DiGianno Machining Analysis

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New Jersey Institute Of Technology *

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Jan 9, 2024

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Mechanical Engineering Laboratory New Jersey Institute of Technology Report Submitted by Michael F. DiGianno Experiment No. 3 Date Performed 9/19/23 Date Submitted 9/26/23 Course & Section ME215-101 Instructor Naruemon Suwattananont Machining Analysis Experiment Title Performed by Group 101b With TA Md Sojib Kaisar Group Members Michael D Bauly S Yahia Elmanier Marta D Stephen M Jonathan G Braeden G

2 Table of Contents Abstract 3 Introduction 3 Objectives 3 Background and importance 3 Procedure 3 Original Data Sheet 5 Results and Calculations 6 Discussion 8 Conclusion 8 Questions and Answers 9 References 10 Appendix A 10 2

3 Abstract This laboratory focuses on the implements in machining and the forces that are involved. The purpose is to understand the way cutting implements exert work on the workpiece. The lab focuses on the lathe, and its cutting implement. The operation of the lathe was demonstrated by a faculty member. The main result is the forces exerted on the workpiece by the lathe. Introduction This laboratory module will introduce students to the principles of engineering and machining. This is done through various demonstrations, and measurements. These will be used to assemble data that provides a better understanding of the forces produced when machining. Objectives Obtain a reading of wattage to force. Have the operation of the lathe demonstrated, and an analysis cutting tools of the lathe and their angles. Use this data to calculate the correct angles of the cutting tools. Understand how tool geometry will affect the cutting motions such as turning, boring, and facing. Analyze the data obtained from the lathe cutting to determine the force exerted on the workpiece. Background and importance Machining can be defined as the use of a machine to cut, drill, shape or otherwise use negative processes to increase or decrease features on a workpiece. Figure 3, see appendix A depicts several different operations that can be performed on a workpiece. More directly related to the lab, the lathe. The modern industrial lathe can trace its roots as early as the fifteenth century, but truly started to take form in the later half of the seventeenth century. As seen in figure 4, the machine is recognizable as a lathe, and even has variable speeds. This machine and others of its time were meant for softer materials such as wood, ivory, and horn. That was until a man named Plumbier revealed in his treatise that there was a technique for metal cutting. “Therefore the most significant portion of Plumbier’s treatise is his chapter IV “How to Turn Iron””. (Woodbury 1961) Procedure The process of understanding the forces involved in machines include the following. First we use a machine to measure how much voltage is required to resist forces. The cutting tools of the lathe are inspected to determine their angles. Then voltages will be measured from the lathe 3

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4 operations. Using the data collected and measurements made, students can perform the calculations needed to answer the remaining questions. Original Data Sheet 4

5 Results and Calculations We measured the rake, clearance, and wedge angles of the lathe tool by hand, and then under a microscope we calculated the angles using the distances observed. The numbers in the table below were obtained from a protractor provided. Tool # Rake (degrees) Clearance (degrees) Wedge (degrees) 1 4 8 78 2 7 8 75 A comparator was used to obtain x and y coordinates for the different tools. These were used to calculate angles using the following. Clearance= Tan^-1 (y/x) Rake= tan^-1 (x/y), Wedge= 90- (Clearance+Rake) Tool # (x,y) #1 (x,y) #2 Rake (Degrees) Clearance (Degrees) Wedge (Degrees) 1 (0.3462, 0.0624) (0.0126, 0.1544) 4.67 10.22 75.12 2 (0.3744, 0.0341) (0.0334, 0.1808) 5.2 10.47 74.33 Google sheets has an in-built function for calculating slope and making graphs.Imputing the data received from the hanging weights will output the following graph, and slope below. 5

6 Figure 1: A graph showing the wattage required to resist pounds of force Figure 2: A graph showing the work applied by a lathe in four cuts 6

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7 Discussion To restate, the main objectives of this lab module are to have the lathe demonstrated to the class, learning its various parts and cutting capabilities. We then obtained numerical data related to the work needed to resist a constant load. Students then took the lathe cutting tools to be measured, once by hand and once using the microscope. Finally more numerical data was collected regarding the force exerted by the lathe. Firstly regarding the tool measurements, one was fairly accurate while the other missed the mark. Human error is the main factor when dealing with hand measurements, but tool quality is also in the conversation. After doing the mathematics we see that the tools have a wedge angle of seventy five degrees. This is fairly wide and helps the tools in various ways. The larger size helps its ability to hold its edge as well as resist heat deformation. The data recorded of the forces was logged and emailed to us. It was logged under time signatures, this important to note for figure 3 as some of the data points may be logged under the incorrect weight. When transitioning from one weight to another, the meter tended to read in the middle of the two plateaus. This made it hard to attribute the data point to one spot or another. This may have caused some slight shifts, but its clear to see the linear relationship. As more weight is applied to the rope, the work needed to resist it increases as well. I used google sheets to quickly create a graph as well as using the slope function [=slope(xvalues , yvalues)] to determine the m value from our two hundred and fifty data points. Figure 2 shows the data collected from the lathe. When operating the lathe, two main variables were changed, feed rate, and cut depth. We see that cut two was run on the higher feed rate as well as the deeper cut. This provided the largest force. This makes sense as faster and deeper means more friction and surface area. These factors contribute to the large amount of heat that the machine creates and deforms the tools. When these types of forces are produced, many manufactures use a cutting fluid that wicks away much of the heat in the system. Overall, we can now see the fundamental principles of machining, and how they are applied to the workpieces. Conclusion In conclusion, we understand the lathe and its basic functions now. The three main cutting operations and the various parts of the lathe were demonstrated. We also better understand the relationship between force applied and the energy released. We can see from figure 1 the relationship between force applied and work. While rougher, figure 2 paints a clear picture of the forces at play. Making a faster deeper cut, will create a larger force application. I feel that we have met the objectives of the lab. 7

