A Level Design and Technology Digital Technologies PDF

## A Level Design and Technology: 4.1 - Digital Technologies ### - Computer-aided design (CAD) * CAD: The use of computers to design and develop products. * CAD can develop 2D and 3D drawing and computer models with a range of file types. * These CAD files are often transferred to CAM machine...

## A Level Design and Technology: 4.1 - Digital Technologies ### - Computer-aided design (CAD) * CAD: The use of computers to design and develop products. * CAD can develop 2D and 3D drawing and computer models with a range of file types. * These CAD files are often transferred to CAM machines. What are the applications of CAD? 1. Product, industrial and architectural design 2. Civil and electrical engineering ### Advantages of CAD 1. Provides greater accuracy in the design process by reducing human error; in addition there are also tools for measuring the precision, skill and accuracy of the design. 2. Increases designer productivity, allowing rapid changes and iterations, also making it easy to edit any errors. 3. Easy to share as files can be saved and stored, allowing them to be used again and shared with minimal hassle. 4. Saves time as more designs with greater accuracy can be produced in a shorter amount of time. 5. Integration with CAM systems is possible, which facilitates a streamlined product development process. ### Disadvantages of CAD 1. Introducing CAD systems could involve a high initial investment, including training staff and purchasing software licenses. 2. Using complex CAD software requires specific skills and training, and it could be time-consuming and costly to train employees. 3. Risk of over-reliance on CAD systems, potentially leading to a loss of highly-skilled employees in the workforce. 4. Requires regular updates and maintenance, which can be time-consuming and costly. ### Elements of CAD 1. Working drawings * Can either be drawn by hand or drawn with CAD. * They include the following details for manufacturers: dimensions, elevations, sectional views, notes on manufacturing details. 2. 2D CAD software * Used for artwork, to show technical details and can be used to export files for CAM. 3. 3D CAD software * Presentation drawings offer virtual 360° views and walk-through tours. * Gives clients and focus groups a realistic idea of the final product. * Can be used to quickly compare different materials and colorways. 4. Virtual modeling * Virtual modeling: the use of 3D CAD files to simulate aspects of the performance of products before they're manufactured. * Used for designs such as car engines to check for fit and clearance. * CAM processes can be simulated to ensure error-free machining. * Production system planning is possible before investing in the equipment. List the six elements of CAD 1. Working drawings 2. 2D CAD software 3. 3D CAD software 4. Virtual modelling 5. Simulations 6. Finite element analysis (FEA) 5. Simulations * CAD/CAM simulation: a run-through of a CAM process, which can be viewed by the designer who also receives reports on its success. *Advantages of simulations* 1. Highlights potential problems and shows if production will be as expected. 2. Indicates how long the item will take to be machined. 3. Clashes with clamps and vices, or the tool moving beyond the X, Y or Z limits will shows up. 4. Facilitates 'nesting' of multiple parts to reduce waste. Below is an excerpt from a sample CAD/CAM simulation code: ``` F = 1200.00 (mm/min) S = 2300 [rpm] X = 72.81 [mm] Y = 52.90 [mm] Z=-19.50 [mm] G43 G48|G88|G98 1 00001 00002 00003 00004 00005 N150 G2 J-30.; N160 G90 GO XO. YO. 25.; N170 X90.; N180 G1 Z-5. F1200; N190 G2 Z-10. 1-90. 30.; N200 G2 Z-15. I-90. 30.; N210 G2 Z-20. I-90. 30.; N220 G2 Z-25. I-90. 30.; N230 G2 1-90. 30.; N240 G90 G0 Z5. M9; N250 T2 M6; N260 S2300 M3; ``` 6. Finite element analysis (FEA) * FEA: the virtual testing of components and products to identify stress or weak points, by allowing designers to simulate forces, vibration or shock loads. * Tests how a product component will withstand the conditions that it will likely be subjected to. * Any weak points are highlighted using a color coded scale. * FEA saves money and time as designs can quickly and easily be modified before manufacture. ### Disadvantages of virtual modeling, simulations and FEA 1. High initial investment due to hardware and software costs and employee training. 2. Software requires regular updates and ongoing technical support. 3. Software compatibility may be an issue when dealing with different companies' systems. ### - Computer-aided manufacture (CAM) and rapid prototyping * CAM: the use of software and computer-controlled machinery to simplify manufacturing processes. * CAM works with CAD software. ### CAM processes * How does CAM work? 1. CAD files are downloaded to CNC machines for cutting and shaping tools. 2. The machine generates a control program, facilitating settings such as tool selection, feed rate, cutter speed, etc. to suit the material being machined. * One-off production is viable, due to the simple and seamless transfer of files from CAD to CAM. ### Computer numerical control (CNC) * CNC: the use of a program, converted from CAD files, which uses special codes to control CAM equipment. What is the general setup for any CNC machine? 1. A machine/STL/DXF file is created from a CAD drawing. 2. A simulation test is run to generate a tool path. 3. The CAD/STL/DXF file is downloaded to the machine. 4. The material type and size, feed rate and spindle speed is entered into the machine. 