The engineer or designr first draws the part on the screen of computer. This part drawing is actual part geometry. The sizes and locations are all correct so that the information can be used later to create a program to machine the part . Actually, you can also draw the geometry of a workpiece with CAD software on a computer. You may create the design model by applying graphics commands stored in the computer. You have complete freedom to zoom and view the mold at different orientations and then represent the design as a set of points, lines, arcs, and so on by using basic CAD software. Actually, graphics editing commands allow for easy modifications as required.

  AutoCAD is a computer-aided design (CAD) program used by just about every engineering and design office in the world. When you start AutoCAD window will open. The window is actually your design work space. How to create a new drawing with AutoCAD? Firstly, you choose "New" from the file meau. The dialogue box will appear in the command window underside of the AutoCAD window. Secondly, you can choose "Start from Scratch". Under"Select Default Setting" select "English" or "Metric", and then choose "OK". In this way, the drawing opens with the default AutoCAD settings. Finally choose "Sava As" from the "File" menu and enter a file name, then you can save the drawing.

  The AutoCAD interface has serval different components, each of which provides different information of command options for the user.