Our company want to implement selective laser melting(metallic powders). But our building close to the road plus we have industrial machines near us, what vibration levels are dangerous in SLM printing? What numbers is admissible? Vibration are dangerous because of lasers? Or because layer of powder can be distracted during the build?

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    $\begingroup$ You should discuss that with the manufacturer of the SLM machine when you ask for a quotation (and discuss resolution with the end user you are creating parts for). The machine could be placed onto a pad to reduce the vibration. Our company had to produce space quality mirrors, we had the road closed during the fabrication for vibration reasons, but these mirrors were made with conventional machining techniques not SLM. $\endgroup$ – 0scar Dec 9 '20 at 8:02

That depends...

Among the fact that can influence if vibrations could be the problem in this case, I see the following s is the most prominent:

  • Powder grain diameter
  • Powder composition
  • Powder shape
  • Aimed for resolution

The grain diameter and composition are the more influencing factors: fine powders of low-density metals will be much more affected by vibrations and almost behave like dust or fluid under resonating vibrations. On the other hand varicose powders of high-density metals will more easily settle down and have much higher thresholds for how much vibration affects them.

The shape mainly influences how particles coagulate: very coarse particles, think snowflakes, will interlock and bond to one another creating flakes of several powder particles. Vibration can influence the formation and compactness of such flakes and such influence the resolution.

If you want to print very coarse with rough, large powders, vibrational mitigation might be not needed. But should you want to print pretty much in aluminium dust... you need to take it into account.

Vibration mitigation

If the Vibrations influence your prospect machine placement, you'll have to inquire about at your machine manufacturer, best with a seismometer measurement of the places where you want to build. By placing special fasteners and vibration dampeners (springs or rubber feet) in between the machine and the floor, anchoring it to a separate foundation that is not connected to the surrounding building, or even by having the machine float, vibrations can be mitigated.

It's often much easier to install larger vibration mitigation equipment on lower floors and mounting it directly to the foundation of a building (ground floor and basement) is often preferred.

In case of special projects, the local municipality might allow banning (heavy) road traffic or even pedestrians from areas that affect the manufacturing in such a way - the Cologne Opera is partially under a public space right next to the cathedral, and during events, pedestrians may not use a chunk of it. In my city, the use of one road with trucks is banned due to vibrations they can cause in a nearby old building.

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    $\begingroup$ Our electron beam microscopes (they also don't like vibrations) are placed on a separate structure that is not part of the office building, but directly onto the earth surface, probably on a gigantic slab of concrete or something. When accuracy/resolution matters, vibration may be an issue, it is how you mitigate the vibrations or what the end user requirements are. $\endgroup$ – 0scar Dec 9 '20 at 9:15
  • $\begingroup$ Someone experienced with building wafer fabs and installing fab equipment would be an expert at eliminating vibration. $\endgroup$ – Perry Webb Dec 9 '20 at 15:34
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    $\begingroup$ Without modifying facilities usually vibration is lower on your lowest floor, especially in basements. $\endgroup$ – Perry Webb Dec 9 '20 at 15:36
  • $\begingroup$ @PerryWebb Unless the road (or footwalk) is right over the equipment, then you get the cologne opera effect. $\endgroup$ – Trish Dec 9 '20 at 16:04
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    $\begingroup$ Many fabs would have a separate inner foundation from the foundation supporting the outer walls. $\endgroup$ – Perry Webb Dec 9 '20 at 19:55

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