High Temperature Capability

Last week, a customer called in to talk about their application.  After aluminum and steel machining operations, parts are run through a washer system. The drying portion utilized a Super Air Amplifier to dry the sides and a Super Air Knife to dry off the top. The wash temperature was running at 185°F.  The customer wanted to review the application and make sure the EXAIR products utilized in the process were rated to this temperature and to check on high the products could go, since the maximum possible temperature for the washer was listed as 250 °F.

air-knife-air-amplifer

Drying Section – Utilizing EXAIR Air Amplifier (near top) and Super Air Knife

The Super Air Amplifier is rated to 275°, above the maximum possible condition.  The Super Air Knife was pre-installed with a stainless steel shim, enabling a maximum temperature rating of 400 °F. Both of the components are rated for temperatures in excess of the maximum possible washer temperature condition, and the customer felt confident with the system design.

EXAIR has several options in the Air Amplifier and Super Air Knife product families to allow for operation in high temperature applications.  For the Air Amplifier, the Super Air Amplifier and Aluminum Adjustable Air Amplifier have a maximum temperature rating of 275°F.  The Stainless Steel Adjustable Air Amplifier is rated to 400°F, and for the hottest of conditions, the High Temperature Air Amplifier is rated to 700°F.

Relating to Super Air Knife, the aluminum Super Air Knife is rated to 180°F.  With a stainless steel shim installed, the maximum increases to 400°F. The PVDF Super Air Knife, used in applications where chemical resistance is needed, can withstand temperatures up to 275°F. And for the most extreme temperature environments, the Type 303 and Type 316 Stainless Steel Super Air Knives are rated up to 800°F.

To discuss your application and how an Air Amplifier and Super Air Knife or any EXAIR Intelligent Compressed Air Product can help your process, feel free to contact EXAIR and one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Non-Contact Wiping with the Super Air Knife

A glove manufacturer needed to decrease the reject rate with their natural rubber gloves. They were seeing brush marks in the rubber material which was a visual defect.  Their operation used a ceramic hand that was used to form the size of the glove.  After the rubber material was applied, it was dipped into water to set the material.  It would come out of the water tank, and a mechanism on the conveyor would rotate the hands to “shake” off the excess water.  It would then go over brushes to wipe the water from in between the fingers.  Much of the water had to be removed before it entered into the coagulation tank because it would affect the stretching ability of the glove.  With their current operation, they were seeing the scuff marks from the brushes which was a visual defect.  This cost them down time and product rejects.  So, they contacted EXAIR to see if we could help.

Brushes used to wipe the gloves

Brushes used to wipe the gloves

In looking at their process, they had two conveyors running side by side with each other. This made it a bit more difficult as we could only work on one side.  Being that the ceramic hand rotated around twice in 36” before hitting the brushes, I could focus in this area.  When it comes to wiping products without touching it, air is required.  And EXAIR knows how to use compressed air very efficiently, safely, and effectively.  For this application, I suggested our model 110236 Super Air Knife kit.  It has an overall length of 36” which could span the target area.  It comes with a filter, regulator, and shim set to clean and control the air flow.  It would be able to “wipe” the water off the hands like a non-contact squeegee.  The air flow from the Super Air Knife will hug the exterior portion of the hand; removing the water from the surface and in between the fingers.  They removed the brushes and did not have to worry about brush marks on the glove.

EXAIR Super Air Knife

EXAIR Super Air Knife

If you require a non-contact wiping in your application, use EXAIR Intelligent Compressed Products to accomplish this. You will not have to keep replacing items that wear or use items that cause damage to your product. EXAIR has the ability to use compressed air to create a strong force without scraping or scratching your material.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

More Power May Not Be The Solution

I can’t tell you how much it pains me to write this after last week’s blog. But, if we’re being honest here, every Tim “The Tool Man” Taylor (“More Power!”) does indeed need an Al Borland (“I don’t think so, Tim.”) As evidence of this, I had an opportunity to provide reasoned advice to a caller on the tech support line this week:

They had just purchased a Model 110224 24″ Aluminum Super Air Knife Kit. The flow it produced wasn’t powerful enough for their needs, so they installed extra shims from the Shim Set (which comes with the Kit) – increasing the shim gap to 0.009″ (which can produce a great deal more air flow and force)…more power, right?

Super Air Knife Kits include a Shim Set, Filter Separator, and Pressure Regulator.

Super Air Knife Kits include a Shim Set, Filter Separator, and Pressure Regulator.

