Industry News
What Is the Best CNC Machining Process for 18/10 Stainless Steel?
2026-07-20
In the field of precision machining, 18/10 stainless steel (i.e. 316 austenitic stainless steel) is widely used in high-end sectors such as medical equipment, food processing, marine engineering and chemical processing equipment, thanks to its excellent corrosion resistance and high-temperature stability. However, its high toughness and tendency to work-harden also present many manufacturing workshops with challenges such as high tool wear, low machining efficiency and inconsistent yield rates for finished products. As a manufacturer with many years of specialised experience in precision CNC machining, FRIMA has accumulated extensive mass-production expertise in the machining of 18/10 stainless steel. This article will systematically analyse the challenges involved and outline the optimal machining processes, helping customers to efficiently produce high-quality components.
Can 18/10 Stainless Steel be CNC Machined?
The answer is yes. 18/10 stainless steel is fully compatible with CNC machining processes such as turning, milling and drilling; however, compared to free-cutting materials such as aluminium and low-carbon steel, the machining requirements are significantly higher.
As a typical austenitic stainless steel, 18/10 stainless steel presents two key machining challenges: firstly, it exhibits a pronounced work-hardening effect, whereby the surface layer of the material hardens rapidly due to plastic deformation during cutting, resulting in a significant increase in hardness and accelerated tool wear; secondly, its high strength at elevated temperatures and poor thermal conductivity cause cutting heat to concentrate in the cutting edge area, which can easily lead to tool softening and chipping, whilst also compromising the surface finish of the workpiece.
Consequently, the efficient machining of 18/10 stainless steel requires specialised cutting tools, optimised cutting parameters, an adequate cooling system and a high-rigidity machine tool clamping system. Through systematic process control, the inherent machining disadvantages of the material can be mitigated.
Comparison of Machinability Across Stainless Steel Grades
The stainless steel family comprises numerous grades with vastly different machining characteristics; selecting the right grade requires balancing material properties against processing costs:
● 303 Stainless Steel: Widely recognized as the austenitic stainless steel with the best machinability. The addition of sulfur acts as a chip breaker, fragmenting chips into fine particles; this significantly reduces tool wear and enables higher cutting speeds and superior surface finishes. However, sulfur slightly compromises corrosion resistance and formability, making this grade best suited for applications requiring high machining efficiency in mildly corrosive environments.
● 304 Stainless Steel (18/8): The most versatile stainless steel grade. It is easier to machine than 316 and serves as the mainstream choice for most consumer and industrial equipment. While it exhibits work-hardening characteristics, the absence of molybdenum results in lower toughness and cutting resistance compared to 316, offering advantages in machining efficiency and tool life.
● 18/10 Stainless Steel (316): The addition of 2%–3% molybdenum significantly enhances resistance to chloride-ion corrosion. Known as "marine-grade stainless steel," it is the preferred material for marine, medical, and food-grade applications. However, molybdenum also increases the material's strength and toughness, resulting in higher cutting loads; consequently, it is the most difficult of the three to machine and demands the strictest process control.
● 304 Stainless Steel (18/8): The most versatile stainless steel grade. It is easier to machine than 316 and serves as the mainstream choice for most consumer and industrial equipment. While it exhibits work-hardening characteristics, the absence of molybdenum results in lower toughness and cutting resistance compared to 316, offering advantages in machining efficiency and tool life.
● 18/10 Stainless Steel (316): The addition of 2%–3% molybdenum significantly enhances resistance to chloride-ion corrosion. Known as "marine-grade stainless steel," it is the preferred material for marine, medical, and food-grade applications. However, molybdenum also increases the material's strength and toughness, resulting in higher cutting loads; consequently, it is the most difficult of the three to machine and demands the strictest process control.
|
Grade |
Key Additive for Machinability |
Relative Machinability |
General Corrosion Resistance |
|
303 |
Sulfur |
Excellent |
Good |
|
304 |
None specific for machinability |
Fair |
Very Good |
|
316 (18/10) |
None specific for machinability |
Poor to Fair |
Excellent (superior to 304) |
Key Process Points for CNC Machining of 18/10 Stainless Steel
Based on FRIMA' s extensive experience in mass production, machining 18/10 stainless steel requires strict control across five key dimensions to ensure stable output characterized by high efficiency, low cost, and superior quality:
1. Tool Selection: Carbide-based with optimized coatings
High-speed steel (HSS) tools are strictly prohibited for machining 18/10 stainless steel; ultra-fine-grained carbide tools must be used to ensure cutting edge strength and wear resistance. For continuous cutting operations, TiAlN (Titanium Aluminum Nitride) coated tools are recommended due to their excellent high-temperature hardness and oxidation resistance, which effectively withstand cutting heat. For interrupted cutting or deep-cavity machining, carbide grades with higher cobalt content should be selected to enhance impact toughness.
Maintaining a sharp cutting edge is essential during production; dull or chipped tools increase friction and accelerate work hardening, creating a vicious cycle where the material becomes harder as it is machined, leading to further hardening. FRIMA’s machining standards include specific tool life thresholds for 316 stainless steel, mandating regular tool changes to guarantee machining stability.
