Understanding 3D printing 2

Thanks to great leaps in 3D printing technology and a large drop in machine prices, now is a great time to consider purchasing one of these remarkable machines. Firstly however it’s important to understand exactly what 3D printing is. There are a few common 3D printing technologies and a myriad of considerations to take into account when determining whether 3D printing may be beneficial to your business.

3D printing comprises any process whereby materials are joined or solidified under computer control to create a three-dimensional object. 3D printing is commonly referred to as an additive manifesting process. This means that material is built up in layers versus the removal of material in processes such as CNC turning and milling. This additive process allows for virtually any shape to be constructed from a digital CAD (computer aided-design) model by successively adding material layer by layer.

3D printing has revolutionised rapid prototype and it has the potential to have an equally large impact on the manufacturing sector. 3D printing as a whole is credibly versatile with more costly machines having the capability to print multiple materials with varying physical attributes. Materials for 3D printing can include plastics, gold, titanium, ceramics and marble powder to mention a few.  Additive manufacturing also allows for the creating of complex parts which would otherwise be impossible to make by traditional means such as moulding or milling.

3D printing technologies

The three most common technologies used for 3D printing are as follows, Stereolithography (STL), Selective Laser Sintering (SLS) and Fused Deposit Modeling (FDM). As with everything, each of these printer types has their benefits and drawbacks. All 3D prints start with a CAD model. The Cad file is processed and sliced into layers and then exported for printing. There could be up to ten layers (slices) per each millimetre. Below is a brief overview of how the above mentioned  three printers go about building a model.

STL

A STl printer converts liquid plastic into solid 3D objects. The machine use a laser to harden the plastic liquid as per the first slice of the CAD model. The build platform is then lowered and the next slice is hardened by the laser and this process is repeated until the model is completed.

SLS

Selective Laser Sintering (SLS) is another technique that uses lasers to form a object. The main difference between SLS and SLA is that SLS uses powdered material in the vat instead of liquid resin as stereolithography does. Unlike some other additive manufacturing processes, such as stereolithography (SLA) and fused deposition modelling (FDM), SLS doesn’t need to use any support structures as the object being printed is constantly surrounded by unsintered powder.

FDM

3D printing machines that use FDM Technology build objects layer by layer from the very bottom up by heating and extruding thermoplastic filament from a nozzle. When the thin layer of plastic binds to the layer beneath it, it cools down and hardens. Once the layer is finished, the base is lowered to start building of the next layer. The printer can also extrude support materials for the model.

SLA and SLS 3D printers are generally considered industrial machines and they have a much higher price point. Higher end printers usually sport a lower layer resolution (thinner layers), shorter print times, larger print beds and they can easily run into the $100,000 of dollars per machine. There are however a variety of cheaper desktop SLA and SLS printer available such as the Formlab Form2, Sinterit Lisa and Sprintray Moonray but these machines are still far more expensive than the multitude of FDM options on the market.

On the consumer side of the spectrum we have FDM printers which are easily accessible and incredibly popular due to their low barrier to entry. The online 3D printing service 3D hubs, rates the Ultimaker 3, Prusa I3 MK3 and the Zortrax M200 as some of the best machines in this category. Some of their features include a variety of low cost materials and a layer thickness as low as 60 microns (0.06mm) per layer. These machines are great for quick iterative low-fidelity prototyping due to their low running and material costs. Some of the more advance options can produce models with incredible details when considering their price compared to some of their industrial counterparts.

Consideration when selecting a printer

Below are a few point to considerations when selecting a 3D printer.

  • Printer technology – One of the primary consideration when 3D printing is which printer type to utilize. As previously mentioned, STL, SLS and DMF 3D printers all have their pros and cons. Prior to 3D printing I recommend familiarizing yourself with the differences in prints created by these machines. Selecting the wrong technology for a print can be a costly exercise. You could print an adequate prototype for your purposes for a fraction of the price by using a appropriate technology.
  • Printer bed size – Printers come with varying bed sizes. If your object is too large for the printing bed, you will need to split the CAD model into section, print these separately and finally assemble these once the parts have all been printed.
  • Materials – There are a staggering amount of materials available for 3D printing but not all printers are capable of printing in all materials. Do you research to determine the optimum material for your prototype and then select a machine accordingly. Ideally you want to prototype with a material that is as close as possible to that of your end product. Certain materials are naturally more costly so this is another important factor to consider when selecting a material.
  • Part complexity and printer accuracy – 3D printers vary in accuracy. If you are looking at printing very complex parts accurately, SLA and SLS are the best options. This is particularly important if your part has both complex geometry and is small dimension.
  • Printing time – Your models dimensions and print settings such as later thickness and infill drastically effects print times. The print infill refers to the honeycomb like structure the printer fills your part with to reduce material usage. One again the denser the infill, the longer the printing time but the stronger the part. As a rule of thumb a thinner layer thickness, larger size and higher infill will result in longer print times and result in a more expensive print.

What do I need to get started?

Above and beyond a 3D printer and some printing material, there are a few things one needs prior to getting started with 3D printing. The first being a 3D model of the object you want printed. If you don’t already have a model, you will have to build one using CAD software so a degree of CAD skill is required. Alternatively you can commission a designer or engineer to build a CAD model of your object. We provide CAD modelling services and we have extensive experience working with a range of CAD packages.

 Secondly like all manufacturing processes, 3D printing has its own constraints. Knowledge on designing parts specifically for 3D printing is a huge plus and will go a long way to ensuring your model turns out as expected. Core77 has a great article explain how to design for the various 3D printing technologies. If you’re looking at going it alone, I would highly recommend you give it a read.

This article will be followed up by one elaborating on the multitude of ways 3D printing can benefit your business. Sign up to our newsletter and we will notify you when this post is published.

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