Machining stainless steel can be challenging due to its toughness & tendency to work-harden. In this blog, we will share tips to machine SS
Stainless steel is a popular material for a wide range of applications due to its corrosion resistance, strength, and durability. However, machining stainless steel can be challenging due to its toughness and the tendency to work-harden. In this blog, we will share some tips and techniques for successfully machining stainless steel.
I. Introduction to Stainless Steel or SUS : Stainless steel can be found in many shop floors especially places where Automotive & aerospace parts are manufactured . Below are different Groups / categories of Stainless steel avaialble and there common uses with most common grades are listed below :
| Group | Characteristics | Common Grades | Uses |
| Austenitic | Non-magnetic, outstanding corrosion and heat resistance. | 304, 316 | Food processing, gutters, bolts, nuts, fasteners. |
| Ferritic | Magnetic, lower corrosion and heat resistance than Austenitic. | 430, 446 | Automotive components and kitchen appliances. |
| Martensitic | Magnetic, moderate corrosion resistance – not for severe corrosion. | 416, 420, 440 | Knives, firearms, surgical instruments, hand tools. |
| Precipitation Hardened (PH) | Strong grade, heat treatable, severe corrosion resistance. | 17-4 PH, 15-5 PH | Aerospace parts |
| Duplex | Mixture of both Austenitic and Ferritic. | 244, 2304, 2507 | Water treatment plants, pressure vessels |
II. Difficulties in machining Stainless Steel
- Quick Tool Wear hence low tool life resulting in higher Tool Cost Per Components (CPC) which in turn results in Non-viable projects
III. Use Sharp Tools always for milling Stainless Steel
- It is important to use Carbide End Mills / Tools that are sharp and in good condition when machining stainless steel. Dull or damaged tools can cause a poor surface finish, increased tool wear, and even tool breakage. To ensure a clean and accurate cut, make sure to regularly check and maintain your tools.
IV. Use high-quality cutting fluid
- Cutting fluids can help to reduce heat and friction during the machining process, which can improve tool life and surface finish. When machining stainless steel, it's important to use a cutting fluid that is specifically designed for use with stainless steel.
V. Use the right cutting speed & right feed rate
- The cutting speed is an important factor when machining stainless steel. Too slow of a speed can cause the tool to rub and generate excess heat, while too fast of a speed can cause the tool to break or produce a poor surface finish. It's important to consult the manufacturer's recommendations for the appropriate cutting speed for the specific tool and material you are working with.
- The feed rate, or the speed at which the tool moves through the material, is also important when machining stainless steel. A feed rate that is too fast can cause the tool to break or produce a poor surface finish, while a feed rate that is too slow can cause the tool to rub and generate excess heat. Again, it's important to consult the manufacturer's recommendations for the appropriate feed rate for the specific tool and material you are working with.
VI. Use the correct tool geometry
- The tool geometry, or the shape and angle of the cutting edge, have an impact on the machining process. Using the correct tool geometry can help to improve the surface finish and extend tool life.
- Variable helix end mills provides the best finish & tool life in stainless steel milling , so you can opt for ROHIT make 4flute 330 Series Or 5-flute 333 Series
- Variable Index End Mills with 38* Helix angles can be used for Austenitic & Ferritic Stainless Steel only for the same you can opt for ROHIT make 4-flute 322 Series (This is always second option to Variable Helix End Mills when machining Stainless Steel)
VII. Use of Right Coolant , Coolant Mix & Coolant Pressure
- Coolant can help to reduce heat and improve the surface finish when machining stainless steel. It's important to use the correct type of coolant for the specific tool and material you are working with. Thumb rule for coolant mix %age for Steel is 5~6% however for Stainless steel it needs to be increased to 8~10% depending on hardness of the SS you are machining.
By following these tips and techniques, you can improve the efficiency and accuracy of your machining operations when working with stainless steel. With the right tools, techniques, and practices, machining stainless steel can be a successful and rewarding process instead of a headache for machinist around the globe.