Detailed Notes on Digital Design and Manufacture

Digital Design and Manufacture

Learning Outcomes

  • By the end of this unit, students should understand:

    • The use of Computer-Aided Design (CAD) for developing and presenting product ideas.

    • How Computer-Aided Manufacturing (CAM) is used in product manufacturing.

    • Virtual modeling/testing procedures used in the industry.

    • Rapid prototyping processes and additive technologies.

    • The use of Electronic Point of Sale (EPOS) for marketing and data collection.

    • The role of Production, Planning, and Control (PCC) systems in manufacturing.

Introduction to CAD and CAM

  • CAD has become a key method for product development and manufacturing in education and industry over the last few decades.

  • Advances in CAM enable the quick manufacturing of CAD models and components using CNC and CAM machinery.

Computer-Aided Design (CAD)

Advantages of CAD

  • CAD speeds up the product design development process.

  • It facilitates collaboration among teams, even in different geographic locations.

  • CAD drawings and models can be shared digitally.

  • CAD models do not require physical space.

  • Aesthetic properties can be easily modified without affecting the original model.

  • Numerous variations can be produced quickly.

  • CAD models can be sent to CAM and RPT machinery for rapid realization of ideas.

Disadvantages of CAD

  • CAD software can be expensive (though often free for educational institutions).

  • Staff training is required, which can be complex.

  • Software updates are necessary to fix bugs and enhance features.

  • CAD may not be ideal for quick ideas, although some users are very efficient with it.

  • CAD is subject to human error due to user input.

Use of CAD for Product Development and Presentation

  • Modern CAD can create 3D models and render them indistinguishable from real objects.

  • This allows designers and clients to visualize the final product, making quick changes to shape, color, and finish.

  • The results can be photorealistic.

2D CAD

  • 2D CAD packages (e.g., Adobe Illustrator, Techsoft 2D Design) are used with laser cutters and plotters to cut shapes from sheet materials.

3D CAD

  • 3D CAD software can produce full 3D models and assemblies.

  • Suitable for younger students with programs like Tinker CAD and Onshape.

  • Professional packages like AutoCAD, Fusion 360, and SketchUp are free for educational use but expensive for industrial use (e.g., Solidworks).

Parametric CAD

  • Parametric CAD allows for dimensions to be changed at any time, with corresponding measurements adjusting automatically.

  • Example: Adjusting the width of a bed in CAD will automatically reposition pre-set holes.

  • Useful for producing a range of configurations from a single 3D model.

  • Ready for conversion to CNC machining.

3D CAD and Manufacturing Drawings

  • 3D CAD models can be quickly used to produce dimensioned and annotated working drawings.

  • Software can nest parts for cost-effective solutions.

  • Cutting tools can be set up to automatically cut, drill, and route parts using CNC.

Virtual Reality (VR)

  • VR is an immersive process that creates a 3D world viewed through a headset.

  • Early VR in the 1980s was crude, causing nausea and impracticality.

  • Advances in technology now allow for lag-free and photorealistic visuals.

  • VR is becoming an essential tool for designers and engineers.

Augmented Reality (AR)

  • AR is a non-immersive process that overlays information, graphics, and 3D models onto an existing display using a device's camera and software.

  • Examples: Seeing how a room looks painted in different colors, road maps on car screens, virtual X-rays for doctors.

  • Apple is developing AR technology for glasses.

Computational Fluid Dynamics (CFD)

  • CFD simulates the flow of fluids or gases in or around a product.

  • Used to improve the efficiency of fans, turbines, and other flow-dependent elements.

  • Example: Used in the development of Dyson fans and hairdryers.

Finite Element Analysis (FEA)

  • FEA calculates forces applied to a structure based on the mechanical properties of the material.

  • Visual data shows stresses and loads, highlighting potential problems.

  • The product can be re-engineered to reduce potential issues.

Generative Design

  • Generative design software analyzes the geometry of a component and generates numerous variations to reduce material/weight while increasing strength.

  • Designers can choose the variation with the right combination of visual appeal and technical performance.

Generative Design Case Study

  • Honda used generative design to develop a crankshaft 50% lighter than previous components while retaining strength and performance.

  • This process can lead to considerable savings in power consumption across a range of car components.

Computer-Aided Manufacture (CAM)

  • CAM involves downloading completed CAD drawings to machines that cut and shape materials.

  • CAM machines convert drawings into a Computer Numerical Controlled (CNC) program.

  • The CNC program is translated into movement in 2 or 3 axes by the cutting or shaping tool.

  • Most modern tools and machines have a CNC version.

Laser Cutting

  • Laser cutting uses a high-energy laser beam to cut or vaporize materials.

  • Compressed gas or air blows away waste material.

