Cutting Force Analysis for Machining Indicator Performance

Question: Describe about the Cutting Force Analysis for Machining Indicator Performance. Answer: Introduction The cutting force measurement is the most effective indicator of the machining performance. There are two components of the cutting force, one is static and the other one is dynamic, which provide information about the state of the chip formation and of the cutting tools (Mfg.mtu.edu, 2016). The piezoelectric force measurement system measures the force with the help of piezoelectric effect which generates charges depending upon the applied mechanical force. This work presents the analysis and review of the data obtained regarding the cutting forces obtained during end milling of different metal and alloys from the piezoelectric dynamometer. Experiment Procedure The aim of the milling is to produce the various shapes that by the process of material removing. For the process, different tools are used for varied applications (Li et al. 2016). For the experiment one block each of aluminum, brass, and stainless steel is required and finally the piezoelectric dynamometer is required for measuring the cutting force. Metal cutting mechanics Metal shaping and cutting is done by moving the work piece and the cutting tool by using the relative motion to scrap off the metal off the surface. There are two types of metal cutting procedure involving single point cutting tool. If the cutting edge, that rubs the surface, is at 90o to the travel direction of the block then it is called vertical mill and if the angle between them is zero, i.e. the plane of the tool and metal is same then the tool is call the horizontal mill. For the investigation of the performance of the cutting tools, the cutting force measurement is essential (Mehta et al. 2016). Cutting forces Single point cutting tool cut the block at a single point, hence the force applied is on a single axis but for the ease of understanding it is divided into two components. The figure depicted below shows the components of milling tool and the force that is being applied in order to cut the metal into desired shape, the components of the force are shown as P1 and P2 (Sequeira et al. 2012). These components are-: Fx: The thrust force that acts in radial direction (Shown by P1). Fy: The cutting force acts to remove the metal (Shown by P2) Figure 1: Shows the milling process Image source: Dombovari and Stepan, 2015 Dynamometer The dynamometer used here is the piezoelectric dynamometer which uses piezoelectric components for measurement of forces. Dynamometers are the devices that are used to measure physical parameters like force and torque. Dynamometer measures the two cutting force components, which are perpendicular to each other. The measured numerical values that has been generated during milling is stored in computers with the help of DAS(Data Acquisition System) (Kistler.com, 2016). The piezoelectric outputs are initially amplified and are then sent to computer for storage and analysis as depicted in figure. Figure 2: Represent the force measurement by Piezoelectric Dynamometer (Image Source: As created by Author) Block Materials Aluminum Brass Copper Results Fx is the Thrust cutting (N) Fy is the Cutting force (N) T is the Time (s) Aluminum Figure 3: Shows the obtained data for Aluminum Figure Source: As created by author Brass Figure 4: Shows the obtained data for Brass Figure Source: As created by author Stainless steel Figure 5: Shows the obtained data for Stainless Steel Figure Source: As created by author Comparison and discussion The three graphs that have been obtained during the experimentation can be seen in the previous section. Aluminum is a high strength, malleable and low density metal contributing to its low weight. This can be seen in the figure; the low density allows lesser force required for cutting but the higher metal strength makes the thrust force required for the movement very high. In case of brass the alloy is extremely malleable but the hardness is lesser compared to steel. The high malleability makes the starting thrust force very high but as the transient phase passes, the force ease and decreases, and the cutting force is high as the metal is very tough. In case of stainless steel the metal is hard but brittle hence the cutting force is high but the thrust force is very less compared to other metals. Conclusion This report discusses the various data that has been obtained and realized during performing the experiment. The experiment was done in a CNC and the force data were obtained with the help of the piezoelectric sensor available in the dynamometer. Finally the obtained data was compared and summarized which helped in understanding the property of the material. 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