ME350 CAD/CAM Background Information 11 Overview of Computer-Aided Manufacturing1.1 BackgroundThis laboratory will introduce you to the process of Computer-Aided Manufacturing (CAM), in which a 3D CAD model will be used to machine your design from an aluminum block using a Tormach 3-axis CNC mill. The mills instructions come in the form of G-Code, which needs to be generated from your CAD model using Pro/Engineer software. By defining machining parameters such as tool type, cut feed, and spindle speed, an appropriate tool path is automatically generated by Pro/E. You will generate multiple tool paths for roughing, re-roughing, and finishing processes by varying the tool type and machining parameters. The roughing process will be used to machine the rough outline of the part, while the finishing process will be used to machine fine details and to improve the surface finish.1.2 Definition of Computer-Aided ManufacturingComputer-Aided Manufacturing (CAM) refers to the use of specialized software in order to facilitate the transition from design to manufactured part. In typical applications, a 3D CAD model is used as a reference from which to generate Numerical Control (NC) code. This allows the connection from design to manufacture to become increasingly automated and precise since human inefficiencies and inaccuracies are greatly reduced. While human processing is replaced by computers, CAM requires specialization in order for technicians to become proficient with the software and computer systems. This fact along with a high initial capital investment implies a high initial cost, although this may be offset by a lower running cost.1.3 G-CodeThe code that will be used as instructions for the CNC mill is referred to as G-Code. G-Code consists of a variety of commands that specify the geometric and kinematic properties of the machine and tool path in order to machine the desired part. Each line of code begins with an “N#” statement that defines the line number. The line may then include commands from the following categories (only select categories are listed): G Positioning commandsT Tool commandsM Machine commandsS Tool speed commandME350 CAD/CAM Background Information 2F Tool feed commandWhile it is certainly possible to write the G-Code manually using a text editor, it becomes a very tedious and difficult process for complex geometries. CAM allows the code to be automatically and rapidly generated based on a few user-input parameters.2 Overview of Pro/Engineer as a CAD/CAM ToolYou will be using Pro/Engineer to generate tool paths and G-Code for your 3D CAD part. The following sections give a brief overview of steps you will be required to take. Consult the Lab Instructions handout for detailed instructions.2.1 Establishing References In order for Pro/E to determine what material you wish to remove, it requires you to establish both a reference model (your part) and the original workpiece (the blank aluminum block). After importing both parts, you will be required to establish a properly-oriented coordinate system so that the model coordinates are consistent with those of the CNC mill. Finally a milling window needs to be established to define the edges of the workpiece.2.2 Defining ToolsThe tools that will be used in this lab are a ” end mill and a 1/8” ball mill. The tool parameters must be defined in Pro/E to ensure that an appropriate tool path is generated. You will be required to input a tool name, tool number, type (end/ball), and diameter for each tool. 2.3 Generating Tool PathsYou will be creating three sequences (roughing, re-roughing, and finishing) for your part. Each sequence is defined in Pro/E by specifying the following machining parameters:a. Cut_Feed: The speed at which the cutter will move horizontallyb. Max_Step_Depth: The vertical depth of cut for each layerc. StepOver : The lateral displacement at the beginning of each run of the cutter. d. SpindleSpeed: The angular speed (RPM) at which the cutter rotatese. ClearDistance: The distance between the cutter and the top face of your part at the very start of the cuttingf. Tool: One of the tools that was previously definedME350 CAD/CAM Background Information 3A summary of the input parameters is presented in Table 1 below:Roughing Re-Roughing FinishingTool ” End Mill 1/8” Ball Mill 1/8” Ball MillCut Feed (in/min) 10 9 15Max Step Depth (in.) 0.09 0.05 -Step-Over (in.) 0.1 0.05 0.05Spindle Speed (RPM) 4000 4000 4000Table 1 Tool path specificationsA maximum step depth is not defined for the finishing process since it is a finishing operation and not a bulk material removal operation. A smaller step-over distance is used for the re-roughing and finishing processes in order to obtain a better surface finish (at the expense of increasing machining time).Once all of the parameters are properly specified, Pro/E will allow you to preview the actual tool path that the mill will follow. 2.3 Generating G-CodeOnce all of th