CNC Machining Stainless Steel: An Ultimate Guide

Stainless steel is very commonly used in multiple applications but shaping and forming this material needs a CNC machining process. In order to come up with adequate stainless steel machined parts you can take help from this guide. It features a detailed insight into everything you may need to know about CNC machining stainless steel, so let's take a look.

What is CNC Machining Stainless Steel?

Stainless steel components are widely used in different applications and to manufacture them with accuracy and precision, the process of CNC machining is undertaken. Stainless steel is a robust material which is corrosion-resistant and hence suits various applications.

Moreover, the process of CNC machining is quite flexible and helps to manufacture intricate and precise stainless steel machine parts. When it comes to understanding CNC machining, stainless steel parts are created by first designing a digital model of the parts in software. The software then converts the design into machine codes (G-code or M-code) that the CNC machine can read and understand.

The CNC machine with the help of the code moves accordingly and the cutting tool then eliminates the material from the workpiece of stainless steel. The machine uses the software program and carries out the machining process.

CNC machining offers multiple operations for stainless steel which include milling, turning, drilling, and grinding, and also repeatable operations can be performed with high precision and accuracy.

5 Types of CNC Machining Stainless Steel

Various types of stainless steel material can be opted for CNC machining to manufacture CNC machined parts, different types of CNC machining stainless steel are as follows:

Austenitic Stainless Steel

Austenitic stainless steel is a type of stainless steel that is corrosion-resistant, formable, and weldable. Austenitic stainless steel has a non-magnetic nature.

The application of austenitic stainless steel can be seen in dishwashers, water tanks, washing machines storage equipment, cutlery, mining tools etc

Martensitic Stainless Steel

Martensitic stainless steel is exceptionally hard, it is subjected to heat treatment and aging to attain tempering and hardness. It can have either high or low carbon quality as required for the applications.

Martensitic stainless steel is used widely in medicine like for dental equipment and surgical tools, apart from this it is also used in cutlery and firearms.

Ferritic Stainless Steel

Ferritic stainless steel does not have the shine like other forms of steel but they are known for its excellent magnetic nature and resistance against chemicals. The ferritic stainless steel also resists stress corrosion and cracking.

Ferritic stainless steel has applications in the automobile sector and is also used for making industrial tools.

Duplex Stainless Steel

Duplex stainless steel is achieved by combining ferritic and austenitic stainless steel. Duplex stainless steel enhances the structural integrity of components and it consists of three different grades which include super duplex, standard duplex, and lean duplex.

Duplex stainless steel is used commonly in condensers, piping systems, heat exchangers, etc.

Precipitation Hardening Stainless Steel

Precipitation Hardening Stainless Steel is a stainless steel alloy consisting of some other elements like copper, titiakum, aluminum, or phosphorus.

These alloys go through hardening treatment after the formation and have excellent strength. This type of steel is used in high-strength environments like aircraft, chemical industries, marine constructions, and nuclear plants.

Different Grades of Stainless Steel

When it comes to CNC machining stainless steel there are various grades that are opted and some of these are as follows:

Alloy 302

The stainless steel 302 has a high grade of carbon. It is highly resistant to corrosion and is quite effective for CNC machining. It is ideal for the manufacture of structural parts, weldments, non-magnetic parts and cryogenic components.

Alloy 303

Stainless Steel 303 is very easy to machine. It is highly machinable due to the ample amount of sulfur present in its composition. It is primarily used for manufacturing various precision parts and decorative materials, offering good corrosion resistance and weldability. However, it has a relatively low hardness, making it unsuitable for parts that need to withstand heavy loads.

Alloy 304

Stainless Steel 304 is commonly used in CNC machining stainless steel. It has less carbon and it doesn't even need post-welding. It offers the right toughness level which is required for the tools of machining. It is suitable for manufacturing deep-drawn parts and acid pipelines, containers, structural parts, etc.

Alloy 316

Stainless Steel 316 is very common and it comprises molybdenum which makes it highly resistant to corrosion. It offers weldability and formability which makes it popular for machining. In seawater and other various media, the corrosion resistance is better than SUS 304, and it is mainly used for pitting corrosion resistant materials.

Advantages of Stainless Steel in CNC Machining?

The stainless steel machined parts are widely popular when manufactured using CNC machining, some of the advantages the process of CNC machine offers for stainless steel are as follows:

• The process of CNC machining allows the machine to be made of stainless steel in a massive volume as the process supports repeatability.
• The stainless steel material is quite flexible and offers versatility, it allows CNC machining for highly complex parts even when the stainless steel belongs to austenitic grades.
• The machining stress imposed by CNC machines can be handled by stainless steel as it is very robust.
• The CNC machining process when opting for stainless steel parts that have tight tolerances, proves to be highly accurate.
• Stainless steel is aesthetically pleasing which makes it suitable for being machined through the CNC process in various applications because it shows a contemporary look without loss of its functionality when machined.

