How to turn different materialsIssuing time:2024-04-09 09:28 Turning SteelSteels can be classified as unalloyed, low alloy and high alloy, all of which affect machining recommendations for turning. Turning of unalloyed steelMaterial classification: P1.1Unalloyed steels have carbon contents up to 0.55%. Low carbon steels (carbon content < 0.25%) require special attention due to difficulty in chip breaking and the tendency to stain (built-up edge). To break and guide the chips, the feed rate should be as high as possible. Wiper inserts are highly recommended. Use high cutting speeds to avoid built-up edge on the insert, which can negatively affect the surface. Sharp edges and lightweight cutting geometries will reduce the tendency to smear and prevent edge deterioration. Low alloy steel turningMaterial classification: P2.xThe machinability of low alloy steels depends on the alloy content and heat treatment (hardness). For all materials in this group, the most common wear mechanisms are crater wear and flank wear. For hardened materials, plastic deformation is also a common wear mechanism due to the higher heat in the cutting zone. For low alloy steels in the non-hardened condition, the first choice is the steel family of grades and geometries. In hardened materials, the use of harder grades (cast iron grades, ceramics and CBN) is beneficial. High alloy steel turningMaterial classification: P3.xHigh alloy steels include carbon steels with a total alloy content of more than 5%. This group includes both soft and hard materials. Machinability decreases at higher alloy content and hardness. For low alloy steels, the first choice is the steel grade and geometry. Steels with alloying elements above 5% and hardness above 450HB have additional requirements for plastic deformation resistance and edge strength. Consider using harder grades (cast iron grades, ceramics and CBN). Turning stainless steelStainless steels can be classified as ferritic/martensitic, austenitic and duplex (austenitic/ferritic), each with its own turning recommendations. Turning of ferritic and martensitic stainless steelsMaterial classification: P5.1This stainless steel is classified as a steel material and therefore has the material classification P5.x. General recommendations for machining this steel are our stainless steel grades and geometries. Martensitic steels can be machined in the hardened condition with additional requirements on the insert's resistance to plastic deformation. Consider using CBN grades, HRC = 55 and higher. Austenitic stainless steel turningMaterial classification: M1.x and M2.xAustenitic stainless steels are the most common type of stainless steel. This group also includes super-austenitic stainless steels, defined as stainless steels with more than 20% nickel. Recommended grades and geometries are our CVD and PVD grades of stainless steel. For intermittent cutting, or where chip hammering or chip jamming is the dominant wear mechanism, consider using a PVD grade. Other considerations: Always use coolant to reduce crater wear and plastic deformation, and select the largest possible nose radius. Use round inserts or a small entering angle to prevent notch wear Smearing tendencies or built-up edge are common. They both negatively affect surface finish and tool life. Use sharp edges and/or geometries with a positive rake face Turning of duplex (austenitic/ferritic) stainless steelMaterial classification: M3.4For high alloy duplex stainless steels, names such as super duplex stainless steel and even hyper duplex stainless steel are used. The higher the mechanical strength, the more difficult these materials are to machine, especially in terms of heat generation, cutting forces and chip control. Other considerations: Use coolant to improve chip control and avoid plastic deformation. Use tools with internal coolant supply, preferably precision coolant. Use a small entering angle to avoid notch wear and burr formation
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