CNC Steel milling

Often, words such as CNC metal milling can be found on the internet. Over 70 elements belong to the group of metals. Thus, metal milling or metal machining are very general concepts and when someone says them, they usually mean milling in steel. Stainless steel processing is also an ambiguous concept, it is a separate category. The stainless steel itself is divided into ferritic, martensitic and austenitic. There are separate milling recommendations for each type. Ferritic stainless steel has a machinability comparable to low alloy steel, which is why steel milling recommendations can be used.

Milling incl. stainless steel

Steel, i.e. an iron alloy containing less than 2% carbon and being forgeable, gives a different chip depending on the composition, heat treatment process and production technology. The type of chips produced is one of the factors characterizing the material’s susceptibility to machining, i.e. its machinability. Machinability of the workpiece should always be assessed in conjunction with the machining technology used, cutting tool material and cutting data.

Steel machinability is determined by the structure and mechanical properties (hardness, strength). The main problems in machining soft, low carbon steels are edge build-up and burr formation. When machining harder steel types, it is important to position the cutter to avoid chipping the edges. Currently, CNC dry milling of steel is recommended. Milling hardened steel can only take place dry, and for better chip evacuation use compressed air.

Martensitic stainless steel hardens during machining and exerts very high forces when the blade enters the material. To achieve the best results, use the correct tool path and arc approach (circular interpolation) and use a higher cutting speed, vc, to ensure better chip breaking during machining. Higher cutting speeds and cutters made of high impact material with reinforced cutting edge for greater safety.

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