# Influence of Cutting Parameters and MQL on Surface Finish and Work Hardening of Inconel 617
## 5 Conclusions and Future Directions  
### Conclusions  
In this paper, the influence of the tool coatings, feed rate, cutting speed, depth of cut, and MQL deposition on the surface integrity of turned Inconel 617 was observed. The purpose of this research was to address the gap in the existing literature about the lack  
Figure 11: Interaction plot for work hardening recovery.  
Figure 10: Main effect plot for work hardening recovery.  
of research in machining Inconel 617, studying the effectiveness of MQL in machining Inconel 617 for nuclear applications, as well as the impact that machining may have on the subsurface material to better measure the machined surface quality. The following are the conclusions reached through the studies conducted in this paper:  
* The addition of an AITiN tool coating deposited on a K313 tungsten carbide tool insert increased the tool life in turning Inconel 617 from a 5460 m cutting distance to 10,350 m, doubling the tool life, and improving the rate of flank wear by 75.89%. This large improvement in tool life creates a more efficient manufacturing line by minimizing downtime caused by tool failure and reducing costs associated with labour in tool changes and scrapped components.
* It was found that MQL generated a better surface finish in comparison to the conventional flood coolant in all cases of varying cutting parameters, with a maximum improvement of 47%. In the flood coolant, the variation in cutting parameters had a minimal effect on the surface finish, whereas varying the cutting parameters in MQL cooling generated large differences in the surface finish.
* Observing the influence of tool wear, it was found that MQL deposition generated a larger amount of flank wear compared to those turned using flood coolant. A cause of this difference in wear was identified as the location of oil deposition in MQL. Due to the single nozzle depositing oil on the rake face, the flank face may not have been sufficiently lubricated and cooled, leading to increased flank wear.
* Measurements of work hardening in this study revealed that MQL generated larger levels of work hardening compared to the flood coolant in all cases. MQL turning generated hardness levels between 495 and 550 HV, whereas the coolant in turning generated values between 410 and 500 HV. The mean of means revealed that the coolant used had the largest impact on the level of work hardening, with tool wear closely second.
* From the existing literature that studied the machining of Inconel 718 and similar alloys, the machining of Inconel 617 was able to be compared and understood further.
* Multi-layered coatings have the tendency to delaminate and cause tool failure in machining Inconel alloys. Monolayer coatings greatly improved tool life in machining Inconel 617 in comparison to Inconel 718.
* The impact of cutting parameters on the surface roughness of Inconel 617 is similar to that of Inconel 718, suggesting that the influence of cutting parameters is consistent across various Inconel grades.
* MQL deposition reduces the surface roughness while increasing the level of tool wear in both grades of Inconel; however, the surface hardness of Inconel 617 was much larger under the MQL conditions compared to other grades where the surface hardness was reduced.