All you need is love… or a 3D printer?
by Rahul Rao, Varun Rao, and Yasir Aheer
The 18th-19th century industrial revolution gave birth to many of the manufacturing processes we use today. Welding, a staple of modern metalworkers, was first performed in 1881. Although lathes in some form go back over 3000 years, the modern screw-cutting lathe was invented in 1797. The milling machine, invented sometime in the early 1800, greatly reduced the need for elbow grease when manufacturing intricate shapes or perfectly square parts.
Manufacturing processes in modern factories are a thing of wonder. Gigantic machines that press weird and wonderful shapes into metal, massive moulds used to cast plastic parts, and futuristic robotic arms that assemble these parts with hitherto-unimaginable speed and precision.
Till date, most of these manufacturing machines have remained outside the scope of ownership of the average Joe. Sure, hobby lathes and mills abound, but even the hobby versions are large and somewhat expensive. Furthermore, these machines are limited in what they can manufacture - for example, fashioning a cube of metal from a lathe, while not impossible, is difficult and time-consuming. A mill is the correct tool for this job, but struggles to make cylindrical objects, which the lathe excels at. Most hobbyists would likely need both machines to cover the range of parts for their hobby, driving up both the cost and the space required.
A hobby mill, currently priced at 1155 AUD and weighing 78kg
But what if you had a truly all-purpose manufacturing machine? Cubes, spheres, cylinders, and any random shape? As with the Lord of the Rings, one machine to rule them all? Enter 3D printing.
Different strokes for different folks
There are three main technologies for 3D printing plastic parts. First, SLA or stereolithography. SLA uses a UV laser to draw shapes onto the bottom of a vat of photosensitive resin. The areas of the resin struck by UV light harden and stick to the underside of the “build surface”, which is a plate of material sitting just above the bottom of the vat. For each additional layer, the build surface moves up a small amount and the UV laser is fired again. SLA resins are available in a bewildering array of forms. Some harden to form parts that are remarkably heat-resistant, others never fully harden but form soft flexible parts instead, and yet others are biocompatible, making them useful in the medical field. The use of lasers means parts with very precise tolerances can be manufactured and the speed of printing makes SLA 3D printers feasible even in industrial settings.
How stereolithography works
For the Star Wars fans amongst our readers, this timelapse of the making of a Millennium Falcon makes for particularly interesting viewing.
Selective Laser Sintering (SLS) is another 3D printing technology that uses lasers; SLS uses them to selectively melt and fuse together grains of powder, in a manner reminiscent of welding. The build plate is coated with a layer of powder. The laser traces the required pattern over the powder, melting and fusing together the grains in the required shape. The build plate is then re-coated with powder for the next layer, and the laser is fired again. SLS 3D printers also have a wide range of materials to choose from. Parts made via SLS are chemically and physically durable and often bio-compatible. Surrounding fused material with powder grains allows the creation of incredibly complex geometry, which is useful when designing features like cooling channels deep within a part. Importantly, a derivative of SLS called SLM (selective laser melting) allows the 3D printing of metal parts, which represent a quantum leap in strength, toughness and durability over the plastic parts other 3D printing technologies are limited to. NextAero, a team formed by Monash University engineering doctorates, teamed up with Amaero to develop a 3D printed rocket engine of a design that traditional manufacturing methods would not have allowed [disclaimer: the authors of this piece are ex-colleagues of the fine folk at NextAero].
How SLS 3D printers work
Finally, Fused Deposition Modelling (FDM) is the most common technology used for 3D printing parts at a consumer-level scale. FDM makes use of a thermoplastic filament (typically PLA, ABS or PETG) along with a heated extruder that melts and forces molten plastic out onto a build plate. The extruder is moved up an amount equal to the layer thickness at the completion of each layer. The complex interaction between extruder motion, print speed, and extruder temperature makes tuning the working of these printers somewhat of a dark art, particularly when materials or even suppliers of materials are changed. Despite this, PLA is extraordinarily easy to print, even with entry-level printers, and is biodegradable; ABS is more difficult to print, requiring a heated build plate, but brings incredible toughness and heat resistance; PETG is strong and tough and is also safe to store food and/or water in. Several other less common materials may be used to give the finished product different properties, including TPU for softness and flexibility (think phone cases), polymer matrix composites for structural strength, and bioink for biocompatibility.
Watch the birth of baby Groot on an FDM printer in the video below.
Consumer 3D printers and the open-source community
For the average consumer, FDM printers are the most cost-effective option. Printing speed generally is not of much importance and the type of consumer who purchases a 3D printer is likely the type who is also happy to spend time tinkering with their printer to achieve quality prints. FDM printers start from as low as $200 and, depending on the features added, can vary quite widely in price. Features such as an enclosure, a heated build plate, multiple extruders and WiFi capability push the boundaries of what these printers can do.
Printers with dual extruders can print in different colours on the same print (left), while printers with a single extruder can only print in one
Creality is known for making excellent low-end 3D printers. Their Ender 3 and its variants (Ender 3 Pro and Ender 3 V2) have taken over the low end of the market and are continually adding features at very attractive price points.
Prusa Research, founded by Josef Prusa, a pioneer of 3D printing a decade ago, is widely recognised as being at the forefront of innovation in the FDM 3D printing world. Interestingly, their most popular offering, the Prusa i3, is open-source. Its plans are freely available, and many parts for it can be printed by other 3D printers themselves.
Continuing with the open-source theme, the RepRap (replicating rapid-prototyper) project was founded in England in 2005 with the aim of developing an inexpensive 3D printer that was able to print most of its own parts (hence replicating). This project has spawned a number of 3D printers that are all, per the terms of the project, subject to very permissive licenses.
The thriving open-source community around 3D printers is not limited to the machines themselves. The designs for 3D printed parts are also freely available on websites like Thingiverse, where items as diverse as phone holders, self-watering planters, egg dispensers and the Jabba the Hutt may be found.
Parting thoughts
Whilst the technology, motivation, and physics of 3D printing are not new, it is only recently that FDM 3D printers have dropped to a low enough price point for consumers to avail of their benefits. The easy accessibility of these printers to the average consumer has led to a thriving open-source community around both the printers and the parts they make.
With the ever-evolving capabilities of 3D printers, it is not inconceivable that future consumer printers may be able to manufacture parts that contain glass, metal, and similar materials. Imagine a modular cell phone kit - buy the battery, memory, camera and chips, but design your own housing and other circuitry to your liking. Or buy a CCD sensor and design your own professional SLR camera.
Soon, all you may need is a 3D printer.
Co-Authors:
Disclaimer: This article is based on our personal opinion and does not reflect or represent the views of any organisation that we might be associated with.