5. The material is placed/clamped/fixed into the machine. 6. The guard/machine doors are closed. 7. Extraction is turned on. 8. The cutter/laser is homed. 9. The machine is started by pressing the start button. ### CNC laser cutting * 2D CAD files are converted into a CNC program. * The X and Y axes, speed and strength of power are programmed to cut and engrave a range of materials (typically acrylic) using a high-energy laser beam. * Compressed gas/air blows the waste material away to leave a clean edge. * Extraction is required as some materials will produce toxic fumes. *CNC laser cutter setup:* 1. Select the material on the laser settings. 2. Ensure the Y axis is adjusted according to the height of the material. 3. Focus the laser beam, typically using a piece of measured acrylic. 4. Adjust the settings for speed and strength of power. 5. Some CNC laser cutters need checks on color on the CAD file. ### CNC routing * CNC routers use high-speed cutters that machine 2D and 3D CAD files. * The cutter moves in the X, Y and Z axes. * The workpiece is fixed to the machine bed. * Cutting tools can be changed automatically. * Requires extraction. *CNC router setup:* 1. Check the depth is accurate for the cut. 2. Ensure the correct cutter size is installed. 3. Ensure the machine is aware of the material type and thickness. 4. Check the offset and height of the material. ### CNC milling * CNC milling machines are used to cut complex 3D forms. * Milling machines move the workpiece in the X, Y and Z axes, and may have additional axes of movement for the cutting head and the workpiece. * The machines is typically fully enclosed to improve safety. * Tools can be automatically selected to drill holes, cut slots and shape complex surfaces and edges. * Coolant is used when machining metals to improve tool life and quality of finish by providing lubrication and reducing heat. * CNC milling machines operate more quickly, accurately and with greater endurance. *CNC milling machine setup:* 1. Load the correct tool to be used. 2. Place the workpiece and ensure it's secured. 3. Adjust settings for the axis/height. 4. Ensure the machine is aware of the tool size. 5. For machining metal, apply coolant to the workpiece. ### CNC turning * CNC lathes use a spinning workpiece and a cutting tool to manufacture shapes that require rotational symmetry along the central axis. * They can automatically change tools, which typically use disposable tungsten carbide tips. * CNC lathes are often used alongside CNC milling machines and robot arms in FMS cells. *CNC lathe setup:* 1. Install and secure the tools in the tool holders. 2. Secure the workpiece in the chuck/collet. 3. Indicate the workpiece's position according to the machine's reference point. 4. Load the CNC program into the machine's control system and simulate the CNC program. 5. Set the machine datum for the workpiece and tool paths. 6. Set the spindle speed and feed rates according to the material and tools used. 7. Establish the home position for the machine. ### CNC plotter cutting * CNC plotter cutters are used to cut out shapes in materials such as vinyl, paper and card. * They generate an X and Y coordinate cutting path from 2D CAD files. * The sheet material is pulled in and out of the machine (Y axis), while the cutter moves from side to side (X axis). *CNC plotter cutter setup:* 1. Check for correct color on the CAD file. 2. Check the vinyl material being used is correct. 3. Ensure the vinyl is smooth and free from defects. 4. Check the quantity/size of the vinyl. 5. Check the thinckness of the vinyl. ### Advantages of CAM 1. Requires little supervision and can be completed during off-hours, as machines can run indefinitely. 2. Less labor-intensive and saves money on labor. 3. Machines are precise and large batches of manufacturing can be repeated. 4. Errors rarely occur. 5. Prototypes can be quickly created for inspection, before making any modifications to the design for manufacture. 6. On the screen, virtual machining can evaluate machining routines and outcomes. ### Disadvantages of CAM 1. High initial investment and high setup cost. 2. Regular maintenance is required for the machines, which can be costly. 3. High-level manual skills in the workforce may be lost. 4. Requires highly-trained technicians. ### Rapid prototyping processes * Rapid prototyping: the use of computer-controlled machines to produce realistic 3D models from CAD files. ### Advantages of rapid prototyping 1. Rapid process, as it requires minimal human input. 2. Rapid prototypes can function as molds for casting and producing dies. 3. Eliminates some of the issues involved with producing prototypes manually, as prototyping was previously highly-skilled, expensive and time-consuming. 4. Allows designers, manufactureres and clients to view the prototype before modifying the design and manufacturing the final product. ### Fused deposition modeling (FDM)/ 3D printing * The 3D CAD file is sliced into layers that are extruded too build the product from the bottom up, layer by layer. * 3D printers can be used for one-off production of bespoke items. *What is the purpose of 3D printing?* *3D printers build a 3D model from 3D CAD files using FDM* 1. After the CAD data is put into the machine from the slicer software, the filament is liquified using heat in the liquifier head. 2. The molten plastic is fed onto the build platform/machine bed through the extrusion model, which moves in all directions. 3. This process is repeated until multiple layers are produced. 4. Any support structures (scaffolds) are broken away after manufacture.