2” Flat Super Air Nozzles Separate Sheets of Metal Film

Heat Exchanger plates

An overseas company manufactures brazed plate heat exchangers. This type of heat exchanger has a series of corrugated plates that are stacked onto each other. It is designed to create a turbulent flow for better heat transfer in a very compact size. The plates inside the heat exchanger are made of 321 stainless steel which is basically a 304 type of stainless steel but with a titanium stabilizer. This company would receive plain sheets of stainless steel material that were stacked on each other in a column. The dimensions of the plates were as follows: 305mm wide by 520mm long with a thickness of 0.5mm (12” Wide X 20.5” Long X 0.02” thick respectively). Each sheet weighed 635 grams (1.4 lbs.). They would set a stack of the stainless-steel sheets at the beginning of a press machine. The press machine would form the corrugated design into the face of the sheet. They were using a pick-and-place vacuum system to lift one sheet at a time to place inside the press. They started having problems with their process when occasionally two or three sheets would stick together. The underlying sheet could either fall onto the floor which would bend the sheet or be stacked inside the press which would cause an improper corrugation. Both issues were causing much scrap as well as downtime in their process .

They contacted EXAIR to find a way to improve the efficiency of their process. They wondered if static could be causing the “sticking” issues. Generally, static forces are really noticed with sheets made of plastic or non-conductive materials. The stronger the static force, the more issues with sticking and misalignment. EXAIR does offer Static Eliminators to remove static forces in applications just like this. But, with plain metal sheets, static is not a problem as the ions are able to balance themselves.

Typically, the main cause for metal sheets to “stick” together is surface tension. Liquid like water has a strong affinity to itself within the molecular structure, called cohesion, and to the surface that it lies on, called adhesion. The cohesion plus the adhesion to the metal surface can have a strong enough force to overcome the weight of the sheets. To break the surface tension, an additional force is required.  An example of surface tension is with nylon tent material. The surface tension of water is strong enough to keep rain drops from penetrating the fabric. If you break the surface tension by touching the tent material, the surface will start to leak water. The same goes for the thin sheets of metal. We just need to break the surface tension to allow the sheets to separate.

2″ Flat Super Air Nozzle

I recommended two pieces of the model 1122, 2” Flat Super Air Nozzles. This nozzle gives a flat air pattern to force air between the sheets. Surface tension is based on force over length. Once the sheets start to separate, the contact length will decrease thus reducing the “sticking” force caused by surface tension. In this application, the amount of cohesion and adhesion forces caused by surface tension were unknown. Oil, water, and other liquids have different surface tensions which would require different amounts of blowing forces. To ensure the proper amount to separate the sheets, I recommended the shim set, model 1132SS.

The shims have different thicknesses that can be installed easily into the 2” Flat Super Air Nozzle to change the amount of blowing force.  In conjunction with a regulator, this customer could “dial” in the proper amount of force required to counteract the surface tension from any type of liquid that may be on the surface of the sheets.  I had them mount one nozzle at two different corners to help “peel” the sheets apart. The customer also tied in a solenoid valve into the compressed air system to cycle on the 2” Flat Super Air Nozzles only during the time when the vacuum system wanted to grab the top sheet. This reduced the amount of compressed air needed for their operation.  After the installation, the procedure ran smoothly without downtime and scrap waste.

If your application is creating scrap and downtime caused by sheets sticking together, EXAIR has many types of products to help eliminate this. Whether the “stickiness” is caused from static or liquid adhesion, an Application Engineer can direct you to the best product to eliminate the “stickiness”. For the overseas company above, we were able to apply a sharp flat burst of air to overcome the surface tension between the sheets.

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

 

Heat Exchanger Plates by epicbeerCreative Common by 2.0

 

E-Vac For Lubricant Recovery

Over the last 3 months, I have been in contact with a customer, keeping track of an application that involved the EXAIR E-Vac.  The customer had reached out to us looking for some advice on how to solve a process problem. The operation is a drawing/stamping process, and the when the part exits the machine there is coolant that resides in a deep draw section, approx 0.4″ in diameter by 3.5″deep.  About 1 oz of coolant per part is retained, and over many 1000’s of parts, would add up to lost dollars and messy clean up.

The customer was looking for an automated process that would be able to draw out the coolant and direct the liquid back to the coolant reservoir, all while maintaining the current machine run rate. We settled in on the model 840015 Adjustable E-Vac Generator. The Adjustable E-Vac has a straight through pathway from suction through to discharge, allowing for fast evacuation times.  A simple turn of the unit changes the vacuum and flow levels to best match the needs of the application.  The Adjustable E-Vac coupled to a solenoid valve controlled by the stamping machine resulted in the automatic system the customer was looking for.

Adjustable EVac
Adjustable E-Vac Family

The customer ordered a unit, and based on the preliminary bench testing, it was approved for a production run trial. After some tweaking in the production environment, the unit was performing to spec, and was then subjected to a 100,000+ part run.  The results were a success!  Instead of the parts exiting onto an inclined conveyor, relying on gravity to drain and causing coolant to collect under the conveyor, the coolant could be removed in a controlled manner and sent back to the reservoir.  Less mess and no coolant loss.

