Kennametal Stellite alloys protect critical oil and gas exploration, production, and transportation equipment. This equipment is often exposed to high temperatures and wear.
In the current study, the machinability of Stellite 6 was evaluated using an end milling EDM process with coated binary inserts. An experimental design was employed to analyze the effects of machining parameters and environmental conditions on surface roughness.
Stellite is an excellent choice for precision metal components due to its nonmagnetic and anticorrosive properties. It can also withstand high temperatures and is available in various compositions. Stellite is often used in saw blades, hard-facing equipment, and acid-resistant machine parts.
Because satellites are very hard, they can be challenging to work with. It is especially true for stellite machining, which requires a high cut and grind power. However, with the proper machining techniques, satellites can be turned into functional metal components quickly and efficiently.
In this study, the optimum tribological conditions for improving wear-resistant characteristics and surface roughness of age-hardened Stellite 6 alloys during Wire Electric Discharge Machining (WEDM) have been identified using Analysis of Variance (ANOVA), Taguchi’s Design of Experiment (TDOE), Response Surface Methodology(RSM) and Desirability Function Analysis(DFA). From ANOVA results, it was found that peak current (12A), pulse on time, and pulse off time were significant control factors influencing machinability during WEDM.
Because of their extremely high melting points, cobalt and chromium alloys like satellites are often used in applications where resistance to wear is required. Stellite is also nonmagnetic and anticorrosive. It enables them to be used in medical devices such as surgical tools, bone and tooth implants and replacements, heart valves, and pacemakers.
However, the machinability of these alloys is challenging. Their dense, non-homogeneous molecular structure and lower thermal conductivity make them difficult to cut. It is why satellite components are typically deposited onto steel substrates instead of being machined out of solid stellite bars.
To improve the machinability of the satellite, researchers have been focusing on identifying the optimal machining parameters to achieve better surface roughness and minimum wear during wire electric discharge machining. To achieve this goal, they have been using Taguchi’s design of experiment, response surface methodology, and desirability function analysis. The results found that peak current, pulse on time, and pulse off time had the most impact on surface roughness.
Reduced Maintenance Costs
While the wear resistance properties of Stellite are renowned, it can be challenging to work with in industrial applications. It is brittle, requires specialized tools and machinery, and can be more expensive than alternative materials such as stainless steel or aluminum. However, this can be overcome with a few advanced processing techniques.
One method involves welding a stellite overlay onto valve wear areas to prevent erosion, scale buildup, and rust. This process eliminates the need for costly replacements and repairs.
Another method involves gas nitriding, which can increase wear life and extend the lifespan of parts. It is significant for turbines, which are subject to extreme temperature fluctuations.
The study also investigated the machining parameters of age-hardened Stellite 6 alloy deposited on a 4140 substrate. Based on the analysis of variance and Taguchi’s Design of Experiment (TDOE) and Response Surface Methodology(RSM), a model was created to predict the key factors that influence surface roughness during WEDM. The model was tested and validated using experimental data.
Stellite is hard, dense, and provides excellent wear resistance. However, its high thermal conductivity during machining results in high temperatures and makes cutting difficult. It makes machining costly, which limits the use of this material in industrial applications.
This study aimed to evaluate the machining process parameters and their effect on the surface roughness in the end milling of Stellite 6. This evaluation involved the application of a linear regression model with ANOVA. The results of this analysis revealed that the depth of cut and insert type have a significant influence on surface roughness during Stellite 6 end milling.
ANOVA, Taguchi’s Design of Experiment (TDOE), Response Surface Methodology (RSM), and Desirability Functional Analysis were used in the research. It allowed for the precise optimization of machining parameters to improve surface roughness, body wear, and electrode erosion for age-hardened Stellite 6. These optimized machining parameters resulted in better wear performance and higher dimensional accuracy.