12: Additive Manufacturing and Material Properties

Engineering Design and Material Selection

• Lecture 12 covered Manufacturing Processes and Process Selection
• The course schedule details topics, case studies, quizzes, and lecturers for each week of the course.
• Week 12 covered Manufacturing Processes and Process Selection.
• Lecture 13 covered Review and Q+A.
• Question and Answer sessions are available for lectures.
• A clicker question session is open to help students vote on which lectures to revisit and discuss specific topics or questions.

Learning Objectives

• Understand the link between manufacturing processes and material properties and feasible shapes and part function
• Learn the classification of manufacturing chains and processes
• Understand the fundamentals of selected manufacturing processes
• Learn about Design for Manufacturing and Design for Additive Manufacturing
• Understand the role of the choice of manufacturing processes during the design process

History of Material Shapes Technology

• A timeline of materials and their development in significant periods are shown
• The relative importance of various materials and their associated dates shows how materials have developed over human history

Manufacturing Processes in Engineering Design

• The manufacturing process is defined in each design step iteratively.
• The choice of the manufacturing process relates to many aspects like shape, material, cost, quality, and environmental factors.

Manufacturing Methods Influence Design Process

• The choice of a manufacturing process can be limited by factors such as availability and cost.
• The material and shape needed to fulfill the function restrict the possible manufacturing processes.
• Manufacturing imperfections caused by material treatment can differ when varying manufacturing processes are used.

Materials for Oxo Goodgrips Peeler

• Santoprene polymer is used for the handle.
• This material behaves like rubber (elastomer), but is processed like a thermoplastic (e.g., molding).

Manufacturing Processes Involved in Ski Fabrication

• The process flow highlights various manufacturing steps involved in ski fabrication, including milling, laminating, cutting (laser and mechanical), grinding, 3D printing, and bending.

Manufacturing Process as a Chain

• Manufacturing is a process chain, starting with primary production (nature)
• Then sourcing, preparation, creation of feedstock to shaping, finishing and joining.
• The path ends with the product.
• Steps used in this process also include recycling and repairing.

Example of Wood Use in Ski Fabrication

• Sourcing by harvesting
• Preparation by drying
• Feedstock creation by sawing
• Shaping by milling
• Finishing by painting
• Joining by laminating, and,
• Adding a final protective coating by oiling

Example of Metal Use in Ski Fabrication

• Sourcing by mining
• Preparation by processing
• Feedstock by creating
• Shaping by bending
• Finishing by shaping
• Joining by gluing, and
• Adding a protective final coating by laminating

Edge Bending Machine

• This was a Master Thesis by Andrin Widmer in 2024 at ETH Zurich.

Manufacturing Steps

• Subtractive (material removal)
• Additive (adding material)
• Joining (combining multiple parts)
• Deforming (changing raw material)

Machining

• Milling, drilling, turning, and cutting are subtractive manufacturing processes, where material is processed by cutting with a blade.
• Relative movement and the tool's geometry differentiate the machine processes

Machining Advantages and Disadvantages

• Advantages: wide range of shapes and dimensions, suitable for many materials, very high automation
• Disadvantages: tools can be expensive and require high skill levels to operate, very complex geometries are hard or impossible to manufacture, high waste potential

Casting

• The general term to create shapes by pouring liquid material into a mould.
• Sand casting is the prominent method to incorporate this process.
• Molten material is poured into a negative mould from sand.
• Air escapes from the mould, and cores are placed inside for complex shapes.

Casting and Molding Advantages and Disadvantages

• Advantages: fast and low cost per unit, suitable for mass production, suitable for many materials, complex geometries
• Disadvantages: individual parts can be expensive, molds can limit geometries, design revisions are difficult

Additive Manufacturing

• Generative process, building up layers upon layers on pre-existing parts.
• Processes include:
  • Powder-based (Selective Laser Sintering, Selective Laser Melting, Electron Beam Melting)
  • Liquid-based (Stereolithography, Inkjet/PolyJet Printing, Direct Ink Writing)
  • Solid-based (Sheet Lamination)
• Fused Filament Fabrication (FFF) uses a filament heated to a molten state to build layers

Additive Manufacturing Applications

• Prototyping (physical models)
• Tooling (molds, dies)
• Manufacturing (end-use, single/series parts)

Additive Manufacturing Advantages and Disadvantages

• Advantages: low material waste, low setup time, suitable for prototyping, part customization possible for each part, free-form possible, multi-material possible
• Disadvantages: material choices limited, relatively new process, parameter influence on new materials limited, limited for mass production, the production and processing of individual parts are relatively high

Process Selection Strategies - General Approach

• Translation, Screening, Ranking, Validation
• Compatible matrix of material, process, function, and shape; tolerance and roughness criteria.

Process Selection Strategies - Case Study

• Case study on "sharpening a pencil," focusing on cost vs. batch size, and criteria, including function, material, technical, quality, tolerance, surface roughness, economics, and batch size.
• Consideration of different processes (e.g., manual vs. automated sharpening) based on their cost curves relative to the batch size

Design for Manufacturing (DfM)

• Aims to facilitate the manufacturing process while also reducing costs.
• Considers manufacturing processes in parallel with other design requirements.

Design for Additive Manufacturing (DfAM) Methods

• Restrictive DfAM Methods:
  • Follow catalog process restrictions.
  • Optimize the AM fabrication process.
  • Design complex geometries.
• Opportunistic DfAM Methods:
  • Understand how and when to consider AM.
  • Transfer of AM knowledge.
  • Break out from conventional mindsets and bias

DfAM Considerations

• Part surface quality.
• Support material.
• Anisotropy.

DfAM—Balloon-Powered Car—Impact of Part Orientation

• The impact of part orientation on support material, print time, and part fit is discussed with examples.
• Various part orientations are tested and analyzed to maximize the design quality and effectiveness of the project.

25 Design Heuristics for AM (DHAM)

• Categorizing 25 heuristics into 8 categories, enabling consolidated design solutions.
• Techniques like part consolidation, customisation and information conveyance.

Convey Information with Geometry

• Using design elements (e.g. indicators, guides) in geometrical layout to convey information (like instructions, warnings), useful for AM designs.

Allow Movement with Small Interconnected Parts

• AM processes enable the creation of complex structures for interconnected parts, which can be mechanically useful, or aesthetically desirable.

25 DHAM Objects

• Provides physical representation of each heuristic for better understanding of design problems and their solutions.

Manufacturing Processes - Wrap Up

• Classification according to material forming.
• Manufacturing processes heavily influence performance, cost, and environmental impact of products.
• DfM method for designing with manufacturing processes in parallel for more innovative and effective final product.

Exercise 12

• Students must analyze how to fabricate several objects using discussed manufacturing processes.

Examinable Material

• All lecture material, in particular the mentioned manufacturing processes which are to be studied and the exercise material, which emphasizes milling, turning, drilling, cutting and sawing, injection molding and additive manufacture are examinable.

Test your knowledge on Santoprene material characteristics and the principles of additive manufacturing. This quiz covers the advantages, applications, and limitations associated with these topics. Dive into the world of modern manufacturing techniques and refine your understanding.