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What is 3D Printing?
The Expert Guide

Learn all you need to know about 3D printing & rapid prototyping in 30 minutes or less. Whether you’re completely new to this or an experienced engineer there’s something for everyone to learn! You’ll find loads of helpful tips and tricks updated for 2019. 

Part 1.
The Basics of 3D Printing

What is 3D printing? What are the benefits, downfalls and limitations?

Part 2.
3D Printing Processes

A definitive overview of all the rapid prototyping processes available.

Part 3.
3D Printing Materials

Learn more about 3D printing materials & limitations

Part 4.
Design For 3D Printing

Learn how to incorporate 3D printing into your design process.

Part 5.
Start 3D Printing

Tips on starting, from ordering online to buying a printer.

Part 6.
3D Printing
Quality Guide

A comprehensive list of resources for further reading.

Part 1.
The Basics of 3D Printing

What is 3D printing? How does it work? 

Here in this definitive guide, we’ll go through all aspects of 3D printing and examine how it compares to other methods of modern manufacturing. 

What is 3D Printing?

3D Printing is an expanding method of industrial production that enables the creation of lighter, stronger parts & systems that drastically cuts product lead times. 

How Does 3D Printing Work?

Every 3D printer works on the same principle: using data from 3D computer aided design (CAD) or 3D scanners they transform them into a physical model by depositing material layer by layer. This type of process is widely known as ‘Additive Manufacturing’.

Compared to other methods of plastics processing; CNC machining, Injection Moulding, Vacuum Forming, Blow Moulding, Extrusion & Rotational Moulding. This additive method of manufacture requires the least amount to setup and has the lowest overheads. 

Additive manufacturing processes such as 3D printing, required no special tools are required (for example; a cutting tool for machining or a mould). Instead the part is manufactured by depositing material layer by layer onto a build platform to create precise geometric shapes. With all processes, this has its benefits and limitation – more information here.

History of 3D Printing

1987 – Chuck Hull of 3D Systems released the first Sterolithography (SLA) printer.

1990’s – 3D Systems invents the first Selective Layer Sintering (SLS) printer.

1990’s – Stratasys releases the first Fused Deposition Modelling (FDM) printer.

2005 – University of Bath releases a new initiative called the RepRap project to create a low-cost printer.

2009 – ATSM International Committee publishes paper defining the standard terminology on Additive Manufacturing.

Benefits & Limitations of 3D Printing

With all manufacturing processes, it’s important to understand its benefits and limitations. It comes with a unique set of advantages, however can be disadvantageous in certain scenarios. Here in this guide we summarise we take into account the pros and cons of all the different 3D printing processes currently available:

Benefits:

Complex Geometry

3D printing enables users to produce parts with complex geometry which is in some instances impossible for subtractive & formative methods to create. 

Low Cost

Compared to other plastic processes, there are little to no initial setup costs to get parts made. You just need the printer and material to get started.

Part Customisation

Parts can be made in custom materials, colours or finishes with engravings or logos to make a part personal to that individual or company.

Quick Lead Times

With formative processes such as; injection moulding, blow moulding or roto moulding new parts can take up to 12-weeks to go into manufacture. However 3D printing can considerably reduce this initial lead time.

Large Range of Materials

There are a number of different materials available for 3D printing, including conductive, metal and ceramics. 

Limitations

Low Strength & Antriscopic Properties

Due to the process of 3D printing where layers are deposited on each other, if not properly fused these layers can separate. It’s important to consider print orientation when printing parts to ensure and loads applied are perpendicular to the layer direction.

Part Cost at High Volumes

Due to the nature of 3D printing, it’s a time expensive process which becomes expensive when printing multiple parts. Where cycle times are hours, sometimes days compared to seconds for injection moulding. 

Limited Accuracy & Tolerances

Compared to other processes such as subtractive CNC machining, 3D printing has much lower tolerances.

Post Processing & Support Removal

Due to the process of 3D printing, this leaves layer lines in parts. Compared to other plastic manufacturing methods, this can give an undesirable finish which requires some form of sanding, polishing or painting to give a smooth and even finish. 

