Machining Technology is a manufacturing process that involves the foundational and basic principles about cutting via the application of various cutting tools. Despite the many modern technological advancement in this field of material science, it cannot be denied that there are the same principles involved both from the traditional and modern up-to-date techniques. Machining is the application of process used for shaping metals as shown in Figure 1.
Figure 1. Cross sectional view of the machining process.
The machining technology is applied in various work materials especially in the use of metals. It is used to shape and create forms with regular geometries through the introduction of sharp tools following tool paths. The creation of irregularly shaped geometries involves combination of various tools, sequence of operations, and following irregular cutting paths. The process offers tolerances that are accurate and calculated, resulting to smooth finishes. However, this material technology application yields to material waste where metal chips removed are considered as waste materials. Some wastes can be recycled, while some are subject for throwing. The process also includes time and effort in order to gain the desired form or output (Grover, 2010). The removal efficiency of chips however, is limited by the metal’s mechanical properties and the steels that are hard and highly tempered. The machines used for chip removal are also not applicable when materials machined have sharp inner edges and deep cavities (Klocke, nd).
The machining technology has greatly developed through the years. The metal removal involves a method where a wedge-shaped tool is used in the removal of the surface of the metals in the form of chips. In this process, the cutting tool is engaged upon the material work piece. The metal touched by the cutting tool is being sheared into chips while the whole material deforms into chips. When the cutting tools are in contact with the materials, the material is deformed through the enough force exerted. These chips are then subject to reshaping and recycling. Some of the deformations brought about by cutting forms include the following (SPSU, nd).
Tangential force – this is the force that is directed tangenti ally through the revolving of the work piece. It is the highest type of force giving out around 99% required total power.
Longitudinal force – this is the force that acts in direct parallel with the work axis that is about 50% as great as the tangential force.
Radial Force- This force is directed radially from the work piece centerline. This force has the least force generated among the three types.
The metal cutting technology has changed significantly as a result of the interactive and evolutional improvements of the various machine tools, cutting tools, design, and the clamping systems. The rapid changes and evolution in the metal cutting and metal removal machining techniques are influenced by various factors that can be summarized in the Figure 2. Through the years, man has continued to seek for the achievement of the highly optimized cutting tool design and geometry that would yield with optimal cutting parameters. Consequently, the implemented concepts in the machining of metals that gained positive output have been applied in various industries (Grzesik, 2008).
Figure 2. Influences of the Evolution of machining method
Some of the successful applications include the High Speed Machining (HSM), High Performance Machining (HPM), and the High Velocity Machining (HVM). Other modern technologies include High Efficiency Machining (HEM) that offers the advantages of the High Speed Machining and also the High Material Removal techniques. In the HEM, the use of the hydraulic expansion clamping devices and the heat shrinking chucks are frequently used. Later, the evolution of the dry machining and rapid developing near dry (MQL- minimal quantity lubrication) technologies has evolved in search for the best methods in eliminating the cooling lubricants (Grzesik, 2008).
The HSC or the high speed cutting technology has been used recently for the cutting of hard steel materials. Previously, this method is used for materials that undergo annealing, heating, treating, and grinding. Today, with the use of advanced cutting tools, the shaping of the hard metals to their desired forms is done even without the process of grinding. This process offers advantages and benefits that include (De Lacalle et al, nd):
Finishing operations are reduced
Distortion process is eliminated
There is high rate for metal removal
Optimum Surface Integrity
Cost efficiency
Some of the challenges for this operation include:
High stress and temperature requirement for the interface of material used
Cost efficiency is subject to the relationship of the process variable, tool life, and the surface integrity
The method of HSC requires the understanding of the influence of the tool failure and tool wear. Various researches and experiments have shown that with the use of hardened steels, the chip flow is affected by the thermal properties and the microstructure of the work piece material. The theory of the deformation and application of the numerical methods can help in the achievement of quality output and assist the improvement of advanced applications that include, high speed milling, hard turning, and high throughput drilling (De Lacalle et al, nd).
The cutting technology is an important aspect in the machining process that affects the economy significantly. Today, the modern cutting technology has been integrated with IT for improved process of planning, designing, production planning, manufacturing systems simulation, redesigning of new products, agile manufacturing, manufacturing equipment performance modeling, and analysis of functional process, virtual machining, algorithms inspections, and others. The cutting technology is driven by various factors that include, quality enhanced surface, component size diminishing, tight tolerances, high accuracy, cost reduction, reduced batch sizes, ad component weight diminishing. The cutting technologies for metals have been developed through simulation and modeling computer techniques. Most of the categories involved: the analytical model, mechanistic modeling, slip-modelling, and the finite element modeling. The cutting processes and characteristics covers include cutting forces, ool wear and life, power, chip flow angle, chip-bring, build up edge, temperature. Etc (Grzesik, 2008).
