Stainless Steel CNC Machining Material Grade Selection Guide

• Stainless Steel CNC Machining Material Grade Selection Guide
  • Classification of stainless steel alloy materials
  • How to select the appropriate stainless steel grade for CNC part projects ?
    • Functional requirements
    • Assessment of corrosion resistance
    • Considering manufacturability and cost
  • Recommendations for selecting the correct grade of stainless steel for CNC machining
  • What is the best grade of stainless steel for machining?
  • Elimold’s stainless steel CNC machining services
  • in conclusion
  • FAQ

Stainless steel is more than just a shiny material. At its core, it’s an alloy that uniquely combines durability, resilience, and aesthetics. Its history, composition, and grading system are both complex and fascinating. The story of stainless steel begins in the early 20th century when metallurgists began experimenting with different alloy combinations. Their goal was to find a material that could resist corrosion while maintaining the strength of steel. In 1913, Harry Brearley, a materials scientist in Sheffield, England, discovered that adding at least 12% chromium to steel could transform it into stainless steel, paving the way for the material we know today.

In this blog post, we will explore how to choose the right stainless steel material for CNC machining and provide guidance on how to select the best material for your CNC machining projects.

Classification of stainless steel alloy materials

Stainless steel comes in various forms, depending on the percentage of alloying elements, especially chromium, which ensures differences in alloy properties. Below, we categorize this alloy into five main types.

Ferritic stainless steel	This type of stainless steel contains 10.5% chromium as its main alloying element, ensuring its excellent corrosion resistance. This steel is magnetic and suitable for a variety of automotive applications, including annealing conditions to improve strength. However, compared to some other stainless steel variants, it has lower toughness, making it easier to use as sheet metal and giving it a cool look. Typical examples include SS 409 and 430.
Austenitic stainless steel	This grade of stainless steel contains approximately 17% to 25% chromium and 8% to 20% nickel, along with other elements that further reduce its iron content. Therefore, it is non-magnetic but possesses excellent ductility, toughness, and corrosion resistance. Furthermore, it exhibits good weldability and formability, making it suitable for a wide range of applications, such as chemical processing and the manufacture of medical equipment, kitchen and household appliances. Typical examples include SS 316/316L, 304/304L, and 253.
Martensitic stainless steel	Martensitic stainless steel contains 12% to 16% chromium and no more than 2% carbon. However, it is known for its considerable strength, hardness, and wear resistance. Furthermore, it responds well to heat treatment, but its ductility and weldability decrease. Its applications include the manufacture of kitchenware such as cutlery, bearings, and valve components. Examples of this stainless steel grade include 410, 431, and 420C SS.
Precipitation hardened stainless steel	Like martensitic stainless steel, precipitation-hardening stainless steel contains 12% to 16% chromium, but with more alloying elements. It contains approximately 3% to 9% nickel and trace amounts of other elements such as aluminum, titanium, and copper, forming precipitates. This alloy gains considerable strength through heat treatment. Furthermore, it is strong, ductile, and corrosion-resistant. Due to these properties, its main applications include aerospace and high-stress applications.
duplex stainless steel	Duplex stainless steel grades are more or less a mixture of austenitic and ferritic variants, giving them characteristics of both stainless steels. The alloy contains approximately 18% to 29% chromium and 3% to 8% nickel, along with other elements such as nitrogen and molybdenum. The resulting alloy exhibits excellent corrosion resistance and strength, as well as resistance to chloride stress and pitting corrosion. However, it is not heat-treatable and is unsuitable for cold working. Nevertheless, it is magnetic and possesses good weldability and formability, making it suitable for a variety of engineering applications. Typical examples include grades S32750 and 2205 SS.

How to select the appropriate stainless steel grade for CNC part projects ?

Still confused about the different grades of stainless steel for your CNC machining projects ? Choosing the wrong stainless steel not only wastes money but can also damage parts. We can simplify this process for you. Your choice needs to strike a balance between performance, machinability, and cost. It can be done in just three simple steps. When I help clients, I have them consider three key questions. This makes the selection process much easier.

Functional requirements

The functional requirements of the manufacturing process play a crucial role in determining the appropriate steel alloy type for your project. For example, if the primary requirement is strength, such as in construction engineering, steel is a better choice. However, if the component will be used in harsh environments, such as exposure to moisture or chemicals, then stainless steel is a better option.

