Rapid prototyping and digital fabrication
Before manufacturing a part in large numbers, it is a good idea to test it physically. Rapid prototyping lets you go from an idea on a screen to an object in your hand in just a few hours, spot design errors early and correct them without having spent the budget on a mould.
From digital model to part: CAD, STL and slicer
Digital fabrication turns a 3D model into machine instructions through a chain of programs with clearly distinct functions.
Explain what rapid prototyping is and why it is useful to manufacture and test a prototype before launching mass production of a product.
Explain what rapid prototyping is and why it is useful to manufacture and test a prototype before launching mass production of a product.
These stages of the Fused Deposition Modelling (FDM) 3D printing process are out of order: (a) print the part layer by layer, (b) model the part in a CAD program, (c)…
These stages of the Fused Deposition Modelling (FDM) 3D printing process are out of order: (a) print the part layer by layer, (b) model the part in a CAD program, (c) remove supports and smooth the finish, (d) slice the model with a slicer program that generates the toolpaths. Put them in order and explain what is done in each stage.
Explain what an STL file is, which program generates it (the CAD program when exporting the model), and which other program then converts it into instructions for the 3D…
Explain what an STL file is, which program generates it (the CAD program when exporting the model), and which other program then converts it into instructions for the 3D printer.
FDM 3D printing: parameters and typical faults
Two slicer parameters are enough to radically change the time, cost and strength of a printed part, without touching the CAD model.
In FDM printing, what is layer height? Explain how it affects printing time and the surface finish of the part.
In FDM printing, what is layer height? Explain how it affects printing time and the surface finish of the part.
Explain what infill is in a 3D-printed part and why 100% infill is not always necessary (weight, time and material consumed vs strength provided).
Explain what infill is in a 3D-printed part and why 100% infill is not always necessary (weight, time and material consumed vs strength provided).
A part with a height of $60\ \text{mm}$ is printed with layer heights of $0{,}2\ \text{mm}$ and each layer takes about $30\ \text{s}$. (a) Calculate how many layers it…
A part with a height of $60\ \text{mm}$ is printed with layer heights of $0{,}2\ \text{mm}$ and each layer takes about $30\ \text{s}$. (a) Calculate how many layers it will have and the total printing time, expressed in hours. (b) Calculate the new time if the layer height is reduced to $0{,}1\ \text{mm}$. (c) Comment on what is gained and lost with this change.
Subtractive manufacturing: CNC and laser cutting
Unlike additive manufacturing, subtractive manufacturing starts from a block of material and removes the excess with numerically controlled machines.
Explain what a computer numerical control (CNC) milling machine is and what fundamental difference its process has compared to a 3D printer (removing material from a…
Explain what a computer numerical control (CNC) milling machine is and what fundamental difference its process has compared to a 3D printer (removing material from a block vs adding layers).
Explain what laser cutting is, what typical materials in a school workshop it can cut (cardboard, wood, acrylic) and an advantage over cutting those parts by hand.
Explain what laser cutting is, what typical materials in a school workshop it can cut (cardboard, wood, acrylic) and an advantage over cutting those parts by hand.
Distinguish between additive manufacturing, subtractive manufacturing and material forming, and give an example of a technique and a product for each of the three.
Distinguish between additive manufacturing, subtractive manufacturing and material forming, and give an example of a technique and a product for each of the three.
Choosing a technique: prototype, series and cost per part
No manufacturing technique is the best in every case: the decision depends on how many identical parts are needed, because the cost of each technique is split differently between tooling and the part itself.
You are going to design a mobile phone case for mass production. Describe the sequence of prototypes you would make before paying for the injection mould (cardboard…
You are going to design a mobile phone case for mass production. Describe the sequence of prototypes you would make before paying for the injection mould (cardboard model, 3D-printed prototype, small validation batch) and what exactly each prototype validates (size, fit, real use, process).
A small company wants to manufacture 200 custom bicycle grips. Analyse whether it is better to produce them using 3D printing or injection moulding, taking into account…
A small company wants to manufacture 200 custom bicycle grips. Analyse whether it is better to produce them using 3D printing or injection moulding, taking into account cost per part, initial tooling cost, lead times and customisation capabilities, and conclude with a recommendation.
A company compares producing a part using 3D printing ($1{,}20\ \text{€}$ per part, no tooling) or plastic injection (mould of $900\ \text{€}$ plus $0{,}40\ \text{€}$…
A company compares producing a part using 3D printing ($1{,}20\ \text{€}$ per part, no tooling) or plastic injection (mould of $900\ \text{€}$ plus $0{,}40\ \text{€}$ per part). (a) Calculate the total cost of each option for 300 parts. (b) Calculate the number of parts at which the mould becomes cost-effective. (c) Decide which process you would choose for 300 and for 2 000 parts, justifying your decision using the numbers.