Introduction to Design for Additive Manufacturing Nick Meisel

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Introduction to Design for Additive Manufacturing Nick Meisel Assistant Professor of Engineering Design and

Introduction to Design for Additive Manufacturing Nick Meisel Assistant Professor of Engineering Design and Mechanical Engineering nam 20@psu. edu 814 -865 -3163 1

Many traditional manufacturing methods can be classified as “subtractive manufacturing” 2

Many traditional manufacturing methods can be classified as “subtractive manufacturing” 2

Over the past 20 years or so, we’ve seen the rise of new “additive

Over the past 20 years or so, we’ve seen the rise of new “additive manufacturing” methods 3

Modern AM is used to create a wide variety of both prototypes and end

Modern AM is used to create a wide variety of both prototypes and end use parts Renishaw GE Aviation Local Motors & ORNL Cortex Normal 4 Nike ORNL

Additive manufacturing (AM, aka 3 D printing) builds objects in a layer-wise fashion 5

Additive manufacturing (AM, aka 3 D printing) builds objects in a layer-wise fashion 5

After CAD design is created, “Save As . STL” 6 Printer software identifies toolpath

After CAD design is created, “Save As . STL” 6 Printer software identifies toolpath Uses triangular mesh to describe surfaces One of 7 process types builds the part

Before printing, an orientation must be chosen for the manufactured part • Defined in

Before printing, an orientation must be chosen for the manufactured part • Defined in the X (side-to-side), Y (front-to-back), and Z (up-and-down) directions Z Y X • 1 st Letter: Direction for Longest Dimension • 2 nd Letter: Direction for Second Longest Dimension 7 XY YX ZX

Material Extrusion uses a heated nozzle to melt plastic filament and extrude it onto

Material Extrusion uses a heated nozzle to melt plastic filament and extrude it onto a build tray • Simple process to understand implement (low barrier to entry) • Materials: Polymer filament (PLA, ABS, Composite filaments) 8

Material Extrusion requires support material in order to enable printed overhangs Sacrificial material supports

Material Extrusion requires support material in order to enable printed overhangs Sacrificial material supports all of the overhanging layers With nothing underneath, this layer (and the ones on top of it) will droop down

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Group 1, please leave now 11

Group 1, please leave now 11

For Design for Additive Manufacturing (Df. AM) we have two distinct things to consider

For Design for Additive Manufacturing (Df. AM) we have two distinct things to consider 1. Restrictive Design: Specific manufacturing limitations imposed by our chosen AM process type 12

For the next part of this session, we’ll focus on the following restrictive Df.

For the next part of this session, we’ll focus on the following restrictive Df. AM concepts: • Build time • Minimum feature size • Support material use • Self-supporting angles • Bridging limits Build Time 13 Minimum Feature Size Support Material • Material anisotropy • Surface finish • Warping Material Anisotropy Surface Finish Warping

Often, we will need to consider build time as key factor in preparing our

Often, we will need to consider build time as key factor in preparing our print • Though build time does not directly affect the structure, it is driven in part by orientation which will have an effect on structure through other means Stair-stepping Smooth in cross-section ~ 1 hours hour ~5 Build Time 14 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Material extrusion printers are slowest in the vertical Z-direction • Rule of thumb: for

Material extrusion printers are slowest in the vertical Z-direction • Rule of thumb: for the fastest print, put the shortest dimension in line with the z-axis • This may be invalid if the XY orientation requires significantly more support material Build Time 15 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Every printer has a minimum feature size which determines how small an object it

Every printer has a minimum feature size which determines how small an object it can create Tied to the X-Y motor resolution, deposition method, material type Build Time 16 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Different process types often have drastically different minimum feature sizes • The typical minimum

Different process types often have drastically different minimum feature sizes • The typical minimum feature size for desktop material extrusion is ~1 mm • Wall thickness • Cylinder diameter • Can depend on the thickness of each layer Example of FDM minimum wall thickness from Stratasys Build Time 17 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