Bottom, free-hanging surfaces usually have inconsistent surface finishes as well. As these areas usually come into contact with supports which are removed once the parts are finished printing.

Applications of 3D Printing

We put together a few examples to show the different applications of 3D printing and how it can be applied practically.

Aerospace

Aerospace & space engineering firms use 3D printing to produce accurate, high-performance, lightweight components that have complex geometries. 3D printing allows complex assemblies to be simplified into a singular part. 

Automotive

The automotive industry has benefitted hugely from 3D printing. Whether it be used to support research and development during the design stages or used in a support role during manufacture & assembly (jigs & fixtures).

Civil Engineering

Low cost & constructed in less than 24 hours, 3D printed houses are now a reality. Eindhoven University of Technology are proposing plans to implement this, with the first house ready for occupation in 2019.

Education

Often in classrooms, its difficult for educators to engage with students. Through 3D printing, course subjects can be brought to life through physical models. This provides students with an unforgettable learning experience.

Medicine

Advances in modern medicine can help prolong life expectancy and prevent disease. 3D printing is a key tool in accomplishing this, helping to create synthetic organs, devices or even used in planning complex surgical procedures.

Manufacturing

Numerous companies are now implementing 3D printing into their manufacturing processes. Audi for examples currently provides all factory employees with bespoke orthopaedic devices for pushing snap-fit components

Part 2.
3D Printing Processes

The ISO / ATSM 52900 standard classifies all the different 3D printing processes into seven main categories:

FDM 3D Printing Diagram

Material Extrusion (FDM)

Material Extrusion otherwise known as Fused Deposition Modelling (FDM) is the most common type of 3D printing available. Originally trademarked by Stratasys, the process involves material being drawn through a nozzle where it is headed and deposited layer by layer to create a 3D shape.

SLS 3D Printing Diagram

Powder Bed Fusion (SLM & SLS)

Using either a laser or electron beam, Powder Bed Fusion (PBM) harnesses this energy to melt and fuse material powder together. This process involves the spreading of fresh powder material over the previously fused layers, there are a number of different mechanisms that enable this including a roller or a blade.

SLA 3D Printing Diagram

VAT Polymerisation (SLA & DLP)

Stereolithography (SLA) or Digital Layer Projection (DLP) is the process in which UV reactive, liquid copolymer resin is cured by a projected or drawn outline. This process produces highly detailed parts, as the laser / projector resolution defines the accuracy of the part. 

Material Jetting 3D Printing Diagram

Material Jetting

Similar to an inkjet printer, material is jetted onto a build platform using either a continuous or Drop on Demand (DOD) process. Nozzles move horizontally across the platform similar to material extrusion (FDM), then the layers are cured using Ultraviolet (UV) light.

Binder Jetting 3D Printing Diagram

Binder Jetting

This process involves two materials; a powder based material and a binder. The binder usually in liquid form, acts as an adhesive where it is deposited from the print head to fuse with previously printed layers. This process isn’t suitable for structural & functional parts and requires post-processing.

DED 3D Printing Diagram

Directed Energy Deposition (DED)

Using a 4 or 5-axis arm this process uses a nozzle that mixes material whilst being delivered using a laser or electron beam. DED is typically used for 3D printing metals, however can also be used to print ceramics and polymers. 

Sheet Lamination 3D Printing

Sheet Lamination

Broken down into two different processes Ultrasonic Additive Manufacturing (UAM) and Laminated Object Manufacturing (LOM). These processes involve the layering of sheet or ribbon material and then being cured or bonded. Both processes require additional CNC machining and post-processing. 

Part 3.
3D Printing Materials

In this section, we’ll go through materials currently available on the market today.

Polymers

In this section, we’ll go through materials currently available on the market today.

ABS

Acrylonitrile Butadiene Styrene (ABS)

One of the first 3D printing materials available on the market. This material is well-regarded for its toughness and impact resistance. 