The understanding of the metal forming technology has been enhanced with the many computer-aided engineering (CAE), computer-aided manufacturing (CAM), and computer-aided design (CAD) technologies. The use of computers has contributed to the advancement of modern metal machining technology. Through the computer software application, most of the manufacturing processes elevated the development of the process of metal formation. The traditional methods of metal forming have been modified. Processes such as the conventional shear formation and spinning can be localized to smaller portions that resulted to detailed, controlled, and accurate deformations. The recent computer power controlled techniques such as numerical control (CN) and Computer Numerical Control (CNC) systems made the metal cutting and deformation easier eliminating the use of hands. Through these programs, cutting tool paths are programmed for a more accurate path taking a more specific shape for metals. The Programmable Numerical Control (PNC) that uses playback technology is also another way of gaining accurate control for metal cutting and metal removal techniques (Hagan and Jeswiet, 2003). The CAD/CAM system offers great modeling techniques for the metal deformation processes. The process for closed-die forging process includes the simulation of metal flow, analysis of die failure and optimization of design, and the machining code development and implementation. The use of this technology enables the manufacturer to study the flow of metals, fill dies, retains the involved non-linearity in the process of changing shape. It also provides continuous change in the condition of contact surfaces, and other work-hardening characteristics for isotropic materials. The analysis of the finite elements of the metals formed can be carried via the LUSAS software that is available in the market, while the machining codes are readily developed using the CNC and UniGraphics machines (Jolgaf, M., Hamouda, AMS., and Hamdam, MM. (2003).
The CNC controlled metal cutting technique is applied in the process of laser cutting. The use of this technique for metal removal offers high degree of precision. It offers a cutting process that is mechanized, non-contact, and thermal method where a high degree of accuracy and precision is achievable. Two of the most commonly used cutting lasers are Nd:YAG and the CO2. These two lasers utilized the use of the small monochromatic light beam where the power density of the beam is strong enough the material where the beam is focused locally. This cutting process is directly related to the beam of light focused on a certain spot with a diameter of around 0.5mm for better power densities. The cutting process is fast with little distortions happening to the materials since the travel of heat source is fast enough to cause little effect to its environment (Howse and Woloazyn, 2015).
Recent studies have integrated the use of CNC technology with industrial robot technology. The CNC method in the metal cutting and metal removal offered various advantages such as market flexibility, weight reduction, dimension optimization, quality output surface, high level of accuracy for the output. The application of this method with robotics further add to it benefits offering time and cost efficiency. The use of robotic cells has been implemented already in various processes such as welding and handling of materials. According to the Industrial Robot Statistics (2010), the utilization of the operational robotic cells has been increasing significantly through the years. It is also forecasted that the robot market involved in metal cutting and removal will increase through the coming years (Industrial Robot Statistics, 2009).
Figure 3: Operational Stock of Industrial Robot (industrial Robot Statistics, 2010)
The utilization of the industrial robots are gaining an increase in the sophisticated tasks, and the non-structured sophisticated tasks. For instance, the automotive industry employs the machine vision. Through this, the welding and finishing touches are forwarded to KI. The use of this machine fulfills the need for the flexibility, fixturing, and tooling. As Asakawa (1995) proposed in his paper, the robots are polished further with the CAD/CAM systems and the ultrasonic vibrational tool. Other scientists such as (Sanders, Lambert, Jones, and Giles, 2010) proposed the welding system with the data gathered to generate the programs for the robot. There is higher accuracy for the industrial robots over the conventional methods for cutting metals. Robots can also machine other materials aside from metal such as the foams, wood, wax, and others without compromising the accuracy of the cutting methods. The surface quality for robots doing the cutting processes is better achieved with robots than the conventional methods. Robots generally have low natural frequency that result to resonance from the vibrations of the process of machining. These robots gained high quality surface without resonance issues during the high speed cutting process. The vibrations are restrained, and there are no resonance that occurred. These robots just need to calibrated for the achievement of high level frequency. In this way, tolerances can be computed, and the geometric errors are calculated and predicted. These robots need to be programmed. Unlike with CNCmachines, the robots are programmable that enables them to teach ad repeat (Pandremenos, 2011).
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