Custom 304 and 316 stainless steel parts: machining challenges, applications, and post-processing

• Custom 304 and 316 stainless steel parts: machining challenges, applications, and post-processing
  • Understanding the basics of stainless steel materials
  • Comparison of elemental contents of two stainless steel grades
  • Performance parameters of 304 and 316 stainless steel grades
  • Challenges and difficulties in CNC machining of 304 and 316 stainless steel
  • Common surface treatment methods for general stainless steel CNC parts
  • and applications of CNC machining of stainless steel parts
  • the Development Trend of Stainless Steel Parts
  • Why did we choose Elimold to collaborate on a custom stainless steel parts project?
  • Summarize
  • FAQ

The superior precision, ability to manufacture complex geometries, rapid production to meet high-volume demands, consistent repeatability in large-scale production, and flexibility to adapt to various customizations make CNC machining an indispensable technology for manufacturing various stainless steel parts . Stainless steel CNC parts are renowned for their durability, corrosion resistance, and high heat resistance , making them the material of choice for industries requiring robustness and hygiene, such as medical, aerospace, and food processing.

This article delves into the CNC machining complexities of 304 and 316 stainless steel, highlighting their unique advantages, machining challenges, and surface treatment methods to enhance performance. We will cover the technical details and cost-effectiveness of the machining process, emphasizing the crucial role these materials play in the ever-evolving manufacturing technologies.

Understanding the basics of stainless steel materials

Steel is an alloy of iron and carbon, containing varying amounts of other elements such as manganese, nickel, and vanadium. Similarly, stainless steel is also an alloy of iron and carbon, composed of other similar alloying elements. However, unlike ordinary steel alloys, stainless steel contains a significant amount of chromium, giving it corrosion resistance. Therefore, the main difference between stainless steel and steel lies in the former’s high chromium content, which enhances its rust resistance and overall durability.

However, stainless steel alloys come in various grades, each designed for specific applications. Grades 304 and 316 stand out due to their widespread use in CNC machining. Their properties differ, and understanding these properties is crucial when selecting the appropriate stainless steel grade for a CNC machining project, as it directly impacts the performance and lifespan of the parts.

Comparison of elemental contents of two stainless steel grades

304 stainless steel contains approximately 18% chromium and 8% nickel. It does not contain molybdenum, therefore its resistance to chloride and acid corrosion is inferior to that of 316 stainless steel. 316 stainless steel, in addition to containing 16-18.5% chromium and 10-14% nickel, also contains 2-3% molybdenum. Molybdenum significantly improves its resistance.

Both 304 and 316 stainless steels are austenitic stainless steels with a face-centered cubic crystal structure. Although the chromium content differs between the two types of stainless steel, both can form a protective oxide layer on their surface, resulting in excellent corrosion resistance. This oxide layer prevents rusting and corrosion in various environments.

While these two grades share many characteristics, the key difference lies in the presence of molybdenum in 316, which gives it superior resistance to chemical and salt water corrosion. Therefore, 316 is ideal for marine or pharmaceutical equipment applications where high corrosion resistance is required. 304 stainless steel is suitable for applications without extreme conditions, providing a cost-effective solution without compromising quality.

Performance parameters of 304 and 316 stainless steel grades

As two of the most commonly used grades in the stainless steel family, 304 and 316 have found their place in various industries and applications. However, when it comes to choosing between them, understanding their physical properties is crucial. Below is a table of their basic physical properties.

S/N		304	316
1	Composition	Primarily composed of 18% chromium and 8% nickel, with small amounts of carbon and manganese .	Contains 16-18% chromium , 10-14% nickel , and additional 2-3% molybdenum .
2	Corrosion resistance	Excellent resistance to a wide range of atmospheric environments and many corrosive media.	Superior resistance to chlorides and acids, particularly sulfuric, hydrochloric, acetic, formic, and tartaric acids.
3	Temperature tolerance	Up to 870°C (1600°F)	Higher temperature tolerance, up to 925°C (1700°F)
4	Formability	Good formability, suitable for various shaping processes.	Similar to 304, but slightly less ductile due to higher alloy content.
5	Weldability	Easily weldable using common methods (TIG, MIG, etc.).	Weldable, but requires more care due to molybdenum content.
6	Strength	Good strength, suitable for structural applications	Slightly higher strength than 304 due to molybdenum addition.
7	Cost	Generally more affordable than 316.	Typically more expensive due to higher alloy content.

