CNC machining efficiency and accuracy. Therefore, a thorough understanding of the characteristics of each metal material, combined with specific machining requirements, and optimization of the machining process are key to ensuring successful CNC machining.