High speed machining of titanium Research Papers (original) (raw)

This paper presents a study that aimed at comprehending the physico-chemical mechanisms of coating delamination when dry machining aerospace materials. The study employs a synergetic approach that teams finite element-based computations to experimental observations to examine the failure modes and wear mechanisms for two groups of alloyed carbide inserts, (coated and uncoated). The results presented in this study pertain to cutting experiments performed at cutting speeds of 100-125 m/min and feed rates of 0.15 to 0.20 mm/tooth. Post experimental SEM micro-graphical analysis reveal that while delamination is the primary wear mechanism for different cutting conditions, the major portion of delamination takes place at the very initial moments of cutting (first few seconds). Through combining finite element based computations and metallographic observations a proposal concerning the mechanistic stages of the coating delamination is reached. This proposal takes into account both the thermomechanical interactions as well as the physico-chemical mechanisms at the early stages of cutting. Consequences of delamination on wear and the implications on the dry machining process of titanium and titanium based alloys are discussed.

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- Materials Engineering, Mechanical Engineering, Titanium, Finite Element

Titanium alloys are used for the manufacturing of femoral heads for orthopaedic implants. Poor machinability of these materials, especially at high speeds, creates the need for more detailed investigations on this subject. The at hand study analyzes the construction of 3D Finite Element Method (FEM) models pertaining to the manufacturing of femoral heads made from Ti-6Al-4V. For this purpose a commercial FEM programme is employed, specialising in machining modelling, namely AdvantEdge. The validation of the model is provided through experiments on actual femoral heads cut in a CNC lathe at high cutting speeds. Comparison between experimental and numerical results on cutting forces and chip morphology exhibits a good agreement, indicating the success of the proposed models. These 3D models can be used for realistically estimating the influence of cutting conditions on the final product, without performing time and money consuming experiments.

- by Dimitrios Manolakos and +2
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- High speed machining of titanium, Finite Element Analysis (FEA), 3d Modelling, High Speed Machining

Titanium usage for aerospace growing day by day as application of titanium and its alloys covers wide range. Most of the aerospace components made up of wall structure involves lot of pocket slot milling since those components are monolithic components, eliminating need to manufacture multiple pieces for assembly into one final part. The increasing complexity of titanium parts used in aviation industry, increasing demand for productive manufacturing methods like trochoidal milling. This paper aims at evaluating its potential in slot milling for Ti6Al4V component by conducting experiments on 5-axis CNC machine. This study focuses on Productivity, Quality and Machine tool Dynamics.

- by Ashwin Polishetty
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- Titanium, High speed machining of titanium, Titanium alloys, Titanium machining

- by Ashwin Polishetty
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- Titanium, High speed machining of titanium, Titanium alloys, Titanium machining

Titanium usage for aerospace growing day by day as application of titanium and its alloys covers wide range.
Most of the aerospace components made up of wall structure involves lot of pocket slot milling since those
components are monolithic components, eliminating need to manufacture multiple pieces for assembly into one
final part. The increasing complexity of titanium parts used in aviation industry, increasing demand for
productive manufacturing methods like trochoidal milling. This paper aims at evaluating its potential in slot
milling for Ti6Al4V component by conducting experiments on 5-axis CNC machine. This study focuses on
Productivity, Quality and Machine tool Dynamics.

- by Prasad Patil
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- Titanium, High speed machining of titanium, Titanium alloys, Titanium machining

ABSTRACT Machining in dry mode is characterized by intense thermo-mechanical loading. The coupling between the thermal and the mechanical loads may lead to tool failure, especially when machining the so-called hard-to-cut alloys. Within such environments the efficiency of heat removal plays an important role in preserving the structural integrity of the tool. Efficient heat removal in dry machining depends solely on the intrinsic thermal properties of the tool for uncoated tools and on the effective properties of the tool-coating combinations for coated tools. Thermal loads may also accelerate wear of the tool. As such, a relationship between the wear and the intrinsic thermal properties of the tool is worthy of investigation. This paper investigates such a relationship. Here we team numerical simulations to SEM-imagery to map the thermal conductivity within the tool zone of action of a coated carbide tool. The results indicate that, depending on the temperature rise, the tool-tip might undergo a severe drop in thermal conduction. This drop may locally restrict the ability of the tool material to dissipate the applied thermal load. This may nucleate thermally congested clusters within the tool-tip where the material completely loses the ability to transport heat. Thermal congestion renders an energetically active zone where the thermal energy available may be used to activate wear through different mechanisms. It is also found that the immediate layer under the surface of the tool tip is important to enhance the ability of the tool material to dissipate the thermal loads. The results also highlight the importance of matching the temperature dependant properties of the different coating layers in order to enhance delamination resistance.

