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ME350 – DoE Lab Background Information 1 Overview 1.1 Background This laboratory will serve for several purposes: first, it will introduce you to the turning process (remember, you were introduced to milling process in the CAD/CAM Lab). Second, you will learn how surface roughness is measured using the Starrett Procedure. Finally, and most significantly, you will be exposed to a mathematical tool called Design of Experiments, through which you will obtain an understanding of how the outcome of a manufacturing process can be predicted and improved. 1.2 Overview of Procedure The workpiece for this lab is a cylindrical aluminum bar. Based on the instructions given in the Instructions Handout, you will perform a turning operation on the bar by executing a given segment of G-Code. The code will machine eight different sections on the aluminum bar, each of which corresponds to a different combination of three varying process parameters. The three process parameters that are being varied in this lab are: Feed rate Cutting speed Lead angle Each process parameter will vary between two different values, giving 2 3 =8 combinations. Below is the table showing the different combinations of parameter values for each section. O0700 Feed Rate Cutting Speed Lead Angle 1 0.08 300 40 2 0.02 300 40 3 0.08 150 40 4 0.02 150 40 5 0.08 300 -5 6 0.02 300 -5 7 0.08 150 -5 8 0.02 150 -5 1 Table 1 - Pass Settings for O0700

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After the machining is complete, you will use the Starrett Machine to take surface roughness measurements for each section on the aluminum bar. You will have to take several measurements for each section in order to average out statistical variations and random error. All surface measurements will be recorded on a data sheet that will be used for the lab report analysis. Turning and surface roughness measurements make up one half of the lab. The other half of the lab is on Design of Experiments methodology. The DOEExample. doc document consists of an example of the calculations required in the DoE process. The same process will be followed for this lab’s report by applying the procedure to the data acquired during the lab session. 2 Turning 2.1 Overview Turning is a cutting process used for the generation of cylindrical surfaces. The workpiece is rotated on a spindle while the tool is fed into the workpiece in a radial, axial, or simultaneously radial/axial manner. The term ‘turning’, in the general sense, refers to the generation of any cylindrical surface with a single point tool. The generation of surfaces oriented primarily perpendicular to the workpiece axis is called ‘facing’ (Figure 1). In the facing procedure, the feeding motion is predominantly in the radial direction. For turning, on the other hand, the dominant feeding motion is in the axial direction. Combining both radial and axial directions of feed, tapered or contoured surfaces are machined using the ‘profiling’ process (Figures 1 and 2). Figure 1 -
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