A carefully considered combination of — or balance between — cutting tool properties and geometries and the application of aggressive cutting parameters can significantly boost productivity in stainless steel machining operations.
Basic stainless steel alloys are categorised as ferritic or martensitic. Ferritic alloys have percent chromium and are not hardenable. Martensitic alloys have higher chromium and carbon content than ferritic stainless steels, as well as additions of manganese and silicon, producing an alloy that can be hardened via thermal treatment.
Today, ferritic and martensitic stainless alloys are not generally used a lot in industrial environments but rather in household items such as kitchen or garden tools. As the utilisation of stainless steel evolved, the alloys were frequently applied in situations that required mechanical strength as well as corrosion resistance. These materials are referred to as austenitic stainless steels, and they are common in industrial applications today where strength and resistance to corrosion and heat are needed.
The alloys typically are used in petrochemical processing, in the food industry where hygiene standards require corrosion resistance and in general machinery intended for use in harsh environments. Inevitably, increasing the performance capabilities of an alloy, such as stainless steel, also multiplies the challenges of machining it. The corrosion-resisting characteristics of ferritic and martensitic stainless steel alloys are basically chemical properties, and as a result these alloys are not significantly more difficult to machine than plain steels.
However, the additions of nickel and other elements in austenitic stainless steels produce increased hardness, toughness, deformation resistance and thermal properties that decrease machinability.
Until recently, machining of austenitic stainless steel was not well understood. Machinists assumed that because the alloys were stronger, mechanical cutting forces would be higher and that it would be necessary to apply stronger, negative-geometry tools at reduced cutting parameters. However, that approach produced short tool life, long chips, frequent burrs, unsatisfactory surface roughness and unwanted vibrations.
Most of the extra energy consumption required to machine austenitic stainless steels is the result of their thermal properties. Metal cutting is a deformation process, and when deformation-resistant austenitic stainless steel is machined, the operation generates excessive heat.
Evacuating that heat from the cutting zone is of primary importance. This leads to faster cutting tool wear. And chip breaking is not easy to bend and break, So it is easy to damage the surface of the part and affect the product quality.
Our company has over 10 years experience in machining stainless steel, every year, we produce hugh quantity stainless steel machined parts. Based on our practice and experience, we believe that the following guidelines should be followed for machining stainless steel material:. All in all, stainless steel is one of the most difficult materials to machine. When debating between the ideal processes for machining vs. Heat treatment may be done to make the metal more machinable.
For example, normalizing heats the steel to a temperature higher than the annealing temperature. It is held long enough to cause smaller austenitic grains.
This improves the machinability of the steel. These types of steel have low thermal conductivity. You need to be careful not to let the surfaces overheat. Overheating can also cause distortion that is hard to correct. Use oil to lubricate reduce tool wear and cool things down. You can use either mineral oils or water-soluble emulsifiable oils. Trust the experts at Geospace Technologies to provide first-rate products and services. Ready to get started? Reach out to a representative today!
What is the difference between and stainless steel? What grade of stainless steel is best for machining? Is vs. What makes some grades of stainless steel easier to machine than others?
How can you increase the machinability of stainless steel? How do you machine vs. Due to the difference in conductivity, care must be taken to ensure adequate removal heat from the workpiece and the tool. Overheating can result in blunting of the tool and localized burning of the workpiece surface.
Columbus austenitic grades are also normally supplied in the annealed condition and of more importance than their increased hardness over carbon steel, is the large difference between proof and tensile strengths. This increased ductility tends to produce stringy chips during machining and due to rapid work hardening can lead to problems. Heavier feeds and slower speeds are employed to reduce tool build up and minimise work hardening.
Where possible it is recommended that cutting tools with chip breakers or curlers be used, especially for the high alloy grades such as types and where exceptionally tough and stringy chips are produced.
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