  • Capable of cutting and engraving incredibly small and detailed parts in various materials (plastic, stone, glass, metal, wood, fabric).

  • Commonly used in schools and industry.

  • Cuts in 2 axes, with depth dependent on laser power; cannot create organic 3D shapes.

Routing/Milling

  • Routing/Milling involve a cutting or shaping tool that moves in 3 axes.

  • Milling is used for harder materials and requires more torque.

  • A 5 or 6-axis milling machine has a cutting head that can move in all directions around the material.

  • Machines range from small tabletop units to large factory-floor setups.

Turning

  • Turning involves rotating the material between two fixed end points (on a lathe).

  • A cutting tool or profile shapes the product.

  • Industrial lathes can be part of a Flexible Manufacturing System (FMS) with milling machines and laser cutters.

  • Robot arms transfer parts between machines.

Plotter Cutting

  • Plotter cutting is similar to printing but uses a blade to cut through the material.

  • Vinyl cutters are common in schools for cutting plastic and paper/card.

Rapid Prototyping and Production Planning

Rapid Prototyping Technology (RPT)

  • Rapid prototyping is the quick production of a model or component without expensive molds or machinery.

  • Objects are made from a 3D model produced in a computer.

  • Early method: Stereo Lithography (STL) used lasers to harden liquid resin layer by layer.

SLA Printers

  • Modern development of stereolithography printers.

  • Produce better quality results in a range of resins.

  • Use a high-powered laser to harden liquid resin in a reservoir.

  • The object is lifted out of the resin rather than being built up from a bed (unlike FDM printers)

Fused Deposition Modeling (FDM)

  • Most commonly known as 3D printing.

  • Uses filament fed into a heated nozzle, printed in fine layers to build a 3D model.

  • The range of usable materials is growing.

  • Metal 3D printers use a laser to selectively bind metal particles on a powder bed (see also laser sintering).

Popularity of 3D Printing

  • 3D printing is becoming increasingly popular for making components and objects quickly and inexpensively.

  • Materials used include ABS, PLA, food, metal, and organic materials like human organs.

Rethinking Structures and Manufacture

  • 3D printing has caused design and engineering communities to rethink traditional structures and manufacturing.

  • Example: Redesigning a hinge for the aerospace industry to be stronger and lighter using complex structures impractical with casting techniques.

Electronic Point of Sale (EPOS)

  • EPOS uses barcoded products scanned at the point of sale.

  • Enables items to be registered with distributors and warehouses for ordering parts or extra stock.

  • EPOS enables manufacturers to produce items ‘just in time’ (JIT), which is essential for Quick Response Manufacturing (QRM).

Production Planning and Control

Kanban

  • Kanban are cards labeled with a barcode, attached to containers of parts.

  • When stock is low, the Kanban is scanned, and parts are automatically reordered via electronic data interchange (EDI).

  • The term Kanban also describes a computer system controlling the flow of products and components.

Sequencing

  • Sequencing is essential for JIT systems, involving the timing of work.

  • Computer-controlled sequencing ensures parts and materials arrive at work cells at the right time; this is a form of computer-integrated manufacturing (CIM).

Master Production Schedule (MPS)

  • MPS is a computer-controlled scheduling system that sets the quantity of each product made in a given period.

  • For cars, this uses order-based scheduling relying on materials requirement planning (MRP) software.

Telematics

  • Telematics electronically tracks a product from receipt of customer orders through assembly and dispatch.

  • For cars, customer data is placed in a ‘black box’ and checked at each assembly stage.

Flexible Manufacturing Systems (FMS)

  • Manufacturers mass-producing items like aerosols and toothpaste use dedicated equipment.

  • Investment is safe due to high demand.

  • In other markets, items may be made in batches using more flexible equipment.

Summary

  • Computer Aided Design (CAD): Uses computers to generate 2D or 3D drawings and models. Modern software is advanced and produces photorealistic images and animations.

  • Computer Aided Manufacture (CAM): Uses CAD-equipped computers connected to advanced manufacturing machines accepting Computer Numerical Control (CNC). These machines perform computer-sent operations.

  • Computer Integrated Manufacture (CIM): Brings design process elements together under computer control. Can also refer to central computers and systems organizing scheduling and materials ordering.

  • Computer Aided Engineering (CAE): Uses computers to test components prior to manufacturing. Examples include testing car models under simulated loads and testing structures in civil engineering and architecture.

Revision Notes

  • Familiarize yourself with modern production techniques.

  • Understand 2D and 3D CAD systems and their possibilities.

  • Use CNC-controlled machinery and understand its operation.

  • Understand CAD and CAM integration and parametric CAD packages.

  • Understand digital production planning and component tracking.

  • Know rapid prototyping processes and their availability for prototyping outcomes.