1.7-Digital design and manufacture

Question 1

What is CAD

Answer 1

-using computers to develop 2D and 2D drawings and computer models with a range of file types that facilitate transfer to CAM equipment

Question 2

Advantages of CAD

Answer 2

• design and development process is faster and more accurate due to advantages of editing and developing files rather than drawing by hand
• networking facilities collaborative work across different offices and countries
• highly accurate files can be sent to a range of CAM machines e.g. laser cutters and routers
• files can be sent to 3D printers to make models/prototypes

Question 3

Disadvantages of CAD

Answer 3

• expensive to set up due to hardware and software costs and training
• software requires regular updating and requires ongoing technical support
• CAD not always convenient for quick recording of ideas

Question 4

Capabilities of 2D and 3D CAD software

Answer 4

• high quality 3D CAD presentation drawings of designs can be created with photo realistic rendering
• designs can be rotated and viewd from any angle
• client and marketing feedbakc possible through renderings
• ideas developed more quickly than with physical models and prototypes
• scan original artwork for more development
• editing tools accelerate developmet of ideas

Question 5

How can CAD be used in industrial applications

Answer 5

• Can incoporate standard component files such as electronics and hydraulics
• 2D working drawings with mutiple layers to show various elements in a design e.g. structure
• CAD/CAM simulations can be executed to anticipate machnining strategies and problems

Question 6

What is CAD/CAM simulation

Answer 6

• a computer ‘run through; of a CAM process which can be viewed by the design, who recieves approporiate reports on its success
• e.g. cutting path on CNC laser, a series of turning tools to create a profile

Question 7

Advantages of CAD/CAM simulation

Answer 7

• 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 vices 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

Question 8

How does the CAM process work

Answer 8

• CAD files downloaded to CNC machines for cutting and shaping
• machine generates a control program, facilitating settings such as cutter speed
• simple and seamless transfer of files from CAD to CAM can make one off production viable in some situations

Question 9

How does a CNC laser cutter work

Answer 9

• lasers 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 converted into a CNC program
• X and Y axes, speed and power and programmed to cut and engrave a range of materials

Question 10

How do CNC routing work

Answer 10

• CNC couters use high speed cutters to machine 2D CAD files in sheet material e.g MDF
• 3D CAD files can be used to machine models, moulds, and other 3D forms in materials such as timber and modelling foams
• cutter moves in the X, Y and Z axes, and the work piece is fixed to the bed of the machine

Question 11

How does CNC milling work

Answer 11

-milling machines move the piece in the X, Y and Z axes, and sometimes have two or three additional axes of movement for the cutting head and work piece

Question 12

How can designers use CNC turning

Answer 12

• CNC lathes 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 roboto arms in FMS cells

Question 13

How can designs use CNC plotter cutting

Answer 13

• plotter cutters used to cut out shapes in compliant materials e.g. self adhedsive vinyl
• they generate an X and Y co-ordinate cutting path from 2D CAD files
• pieces produced often used for graphics applications
• plotter cutters use sheet material in and out out of the machine (Y axis), cutter moves side to side (X axis)

Question 14

What is virtual modelling and why might designers use it

Answer 14

This is the use of 3D CAD files to stimulate aspects of the performance of products before they are manufactured

• virtual models of mechanical designs e.g. car engines checked for fit and clearance
• CAM processes stimulated to ensure error free machining
• production system planning possible before investing in new equipment
• typical example is optimised layout of all elements of a car production system

Question 15

What are computational fluid dynamics (CFD) and why might designers use it

Answer 15

• it is a 3D CAD stimulation tool for fluid or gas flow in or around a product
• vehicle drag can be tested in a stimulated wind tunnel
• test results can informaerodynamic improvements
• marine craft designers use a stimulated wave tank for similar purposes
• designers save time and money that is normally required for physical testing

Question 16

What is finite element analysis and why might designers use it

Answer 16

This is the analysis of stress in elements of a CAD design

• allows designers to stimulate forces, vibration or shock loads on products or components
• weak points highlighted, usually an easily identified colour coded scale
• money and time saved as designs can be optimised by modifying and re testing
• static and dynamic testing useful for many products such as cars

Question 17

What is rapid prototyping and what are the benefits of using it

Answer 17

The use of machines to produce realistic 3D models from CAD files. Models can be made in a range of materials

• it is a fast process, minimal human input
• modelling was previously highly skilled, expensive and time consuming
• rapid prototypes can serve as moulds for casting
• stereolithographic modelling often used by manufacturers e.g. potteries
• stereolithographic models of pottery designs can be sprayed and decorated for apprasial

Question 18

Explain the process of fused deposition modelling/3D printing

Answer 18

• 3D printers use FDM to build or ‘print’ a 3D model from 3D CAD files
• 2D CAD file model sliced into lauers that are extruded
• FDM uses a thin extruded thermoplastic filaments to build model
• supporting scaffold is borken away or chemically disolved after manufacture

Question 19

What are some uses of 3D printers

Answer 19

• one off production of bespoke items such as jewellery
• e.g. production of 3D printed patterns for casting moulds
• customised grips for people with disabilities
• 3D printing of metals for complex bespoke engineering components
• titanium, stainless steel and aluminium parts can be made
• electron or laser beam used to fuse metal powder
• custom made prosthetics, joints, bone replacements

Question 20

What is EPOS and how can it be used

Answer 20

• a computer based scanned barcode system for capturing data when consumers purchase goods
• stock levels and triggering of stock reordering are facilitated in retail/wholesale
• systems collect sales data and customer details for use by marketing departments
• product life cycle status can be stablished to indicate when extension strategies of replacement might be approporiate
• customer’s email addresses and loyalty cards to faciliatate marketing opportunities

Question 21

How can computers be used in production, planning and control networking

Answer 21

• plan and control production
• organise the availability of materials and components
• co ordinate suppliers and customers

Question 22

How can a supply chain network be used in production, planning and control networking

Answer 22

ensures the flow of materials anc components required to manufacture products on a global scale and particularly operate a JiT system

Question 23

What is a master production schedule and how can it be used in production, planning and control networking

Answer 23

-carries out several ordinated PPC functions in a JiT environment e.g. availability of materials, scheduling of machines and people and co-ordinating suppliers and customers

Question 24

How does a master production system monitor availability of materials

Answer 24

• triggers and co ordinates materials suppliers and controls stock inventory
• JiT production requires suppliers of materials and components to deliver stock when needed
• facilitates a JiT system- the flow of materials and components through a factory must be carefully controlled using a Kanban system for re-ordering components
• many of the Kanban cards have been replaced bt RFID tags and scanners linked to MPS software
• car industry- as cars are assembled their progress is tracked using a telemetry device e.g. RFID linked to MPS

Question 25

How does a master production system monitor scheduling of machines and people

Answer 25

• planning of production schedules and timing
• networking with departments such as personnel to ensure the appropriate availability of suitably skilled labour
• automatic configuration of manufacturing plants to facilitate QRM and the re-programming of FMS cells