Unfortunately, not. The Super Air Knife makes a hard hitting curtain of air when supplied properly…but it’s going to need a 1/2″ pipe (ID of ~5/8″) to carry enough compressed air flow to make that happen. Turns out, they were using 1/4″ tubing, which wasn’t even getting enough compressed air flow to the unit with just the 0.002″ shim installed. Putting in the extra shims actually made that worse. Once they ran a 3/4″ hose to the Air Knife (and took out those extra shims,) they were actually able to regulate the air supply back to about 60psig, which provided a strong enough air flow to solve the application.

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.

Sometimes, though, compressed air product applications DO come down to a need for more power.  Next week, I’ll tell you about a caller who said he needed “the biggest and most powerful” Safety Air Gun we had – and unlike the last time I wrote a blog about that – he was RIGHT.

Russ Bowman
Application Engineer
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EXAIR Super Air Knife vs. Blower-type Air Knife

Super Air Knife Blower Air Knife

Super Air Knife                           Blower Air Knife

A plastic company was developing thin layered films in their laboratory on a miniature prototype machine. It was designed for trial runs to make 24” wide material from various plastics, blends, and thicknesses.  They would place the plastic pellets into a hopper, and the material would be melted and extruded into a flat sheet.  To harden the material, it would land onto a cold drum, a large cylinder that had chilled water running through it.  To keep the sheet on the surface of the cold drum, they had a blower air knife.  In addition to the blower air knife, they had to use two ¼” copper air lines blowing on the outside section of the film.  Whenever they decided to make a change to their process, change material runs, or even for clean up; they had to move the blower air knife from the cold drum.  This was a hassle as it had a 3” hose attached to a blower.  It was very cumbersome and awkward to handle.  They heard about the EXAIR Super Air Knives, and they wanted me to do a comparison to their current system.  I was glad to compare the EXAIR 110224 Super Air Knife to their blower-type air knife system.

 

  1. They were getting “stretch” marks on the plastic film.
    • Blower-type air knife – Hot air is generated by the blower system. When the hot air hits the cool surface, it will cause an uneven hardening of the material, causing stretch marks.
    • Super Air Knife – It has a 40:1 amplification ratio. That means that 40 parts of the ambient air is entrained with 1 part of compressed air. Being that the ambient air is much cooler than the hot air from the blower system, it actually aides in cooling. There is no thermal shock to the material, and hardening is better and faster.
  2. They required an even force across the surface of the plastic film to keep against the cold drum.
    • Blower-type air knife – Their design had one 4” line feeding into the side of the blower air knife. This would cause 2 issues for an even force. As the velocity of the air hits the opposite side of the knife, the closed end, a turbulent air flow is developed. Also, there would be a slight negative pressures at the entrance caused by the velocity of the air entering. This turbulent mayhem and slight negative pressure are very inconsistent in force and velocity. The reason that they had to add the additional two ¼” copper lines to blow compressed air on the outside edges.
    • Super Air Knife – The flow that is delivered from the Super Air Knife is laminar. This means that the force and velocity is consistent across the entire length, even on the outside. With this even force, the film is held evenly and securely onto the cold drum.
  3. They needed maneuverability for change overs and clean up.
    • Blower-type air knife – To keep the needed pressure on the film, they had to have the blower air knife ¼” from the surface of the cold drum. So, before a change over or clean up procedure is started, they had to remove the knife and attachments. This was time consuming, cumbersome, and a headache to move.
    • Super Air Knife – With the compact design, the Super Air Knife has a large force in a small package. It has a footprint of 1 ¾” X 1 ½” X 24” long with only two ¼” NPT compressed air lines feeding it. The force measurement is equivalent from 3” to 12” away from the surface. Now, they could mount the Super Air Knife far enough to not disrupt their cleaning or change-over procedures. This saved them much time in changing to different materials and clean up.
  4. They wondered about the compressed air usage.
    • Blower-type air knife – This device does not require any compressed air to operate, but because it could not keep the film against the cold drum on the outer edges, they did have to use compressed air. With the two ¼” copper tubing at 80 psig, they were using a total of 79 SCFM of compressed air.
    • Super Air Knife – As a direct comparison to their air usage, the Super Air Knife would use 70 SCFM of compressed air at 80 psig across the entire width of the film. But with the unique design to entrain 40 parts of ambient air, it gives the Super Air Knife a powerful force. They were able to reduce the air pressure to 40 PSIG to keep the film on the cold roll, which also cut the air consumption to 41 SCFM. This efficient design helped them to save on compressed air without the added cost of the electricity to run the blower motor.
  5. Any other comparisons between the two products
    • Blower-type air knife – With the sound of the blower and the turbulent air flow, the unit was very loud. It had a sound level over 90 dBA, and with the operators working around this system, they required PPE for hearing.
    • Super Air Knife – These units are very quiet. At 40 PSIG, the sound level is only 61 dBA. (Just as a reference, the sound level is 72 dBA at 100 PSIG). This was very nice for the operators as they did not need to wear the ear plugs to work around their machine all day.

