george koller on sat 27 jul 02
William,
We have done rather extensive testing with straight nozzles
atomizing using air, with precisely metered ultrasonic nozzles,
and now with electronic dispensing valves and anytime we
work with suspended materials there is a decrease in reliability.
For example our original cobolt sulfate material came from a
pottery supply and we had considerable problems with this
colorant until we started using reagent grade. We have also
used a 0.2 and 5 Micron filters.
On the encouraging side the electronic dispensing valves are
relatively low cost, and have some rather amazing properties.
One property is that the edges can be amazingly "crisp" if
desired, and another is that the distance between the nozzle
and the sprayed surface can range fom 1/10" to more than 2"
under some circumstances. Also On and Off is extremely
crisp compared to other nozzle types that I am familiar with,
and this is vital to good control.
It is perhaps interesting that at comfortable movement rates
of maybe 18" per minute that you are likely to only want to
dispense about 0.2 CC per minute. This works backwards
that to maintain a "hydraulic stream" (of nothing but liquid)
you need the nozzle size of perhaps 0.002". Well, a nozzle
this size is an experience! - It seems to plug itself up if
you look at it funny. These days we find ourselves using
a much more reliable 0.004" and even bigger nozzles but
cutting down on the pressure and the number of spits per
second.
Do you care to share what it is you are trying to do? And
where are you? We have machines doing this at Alfred, NY
and in Northport, MI. I am looking to decorate tiles using
Kurt Wild's basic method, but we are also doing experiments
direct on porcelain with some luck.
Best,
George Koller
Sturgeon Bay, WI - Door County
William Hendry wrote:
> Anybody out there using an airbrush for applying glazes? I have an Iwata HP-BCS with a .5mm needle/tip and am having problems getting most any thickness glaze (that's not just water) to spray at the finer settings. I can open it up and it'll flat put out some glaze. But for any smaller setting it spits. I'm sieving at 100 and tried 200 but that didn't do much either. I've worked with psi from 40 to 80 and still have the same issue. Now what?
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
William Hendry on sun 28 jul 02
Hi George, thanks for the reply. I'm interested to know more about
electronic dispensing. Is this similar to the airless paint sprayer concept
used in painting houses, etc? Where would I find out more info on this?
As far as what I'm doing, I make handmade tiles that are used in
architectural installations, primarily kitchens and baths. I am in the
Asheville NC area.
William
----- Original Message -----
From: "george koller"
To:
Sent: Saturday, July 27, 2002 1:05 PM
Subject: Airbrush / Nozzles
> William,
>
> We have done rather extensive testing with straight nozzles
> atomizing using air, with precisely metered ultrasonic nozzles,
> and now with electronic dispensing valves and anytime we
> work with suspended materials there is a decrease in reliability.
> For example our original cobolt sulfate material came from a
> pottery supply and we had considerable problems with this
> colorant until we started using reagent grade. We have also
> used a 0.2 and 5 Micron filters.
>
> On the encouraging side the electronic dispensing valves are
> relatively low cost, and have some rather amazing properties.
> One property is that the edges can be amazingly "crisp" if
> desired, and another is that the distance between the nozzle
> and the sprayed surface can range fom 1/10" to more than 2"
> under some circumstances. Also On and Off is extremely
> crisp compared to other nozzle types that I am familiar with,
> and this is vital to good control.
>
> It is perhaps interesting that at comfortable movement rates
> of maybe 18" per minute that you are likely to only want to
> dispense about 0.2 CC per minute. This works backwards
> that to maintain a "hydraulic stream" (of nothing but liquid)
> you need the nozzle size of perhaps 0.002". Well, a nozzle
> this size is an experience! - It seems to plug itself up if
> you look at it funny. These days we find ourselves using
> a much more reliable 0.004" and even bigger nozzles but
> cutting down on the pressure and the number of spits per
> second.
>
> Do you care to share what it is you are trying to do? And
> where are you? We have machines doing this at Alfred, NY
> and in Northport, MI. I am looking to decorate tiles using
> Kurt Wild's basic method, but we are also doing experiments
> direct on porcelain with some luck.
>
>
> Best,
>
>
> George Koller
> Sturgeon Bay, WI - Door County
>
>
>
>
>
>
>
>
>
>
>
>
> William Hendry wrote:
>
> > Anybody out there using an airbrush for applying glazes? I have an
Iwata HP-BCS with a .5mm needle/tip and am having problems getting most any
thickness glaze (that's not just water) to spray at the finer settings. I
can open it up and it'll flat put out some glaze. But for any smaller
setting it spits. I'm sieving at 100 and tried 200 but that didn't do much
either. I've worked with psi from 40 to 80 and still have the same issue.
Now what?
> >
> >
____________________________________________________________________________
__
> > Send postings to clayart@lsv.ceramics.org
> >
> > You may look at the archives for the list or change your subscription
> > settings from http://www.ceramics.org/clayart/
> >
> > Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
george koller on sun 28 jul 02
>>Is this similar to the airless paint sprayer concept
>>used in painting houses, etc? Where would I find out more info on this?
>>As far as what I'm doing, I make handmade tiles that are used in
>>architectural installations, primarily kitchens and baths. I am in the
>>Asheville NC area.
William,
First, strange to say, but I may be leaving Tuesday to help move
some of my father's household items to a new home in Asheville
NC. (He is an aggresive driving "oxygenarian", I thought I should
warn you).
The "Airless" systems, that I am only somewhat familiar, use
electromechanical (piston?) forces to increase the liquid pressure
so that a nozzle can atomize the liquid and keep the flow rate
within a useful range for spray painting houses and such. The
flow from these systems seemed too great and too unfocused to
be of use for our tile colorant dispensing purposes. (Must be
about the opposite of a true HVLP system?)
The Electronic valves I am working with work on an amazingly
simple principle. When OPEN liquid is allowed to flow. When
CLOSED the liquid is not allowed to flow. Its simply a tiny vitamin
sized On/Off valve! Our valve uses a solenoid to activate a "piston"
but the piston does not serve to "slam/force" liquid through, but
it is just used to force a piston down-to & up-from a valve seat.
The valves we use are capable of opening and closing up to about
1000 times per second. Complete control over the opening and
closing allows you to adjust the flow rates very precisely. In working
with these valves you have control of these things:
1. The diameter of the oriface (some valves have interchangeable
nozzles, clearly this is a one time per job kind of control)
2. The pressure over the liquid being pushed through the orifice
3. The duration of the open time
4. The frequency of cycles (upto about 1000 per second)
We have been "dynamically" adjusting the cycles per second to the
current speed of the nozzle. This is giving us a very even distribution.
[Inches per minute of linear movement over the work piece]
With our new on-board micro-processor controller we can actually
adjust parameters #3 & #4 now - on the fly. Parameter #2 can also be
controlled on the fly but we use it to compensate for viscosity
variation and have been pretty happy to do just this effectively.
William, a few more questions:
Do you work in stoneware or other materials?
Are you familiar with what Postscript (vector/art)
files are?
Are you aware that we have mounted our nozzles on
"CNC tables" with some 15 * 32 square feet of surface
and have better than 1/100th inch location resolution
over this surface?
If things should work out that way, would you be
interested in meeting next week?
Sincerely,
George Koller
Sturgeon Bay, WI - Door County
1-(920) 746-8705
| |
|