EXAIR manufactures (3) types of E-Vacs – Low vacuum generators for porous materials, high vacuum generators for non-porous materials, and the adjustable type for flexible vacuum performance.  They are available in multiple sizes, to best match the vacuum requirements, while using the least amount of compressed air.

To discuss your application and how the EXAIR E-VAC can benefit your process, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Part Ejection Improved by Choosing the Right Air Nozzle

Recently, I was able to work with a gentlemen from a stamping company that produces small metal stamped lids for the cosmetic industry.  He was frustrated because the current blow off setup, a copper tube and nozzle (shown below), was too weak and narrow to be effective with parts ranging from 1″ to 2.5″ wide.  Whenever a lid did not get completely discharged, the machine would jam and double hit on the next cycle, ruining (2) parts in the process, not to mention, potentially damaging the the tooling.

After reviewing the process, which is very high speed, we wanted a strong, concentrated blast of air that matched the part profile to maximize the air flow contact patch.  We agreed the model HP1125 – 2″ High Power Flat Super Air Nozzle would be a good nozzle to implement and test.  In addition to the Nozzle, the customer ordered the model HP1132SS Shim Set, to allow for flow and force adjustment of the nozzle to obtain the best possible performance under production conditions.  The HP1125 nozzle provides 2.2 lbs of force with the standard .025 patented shim installed, and can be decreased or increased by changing the shim to .020″ or .030″ thick. Preliminary testing has proven successful, and reliability testing and data collection is underway.

2 Inch Flat
2″ Flat Super Air Nozzle

EXAIR has available, the Air Nozzles Blowoff Guide, a handy reference with 23 pages of technical data for OSHA safe nozzles and Safety Air Guns for every application imaginable.

blowoff guide
The EXAIR Air Nozzles Blowoff Guide

To discuss your part ejection, blowoff, cooling or drying application, feel free to contact EXAIR and one our  Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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The power of the 2” High Power Flat Super Air Nozzle in a blow-off application

A stamping company contacted me for help in their ejection blow-off system.  Their operation consisted of a punch press that would form two 8” X 8” triangles from a square piece of metal.  The operation of the punch press was to cut the square piece diagonally at the same time forming the outside edges of the triangle.  At the end of each stroke cycle, the formed parts would then be blown off the die with compressed air.  The blow-off system consisted of two pipes, one that was a ¾” NPT pipe and the other that was a ½” NPT pipe.  They both had the ends of a long nipple flattened to concentrate the air flow.  EXAIR has reduced air use, saved money, and lowered noise levels for many similar applications by replacing open blow-off devices with our engineered air nozzles.

In giving me more details about their operation, the system had a timing sequence that controlled an actuator. When the cycle was complete, the actuator, located below the tabletop of the punch press, would open and send compressed air through both pipes.  The positions of the blow-off pipes were designed to eject one part off the side of the die and the other part off the front of the die into a collection chute.  (Reference the picture below)  They were having issues when their blow-off system wasn’t consistently able to eject the 1 lb. part completely off the die.  In manually having to remove the parts, it would cause an unsafe environment as well as a slowdown in operations.  They found that EXAIR manufactures Intelligent Compressed Air Products and wondered if we could help.

Blow-off Setup
Blow-off Setup

With a lack of restriction at the end of the pipe, the air pressure will drop quickly as it travels through a relatively long length of pipe. The actuator, which was more than 3 feet away from the end of the pipes, had a line pressure of 90 psig (maximum that they could supply).  By the time the compressed air reached the ejection site, the pressure was much lower; thus, not quite removing the part from the die.  An example that I like to use is a garden hose attached to a spigot outside your house.  As you open the spigot, water will flow out of the hose at a slow velocity; not very strong, that is the same as air through an open pipe.  When you place your thumb partially over the end of a garden hose you restrict the flow and increase velocity. Engineered nozzles from EXAIR work the same way.  They restrict the flow at the nozzle, increasing the pressure for a more effective velocity and blow-off force.  Neal Raker wrote a great blog for EXAIR referencing how the nozzles work; called “What’s in a Nozzle?”

HP1125 2" High Power Flat Super Air Nozzle
HP1125 2″ High Power Flat Super Air Nozzle

I recommended the model HP1125, 2” High Power Flat Super Air Nozzle. It has a 2” wide air stream to allow more contact against the side of the triangle edge.  It has a force of 2.2 lbs. at 80 psig which is more than enough to eject the 1 lb. formed part.  As an added benefit, it only has a noise level of 83 dBA which is magnitudes more quiet than the open pipe.  Also in using the engineered nozzles, they were able to use much less compressed air in their blow-off, saving them over $1,000/year.  If you find that your open pipe blow-off is too loud, not effective, or uses way too much compressed air, you should contact an Application Engineer to see which engineered nozzle would best suit your application.

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