Considerations for Ejecting Parts with an Air Nozzle: Weight and Friction

I had a customer wanting to reject a container off a conveyor belt.  The container held yogurt, and when an optic detected a reject, they wanted to operate a solenoid to have a nozzle blow the container into a reject bin.  They had a range that went from 4 oz. (113 grams) for the small containers to 27 oz (766 grams) for the large.  He wanted me to suggest one nozzle for all sizes, as they would automatically regulate the pressure for the full range of products.  In looking at the largest size, this container will need the most force to blow off the conveyor.  The two factors that affects the force in this type of application is weight and friction.  When it comes to friction, it is generally an unknown for customers.  So, I was able to help with a couple of things to determine the friction force.

Friction is a dimensionless number that represents the resistance created between two surfaces.  We have two types; static friction, ms, and kinetic friction, mk.  Static friction is the maximum amount of resistance before the object begins to move or slide.  Kinetic friction is the amount of resistance that is created when the object is moving or sliding.  So, Static friction is always greater than kinetic friction, ms > mk.  For this application, we will use an air nozzle to “shoot” horizontally to hit the rejected product.

Let’s take look at our customer’s application.  We have a system to reject a non-conforming part with air.  The conveyor has a urethane belt.  The container is plastic.  For the largest container, they have a weight of 27 oz. (766 grams).  Being that the conveyor belt is only 12” (30.5 cm) wide, we can determine that if we get the part moving, it will continue off the belt and into the reject bin.  The equation for the maximum amount of force required to move a container is below as Equation 1.

Equation 1

Fs = ms * W

Fs – Static Force in ounces (grams)

m– Static Friction

W – Weight in ounces (grams)

One way to determine the amount of force is to use a scale similar to a fish scale.  The scale should have a maximum indicator to help capture the maximum amount of force.  You will have to place the object on the same belt material because different types of materials will create different static forces. Keep the scale perpendicular to the object, and slowly pull on the scale.  Once the part begins to move, record the scale reading.  For the exercise above, it showed 9.6 oz. (271 grams) of force to move the 27 oz. (766 gram) object.

Another way would be to calculate the static friction, ms.  Static friction can be found by the angle at which an object starts to move.  By placing the container on a section of supported urethane conveyor belt, you can lift one end until the object starts to slide.  The height of the lift can be measured as an angle.  As an example, we take 3 feet (0.9 meter) of supported urethane conveyor belt, and we lifted one end to a height of 1 foot (0.3 meters) before the 27 oz (766 gram) container moved.  To determine static friction, it is the tangent of that angle that you lifted.  With some right triangle trigonometry equations, we get an angle of 19.5o.  Thus, ms = tanq or ms = tan(19.5o) = 0.354.  If we plug this into Equation 1, we get the following:

Imperial Units                                                    SI Units

Fs = ms * W                                                         Fs = ms * W

= 0.354 * 27 oz.                                                = 0.354 * 766 grams

= 9.6 oz. of force                                              = 271 grams of force

1″ Flat Super Air Nozzles

Now that we have the static force, we want to be slightly higher than that.  In looking at the force requirements that are published in the EXAIR catalog, it shows that the model 1126 1” Super Flat Air Nozzle has a 9.8 oz. (278 grams) of force at 80 PSIG (5.5 Bar).  This force is measured at a 12” (30.5 cm) distance with a patented .015” (0.38mm) shim.  So, this nozzle will be able to slide the largest container into the reject bin.

1″ Flat Super Air Nozzle shims

To expand on the benefits in using the EXAIR Flat Super Air Nozzles, the force can be changed easily with a regulator or with a Shim Set.  This is a unique feature as most competitive flat nozzles do not allow you to do this.  The patented shims control the force rating in a wide range with lower air consumption and lower noise levels; making them safe and efficient.  So, if this manufacturer decided to produce other sizes in the future, then they could change the shim to target even larger containers.  The flexibility of using the EXAIR Flat Super Air Nozzles allow you to increase or decrease the force by just removing two screws and changing the thickness of the shim inside.  EXAIR does offer a pack of shims with different thicknesses which are called a Shim Set.

With air pressure or shim manipulation, the customer could use the same nozzle for the yogurt containers.  If you have any applications that need products to be rejected quickly, an Application Engineers at EXAIR will be happy to help you with a solution.

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

Photo: Yogurt by BUMIPUTRAPixabay Licence

Nozzles for Cleaning Inside Hose, Tube, Pipe and More

Some applications such as blowing chips or debris out of a pipe or blind hole, it may not be possible to blow forward. The pipe may be too long, making it impossible to push the debris all the way down the pipe or the other end of the pipe may not be open. In either of these scenarios, the Back Blow Nozzle is the right tool for the job. An array of holes around the diameter of the Back Blow Nozzles provides a powerful 360° airflow pattern that will clear out any leftover coolant or chips from the machining process.

EXAIR has three different size Back Blow Nozzles; the 1004SS (M4 x .5), the 1006SS (1/4 NPT), and the 1008SS (1” NPT). The 1004SS is recommended for use on pipes as small as ¼” and up to 1”. The 1006SS can be used for a wide range of pipe sizes, from 7/8” up to 4”. The 1008SS nozzle offers the greatest overall force for stubborn or sticky materials stuck to the inside diameter of the pipe. This nozzle is suitable for use in pipes ranging from 2”-16”. As the Back Blow Nozzle will be blowing chips and debris back out of the pipe towards the operator, it is always recommended that a Chip Shield is used. The strong polycarbonate Chip Shield will keep them safe from flying debris and keep you in compliance with OSHA directive 1910.242(b).