Assessment of corrosion resistance

Where will your component be used? If it’s for a dry, indoor environment, a lower grade material like 303 may suffice. If the component will be exposed to moisture, food, or mild chemicals, 304 is a good choice. For harsh environments such as saltwater or medical applications, you’ll need the superior protection of 316.

Considering manufacturability and cost

Budget is always crucial. 303 stainless steel is the cheapest and fastest to process, saving on material and labor costs. 304 and 316 stainless steels are more durable but require more processing time and tools, thus increasing costs. You must strike a balance between performance requirements and production costs.

Recommendations for selecting the correct grade of stainless steel for CNC machining

Regardless of the application your part project will be used for, simply consider the questions above and where you will be using the steel to determine the appropriate stainless steel grade or designation . Below are material selection recommendations for CNC machining of stainless steel summarized by engineers at Elimold :

• For strong rust protection, use 316 stainless steel. This type of stainless steel is best suited for use in environments containing water, salt, or chemicals.
• If you want steel that is easy to cut and inexpensive, you can choose 416 stainless steel. This type of steel is suitable for dry environments or locations where it is not prone to rust.

• In areas near the ocean, at least 316L stainless steel is required. This type of stainless steel can withstand seawater corrosion and is extremely strong and durable.

• If you need to manufacture a large number of parts quickly, 416 stainless steel can save you time and money because it is easy to process.

Finally, it is essential to choose steel suitable for the environment. Humid, saline, or acidic environments require steel with good rust resistance. Dry indoor environments can use steel that is easy to cut.

Choosing the right steel depends on your specific needs. If you want to save costs and speed up construction, 416 stainless steel is a wise choice. If you need parts to be durable and long-lasting in harsh environments, 316 stainless steel offers better protection.

What is the best grade of stainless steel for machining?

Need quick and economical parts machining? Some stainless steel parts are extremely difficult to machine, which can increase costs. Let us help you find the most convenient solution.

Austenitic stainless steel is generally considered difficult to machine. 400 series stainless steel is easier to machine than 300 series stainless steel. This includes grades 304 and 316. The machinability of 304 and 316 stainless steel does differ. Type 303 stainless steel is perhaps the easiest to machine in the 300 series. It is easier to machine than 304. This makes 303 grade steel the preferred choice for fittings, gears, and fasteners with tight tolerances. Its relative weakness means it is not used as frequently as 304 grade stainless steel.

304 stainless steel is easier to work than 316 stainless steel. Not only is 304 grade easier to work, but it’s also easier to clean, which is one reason it has so many different finishes and is used on surfaces visible to the public. 316 stainless steel is not only difficult to work, but also requires special tools for cutting. It performs well in terms of pitting corrosion resistance, but is less formable, which explains why it’s reserved for applications where other types of stainless steel cannot be handled. Stainless steel grades have a range of permitted additional metal contents to maximize machinability. In addition to the differences in machinability among various types of stainless steel,

Elimold’s stainless steel CNC machining services

Prolean offers a complete suite of stainless steel CNC machining services, tailored to the unique challenges and advantages of stainless steel. Our state-of-the-art equipment ensures that every cut, bend, and weld meets the highest industry standards. We continuously update our machinery to utilize the latest technologies, ensuring precision and consistency. Our team has years of experience CNC machining stainless steel. We understand the nuances of each grade, ensuring your project has optimal performance and lifespan. Every project is unique. At Elimold, we pride ourselves on providing bespoke CNC machining solutions to meet the specific needs of each client, whether it’s complex design requirements, unique surface finishes, or specific performance properties. Contact us now.

in conclusion

In summary, choosing the right type of stainless steel for your project depends on a variety of factors, including your specific application requirements, budget, and production constraints. While both 304 and 316 stainless steels offer excellent properties, they differ significantly in chemical composition, mechanical properties, corrosion resistance, high-temperature resistance, and weldability.

When selecting materials, it’s essential to assess the specific requirements of your project to determine which material is most suitable. By considering the factors mentioned above, you can make an informed decision, ensuring your CNC machining projects achieve optimal performance and lifespan. Elimold specializes in manufacturing a wide range of CNC parts in stainless steel. Contact us now for a free quote.

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