Challenges and difficulties in CNC machining of 304 and 316 stainless steel

Processing stainless steel, primarily 304 and 316 grades, presents a unique set of challenges, pushing the limits of modern manufacturing technology. While these materials offer exceptional durability and corrosion resistance, careful handling methods are necessary to maintain the integrity of the final product. Some of the challenges in processing 304 and 316 stainless steel include:

tool wear	The high strength and toughness of stainless steel can lead to accelerated wear on cutting tools, requiring more frequent tool replacements.
work hardening	Both 304 and 316 stainless steels are prone to work hardening, which makes subsequent machining operations more difficult and affects tool life.
Heat Management	The processing generates a lot of heat, which can affect the material properties and dimensional accuracy of the parts.
Surface smoothness	High-quality surface finish requires careful selection of cutting tools, cutting parameters, and machining strategies.
cost	The challenges of stainless steel machining may lead to increased production costs due to increased tool consumption and reduced machining speed.

Common surface treatment methods for general stainless steel CNC parts

The versatility of CNC-machined stainless steel parts makes them indispensable across various industries. Their toughness and adaptability allow for a wide range of applications, from everyday items to specialized industrial components. Depending on the application environment, different surface treatment processes are used for stainless steel CNC parts. The following are commonly used surface treatment processes for stainless steel materials.

passivation	Removes iron contamination, enhances the natural chromium oxide layer, and improves corrosion resistance.
Electropolishing	It makes the surface smooth, reduces material adhesion, and enhances aesthetics and corrosion resistance.
plating	It can be plated with another metal, such as nickel or chromium, to improve durability and appearance.
Powder coating	It provides a durable and protective coating that is more environmentally friendly than traditional liquid coatings.
Black Oxidation	This surface treatment represents a recent advancement in stainless steel machining. It involves using a black oxide tool without any coating. The surface is very rough, with deep scratches and pits.
Sandblasting	Sandblasting gives parts a clean, smooth appearance and makes them very durable. During sandblasting, the blasting medium (usually sand) is propelled at high speed into the nozzle. This causes the medium to impact the surface of the part, creating a matte finish.
Mirror finishing	Mirror polishing is a technique that achieves an extremely high degree of smoothness on the surface of metal parts. After CNC machining of stainless steel, this technique can be used to polish the parts to a mirror finish.
Chemical polishing	Chemical polishing is a surface treatment process that uses chemical compounds to smooth metal surfaces. These compounds can be acidic or alkaline solutions, depending on the type of metal being polished. This polishing process offers high corrosion resistance and good mechanical properties.

and applications of CNC machining of stainless steel parts

304 and 316 stainless steels are both austenitic chromium-nickel alloys and are among the most widely used stainless steel grades, renowned for their excellent balance of properties. Their versatility and durability make them the material of choice for numerous applications across various industries. This section will explore the common applications of 304 and 316 stainless steels, highlighting their key uses in different fields .

Aerospace	Used for components that must withstand extreme pressure and temperature while maintaining structural integrity. Examples include landing gear components, hydraulic systems, and turbine engines.
Medical	Used for medical devices, implants, and equipment that require sterilization and corrosion-resistant cleaning agents. For example, orthopedic implants, scalpels, and forceps.
car	Used in engine parts, exhaust systems, and trim pieces to improve durability and aesthetics. Examples include fuel injectors, transmissions, and trim pieces.
Food processing	Hygiene and corrosion resistance are crucial for machinery and surfaces that come into contact with food, such as conveyor belts, mixing tanks, and tableware.
ocean	Used in shipbuilding and fittings to resist seawater corrosion, such as propeller shafts, deck hardware, and railing systems.

the Development Trend of Stainless Steel Parts

Driven by technological advancements and a growing emphasis on sustainable development, innovations in materials science promise to produce stainless steel grades that are more resilient and versatile. Industries will continue to seek materials capable of withstanding harsher environments and offering longer service lives, and stainless steel will remain a preferred choice, particularly in environmentally conscious sectors that prioritize its recyclability and longevity.

Why did we choose Elimold to collaborate on a custom stainless steel parts project?

We understand your needs are unique, which is why we offer custom manufacturing solutions. Our team excels at tailoring our machining processes to different projects to meet your specific design requirements. This customization capability sets us apart, ensuring you receive components perfectly suited for your unique application.

Furthermore, our commitment to you extends beyond simply delivering parts. We’ve also established a robust customer service and support system. From your initial inquiry to after-sales service, our team will provide comprehensive support throughout the entire manufacturing process. Choosing us means choosing a partner who understands your needs and is dedicated to meeting them with excellence. Send us your drawings now for a free, instant quote.

Summarize

While the average person might think that 304 and 316 stainless steel are the same thing, manufacturers should absolutely not make that mistake. Although the materials are steel alloys, they have different mechanical and chemical properties. The main difference is that stainless steel has a higher corrosion resistance than steel. However, both alloys possess other good mechanical properties such as toughness, hardness, and strength, and support a wide variety of manufacturing processes.

When choosing between 304 and 316 stainless steel, the specific requirements of the project must be assessed 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.

The Elimold team is highly skilled in manufacturing a wide range of stainless steel materials, including prototypes and high-volume parts. If you encounter any difficulties in comprehension of such materials, contact us today for a quote.

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