What is it?
3D printing is a popular term for additive manufacturing and refers to various processes that layer material on top of each other, through computer control, to create a 3 dimensional object. Each layer is like a printed cross-section of the final object, allowing complex shapes and geometry to be produced that would otherwise be too difficult by hand. There are many different 3D printing technologies and the DPL has the following:
Also known as binder jetting, this process uses two materials: a gypsum based powder base material and a liquid binder. In the build chamber of the printer, the powder is spread onto a flat build-plate. An inkjet print head then moves across the bed of powder, selectively depositing a liquid binding material that “glues” the powder particles in the shape of a cross-section of the final object. A thin layer of powder is then spread across the completed section and the process is repeated with each layer adhering to the last and the build-plate lowering as the print grows in height. When the model is complete, the unbound powder is removed in a process called “de-powdering” and can be reused for the next print. The de-powdered part can also be infiltrated with cyanoacrylate to solidify it further.
Fused Filament Fabrication
The FFF process works by using a plastic filament which is unwound from a coil and slowly pushed through a heated nozzle, extruding molten material onto a build-plate. The nozzle moves laterally, on a gantry system, depositing a layer of material in the shape of a cross-section of the desired object. The build-plate then lowers and the nozzle repeats the process forming the next layer on top of the first. Since the extruded material is so thin, it hardens almost immediately, which allows the process to constantly repeat itself until the object is finished. This technology is most widely used with two plastic filament material types: ABS (Acrylonitrile Butadiene Styrene) and PLA (Polylactic acid).
This process works by focusing an ultraviolet laser on to a vat of photopolymer resin to build an object’s layers one at a time. To do this, a build-plate is submerged into the vat of resin so the laser can trace a cross-section of the object on its surface, solidifying it, before the build-plate raises by the thickness of one layer. The laser then traces the next layer onto the previous one and this continues as the object is slowly drawn up out of the resin vat. For complex geometry supporting structures are required to attach every part of the object to the build-plate, as this stops it floating away in the resin vat. These supports are then removed manually once the object is printed.
Selective Laser Sintering
The top end of 3D printing; this is a similar process to Powder Bed printing, involving a powder build chamber, but instead of depositing a liquid binder to solidify the layers, it uses a laser to sinter them. This results in much stronger printed objects and can even produce fully functioning moving parts. Although the DPL does not currently have this technology, it is very much in the pipeline for the near future.
What’s it for?
3D printing is used everywhere – from medical research to aerospace. However it’s capability as a prototyping and design tool make it very useful in architecture. FFF and stereolithograthy printing are quick, cheap ways to produce objects of up to a medium level of complexity, and due to the nature of the material properties, they are quite strong. Powder Bed printing can be used to produce more complex geometry as it doesn’t require any supporting structures to hold the print together, so is best used to create objects that would seem impossible by other means. At the DPL, students use 3D printing to produce highly detailed architectural models, components and machine parts and even items such as jewellery.
How can I use it?
First you need a virtual 3D model. There are various software packages that you can use to produce one, however the DPL highly recommends Rhinoceros due to its engineering standard quality. For help creating a 3D model for printing, please see the tutorials below. Once you have created a 3D model that you wish to print, it then depends which printers you wish to use. For Powder Bed printing you must submit the file to DPL staff in person, between 10am-1pm, Mon-Fri. If it is print ready then it will go in the 3D print queue and will be processed by DPL staff. For FFF printing, you can log in to the DPL Online Booking System (click the link in the top right) and reserve a time slot. During term time the DPL is open for 3D printing between 9am-9pm (Mon-Fri) and 10am-5pm (Sat) with time slots bookable for half day or whole day. Please note there are limitations to booking in some cases – more information can be found on the online booking system. Please bear in mind that only 2.85mm diameter PLA and PLA based materials of authorized brands can be used on the DPL 3D printers.
The DPL has the following 3D printers:
Z-Corp 660pro (powder bed) 254mm x 381mm x 203mm Build Area
Z-Corp 360 (powder bed) 254mm x 203mm x 203mm Build Area
6x Ultimaker 2 (FFF) 220mm x 220mm x 205mm Build Area
Pegasus Touch (stereolithograthy) 177mm x 177mm x 228mm Build Area
The different types of 3D printer at the DPL use different materials, each with their own pros and cons. Please speak to DPL staff if you are unsure which would best suit your printing requirements.