Challenges for Custom Stainless Steel Machined Parts

Some of the challenges faced by the custom stainless steel machined are as follows:

• Stainless steel is a hard material and hence machining this material requires high strength and the tools also need to be robust enough.
• Stainless steel has low thermal conductivity and the heat is not dissipated during the machining process which leads to overheating of the tool.
• Due to the properties of stainless steel, sometimes achieving the desired surface finish may be a bit challenging, in this case, proper adjustments are needed for machining parameters and tooling.
• Some of the grades of stainless steel have a high tendency to deform due to heat and stress which makes it difficult to maintain tight tolerance and careful control is needed.
• The challenges associated with stainless steel machining may lead to increased costs due to tool wear and the slow speed of machining.
• The CNC machining for stainless steel needs highly experienced and skillful operators to ensure that the process is carried out effectively.

Tips to Stainless Steel CNC Machining

CNC machining stainless steel is very important in multiple applications and when opting for these processes some of the important tips to follow are as follows:

1. In order to avoid tool wear and deforming due to the stress of machining, it is suggested to employ radii for the internal edges of the stainless steel workpieces.
2. Features that are not achievable through the CNC machine must not be included and rather other fabrication alternatives can be opted.
3. In order to ensure efficiency in the CNC stainless steel machining, implement parameters like surface feet per minute.
4. To prevent chipping during the CNC machining, it is better to choose the right tool material.
5. CNC machines should be secured and rigid in order to prevent the extreme movements that occur during the operation due to vibration.
6. When machining stainless steel with CNC machines, keep yourself equipped with protective gear like gloves and protective glasses.
7. In order to avoid the high cost of machining and long processing time keep control of the use of tolerances.
8. To prevent the deformation caused by heat use the right coolant during the CNC machining process.
9. The depth-to-width ratio must be considered during the cavity design.

Surface Finishes for Stainless Steel Machined Parts

Stainless steel is known for excellent resistance against corrosion but still, some of the surface treatments may help to enhance the characteristics of the components manufactured through the process of CNC machining. Some of the surface finishing options are as follows:

1. Sandblasting helps to remove the layer of black oxide that can result from welding and rolling, it uses a pressurized adhesive which helps to scrub the layer of oxide.
2. Nitric and hydrochloric acid helps in removing the layer of oxide on the stainless steel components and this process is called pickling.
3. Mechanical polishing offers a mirror-like finish making the components of stainless steel bright.
4. Electrochemical polishing employs the process of reduction with the help of DC current which leads to ionizing the metal surface and also results in a mirror-like shiny surface.
5. An oxidation process can be employed through different chemical solutions that have bases, acids, and mixed salts, and such a process is called chemical oxidation.
6. Immersing the stainless steel component in certain salts under specific conditions to achieve the desired color coating.

Applications of Stainless Steel CNC Machining

The application of stainless steel CNC machining is observed in multiple applications and some of these are as follows:

Aerospace: In the aerospace industry, the airframe, landing gear, and jet engine components are manufactured using stainless steel components which are processed through CNC machining.

Automotive: CNC-machined parts of stainless steel are used in automobiles, parts like connecting rods and engine components are manufactured using the stainless steel material.

Construction: Stainless steel is known for its resistance and strength which makes it suitable for the structure of bridges and it is subjected to CNC machining.

Chemical: The chemical industry uses stainless steel parts made using the CNC machining process due to its durable and corrosion-resistant nature.

Kitchen Utensils: Various kitchen utensils like pans, pots, cookers, and cutlery are made using CNC machining stainless steel.

Conclusion

The significance of using stainless steel in different applications and having custom stainless steel parts processed through CNC machining is quite extensively highlighted in the guide above. The different types, grades, pros, and cons of everything that is associated with stainless steel CNC machining are featured and it will help you decide the processing of your components.

If you are on the hunt for accurate and precise CNC machined components, you can get in touch with DEK. They have implemented the finest CNC machining techniques which help them produce highly accurate stainless steel components customized according to client requirements.

FAQs

Which Type of Stainless Steel is the Most Widely Used?

Stainless steel 304 is one of the most widely used chromium-nickel stainless steel, with good corrosion resistance, heat resistance, low-temperature strength and mechanical properties.

Is Stainless Steel Hard to Machine?

Yes, due to its properties, stainless steel is considered a difficult material to machine. Its poor thermal conductivity can cause chips to accumulate at the cutting edge, leading to tool damage. Therefore, it is essential to choose the appropriate machining methods to effectively work with stainless steel.

Which Stainless Steels are Difficult to Machine?

Austenitic stainless steel is the hardest one to machine. Because this type of steel contains more nickel or manganese, so its organizational structure is stable, heat treatment is difficult to make it strengthened. This type of steel in the cutting process chip continuously, breaking difficulties, while easy to produce work hardening.