8 Questions and Answers 1. Compute the machining time on a lathe to part a 2.873 in diameter rod at 120 rpm by a tool having a feed of 0.004 ipr. LOC= pi*2.873 MT = (9.02 inches) /(0.48 inches per minute) =18.79 mins 2. What are the effects of a large frictional force on a cutting tool and how can they be reduced? Large frictional focus can cause massive issues, namely large heat production. The other issues can lead to the material breaking or warping. The main way friction is reduced is by the application of a cutting fluid. 3. Calculate the revolutions per minute for a lathe to cut a rough finish 3.201 in diameter of gray cast iron shaft with a high-speed steel cutter. Make and explain any assumptions needed and use any data as needed from this manual. I am assuming the desired cutting speed for gray cast iron, certain materials like to be machined at certain speeds. 100=(pi*3.201*N)/12 N=119.38 RPM 4. A bar of steel 3.377 in in diameter is to be machined at 90 fpm. What spindle speed should be used? N= (90*12)/(pi*3.377)= 337.39 RPM 5. A turning operation using a lathe with a 5.5 hp motor incurs an average primary cutting force of 525 lbs, what is the cutting speed? T=(525*0.1667)/2= 43.75 N= (5.5*33,000)/(2*pi*43.75)= 777.63 6. Name four methods for turning a taper on a lathe. ● Form tool ● Compound rest ● Taper turning attachment ● Tailstock overset method 7. What is the function of each of the following lathe parts? •Faceplate- used to secure unhackable workpieces. •Lead Screw-used to provide lengthwise movement to the carriage •Back Gears- provides more speed tuning •Tail Stock- one of the main components of the lathe the tail stock moves and holds the cutting implements. 8.Assuming a feed of 0.020 ipr and a 0.062 in depth of cut to machine a 2.466 in diameter bar of SAE 1020 low carbon content plain carbon steel, calculate the material removal rate in cubic inches per minute as a function of the cutting speed. If necessary, make and explain any additional assumptions and use any data as needed from this manual. MRR=0.6 in^3/min × 0.062 inches × Cutting Speed= 0.0372* cutting speed 9. For turning of annealed alloy steel, production estimates indicate that a single pass turning operation of length 1.955 in at a depth of cut of 0.012 in on a workpiece with an initial diameter of 1.629 in, cannot take more than 2 minutes. If the lathe is operating at 1250 rpm, is this operation advisable? If not, why? And if so, what lathe horsepower is required if an allowance of 0.791 in is used? Make note of any 8

9 assumptions you may need, any data as needed from this manual. MRR= (1.955 in×1.629 in×0.012 in/rev) / Tmachining Now if tmachining is under 2 mins, the operation could be considered viable You can use cutting force to calculate the horsepower, as it is not provided, it must be assumed 10. List the properties of materials used to make cutting tools. There are a few properties that are used to determine materials, but hardness, high temperature resistance, edge retention come to mind. 11. Explain the difference between up-milling and down-milling. In up milling, the cutting piece rotates against the direction of the workpiece; in down milling the workpiece tends to be pulled toward the cutting implement. 12. Name the primary factor that causes a tool to lose its hardness. It’s heat, when the machine is run too fast the heat will create defects within the tool. 13. What type of machining should be used to make a shaft? Generally, turning operations will provide the dimensions required for a shaft. 14. What is the cutting speed in fpm of a 4.180 in cutter rotating at 50 rpm? S= pi*4.18*50=659.72 fpm References Robert Spring Woodbury. History of the Lathe to 1850; a Study in the Growth of a Technical Element of an Industrial Economy . Ohio: Society for the History of Technology, 1961. Appendix A. 9

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10 Figure 3: A diagram of a turning, milling, drilling. sawing, broaching. shaping/planing, and grinding operations Figure 4: A drawing of a late seventeenth century wood lathe 10