Nickel-chromium-molybdenum alloys such as inconel 718 are used in many industries due to their ability to withstand extreme temperatures and corrosive environments. The alloy is used for aircraft and rocket components, nuclear reactors, industrial furnaces, heat exchangers, petrochemical equipment and automotive turbochargers. It is also highly resistant to creep and stress corrosion cracking, oxidation and abrasion.
In the oil and gas industry, inconel 718 is often found in downhole tools, valves and flanges. This is largely due to its resistance to corrosion in sour gas and hydrocarbon environments. It is also suitable for cryogenic applications requiring low temperature strength, and has good formability and welding characteristics.
Despite its excellent properties, inconel 718 can be difficult to machine because of the rapid work hardening that occurs during cold forming. This makes it important to use the age-hardened condition if possible when machining to avoid deformation of the workpiece or tool during subsequent machining passes.
The current study uses a model-based feed forward control system to improve the plasma cutting process of inconel 718 and STS 316L, an austenitic stainless steel. This is done by combining a raster scan and contour scanning strategy. This allows the laser energy to be reduced as a function of layer thickness, and a high degree of machining accuracy is achieved. The results show that the model-based control system can significantly improve the machining performance of inconel 718 and STS 316L, and can also reduce the cycle time by a significant margin.