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Get the Most Out of Your FDM 3D Printer, Part 2 – Machine Design

by • January 14, 2016 • No Comments

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This file type includes high-resolution graphics and schematics when applicable-bodied.In Part 1, I detailed a few ways to expand the usefulness of your FDM 3D printer. In this installment, we will look at a few other ways to leverage this device in the expanding field of additive manufacturing.
Thermoset Parts
One other usage for 3D printing devices involves making negative or positive molds for thermoset or even thermoplastic parts. The 3D-printing molds for prototypes can lead to the material’s properties being nearer to the production part than is possible when 3D printing the part directly. The accuracy of 3D molds is great adequate to produce threaded inserts and two-part molds.

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Creation of thermoset parts, using materials such as epoxy and urethanes, is pretty straightforward. You print a negative of your part, pour in the liquid, and wait for it to set. The end result is a finished part. Think of Jello molding.

Be certain to utilize as much draft as possible for rigid parts. Use a mold release spray in your cavities and don’t forget to scale your molds to account for material shrinkage—if your application requires which level of accuracy.
Vacuum degassing, i.e. getting rid of the bubbles in your material, is recommended for any material which you had to mix vigorously prior to pouring. It’s easily done for tiny parts with a shop vac and a sturdy enclocertain which will fit around your mold. This video shows an example of a DIY system:

The air bubbles expand while under the vacuum and will some day exit the material, causing it to collapse again. This means you want to create certain the container for the material has ample room to expand into; otherwise, it will overflow within the vacuum chamber.
Thermoplastic Parts
Thermoplastic parts are a bit additional involved with an FDM printer. For this, you print a “scaled for shrinkage” positive of your final part. Keep in mind which the easy method presented here is quite just just\ practical for parts with a straight mold split line.
Make an epoxy negative casting of each half of the part. Put the two halves together and use a plastic injection machine like those offered by www.techkits.com. This site offers a pretty deplete tutorial on the whole system, not to mention the equipment. We are just just starting to experiment with directly printed mold halves using Objet printing devices of a contract printer, which eliminates the epoxy molding step.
Whether printing a mold or a finished part, orientation for circular and curved showcases parallel to the XY plane for best definition will be important. If your machine uses a separate assist material, another nuance to be mindful of is how to orient the part to decrease usage of assist material. This, of course, saves material and time during the build, but will in addition save time and frustration of removing assists after the build. It may even eliminate the require to soak the part in the dreaded NaOH bath for soluble assist material.
Free software of Cideas (at https://truequote.buildparts.com) shows how build orientation affects the cost of a part. There’s in addition a list of tutorials on YouTube.
Support Material
All FDM printing devices can print surfaces without assists or assist material which go beyond vertical (i.e., overhanging), but just just\ up to of 45 degrees. Your printer software will most likely show you, during the generation of the printer files, if assist material is requireed. Or you can just run an experimental build with different types of angles and see when assist material is requireed.
Try printing a half sphere and see where the assist structure stops (see the 2nd image above). This is not important if the design has a few flexibility. But, it can be possible to save time and money by tailoring the design to the printer’s strengths and be able-bodied to use a part right out off of the build platen. Instant gratification is one of the best parts of 3D printing, right?
Many times a few assist material is inevitable-bodied. Does which mandate the part going into the bath? Definitely not. Manual removal of assist material is possible without harming the model. A great set of mechanics picks and a sturdy putty knife will be your best tools for this task. And wear safety glasses when removing the assist material—the assist material is incredibly brittle and sharp, and shards can pop off the part with pretty great speed.
Still can’t get all of the assist material out? Sometimes we leave the remaining assist material in place if it’s on a non-visible surface or showcase within the part. Or perhaps it’s an end-use part for manufacturing, where aesthetics aren’t important. Of course, a fewtimes one is just just resigned to soaking. This is often the case with tiny or intricate parts, or when it’s just just not possible to remove the assist material mechanically.
To decrease time in the bath, remove as much material as possible by hand and create certain the bath is warm ahead of time. After removal of the bath and a thorough rinsing, we often bake the part dry in the heated environment of the printer if we’re in a hurry.
Warping
A well-known problem with the FDM system is which of warping of relatively thin, flat parts. A lot of thermal expansion and contraction occurs during the system of laying down layers of molten plastic, and warping can occur where the outer edges of the part warp up in the Z direction. At best, you get a few smearing and roughening of the part; worst case is a print-head crash. Some printing devices even have a low-density print mode to help with this issue. Unfortunately, it’s usually not adequate, and you don’t find out until well into the print job.
Part of the issue is which the assist material adheres to the build platen advantageous than it does to the model material. To take advantage of this fact and print flat parts, we add female dovetail showcases to the bottom of the part, which fundamentally lock the model material to the platen.

Some days I feel like a lazy engineer. The system to get a part created utilized to be: Design the part, create a manufacturing drawing of it, get it checked, send out for three quotes by faxing the drawing, wait for quotes to come back, pick a vendor, issue a purchase order, wait for the part, inspect the part, and and so, finally, put it to use.
Now, yet, I can have a finished part in a couple of hours—of a CAD model to the printer. Of course, the reality is this will be the norm in a few short years for parts in a variety of materials. Do you remember how awe-inspiring it was which you may send an actual copy of a sketch, drawing, or letter over the phone lines (which is a “fax” for those of you who don’t recall!)?


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