Printability

4/5

Strength

2.5/5

Stiffness

2.5/5

Durability

4/5

Cost

1/5

PLA

Polylactic Acid (PLA)

The most commonly available 3D printing material on the market. Derived from crops it’s environmentally friendly as it is renewable and biodegradable. 

Printability

4.5/5

Strength

3.5/5

Stiffness

3.5/5

Durability

2/5

Cost

1/5

Nylon

Polyamide (Nylon)

Popular engineering grade 3D printing material known for its impact resistance, strength and flexibility. Also chemically resistant to diesel and petrol.

Printability

4/5

Strength

3.5/5

Stiffness

2.5/5

Durability

5/5

Cost

3/5

PC

Polycarbonate (PC)

Intended for tough environments & engineering applications Polycarbonate is known for strength, durability and its high heat deflection.

Printability

3/5

Strength

4/5

Stiffness

3/5

Durability

5/5

Cost

3/5

ASA

Acrylic Styrene Acrylonitrile (ASA)

Well known for its impact resistance and strength like its similar counterpart ABS. It’s highly UV stable due to an rubber additive in its formulation.

Printability

3.5/5

Strength

3.5/5

Stiffness

2.5/5

Durability

5/5

Cost

2/5

PEEK

Polyether Ether Ketone (PEEK)

Incredibly temperature and chemically resistant, PEEK is a specialist engineering material which is capable of operating in tough environments.

Printability

0.5/5

Strength

5/5

Stiffness

4.5/5

Durability

5/5

Cost

5/5

TPU

Thermoplastics Polyurethane (TPU) 

One of the few flexible 3D printing materials available on the market today. Useful for parts that require an elastic / rubber feel (tyres for example).

Printability

3/5

Strength

2/5

Stiffness

0.5/5

Durability

4.5/5

Cost

3/5

PEI

Polyethermide (PEI / ULTEM)

Well known for its exceptional heat, chemical and flame resistance properties. Similar to PEEK it performs well in high performance applications.

Printability

1.5/5

Strength

4.5/5

Stiffness

4/5

Durability

5/5

Cost

4/5

Resin

Acrylate Monomer

Produces highly detailed parts with smooth, injection mould-like surface finishes. Excellent for lost casting processes such as for jewellery.

Printability

4/5

Strength

1/5

Stiffness

4.5/5

Durability

0.5/5

Cost

3.5/5

Metals

In this section, we’ll go through materials currently available on the market today.

Stainless Steel

High-performance material with excellent corrosion resistance. Used in parts for applications such as; aerospace, automotive or medical.

Printability

4/5

Strength

2.5/5

Stiffness

2.5/5

Durability

4/5

Cost

2/5

Aluminium

Excellent strength to weight ratio, good thermal & electric conductivity. Typically used in aerospace, automotive and medical applications. 

Printability

4/5

Strength

4/5

Stiffness

4/5

Durability

4/5

Cost

4/5

Titanium

Excellent weight to strength ratio, low thermal expansion and high corrosion resistance. Typically used in aerospace, automotive and medical sectors. 

Printability

4/5

Strength

4/5

Stiffness

4/5

Durability

4/5

Cost

4/5

Part 4.
Design For 3D Printing

For all 3D printing processes a 3D file is required, the most common format for this in additive manufacturing is ‘STL’.

There are a number of software solutions that can export STL files. We’ve listed all the different packages available that are used by ourselves, our customers and our support network. 

Here are some packages we recommend:

  • Autodesk Fusion 360 → CAD / CAM / CAE software free for students & hobbyists.
  • AutoCAD → CAD software for architects, engineers & construction professionals.
  • Blender → Free 3D sculpting software.
  • CATIA → CAD / CAM / CAE software specialising in advanced surface modelling.
  • DesignSpark → Free electrical & mechanical design software.
  • Inventor → Professional mechanical design software.
  • Meshmixer →  Free 3D modeling software that allows users to easily create and correct 3D models. 
  • Onshape → Cloud based 3D CAD & PDM software.
  • Rhino3D → 3D CAD design software, useful with plugins such as Grasshopper.
  • Revit → 3D BIM software, plugins required to export STL files.
  • SketchUp → Free CAD software aimed at Architects, Designers & Engineers.
  • Solidworks → Powerful 3D CAD / CAM software recognised as the industry standard software.
  • ZBrush → Professional digital sculpting software.
  • Modo → 3D modelling, texturing & rendering software.

