Recoating blade speed
Posted by Pulp64
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Recoating blade speed May 07, 2012 07:21PM |
Registered: 12 years ago Posts: 1 |
Hi guys, Im new to this fourm and Ive got a few quick questions I was hoping I could get some help with.
Whats the fastest speed of a powder recoating blade you guys have come accross and what would be the theoretical limit? Either a machine or a paper to back it up would be nice and has anyone seen CO2 laser used to sinter polymer powders in use with DLP tech or are CO2 lasers just too powerful? Or any type of area sintering tech in use for sintering of polymers?
Thanks for reading!
Whats the fastest speed of a powder recoating blade you guys have come accross and what would be the theoretical limit? Either a machine or a paper to back it up would be nice and has anyone seen CO2 laser used to sinter polymer powders in use with DLP tech or are CO2 lasers just too powerful? Or any type of area sintering tech in use for sintering of polymers?
Thanks for reading!
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Re: Recoating blade speed May 08, 2012 03:27AM |
Admin Registered: 17 years ago Posts: 13,995 |
... the systems I've seen were in the range of some ten mm/s, so not really fast.
The limits are either defined by the need to avoid turbulences in the air or electrostatic charging of the particles.
With fluids (e.g. UV-resins in STL-printers) its even slower, as you'll receive problems with viscosity and dynamic pressure-changes when pushing to much of the resin across.
Mostly this isn't dramatic, as the most time consuming step is the curing of the actual slice.
A better point to optimize could be a 'continuous' recoating as in a turning disk.
As you mostly can adjust the power of a laser-puls, this 'to powerfull' won't be a problem.
CO2-lasers are commonly used for sintering plastic powders.
And if you need something for experimenting, I can support you with IR-diodelasers with 5 or 9 Watts @975nm wavelength - here some infos regarding my first DIY-laserheads: [objects.reprap.org]
Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]
Call for the project "garbage-free seas" - [reprap.org]
The limits are either defined by the need to avoid turbulences in the air or electrostatic charging of the particles.
With fluids (e.g. UV-resins in STL-printers) its even slower, as you'll receive problems with viscosity and dynamic pressure-changes when pushing to much of the resin across.
Mostly this isn't dramatic, as the most time consuming step is the curing of the actual slice.
A better point to optimize could be a 'continuous' recoating as in a turning disk.
As you mostly can adjust the power of a laser-puls, this 'to powerfull' won't be a problem.
CO2-lasers are commonly used for sintering plastic powders.
And if you need something for experimenting, I can support you with IR-diodelasers with 5 or 9 Watts @975nm wavelength - here some infos regarding my first DIY-laserheads: [objects.reprap.org]
Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]
Call for the project "garbage-free seas" - [reprap.org]
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Re: Recoating blade speed June 21, 2012 07:58AM |
Registered: 16 years ago Posts: 40 |
3DS/EOS SLS Systems "recoat" at ~250mm/s (default value). Some materials it's possible to go quicker - which is largely unnecessary, but some materials require slower speeds (like the Sintered TPE's).
SLA systems are usually ~50-80mm/s. Most systems only recoat the over the cured area (ie SLA5000/7000/iPro) - so if you're only curing a 50mm*50mm area in a 500mm2 vat, the recoater doesn't need to move over the entire area.
Probably the biggest misunderstanding people have with the SLS process is that the Laser itself is only providing a small fraction of the energy required to melt the material. The entire material bed sits at a temperature only barely below its melt temperature - and variance accross this bed is extremely tightly controlled.
This has two effects - the main one being that it inhibits the curl and warp associated with rapidly cooling materials - without the heated bed the process simply wouldn't be possible to control. And secondly by limiting the energy required to melt the material in any particular area, it limits the "bleed" of that energy to surrounding material (semi-sintering it).
SLA systems are usually ~50-80mm/s. Most systems only recoat the over the cured area (ie SLA5000/7000/iPro) - so if you're only curing a 50mm*50mm area in a 500mm2 vat, the recoater doesn't need to move over the entire area.
Probably the biggest misunderstanding people have with the SLS process is that the Laser itself is only providing a small fraction of the energy required to melt the material. The entire material bed sits at a temperature only barely below its melt temperature - and variance accross this bed is extremely tightly controlled.
This has two effects - the main one being that it inhibits the curl and warp associated with rapidly cooling materials - without the heated bed the process simply wouldn't be possible to control. And secondly by limiting the energy required to melt the material in any particular area, it limits the "bleed" of that energy to surrounding material (semi-sintering it).
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