3D printing is a process by which materials are joined together or solidified under the control of a computer aided system (CAD) to create a solid 3D object. The technical term for 3D printing is Additive Manufacturing (AM), and it is also referred to as rapid prototyping. In contrast to the traditional manufacturing methods, wherein machines chip away at material in order to create the desired shape, 3D printing creates an object by adding material. This results in savings on material wastages. 3D printing is transforming the manufacturing industries, from automobile to aerospace and from construction to healthcare. The major 3D printing technologies include Stereo-lithography (SLA), Fused Deposition Modeling (FDM), Digital Light Process (DLP) and Polyjet.3D printing was once the prerogative of big companies due to higher printer costs. However, with growing awareness about the capability of 3D printing and reduction in printer price, the technology is now increasingly being adopted by even small and medium scale industries. India, which is a manufacturing hub for automobiles, machinery and tools, consumer electronics, and many other products, is especially poised to reap the benefit of reduction in 3d Printer prices.
3D Printers typically use an STL file to produce output. An STL file is a simple, portable format used by computer aided design (CAD) systems to define the solid geometry for 3D printable parts.
Printer Specs
Once you have made a decision to buy a 3D printer, the next logical step is to determine which one, and with what specifications. The common specs for 3D printing include XY resolution, layer thickness, speed, build volume, printing technology, surface finish, accuracy, precision, tolerances and connectivity. While most of the specifications are easy to understand, it can be slightly difficult to understand the differences between accuracy, precision and tolerances. In this article, we will try to simplify these terms.
Understanding 3D Printer Accuracy, Precision and Tolerances
Most people think that accuracy and precision are synonymous. However, there is a technical difference between these two. Accuracy is a measure of how close a measurement is to true value. Precision measures the degree of repeatability or consistency. Let us make this clear with an example. Assume that you are staying at a city in India where there are wide temperature fluctuations and you are in a business that is susceptible to temperature variations (like being an ice cream distributor). You have therefore purchased a thermometer to monitor the daily temperature.
Another example – if you are an archer and hit all your arrows in the circle with the bull’s eye, you are accurate as well as precise. If you hit all the arrows close to each other but in a circle removed far away from the bull’s eye, you are precise but not accurate. If your arrows mostly hit the circle next to the bull’s eye, you are kind of accurate and kind of precise. If your arrows are scattered all over the circle, and some arrows even miss the target completely, you are not accurate neither precise.
Hope you now have a precisely accurate idea about 3D printer accuracy and precision. Let us now turn our attention to tolerances.
Technically, tolerance can be defined as the total amount a dimension may vary and is the difference between the maximum and minimum limits. Tolerances therefore simply define the permitted variation in a dimensional accuracy.
While we are talking about accuracy and precision of 3D Printers, let us talk about 3D printer resolution as well. Resolution in 3D Printers refers to the smallest movement the nozzle can make in the X, Y and Z directions when depositing material. The resolution of a 3D printer is often defined as the minimum layer height / thickness it can achieve, and which is controlled by the Z-axis resolution. It is also the smallest movement the nozzle can make when depositing material. Therefore, resolution of a 3D Printer is determined by both the nozzle size and Z-axis movement precision. Small layers mean better resolution, and better surface quality parts with smoother surfaces and sharper edges. It should be noted that just because a 3D printer has a high resolution doesn’t mean that it will be accurate or precise. It simply means that you have a higher tolerance to work with when it comes to printing finer details.
Why should accuracy, precision, tolerances and resolutions matter? All these parameters affect the final output not only in terms of quality, but in terms of time. For example, higher the 3D Printer resolution, the slower it will perform. Accuracy and tolerances also vary with printing technology and the material used.
A Word for the Wise
With so many technologies and so many choices of 3D Printers, the process can be bewildering for the uninitiated. While you may be convinced that using 3D Printers is the way ahead, you may still be wondering about which 3D printer to opt for. The choice is complicated by the permutation and combination of 3D printing technologies and raw material. Thanks to companies like Stratasys, there is an amazing choice of raw material available for 3D printing today. Due to the advances in 3D Printer technology, it is now possible to print using almost all kinds of raw material – from plastics to food and everything in-between. And as more and more manufacturers turn to 3D printing for rapid prototyping and even final product manufacturing, the prices of 3D Printers are coming down to affordable levels. To choose the right 3D Printer, it may be a good idea to contact a competent engineering company (like DesignTech Systems) that has the expertise and experience to help you choose the best 3D Printer suited for your purpose.