What is 3D printing?
3D printing is a process where a special printer produces a three-dimensional object. To do this, the device needs a three-dimensional blueprint, also known as a 3D model, from which it creates the desired object. The objects are made by layering the material on top of each other, so it is an additive process. Several different technologies are used in 3D printing. The UP-3D Centre currently works with four different technologies: FDM, Polyjet, SLA and SLS.
Types of 3D printing: what technologies are available at the UP-3D Centre?
FDM/FFF fiber drawing technology
Traditional printers work along the X and Y axes and can print text and images.
3D printers, on the other hand, also use the Z height axis, allowing the layering of different molten materials to build spatial models into tangible plastic objects. The print head pushes the thermoplastic material through a nozzle, which melts it at hundreds of degrees Celsius. The material is placed along a predetermined (see Gcode) path, where it cools to form a solid object.
The raw materials are usually different types of plastic material wound on a drum in the form of fibres, called "filaments". Plastics can also be mixed with specific materials (wood, gypsum, etc.) by manufacturers to create unique composites with specific properties.
The most common office and home 3D printers use FDM technology, but its limitations are most apparent in industrial applications. Because it can only work with thermoplastic materials in the print head, the heat resistance of the finished objects is low, so this technology is mainly popular in home hobby printing, where the price of such equipment has decreased significantly in recent years.
Polyjet devices work with photopolymer materials. In the process, the head injects liquid polymer droplets layer by layer onto the work surface, which are then exposed to UV light to cure them.
The technology uses several nozzles at once to deliver the material to the target area. Objects produced in the device require separate support. The water-soluble support material is discharged at the end of printing and forms environmentally friendly waste. Achieving layer thicknesses of up to 16 microns on a single device, it allows for the most accurate and detailed printing and is therefore popular for dental and jewellery applications. High budget film props and stop-print effects are also commonly produced using Polyjet printers. Its unique feature is that it can reproduce up to half a million colours.
These machines are able to operate with biocompatible materials, making them suitable for healthcare applications. For example, the UP-3D Centre has a Polyjet printer optimised for dental work.
SLS (Selective Laser Sintering) technology
Selective laser sintering is more like powder coating than printing. The process involves spreading a layer of extremely fine-grained powdered material over the work surface. The thickness of the material can be up to 60 microns, allowing the print to be produced with a very high level of detail. For each layer, a high-powered laser melts the parts corresponding to the cross-sectional geometry of the model, fusing them to the previous layer.
The laser beam can be positioned more finely than the extruder of an FDM printer, so the technology is very precise. An additional advantage is that the printing material can have a higher melting point than filaments, such as polyamide. Thus, objects made with SLS technology have mechanical properties that rival those of injection-moulded objects. The technology is inherently suitable for industrial-quality production, as the printing time scales non-linearly with the quantity of objects to be printed. Therefore, for large batch production, the unit price and even the unit printing time can be much lower than for a single item.
SLA (stereolithography) technology
SLA printing works with resin. It is based on a photopolymer resin crosslinked by a laser beam. Objects are very often built from the top down and supported this way.
In SLA printing, the gradually dispensed layer of resin is illuminated by the laser at the right places on the 3D models to solidify them. After printing, the printed object needs to be post-treated in isopropyl alcohol to remove excess liquid layers. The support material is then removed and the semi-finished object is then subjected to a UV chamber to achieve the required mechanical properties.
The UP-3D Centre offers SLA printing in a variety of colours and material properties, including transparent and flexible materials. The applications of the technology are most similar to Polyjet, with the difference that SLA objects are monochrome. Its high accuracy and material properties make it suitable for use in jewellery as well as medical and engineering applications.
ABS (acrylonitrile butadiene styrene): what kind of plastic is ABS?
This plastic is a less common raw material for 3D printing and is slowly being replaced by more modern polymers. It is more heat-resistant, softer and easier on machinery than PLA. Its durability and strength make it a favourite material used in the injection moulding industry. It is also used to make children's toys (e.g. LEGO), the casing of household appliances and plastic parts for cars, and it is also used as a base material for mobile phones and phone cases. It can be easily damaged by UV light. It is usually made from petroleum, so 2 kg can be used to make 1 kg of ABS. It can also be recycled. 3D printers melt it at around 250℃. It is harder than other base materials to adhere to a workbench, so printing it requires not only a heated platform, but also an enclosed workspace.