When it comes to using the EXAIR Super Air Knife, it has many benefits over the blower-type air knife. We can even include the initial cost in which we would be about 1/10 the cost of a blower-type air knife system.  For this customer above, they were delighted to replace that system with the Super Air Knife, and start running plastic film effectively, efficiently, and quietly on their miniature prototype machine.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Super Air Knife Provides Tension with Fine Adjustment for a Lightweight Plastic Film

A company had a small converting machine that was winding a plastic film onto a roll. The width of the plastic film was only 3” across, and the amount of tension required for a consistent roll was small. The maximum amount of tension without damaging the plastic film was 16 ounces of force.  In converting media onto rolls, it is very important to control the tension on the web to reduce defects like wrinkles, out-of-round rolls, or stretching.

They explained the setup that they were trying. They had a 4” manifold with two 2” wide “duck-foot” nozzles attached.  They sent a hand drawing to better describe what they were using. (See below).  The issue that they were seeing was too much variation in the blowing force being applied to the film.  To get near the correct blowing force, they had to start at an air pressure of about 18 PSIG.  As they ran the process, the operator would have to adjust the pressure continuously to evenly roll the film onto the core.  The process was out of control, and they wondered if EXAIR had a better way to evenly exert this force.

Dual Flat Nozzle Manifold

Dual Flat Nozzle Manifold

In analyzing the drawing and their setup, I noticed a couple of things that could cause the variations. I modified his drawing to better explain the situation (Reference below).  As compressed air leaves the two flat nozzles, the center section will overlap.  This overlap will cause turbulence in the air flow pattern.  In order to get an even distribution of forces across the width of the product, turbulence cannot exist.  Turbulence is a mixing pattern where the velocity is not linear; thus, causing high and low pressure points on the target.  The other thing that I noticed was the low air pressure that they could not go above.  This limited the precision of the incremental forces.  Because of the fixed openings of the two nozzles, they had to have a ceiling with the air pressure at 18 PSIG for 16 ounces of force.  If they had to “bump” the force level, the change was difficult to hit exactly.  If we divided the 16 ounces of force between 0 – 18 PSIG, we would get roughly 0.9 ounce of force per PSIG.  You lose the accuracy to make fine adjustments.

Overlap of air flow pattern

Overlap of air flow pattern

I recommended our model 110003, 3” Super Air Knife and a model 110303 Shim Set. The Super Air Knife blows compressed air across the entire length.  Without any overlap, the flow is laminar, and the velocity profile is moving in the same direction.  Thus, an even force across the entire 3 inches.  The Shim Set comes with additional shim thicknesses of 0.001”, 0.003”, and 0.004” thick (the standard thickness of 0.002” is installed in the Super Air Knife). In working with such a precise force requirement, they needed additional options for more control.  They could change the shims as a coarse adjustment and adjust their pressure regulator as a fine adjustment.  This combination gave them the best results to accurately dial in the correct force and not damage the material.  With the maximum requirement of 16 ounces across 3 inches of film, they were able to change the shim to the 0.004” thickness.  For the model 110003 Super Air Knife, it put them at a maximum pressure of 86 PSIG, not 18 PSIG.  Thus the increment was now 0 – 86 PSIG for 16 ounces of force, or 0.19 ounces per PSIG.  There was much more resolution to make smaller changes to the force levels thus optimizing their adjustment range.

