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I have a 3D printer, whose extruder I suspect is generating a static charge when the filament is dragging past other plastic parts (nylon). This is bad for the electronics. I want to try and dissipate that charge to earth however I am not sure how that is done. Once the PLA gets to the barrel, the barrel will conduct the charge to earth (as the machine is earthed), however those nylon surfaces do not contact anything conductive.

Question: How to dissipate a static charge on the nylon? Or How do you keep the electronics safe from this charge?

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  • \$\begingroup\$ I would just identify where the transients can enter the electronics, what's sensitive, and add ESD protection. TVS's are cheap, effective, and fast--can easily clamp ESD events. \$\endgroup\$ – Nick T Jun 9 '13 at 2:55
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There are a few basic choices that may help: A) Use conductive (static dissipative) materials to help drain away the charges. Of course any insulating surface can retain a charge despite being sitting on a base with a conductive property, though the smaller the insulating structures or the closer they are to a dissipative surface, the better the charge dissipation will be. You may or may not be able to dope or coat your materials with a dissipative constituent or film; such dissipative film coating materials are available as anti-static wipes, cleaners, floor / worktable treatment solutions, et. al.

B) Use a conductive system like the grounded brushed previously referred to to carry exess charges away.

C) Increase the natural dissipative and charge generating properties of the area / environment, for instance by changing the humidity to promote more leakage and less triboelectric action than one would see otherwise. Cool, moist environments are less problematic than hot, dry ones.

D) This is probably the main "catch all" option you have after having done the basics of preventing charging and dissipating charges through materials and system engineering. There are common ESD control devices that scale from small work area sized (perhaps the size of your machine's bed and immediate environment) to large work table / room sized. They are called bipolar ionizers or static control ionizers / neutralizers. They are ion generators coupled with an appropriate fan to disperse the ionized air, but they have a control system that forces the net ionic output of the machine's air stream to be electrically neutral by generating an equal amount of positive and negative air ions so that the machine itself will not contribute to a net charging of the environment it is treating. The charged ions on undesirably charged surfaces will attract oppositely charged ions in the airstream and so the excess charge will be neutralized. Surplus ions will be neutralized by your grounding / dissipative static control processes and by mutual annihilation et. al.

As for protecting electronics, you should have each electronic assembly's inputs and outputs protected from the amount of ESD that it needs to tolerate. Typically providing a good ground and then using TVS devices between the I/O lines and ground is the first stage of protection and then having some kind of series impedance such as a R/C filter inward of the TVS is another stage. Sometimes you can protect the supply rails with TVS and OVP devices and then use things like rail clamp devices to help shunt transients on other lines to the power rails. Series chokes, ferrite beads, et.al. will protect the I/Os from EMI and help limit fast transients from generating such large voltage spikes inside the protected equipment.

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  • \$\begingroup\$ So make the air more conductive? \$\endgroup\$ – user3045 Apr 28 '13 at 16:15
  • \$\begingroup\$ Very nice, rounded answer. \$\endgroup\$ – rdtsc Apr 11 '16 at 19:11
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Plastic or rubber conveyor belts have the same problem - I've see voltages that literally would make your hair stand on end. They use fine, soft carbon brushes that are earthed.

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Ed Nisley wrote a blog post about controlling static on the Thing-O-Matic printer. He ended up connecting drain wires to various pieces that made contact with the moving filament:

  • Filament Drive Frame
  • Extruder Thermal Core
  • Automated Build Platform Belt
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