- by Hisham Abdel-aal
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- Engineering, Titanium, Structural Integrity, High speed machining of titanium

Machining in dry mode is characterized by intense thermo-mechanical loading. The coupling between the thermal and the mechanical loads may lead to tool failure, especially when machining the so-called hard-to-cut alloys. Within such environments the efficiency of heat removal plays an important role in preserving the structural integrity of the tool. Efficient heat removal in dry machining depends solely on the intrinsic thermal properties of the tool for uncoated tools and on the effective properties of the tool-coating combinations for coated tools. Thermal loads may also accelerate wear of the tool. As such, a relationship between the wear and the intrinsic thermal properties of the tool is worthy of investigation. This paper investigates such a relationship. Here we team numerical simulations to SEM-imagery to map the thermal conductivity within the tool zone of action of a coated carbide tool. The results indicate that, depending on the temperature rise, the tool-tip might undergo a severe drop in thermal conduction. This drop may locally restrict the ability of the tool material to dissipate the applied thermal load. This may nucleate thermally congested clusters within the tool-tip where the material completely loses the ability to transport heat. Thermal congestion renders an energetically active zone where the thermal energy available may be used to activate wear through different mechanisms. It is also found that the immediate layer under the surface of the tool tip is important to enhance the ability of the tool material to dissipate the thermal loads. The results also highlight the importance of matching the temperature dependant properties of the different coating layers in order to enhance delamination resistance.

- by M. Nouari
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- Engineering, Titanium, Structural Integrity, High speed machining of titanium

Cutting tools are subject to extreme thermal and mechanical loads during operation. The state of loading is intensified in dry cutting environment especially when cutting the so called hard-to-cut-materials. Although, the effect of mechanical loads on tool failure have been extensively studied, detailed studies on the effect of thermal dissipation on the deterioration of the cutting tool are rather scarce. In this paper we study failure of coated carbide tools due to thermal loading. The study emphasizes the role assumed by the thermo-physical properties of the tool material in enhancing or preventing mass attrition of the cutting elements within the tool. It is shown that within a comprehensive view of the nature of conduction in the tool zone, thermal conduction is not solely affected by temperature. Rather it is a function of the so called thermodynamic forces. These are the stress, the strain, strain rate, rate of temperature rise, and the temperature gradient. Although that within such consideration description of thermal conduction is non-linear, it is beneficial to employ such a form because it facilitates a full mechanistic understanding of thermal activation of tool wear.

- by M. Nouari and +1
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- Titanium, High speed machining of titanium, High Speed Machining

Machining of space age materials like Ti-6Al-4V is associated with thermally activated wear mechanisms which lead to rapid tool failure and considerable machine downtime. The high strength and low thermal conductivity of Ti-6Al-4V can reduce tool-life to less than a minute at high cutting speeds, further adding to the per-unit cost. A new concept, Micro Quantity Internal Cooling (MQuIC) is proposed in this research to extend the tool-life and/or enable higher cutting speeds, while machining materials such as Ti-6Al-4V. The concept involves introducing flow (water) in a micro-duct placed inside the tool and close to the cutting edge, thus bringing the cooling source close to the heat source (chip-contact area). Two different techniques are utilized in developing and applying the proposed concept. The first uses finite element analyses (structural and thermal) to evaluate the impact on the structural strength of the tool due to the micro-duct and to examine the effect of flow on tool temperatures. These analyses lead to an experimental setup-specific analyses, in order to converge on the final operating parameters. Physical testing employing coolant consumption of less than 5% of the current industry standard has proven the viability of the concept by demonstrating a 100-200% increase in the tool-life. The testing also proves the application of the MQuIC concept to enable higher cutting speeds than the current industry standard for machining Ti-6Al-4V. Further, a lab based technique with a focus on commercial realization has been developed to fabricate tools based on this concept. The developed tools have been successfully tested to validate their performance. A few other concepts for further reducing tool temperatures and extend the benefits of MQuIC are also presented in this dissertation. Conclusions drawn from this research are used to recommend possible future work to further enhance the MQuIC performance during real time machining of difficult to machine materials.

- by Samved Bhatnagar
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- Applied Research, Machining, New Product Development, MACHINE TOOL DESIGN