Super Air Knife with Shim Set

Super Air Knife with Shim Set

In replacing the competitor’s product with a Super Air Knife, our customer had all the necessary control to wrap rolls of film without issue. The setup with the nozzles on a manifold design resulted in turbulence, which was noisy and produced inconsistent results.  It also restricted their adjustment resolution in changing forces, as they do not use shims.  If you would like to exert a greater degree of precision blowing with products like the Super Air Knife, please contact us. We would be happy to discuss your application and help you meet such goals.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Super Air Knife Helps Make More Candy Bars

It’s known in various places as Beggar’s Night, Trick-or-Treat, or just good old Halloween.  Whatever you call it, many of us have fond memories of donning a costume and a mask and roaming the neighborhood in search of candy.  Most of the grownups we encountered were only too happy to oblige our requests, in exchange for the opportunity to spend some time on the porch, enjoying a brisk autumn evening.  We won’t talk about the times when it may have rained, snowed, or been unseasonably hot…like, in the 80F range (yes, I grew up in Ohio.)

As fond as those childhood memories are, I’ve built a solid arsenal of grownup memories too, both passing out candy to neighborhood kids, and escorting my own kids around the neighborhood…of course, I always “suited up” for the occasion…

My neighbors breathed a collective sigh of relief when my sons became old enough to go Trick-or-Treating without Dad.

My neighbors breathed a collective sigh of relief when my sons became old enough to go Trick-or-Treating without Dad.

It’s probably no great secret that candy manufacturers ramp up their production in preparation for the occasion.  I had the pleasure of discussing an application with one of them recently – in fact, it was for some of the bite-size candy bars that they were about to be “Job One.”  This particular treat is produced as a continuous “strand” of nougat that is extruded onto a conveyor.  It’s then covered in peanut pieces and cut to size before being coated in chocolate.  Now, because these are bite-size bars, they’re making 3-4 times as many cuts as their regular candy bars (you know…the ones you got at the “cool houses?”) there’s 3-4 times as many peanut pieces on the belt.

To recover these pieces, they got a Model 110254 54″ Aluminum Super Air Knife Kit, and installed it to blow a light “curtain” of air across the belt in the area where the cutting takes place.  The excess pieces are blown into a trough on the side of the conveyor, where they’re cleanly and neatly recovered & recycled.  They only need about 5psig of compressed air supply pressure to do this, and it’s timed to the indexing of the belt, so not only is it reliable & effective, it’s just about as efficient as they can get.

The EXAIR Super Air Knife – quiet, efficient, and infinitely adjustable to meet the needs of most any blow off situation.

If you’d like to talk about Super Air Knives, Trick or Treating, or Halloween candy, give me a call.  I know a LOT about all of those things.

Russ Bowman
Application Engineer
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A Tale Of Two Cooling Applications

There are many, many ways to cool something down. Which method works best will depend on a number of factors, but the biggies are:

*How hot is it?
*How cool do you need it?

If you call EXAIR to discuss a cooling application, these are most likely the first questions that’ll be asked. And the answers will determine which product line we start talking about. In the title of this blog, I promised you two tales…here’s the first:

A caller from a metal fabricating shop needed to cool down metal cylinders after they were heated to 400F, and was curious to know if this was a good application for one of our products. Now, he had already answered one of our questions, so the answer to the second would tell the rest of the tale.

Turns out, they only needed to get down to 120F or so, which made this an excellent application for our Super Air Knives…they’re going to blow a laminar, high volume flow of ambient temperature air onto the part. We knew this from a past application that was so well documented that we included it in our catalog…you can read all about it on page 21 (if you don’t have one, get one – it’s free.) But for now, here’s a graph of the cooling rate comparison with the Super Air Knife:

While the fans no doubt made for large volume air movement, the laminar flow of the Super Air Knife resulted in a much faster heat transfer rate.

While the fans no doubt made for high volume air movement, it was also very turbulent.  The laminar flow of the Super Air Knife resulted in a much faster heat transfer rate.

When I showed this to the caller, that was all the convincing it took…their goal was to reach 120F in about a minute and a half.  Which, as you can see, will be no problem for the Super Air Knife.

Tale #2 is a bit different.  This was from a firearms manufacturer who needed to cool small, but hot, parts quickly, and they needed to reach room temperature.  Looking at the graph above, we know that blowing room temperature air on a hot part will cool it rapidly, until the temperature of the part begins to approach room temperature.  The solution?  Colder air, of course!

Enter the EXAIR Vortex Tube…after some discussion of the part size, shape, and their compressed air capacity, we determined the Model 3215 Medium Vortex Tube should be suitable for their operation.  By generating a cold air flow of about 20F, this replicated the higher temperature differential we see in the left-hand side of the cooling graph above…where the cooling rate was the highest.

If you’d like to talk about how “cool” an EXAIR product can make your application, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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