Additive process: what makes 3D printing an additive process?
A utilitarian or art object made by additive manufacturing is built by adding extra material until it reaches the desired shape. For example, painting and house building are such activities. A mason builds a house brick by brick, and 3D printing is also an additive process as layers are built up on top of each other to create the shape of an object.
It is the opposite of the traditional subtractive machine process such as milling, carving or grinding, where the desired object is obtained by transforming a larger piece into a smaller one. For example, sculptors usually carve the desired model from a block of stone. In the process, a considerable amount of waste is produced, which is not the case with additive processes.
Prices: how much does 3D printing cost?
3D printing has no set unit price. All enquiries will receive an individual quotation as quickly as possible. This is usually within one working day, but in some exceptional cases it may take longer, and customers will be notified. The price of printing is influenced by many things. The technology and materials proposed will be suggested by the Centre's technicians and, in the case of a specific printer or material requirement, the expected quality of the print will be agreed on with the client. If a printing request is impractical or unacceptable for a particular raw material, we will discuss this issue with the client. Model design is also possible with the machines at the UP-3D Centre.
FDM/FFF: What is thread-fed printing?
The most common, simplest and usually cheapest 3D printing process used in 3D printers involves melting a plastic filament in the print head and building up the object layer by layer, taking advantage of the fact that the plastic quickly solidifies. Most hobby printers use this process. It is easy to learn and requires no special environment or knowledge.
Source file: what is a source file?
The basis of 3D printing is the digital spatial model. The most common 3D file types are generally suitable, as all of them can be converted to .STL or .OBJ format, which can already be interpreted by the slicing programs of the printer. For polyjet printing, the wrl/wrml format is used, which, together with a texture file (usually jpg or png), allows printing coloured/textured files with PolyJet.
Deadline: how long does it take to 3D print?
It is relatively difficult to calculate exact deadlines, often requiring experimentation and model modifications, especially in the case of FDM printing. An approximate deadline can generally be given once the estimate has been made. Printing times depend largely on the technology, the quantity to be printed and the resolution, as well as whether several printers can work on the job at the same time or whether a single, continuous session is required. The two most important factors are the technology and the model. SLS, for example, can print smaller items in large batches much faster than filament-feed technology. A model with a hollow or less detailed surface can be printed much faster than one with a solid or complex surface. Emergency printing is sometimes possible but it is part of a separate agreement.
.gcode or G-code: What is called . gcode?
The ".gcode" extension is used by FDM 3D printing technologies. When the 3D model is "sliced", a set of instructions is generated that the printer can follow until the end of the print. The fineness and detail of the print, and the movement of the print head or tray along the X, Y and Z coordinates are also written to this extension file, which is interpreted by the printer and then executed sequentially.
PLA (polylactic acid): what plastic is PLA?
Plastic is one of the most widely used materials in fibre-drawing (FDM) 3D printing. It is the only plastic manufactured on an industrial scale from biological raw materials. Typically, cane sugar or corn starch is fermented with bacteria to produce lactic acid. This produces an ester, which only needs to open the ring to polymerise. PLA degrades naturally, but it can also be composted under industrial conditions. An advantage it has over ABS is that it is produced in a wider range of colours, has a glossier surface, is harder to abrade and is easier to handle. It can also be used for cosmetics bottles, suture thread and, increasingly, food packaging. PLA softens between 55-80℃ and is ideal for printing between 175-220℃.
PVA (poly vinyl alcohol): what plastic is PVA?
PVA is a water soluble plastic. It is transparent, colourless or white, and it has a shiny surface. It is used as a support material in FDM 3D printing because it can be easily removed with water in small, hard-to-reach areas of many models. Its biggest user is the packaging industry, where it is used to make water-soluble plastic bags, but ophthalmology also benefits from this product, which is used to make overnight contact lenses and artificial tears.
Design: is it possible to design a model at the UP-3D Centre?
A 3D model is required for printing, but the UP-3D Centre can also provide design services. If you do not have a 3D model but only a technical drawing, or if you have a specific or general idea, you can use the order form to briefly describe the model you want to design. Our staff will contact you with an individual offer for the design and construction of your model, whether it is a LEGO cube or a complex mechanical design.