Tuesday, August 30, 2016

A four steps guide for a successful 3D project

The next article published first at  3DPrint.com  magazine

Printed Glasses frames in Aluminum (top) and Titanium
My first 3D printed project was a little bit disappointing. My new innovation looked rough and weak and the 3D model was not functioning well. Obviously, in 2006 we had fewer options for a 3D printed prototype but, the path was similar to what we have today. Therefore, my first experience was very similar to what I saw over the years with many customers and thousands of projects. For first impression, the 3D printed parts looks stunning. It is such a great feeling to see your design come to life in a real 3D model but, when you go into details, something is always missing. The materials, the details, the color or even the mechanical properties are not there.
In order to help you to succeed from the first 3D printed project, I’m posting those simple rules based on my experiences with more then million 3D printed parts in more than 7 different printing technologies and different materials.

  1. Know your 3D CAD software

Popular Solid modeling Software
Popular NON Solid Software

We can’t print in 3D without a 3D CAD model. Also, the print results relay on the suitability of the 3D file and the 3D printing method we intend to use. The standard file we use in 3D printing is the STL file format. Almost all the 3D software can export to STL format but, not all at the same quality.
When it comes to 3D printing, there are two groups of software, 3D Solid and non-solid software (see table below).
a. With a 3D SOLID software, life are much easier. For the best result, learn how to control the STL export options and, in most of the cases, you can SAVE AS STL a print ready file.
b. For Non Solid 3D software, a simple geometry can produce good results but, when the model is complex and the shape is curvy, printing from the exported STL file could be challenging.
c. A professional 3D printing service bureau will prefer to receive the 3D file in a solid neutral format (Step, XT and so,) rather than in STL format and to do the conversion to STL using their own tools.
d. When exporting 3D CAD file, avoid multi body and open surfaces. It is most recommended to save the file in a neutral format (_.XT, STEP, SAT…) and reopen it again to check for multibody, open surface, sketch, and suppress parts.

2. Chose the right Materials and Printing method

Transparent SLA part near opaque SLS
Each and every 3D printing method comes with a limited selection of materials which can be used for printing. The key factor to successful 3D printed project is to understand the available materials and what is the difference between each material and then, to choose the right material for the mission. For prototype model, don’t assume that the same material used with traditional fabrication will give the same results with 3D printing. For example, ABS is very popular plastic material, mostly with injection molding but, for a 3D printed prototype, Nylon 12 from a laser sintering printer (SLS) will give better results than ABS from FDM printer or ABS like materials from a jetting printer or even Nylon from FDM/FFF printer that filament and not powder. Another example is Glass filled Nylon, a very popular material to produce parts with SLS printers, but you can’t compare a GF nylon part with a injection molded Nylon filed with short glass fiber part. The same goes with metal printing. Laser sintering (SLM, DMLS) 3D aluminum parts fells short when you compare them to Aluminum machining parts, but 3D titanium parts have a very good mechanical property that are close to forging.
If you need clear plastic transparent parts, SLA method is the only good option but don’t expect the quality of traditional fabrication. The same goes for flexible printed parts with rubber or silicon like material, using SLA or multi jet printers.They are not a good substitution to traditional methods.

3 Adjust size, scale and tolerances

Each 3D printing technology comes with its limitations. You must learn the volume size, tolerances and minimal thickness limitations and adjust the 3D designed part to meet those limitations. Remember, the manufacturing process is done by sending your 3D files to a printer As It Is, and the printer operator can’t manipulate the 3D file geometry.
A scaled down project like architectural structure, an airplane or a vehicle model needs special care. Small details like railing, bars or windows needs extra care and different scaling ratio in order to meet the printer limitations. If you miss that part and print the file without fixing and adjusting the geometry, you may get very bed results.

4 The art of post processing

Hand painted SLS model near a plain one
With most printing methods, you will end up with a nice part in plain color and rough surface. For best results, post processing is needed. However, those processes require knowledge and the right equipment to get good results. For example, with metal printing, 
the most common post process is polishing and machining that can be done only by an expert with special tools. For plastic parts, polishing and dyeing are most common post process but, polishing and dyeing 3D printed plastic parts is challenging, especially for high quality results.

The lovely thing about 3D printing is that it is the simplest way to fabricate parts. A fast and cheap way to have a ready to use parts without the need to invest in expensive molds or special tools. However, as long as you remember that 3D printing has its limitation, and how to work around them, you will always have a successful 3D printing project.

Gal Raz
Managing Director of UCT Additive Manufacturing Center Singapore. Prior to joining UCT, Gal was the Additive Manufacturing Manager at the largest 3D printing service bureau in Israel. With over 20 years of diverse experience in business development, engineering, designing and innovation, he has vast knowledge in 3D CAD market.

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