Producing a part using a CAD/CAM system
Greg Mc Elroy - 24 March 2011
Contents 1 Introduction 2 CAD/CAM Systems 3 Assignment 4 Dimensioned CAD drawings 5 Spindle Speed Calculation 6 CAM Drawing 7 NC Code 8 Simulation Image 9 Discussion 10 References page3 page3 page4 page5 page6 page7 page9 page11 page11 page12
1 Introduction This report has been compiled to document the processes involved when undertaking a project using a CAD/CAM system. A Brazilian football club’s logo has been chosen as an image to draw using the alphacam software package. The aim of the project is to generate the tool paths required to machine the part using a CNC milling machine. 2 CAD/CAM Systems A CAD/CAM system is a computer based platform used for manufacturing component parts on fully automated Computer Numerically Controled (CNC) production machines, generally milling machines or lathes. The CAD software produces geometries on PCs or laptops, the CAD file is exported to a CNC machine and a finished part is produced at the click of button. CAD/CAM systems are generally used in industry for high spec, high volume production so as to increase output efficiency and lower production costs. Historical development: • 15th century - machining metal. • 18th century - industrialization, production-type machine tools. • 20th century : - F.W. Taylor - tool metal – HSS - Automated production equipment - Screw machines - Transfer lines - Assembly lines - cams and preset stops - Programmable automation - NC - PLC - Robots The primary purpose of CAD/CAM is to describe the geometric form of objects that are to be manufactured. CAD is primarily a visual representation of an object while CAM deals with the physical tool movements required to produce the object. As a result the geometric form of the object is different in CAD than it is in CAM. Therefore in order to transfer information between the two systems there must be some means of translating the CAD model into the CAM model. The basic elements that make up a CAD/CAM system are as follows: CAD PC or Laptop that is powerful enough to support CAD package. CAD software: SolidWorks AutoCAD ProE 3
CAM Process planning. Code generation. Text editing. Communications with CNC and CAD systems. Tool path verification and simulation. (http://moodle1011.dkit.ie/file.php/11512/2_CNC_history_prog.pdf) When embarking on a CAD/CAM project the piece manufactured must be planned with CAM in mind, that is, it must be noted that the amount of complex parts and assemblies a CAD package can generate is limitless. The software is only constrained by the users imagination, however this is not true for CAM. The CAM package has limits to what can/cannot be manufactured. The system is constrained to max part sizes, cutting speeds, number of tools, tool sizes, tolerances etc. It is important for the designer not to get get carried away and draw parts that the available CAM hardware is incapable of manufacturing. These variables must be considered at the concept/sketch stage of the part design so as to avoid problems during the manufacture.
3 Assignment Fig 3.1 illustrates the Sao Paulo FC crest which consists of basic linear shapes, stars and letters
4 Dimensioned CAD Drawing The SPFC crest is a relatively simple symetrical design consisting mainly of linear shapes like rectangles and triangles. The most complex aspect of the design, relative to the fundamental shape, is the stars and the SPFC logo.
(Fig 4.1) Fig 4.2 illustrates the creation of the SPFC logo letters. Alphacam has a database of fonts similar to Microsoft Word and it was hoped that the letters could have been easily typed in. There was one type of font in the list that was similar but did not match the exact font of the logo. It was decided by the designer not to use this font as it would result in the piece looking like a fake counterfit. So as a result the logo was drawn using alphacam. This was done by taking...
References: (http://moodle1011.dkit.ie/file.php/11512/2_CNC_history_prog.pdf) (http://en.wikipedia.org/wiki/G-code) (http://www.cncezpro.com/gcodes.cfm)
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