Optimization of surface roughness in deep hole drilling using moth-flame optimization

This study emphasizes on optimizing the value of machining parameters that will affect the value of surface roughness for the deep hole drilling process using moth-flame optimization algorithm. All experiments run on the basis of the design of experiment (DoE) which is two level factorial with four center point. Machining parameters involved are spindle speed, feed rate, depth of hole and minimum quantity lubricants (MQL) to obtain the minimum value for surface roughness. Results experiments are needed to go through the next process which is modeling to get objective function which will be inserted into the moth-flame optimization algorithm. The optimization results show that the moth-flame algorithm produced a minimum surface roughness value of 2.41μ compared to the experimental data. The value of machining parameters that lead to minimum value of surface roughness are 900 rpm of spindle speed, 50 mm/min of feed rate, 65 mm of depth of hole and 40 l/hr of MQL. The ANOVA has analysed that spindle speed, feed rate and MQL are significant parameters for surface roughness value with P-value <0.0001, 0.0219 and 0.0008 while depth of hole has P-value of 0.3522 which indicates that the parameter is not significant for surface roughness value. The analysis also shown that the machining parameter that has largest contribution to the surface roughness value is spindle speed with 65.54% while the smallest contribution is from depth of hole with 0.8%. As the conclusion, the application of artificial intelligence is very helpful in the industry for gaining good quality of products

Effect of Cutting Parameters on Micro Drilling Characteristics of Incoloy 825

The study focuses on the micro drilling of Incoloy 825 alloy under flood cutting condition. Micro drilling on nickel based superalloy is very challenging process due to the material properties, operating conditions, low thermal conductivity and high quality requirements. Due to low thermal conductivity of material heat is concentrated near tool tip and unable to dissipate for which tool wear occurs. The current study described the machinability of Incoloy 825 in micro drilling operation and also the effect of spindle rpm and feed rate on thrust force, torque, radial component force, tangential component forces, oversize diameter and white layer thickness. The current study investigates the influence of micro drilling parameters on surface profile and circumferential damage of micro holes (in terms of damaged layer thickness). ANSYS simulation was carried out to theoretically determine and evaluated necessary data like equivalent stress and deformation. Statistical analysis was also carried out to develop predictive models for various output characteristics

A STUDY ON STRAIGHTNESS CONTROL IN DEEP HOLE DRILLING OF INCONEL-718

Ph.DDOCTOR OF PHILOSOPH

Tiefbohren von hochfesten und schwer zerspanbaren Werkstoffen mit kleinsten Durchmessern

In industrial practice, high strength and performance-orientated materials contribute to enhance component properties and to improve resource efficiency. Consequently, these materials are constantly in demand and used more and more frequently in challenging applications. Within this context, high-strength bainitic steels as well as high temperature proof nickel based alloys are two of these material groups which are focused increasingly by automotive, aerospace and other applications sectors. The excellent material properties are linked to a sophisticated machining ability. Nevertheless, an economical manufacturing is an essential requirement to exploit the full potential of the use of high strength bainitic steels and high temperature-proof nickel based alloys. Therefore, it is absolutely indispensable to adopt and optimize existing manu¬facturing technologies. The research activities described in this thesis focus on the production of deep bore holes with smallest diameters and high length to diameter ratios based on mechanical processes. However, additional difficulties arise when single lip and twist deep hole drilling with smallest tool diameters are applied. Mentionable examples are very low tool rigidities, high mechanical tool loads owing to the limitedly realizable feed rates and the subsequently strong material squeezing and friction in the rounding of the cutting edge as well as the complicated chip removal through the small cross-sections of the chip flutes. In order to encounter the material and process specific challenges and to achieve a stable and productive deep hole drilling, a determined tool and process design for both materials is carried out. In the course of the experimental investigations the influence of the cutting data, the tool design with respect to the cutting tip design, the tool coating composition and the coating thickness as well as the cooling lubricant in single lip deep hole drilling is evaluated. Furthermore, a comparison of single lip and twist deep hole drilling shows the advantages and disad¬vantages of both manufacturing processes. A comprehensive analysis of the mechanical tool loads, chip formation, tool wear and bore hole quality regarding the dimension and form tolerances as well as the surface quality is made to evaluate the various influencing variables. Additionally, a newly developed methodology of analysis allows a closer look on the chip formation at the corresponding cutting edges and the chip removal along the chip flutes in smallest diameter deep hole drilling for the very first time. Here, samples made of the particular test materials are inserted in transparent acrylic glass carriers and the chip formation in the operating zone is documented by high speed microscopy. At the same time, the findings of this high speed chip formation analysis contribute to a substantial increase in fundamental process knowledge. A concluding comparison of the representative process characteristics and the technological correlations in deep hole drilling of high strength bainitic steels and high temperature proof nickel based alloys with smallest diameters clarifies the significantly divergent tribological application behavior. The differing mechanisms of tool wear as well as the related wear forms result in very individual and particular requirements on an efficient tool and process design. Based on the achieved knowledge, recommendations for the industrial practice are derived which facilitate a reliable and cost-efficient mechanical manufacturing of deep bore holes with smallest diameters for both materials, while simultaneously ensuring high bore hole quality in future