Part 5.
Start 3D Printing

If you are new to design (or if you are simply looking for something to print fast), then one of the many online repositories might already have what you are looking for.

Here are some websites we recommend:

  • Thingiverse → The largest online repository with thousands of free 3D printable files for desktop 3D printing.
  • MyMiniFactory → A popular online repository with free 3D models that are tested for quality and are guaranteed to be 3D printable.
  • Cults → An online marketplace with high quality 3D printable models by professional designers, and curated collections connected to big-name brands.
  • Pinshape → An online marketplace with both free and premium 3D printable files, focusing mainly on hobbyists.
  • GrabCAD → An online repository of many 3D models that also includes some 3D printable files, focusing mainly on engineering professionals.

Part 6.
3D Print Quality Guide

In this section we go through different scenarios and results to help troubleshoot different 3D printing issues. 

    Not Extruding at Start of Print

    Printer does not extrude plastic at the start of the print. 

    Not Sticking To Bed

    First layer doesn’t adhere correctly to the bed and the print quickly fails.

    Under Extrusion

    Printer doesn’t extrude enough material between the perimeter and infill.

    Over Extrusion

    Printer extrudes too much plastic, prints look very messy.

    Gaps in Top Layers

    Holes or gaps in the top layers of the print.

    Stringing or Oozing

    Strings left behind when moving between different sections of the print

    Overheating

    Small features become overheated and deform.

    Layer Shifting

    Layers are misaligned and shift relative to each other.

    Layer Separation

    Layers separate and split from each other.

    Grinding Filament

    Grinding Filament

    Material is no longer being extruded as the filament has become stripped. 

    Clogged Extruder

    The nozzle / extruder has become clogged and won’t extrude any material.

    Stops Extruding Mid Print

    Stops Extruding Mid Print

    Printer stops extruding material mid-print.

    Weak Infill

    Very thin, stringy infill that creates a weak interior and does not bond together well

    Blots & Zits

    Small blobs / zits on the surface of the print.

    Gaps Between Infill & Outline

    Gaps between the outline of the part and the outer solid infill layers

    Curling or Rough Corners

    Corners of the print tend to curl and deform after they are printed

    Scars on Top Surface

    The nozzle drags across the top of the print and creates a scar on the surface

    Gaps in Floor Corners

    Gaps in the corners of the print, where the top layer does not join to the outline of the next layer

    Lines on The Side of Print

    Side walls are not smooth, lines are visible on the side of the print

    Vibrations & Ringing

    Vibrations that cause oscillations on the surface of the print, otherwise known as “ringing”

    Gaps in Thin Walls

    Gaps between thin walls of the print where the perimeters do not touch

    Small Features Not Printed

    Very small features are not printed or are missing from the software preview

    Inconsistent Extrusion

    Extrusion amount tends to vary and is not consistent enough to produce an accurate shape

    Warping

    Warping of large parts, particularly with high temperature materials such as ABS

    Poor Surface Above Supports

    Poor surface quality on the underside of the part where it touches the support structures

    3D Printing Dimensional Accuracy

    Dimensional Accuracy

    Dimensional issues where the measured dimensions do not match the original design intent

    Poor Bridging

    Sagging, drooping, or gaps between the extruded segments of your bridging regions

    About us

    Founded in 2015, SGD is a multidisciplinary 3D printing service & rapid prototyping service specialising in the design and production of plastic parts, components and assemblies.

    Our mission

    To streamline the product design process, offering affordable & fast 3D printing and rapid prototyping solutions. We offer practical design solutions to reduce the impact on the planet.

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