For features next to each other, you need a minimum space so they don’t

For features next to each other, you need a minimum space so they don’t fuse together • Negative space tolerance • Rule of thumb for desktop material extrusion is to leave at least a 0. 5 mm gap • Also comes into play for any parts that need to be put together (e. g. , press fits) Build Time 18 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Desktop extrusion printers require support material that must be manually removed • You must

Desktop extrusion printers require support material that must be manually removed • You must think about whether you’ll be able to physically remove any support material that is placed in your part • Can your fragile structures have it removed without being damaged? (~2 mm to survive) Build Time 19 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Support-based processes all have a selfsupporting angle limit • No support material needed at

Support-based processes all have a selfsupporting angle limit • No support material needed at this angle • Rule of thumb for material extrusion: 45 degrees Support Structure No Support Structure Build Time 20 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Material extrusion systems also have a bridging limit when designing without support • Sections

Material extrusion systems also have a bridging limit when designing without support • Sections supported at ends, but not center • Rule of thumb: bridging distance <36 mm Build Time 21 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

The layer-by-layer nature of AM inherently causes concerns over material anisotropy • What does

The layer-by-layer nature of AM inherently causes concerns over material anisotropy • What does is mean when we say a material is anisotropic? Anisotropic: exhibiting properties with different values when measured in different directions The opposite condition is Isotropic (having uniform physical properties in all directions) Build Time 22 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

As with build time, anisotropy is of biggest concern in the Z-direction Delamination •

As with build time, anisotropy is of biggest concern in the Z-direction Delamination • Magnitude of anisotropy effect is dependent on process type • X-Y anisotropy may exist, but often to a lesser degree than in Z Build Time 23 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Anisotropy concerns are especially important for load-bearing parts • Parts should be oriented to

Anisotropy concerns are especially important for load-bearing parts • Parts should be oriented to ensure that the highest stresses occur in the XY plane • Have to balance this with build time needs and surface finish needs L Good! Bad! L Build Time 24 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Surface finish is often directly affected by orientation • Resolution in XY plane is

Surface finish is often directly affected by orientation • Resolution in XY plane is almost always better than the Z layer thickness • Important curves should be oriented in the XY plane for most processes Bad! Build Time 25 Good! Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Layer thickness drives the phenomenon known as “stair-stepping” • Thinner layers less noticeable stair-stepping

Layer thickness drives the phenomenon known as “stair-stepping” • Thinner layers less noticeable stair-stepping 0. 4 mm Layers Build Time 26 Minimum Feature Size Support Material Anisotropy 0. 1 mm Layers Surface Finish Warping

Support material presence can also impact surface finish • Support material in Material Extrusion

Support material presence can also impact surface finish • Support material in Material Extrusion cause point defects • Avoid having support material touch surfaces where finish is important Defects from support material Build Time 27 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Since material extrusion deposits molten plastic, we have to be aware of contraction during

Since material extrusion deposits molten plastic, we have to be aware of contraction during curling • Depositing hot material onto cooled material causes uneven cooling in part • Results in internal stresses the result in part warping • Similar to gluing a stretched rubber band to a piece of paper Build Time 28 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Build volumes can allow large parts, but we must be aware of curling •

Build volumes can allow large parts, but we must be aware of curling • Large, flat regions are especially susceptible to curling Build Time 29 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

There a variety of design tricks to help avoid curling at the corners “Mouse

There a variety of design tricks to help avoid curling at the corners “Mouse Ears” or Anchoring Thermal Walls When in doubt, try to avoid large, dense regions of material Reducing Infill Build Time 30 Minimum Feature Size Support Material Anisotropy Surface Finish Warping

Group 2, please leave now 31

Group 2, please leave now 31

For Design for Additive Manufacturing (Df. AM) we have two distinct things to consider

For Design for Additive Manufacturing (Df. AM) we have two distinct things to consider 1. Restrictive Design: Specific manufacturing limitations imposed by our chosen AM process type 2. Opportunistic Design: Innovative design concepts that relate well to AM (e. g. , mass customization, “free” complexity, printed assemblies, embedding, etc. ) 32

