21 - Digital Design And Manufacture Flashcards
Advantages of Computer aided design (CAD) (4)
- The design and development process is faster and more accurate due to advantages of editing and developing files rather than drawing by hand
- Networking facilitates collaborative work across different offices and countries
- Highly accurate files can be sent to a range of CAM machines such as laser cutters, routers, lathes and milling machines
- Files can be sent to 3D printers to make models or prototypes
Disadvantages of computer aided design (CAD) (3)
- It is expensive to set up due to hardware and software costs and training
- Software requires regular updating and requires ongoing technical support
- CAD is not always convenient for quick recording of ideas
Use of 2D and 3D CAD for drawings (5)
- High-Quality 3D CAD presentation drawings (‘artist impressions’) of designs can be created with photo-realistic rendering
- Designs can be rotated and viewed from any angle
- Client and marketing feedback is possible through renderings rather than physical models
- Ideas can be developed more quickly than with physical models and prototypes
- Original artwork can be scanned into CAD software for further digital development
Features of CAD in industrial applications (3)
- The ability to incorporate standard component files such as electronics and hydraulics in designs
- 2D working drawings with multiple ‘layers’ to show various element of a design such as the structure, wiring and casing
- CAD/CAM simulations that can executed to anticipate matching strategies and problems
Define computer aided design
Involves using computers to design and develop products
Define computer aided manufacture (CAM)
Using computer-controlled equipment to machine materials
How is CAM used to manufacture products? (3)
- CAD files are downloaded to computer numerically controlled (CNC) machines for cutting and shaping materials
- The machine generates a control program, facilitating settings such as feed rate, cutter speed and other factors to suit the material being machined
- The simple and seamless transfer of files from CAD to CAM can make one-off production viable in some situations
What are the different CAM processes? (5)
- CNC laser cutting
- CNC routing
- CNC milling
- CNC turning
- CNC plotter cutting
CNC laser cutting - CAM processes (4)
- Laser use a high-energy laser beam to cut or vaporise materials
- Compressed gas or air blows the waste material away to leave a clean edge
- 2D CAD files are converted into a CNC program
- The X and Y axes, speed and power are programmed to cut and engrave a range of materials
CNC routing - CAM processes (3)
- CNC routers use high-speed cutters to machine 2D CAD files in sheet materials such as MDF
- 3D CAD files can also be used to machine models, moulds and other 3D forms in materials such as timber and modelling foams
- The cutter moves in the x,y and Z axes, and the work piece is fixed to the bed of the machine
CNC milling - CAM processes (6)
- Milling machines move the park in the x,y and z axes and sometime have two or three additional axes of movement for the cutting head and work piece
- Milling machines are more robust than routers with slower speeds to suit metal casting
- Tools can be automatically selected to drill holes, cut slots and shape complex surfaces and edges
- These machines are usually totally enclosed to improve safety
- Coolant improves tool life and quality of finish by providing lubrications and reducing heat
- CNC milling machines operate much more quickly, accurately and with greater endurance than human operators, needing to stop for only essential maintenance
CNC Turning - CAM processes (3)
- CNC lathes usually machine metals and plastics in bar form to create pre-programmed x and y axis profiles, including threads and bored recesses
- They can automatically change tools, which often use disposable tungsten carbide tips
- CNC lathes are often teamed with milling machines and robot arms in FMS cells
CNC plotter cutting - CAM processes (4)
- Plotter cutter are used to cut out shapes in compliant materials such as self-adhesive vinyl
- They generate an X and Y co-ordinate cutting path from 2D CAD files
- The pieces produced are often used for graphics applications
- Plotter cutters usually pull the sheet material in and out of the machine (y axis), while the cutter moves from side to side in the x axis
How is virtual modelling used in industry prior to product production? (4)
- Use 3D CAD files to simulate aspects of performance of products before they are manufactured
- Virtual model of mechanical designs such as car engines can be checked for fit and clearance
- CAM processes can be simulated to ensure error-free machining
- Production system planning is possible before investing in new equipment
Example of virtual modelling
The optimised layout of all elements of a car production system including FMS cells, conveyors, workstations, robots, AGVs etc
Examples of simulations (2)
- The cutting path of a CNC laser
* A series of turning tools creating a profile for a part being made on a CNC lathe
What is a CAD/CAM simulation?