2. Cutting Parameters: Reduce speed, maintain steady feed, and control depth
● Cutting Speed: Compared to 304 stainless steel, the cutting speed for 18/10 stainless steel should be reduced by 20%–30%. Excessive cutting speeds generate rapid heat buildup, accelerating tool failure; conversely, speeds that are too low cause friction and rubbing at the cutting edge, inducing work hardening. The rotational speed range must be selected based on tool diameter, machine tool rigidity, and cooling conditions.
● Feed Rate: Maintain a steady and sufficient positive feed to prevent the tool from dwelling and rubbing against the workpiece surface. An insufficient feed rate results in a cutting layer that is too thin, causing the tool edge to slide over the work-hardened layer and drastically reducing tool life; an excessive feed rate overloads the machine and tool, leading to chatter.
● Cutting Depth: Follow the principle of "moderate cutting depth." A depth that is too shallow promotes friction-induced hardening, while a depth that is too deep risks overloading and chipping the tool. For roughing, ensure the cutting edge fully penetrates the base material to avoid the surface-hardened zone; for finishing, employ a strategy of shallow cuts and faster feed rates to balance surface finish with dimensional accuracy.
3. Cooling and Lubrication: High-Pressure, High-Flow Precision Coverage
18/10 stainless steel has low thermal conductivity, making it difficult to dissipate cutting heat; the effectiveness of the cooling system directly determines tool life and machining quality. FRIMA employs high-pressure cooling systems across its entire line, using specialized stainless steel cutting fluids delivered at high flow rates and pressures to directly flush the cutting zone. This serves a dual purpose: rapidly removing heat to control workpiece and tool temperatures, and forcefully breaking and evacuating chips to prevent them from re-scoring the workpiece surface or tangling around the tool and causing chipping.
4. Machine Tools and Workholding: High Rigidity as a Core Prerequisite
Machining 18/10 stainless steel involves high cutting forces; insufficient rigidity easily leads to vibration, resulting in surface chatter marks, dimensional deviations, and tool chipping. FRIMA’s approach includes: selecting high-rigidity machining equipment with spindles and guideways capable of handling heavy loads and resisting vibration; optimizing fixture design to increase contact area and minimize overhang; and utilizing auxiliary supports for long-shaft or thin-walled parts to maximize the elimination of machining chatter, thereby ensuring geometric tolerances and surface quality.
5. Process Path Planning: Minimizing Repeated Cutting
To address the material's tendency toward work hardening, process planning aims to minimize repeated passes over the same area. Roughing employs climb milling, allowing the cutting edge to penetrate the base material in a single pass and avoiding repeated cutting within the work-hardened layer; finishing leaves an appropriate allowance to ensure the final dimension is achieved in a single pass, thereby reducing the duration of contact between the tool and the hardened layer.
FRIMA’s Expertise in 18/10 Stainless Steel Machining
As a manufacturer specializing in precision CNC custom machining, FRIMA possesses comprehensive capabilities for processing 18/10 stainless steel parts, offering end-to-end services ranging from single-unit prototyping to mass production:
● Equipped with multiple high-rigidity CNC lathes and machining centers—complemented by high-pressure cooling systems and specialized carbide tooling—we reliably execute multi-process operations such as turning, milling, drilling, tapping, and boring.
● Our technical team brings over a decade of experience in stainless steel machining, allowing us to tailor optimal process plans based on part geometry and precision requirements while balancing production efficiency and manufacturing costs.
● We strictly adhere to the IATF 16949 quality management system, implementing rigorous quality control throughout the entire workflow—from raw material intake to finished product shipment—to ensure that the dimensional accuracy, surface finish, and material properties of our 18/10 stainless steel parts meet all customer specifications.
● Equipped with multiple high-rigidity CNC lathes and machining centers—complemented by high-pressure cooling systems and specialized carbide tooling—we reliably execute multi-process operations such as turning, milling, drilling, tapping, and boring.
● Our technical team brings over a decade of experience in stainless steel machining, allowing us to tailor optimal process plans based on part geometry and precision requirements while balancing production efficiency and manufacturing costs.
● We strictly adhere to the IATF 16949 quality management system, implementing rigorous quality control throughout the entire workflow—from raw material intake to finished product shipment—to ensure that the dimensional accuracy, surface finish, and material properties of our 18/10 stainless steel parts meet all customer specifications.
Conclusion
Although CNC machining of 18/10 stainless steel presents certain technical challenges, it is by no means an insurmountable problem. Through the scientific selection of cutting tools, precise parameter matching, adequate cooling and high-rigidity clamping solutions, it is entirely possible to achieve efficient, stable and cost-effective mass production.
If you are seeking a partner for the machining of precision 18/10 stainless steel components, or are encountering technical issues such as tool wear or low yield rates during the machining process, please do not hesitate to contact FRIMA. We will provide a professional process assessment and bespoke machining solutions tailored to your component drawings and application requirements.