For the rest of this session, we’ll focus on the following opportunistic Df. AM

For the rest of this session, we’ll focus on the following opportunistic Df. AM concepts: • Geometric complexity • Multi-material structures • Mass customization • Printed assemblies & • Functional component embedding part consolidation 33 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

The layer-by-layer nature of AM allows for parts of almost infinite geometric complexity 34

The layer-by-layer nature of AM allows for parts of almost infinite geometric complexity 34 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

Shape complexity allows for bulk removal of material to promote weight savings • Not

Shape complexity allows for bulk removal of material to promote weight savings • Not limited by traditional manufacturing rulesets Delphi Diesel Systems diesel front plate 35 Geometric Complexity Customization Assemblies & Consolidation GE jet engine bracket Multi-Material Structures Functional Embedding

Cellular (or lattice) structures are one of the most intriguing areas in AM •

Cellular (or lattice) structures are one of the most intriguing areas in AM • Reduce Weight, Increased Complexity 36 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

The patternless nature of AM allows for every part/design to be unique, without added

The patternless nature of AM allows for every part/design to be unique, without added tooling cost 37 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

The advantages of AM mass customization can clearly be seen in recent consumer products

The advantages of AM mass customization can clearly be seen in recent consumer products • End-use products designed and manufactured for a single user Protos Eyewear Fingerprint Wedding Bands Normal Earphones 38 Geometric Complexity Customization Sols Orthotics Assemblies & Consolidation Multi-Material Structures Functional Embedding

Using AM for prosthetics and implants allows for perfect, individualized fit 39 Geometric Complexity

Using AM for prosthetics and implants allows for perfect, individualized fit 39 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

By adding in appropriate tolerances, we can print assemblies that work right off the

By adding in appropriate tolerances, we can print assemblies that work right off the tray • 3 D printed measuring tape • Traditionally 114 parts, printed as 1 • Gaps are printed filled with support material, must be removed to function http: //www. tctmagazine. com/prsnlz/a-working -3 d-printed-tape-measure-printed-as-one/ 40 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

With some creativity, we can use this ability to create truly novel products 3

With some creativity, we can use this ability to create truly novel products 3 D printed textiles: Small links printed together like chainmail Printed Origami: Print folded up (faster) and then unfold 41 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

AM also allows us to reduce part counts, which reduces cost, time, and points

AM also allows us to reduce part counts, which reduces cost, time, and points of failure Typical Approach: • Stamping, sheet metal forming, screw assembly • 16 parts & fasteners 42 Geometric Complexity AM Approach: • Printing • 1 part Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

With open-source desktop extrusion, we have a large variety of material options to combine

With open-source desktop extrusion, we have a large variety of material options to combine ABS/PLA Bamboo Nylon Bronze Conductive Stainless Steel Flexible Sandstone 43 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

Multi-material extrusion functions almost identically to single-material • Need to extrude each layer twice

Multi-material extrusion functions almost identically to single-material • Need to extrude each layer twice (once with each nozzle) Must think about how each material interfaces 44 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

Multi-material printing can open up our design space (especially with flexible material) 45 Geometric

Multi-material printing can open up our design space (especially with flexible material) 45 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

AM allows for full access to every point in the volume during manufacture •

AM allows for full access to every point in the volume during manufacture • Specially designed cavities allow for in-situ embedding in AM 46 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

This allows us to make parts with multifunctionality right off the build tray 47

This allows us to make parts with multifunctionality right off the build tray 47 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

For irregular geometries, we have to use something called a “shape converter” 48 Geometric

For irregular geometries, we have to use something called a “shape converter” 48 Geometric Complexity Customization Assemblies & Consolidation Multi-Material Structures Functional Embedding

Introduction to Design for Additive Manufacturing Thanks for participating! Nick Meisel Assistant Professor of

Introduction to Design for Additive Manufacturing Thanks for participating! Nick Meisel Assistant Professor of Engineering Design and Mechanical Engineering nam 20@psu. edu 814 -865 -3163 1