Is a computer ‘run-through’ of a CAM process which can be viewed by the designer, who also receives appropriate reports on its success
Advantages of CAD/CAM simulations (5)
- Highlights potential problems and shows if the production will be as expected
- Indicates how long the item will take to be machined
- Clashes with clamps and vibes or the tool moving beyond the X,Y or Z limits will show up
- Facilitates ‘nesting’ of multiple parts to reduce wastage of sheet material
- 3D printer models’ appearance and support material requirements can be assessed
Define computational fluid dynamics (CFD)
Is the virtual testing of products in liquid or gases, using CAD-based software
Importance of computational fluid dynamics (CFD) (4)
- Vehicle drag (wind resistance) can be tested in a simulated wind tunnel
- Test results can then inform aerodynamics improvements
- Marine crafts use a simulated wave tank for similar purposes
- Designers save time and money that is normally required for physical testing
Define finite element analysis (FEA)
Virtual testing compounds and product to identify stress or weak points
Importance of finite element analysis (FEA) (4)
- Allows designers to simulate forces, vibration or shock loads on products or components
- Weal pints are highlighted, usually using an easily identified colour-coded scale
- Money and time can be saved as designs can be optimised by modifying and re-testing
- Static and dynamic testing is useful for many products, such as bicycle frames and cars
What are Rapid prototyping processes? (2)
- Involve the use of machines to produce realistic 3D models from CAD files
- The models can be made in a range of materials, which are usually a type of polymer
Benefits of rapid prototyping to designers and manufacturers (5’
- It is a fast process, as 3D modelling needs minimal human input
- Modelling was previously highly skilled, expensive and time consuming
- Rapid prototypes can serve as moulds for casting and making production dies
- Stereolithographic modelling, where a UV laser solidifies layers of photopolymer (light sensitive resin) is often used by manufactured such as potteries
- Stereolithographic models of pottery designs can be realistically sprayed and decorated for appraisal by designers and potential customers
What is electronic point of sale (EPOS)?
Is a computer system using barcodes and other devices to monitor product sales
Feature of electronic point of sales (4)
- Stock levels and the triggering of stock reordering are facilitated in retail and wholesale
- Systems collect sales data and customer details for use by marketing departments
- The product life cycle status of products can be established to indicate when extension strategies or replacement might be appropriate
- Customers’ email addresses and loyalty cards facilitate additional marketing opportunities
How can EPOS be used for maintenance of stock levels? (3)
- Many items have barcodes and when they are scanned at the till the details of the sale are recorded
- ‘limits’ can be set so that replacement stock will be reordered from distributors when a certain number have been sold
- As distributors remove stock from warehousing, replacement products will be reordered electronically from the manufacturers
How can EPOS be used to capture customer data? (2)
- Systems collect sales and customer details for use by marketing department
- Customers’ email addresses and loyalty cards facilitate additional marketing opportunities - addresses can be acquired by emailing customer receipts
Importance of Production, planning and control networking
Is vital to ensure the flow of materials and components required to manufacture products on a global scale call and particularly to operate a JIT system
How are computers used in PPC (production, planning and control) networking (3)
- Plan and control production
- Organise the availability of materials and components
- Co-ordinate suppliers and customers
Define master production schedule (MPS)
Is a software-based system to organise and schedule product manufacture
Availability of materials - PPC networking (6)
- Triggers and co-ordinates order to materials suppliers and controls stock inventory
- JIT production requires suppliers of materials and components to deliver stock only when it is needed
- To facilitate a JIT system the flow of materials and components through a factory must be carefully controlled using a ‘kanban’ for reordering components
- Many of the Kanban cards that were once used have now been replaced by barcodes labels, RFID tags and scanned linked to MOS software
- In the car industry parts are often delivered to where they are needed by overhead gantries and conveyors at the precise time needed
- As cars are assembled their progress is tracked using a telemetry device such as RFID linked to the MPS computer
Scheduling of machines and people - PPC networking (3)
- Planning production schedules and timings
- Networking with departments such as personnel to ensure the appropriate availability of suitably skilled labour
- Automatic reconfiguration of manufacturing plants to facilitate QRM and the re-programming of FMS cells to facilitate for example, switching between different car models to suit JIT orders
Co-ordinating suppliers and customers
Links to EPOS for automatic transmission of JIT manufacturing requirements
3D printing as an example of rapid prototyping (3)
- Used for one-off production of bespoke items such as jewellery e.g 3D printed patterns for casting moulds
- 3D printing of metals can produce highly complex bespoke engineering components that would be impossible to make in any other way and have no potentially weak joints - titanium, stainless steel and aluminium parts can be made with metal 3D printers
- Custom Made prosthetics, joints, bone replacements can be 3D printed in titanium
