High alloy steels are alloys of iron based mixed with more than 0.55% carbon and other elements greater than 8%, such as, chromium, manganese, silicon, molybdenium. These elements can give characteristics to the steel such as tensile strength, high hardness, better machinability, heat resistance, wear resistance. The higher carbon content increases hardness.
In this tip, we are going to show you a success case machining High alloy steel with the face milling method. In addition, we are going to give you information about the properties, applications and machinability of High alloy steel.
High Alloy Steel
Lamina Material Group 03: High alloy steel
Features: Material that has high wear, heat, and deforming resistance.
Components: Coil springs, wires, moulds for plastic or aluminium injections.
Machinability: Normally is not complicated, but for milling applications determining appropriate cutting speed is important.
High alloy steel machinability
High alloy steel is not difficult to machine mainly because the low temperature of its shearing point.
For successful machining, material heating during machining should be minimized by applying medium to low cutting speeds, using very rigid set up of tool and workpiece, and minimizing the vibration effect.
Normally the best solutions to machine high alloy steel are submicron carbide inserts with strong geometries and TiAlN/AlTiN PVD coatings. The coating combined with submicron substrate brings to the insert high cutting pressure resistance and better heat dissipation.
High alloy steel challenges
Down we can see a test report of face milling application of ONKX 0806-45 LT3130 of a mould for plastic injection in high alloy steel material.
ONKX 0806-45 LT3130
Company: Mould producer
Lamina cutter diameter 125mm Z= 8 - 16 cutting edges
Competitor cutter diameter 100mm Z=7 - 6 cutting edges
Key success factors
Selection of the right insert:
• The ONKX 0806-45 is the best option for face milling because it’s an economical solution, due to the 16 cutting edges.
Right carbide grade:
• LT 3130 with its submicron grain and PVD coating has excellent performance machining high alloy steel.
• A lower Vc was applied (to reduce heat generation) and more feed per tooth were used to reduce the contact time following Lamina’s way.
• The insert was applied on dry operation.
• Using Lamina inserts the chip removal rate was slightly lower than the competitor, but tool life improvement and number of cutting edges justified the cost savings.
If the first result was not satisfactory, what could do to improve performance?
• Try even lower Vc, compensating metal removal with higher feed rate. Remember, the ONKX insert has a reinforced edge preparation allowing very high feed even machining high alloy steels.
• Use conventional milling direction, in case of appear notch wear on the cutting edge.
In summary, high alloy steels are not difficult to machine on face milling operations if compared to Non alloy steel. It means we can get excellent results if we select the right insert and the right parameters. Remember it is important to select an insert with reinforced cutting edges, to keep the cutting edge integrity and avoiding the premature wear.