Various Views of the Model 1006SS Back Blow Nozzle

All of EXAIR’s Back Blow Nozzles are available with extensions. For the 1004SS we have extensions from 6”-36”, and from 12”-72” for the 1006SS and 1008SS. The Back Blow Nozzle can also be installed on our VariBlast, Soft Grip, Heavy Duty, and Super Blast Safety Air Guns. With such a wide range of available sizes and configurations, we can tackle just about any internal pipe cleaning application. If you have a process in your facility that may benefit from the use of one of these nozzles, give us a call and get one on order today!

Jordan Shouse
Application Engineer

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EXAIR Celebrates Manufacturing Day With A Win For A Manufacturer

In 2012, the National Association of Manufacturers organized an effort to proclaim the first Friday in October (hey, that’s today!) as Manufacturing Day.  According to the Advanced Manufacturing National Program Office (a division of NIST, the National Institute of Standards & Testing,) the purpose of MFG Day is “to raise awareness among students, parents, educators and the general public about modern manufacturing and the rewarding careers available.”

Today is kind of a big deal around here.  Not only is EXAIR Corporation a manufacturer, but many of the companies that use our products are as well.  A lot of us have a rich story, woven into the cloth of the history of American manufacturing (which, in turn, is woven into the larger cloth of American history.)  Have you heard the one about the motivated inventor with an idea to make innovative products who started an operation out of his home that, with inspired direction & vision, became a worldwide leader in their industry?

Yeah; that’s us.  Today, we’re honoring Roy Sweeney’s legacy (he founded the company in October 1983,) and celebrating MFG Day, by publishing a new Case Study, proving out the benefits of the use of EXAIR Intelligent Compressed Air Products in regard to the monetary savings associated with the reduction in compressed air use, and the noise level reduction from the implementation of our engineered products.

You can download the complete Case Study here, but while we’re on the subject, here’s a basic rundown:

  • A roll forming operation used to blow off their product with a combination of loud and inefficient devices: copper tubing and modular flexible hose which is designed primarily for machine tool coolant, but often misapplied for use with compressed air.
  • It worked just fine, but an engineering study noted it as a potential wasteful use of compressed air.  That’s when they called us.
  • By replacing those blow offs with Model 1100 Super Air Nozzles and Model 1122 2″ Flat Super Air Nozzles, their noise levels dropped from 107 dBA to 83.8 dBA.  To put that in perspective, it went from the approximate sound level of a rock concert to that of a leaf blower. (ref: Centers for Disease Control & Prevention: What Causes Hearing Loss?)
  • Compressed air consumption dropped by more than half, from 190 SCFM to 86.8 SCFM…an annual savings of over $3,200.00.  All for an investment of $654.00 (2020 pricing) for those engineered Air Nozzles, Stay Set Hoses, and Magnetic Bases.  That means they’ll have paid for themselves in just under two months.
  • In addition to that, for participation in this Case Study, we’re giving them a generous credit on their order.  Happy Manufacturing Day!

And frankly, I think the engineered products just look better too.

Last but certainly not least, this reduction in compressed air usage decreases the load on their air compressors, reducing the electrical power consumed.  Product impact, along with our own consumption of resources and waste recycling, is a key component of EXAIR Corporation’s Sustainability Plan.  We’re making the world a better place, by making products that make the world a better place, using methods that make the world a better place.  I can’t think of a better way to celebrate Manufacturing Day.  If you want to get in on it, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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MFG Day logo courtesy of nist.gov

Six Steps to Compressed Air Optimization: Step 3 – Use Efficient and Quiet Engineered Products

Compressed air is expensive, and you should treat it that way.  Frequent readers of the EXAIR Blog are familiar with our Six Steps to Compressed Air Optimization, and you may have seen these recent installments on Steps 1 and 2:

Six Steps to Optimization: Step 1 – Measure the Air Consumption

Six Steps to Compressed Air Optimization: Step 2 – Find and Fix Leaks

Now, there isn’t a strict order in which you MUST perform these steps, and they’re not all applicable in every air system (looking at you, Step 5: Use Intermediate Storage,) but these are likely the steps that a certified auditor will take, and the order in which they’ll take them.  If you’re looking for immediate, quantifiable results, though, Step 3 is a great place to start.  Consider:

  • A 1/4″ copper tube blow off can consume as much as 33 SCFM when supplied with compressed air at 80psig.  It’ll give you a good, strong blow off, for sure.  You can crimp the end and get that down to, say, 20 SCFM or so.  Or, you can install a Model 1100 Super Air Nozzle with a compression fitting, and drop that to just 14 SCFM.
    • If you’re tracking your compressed air usage, you’ll see that replacing just one of them saves you 45,600 Standard Cubic Feet worth of compressed in one 5 day (8 hour a day) work week.  That’s $11.40 in air generation cost savings, for a $42 (2020 List Price) investment.
    • If you spend time in the space where it’s installed, you’ll notice a dramatic improvement in the noise situation.  That sound level from the copper tube is likely over 100 dBA; the Super Air Nozzle’s is only 74 dBA.

This user was only a handful of compression fittings & nozzles away from over $800 in annual compressed air savings.

  • Drilled pipes are another common method to create a blow off.  They’re easy & cheap, but loud & expensive to operate.
    • A pipe drilled with 1/8″ holes and supplied @80psig will consume 13 SCFM per hole, and the holes are typically drilled on 1/2″ centers.
    • An EXAIR Super Air Knife consumes only 2.9 SCFM per inch of length, and because it’s an engineered product, it’s a LOT quieter as well.  Drilled pipes are, essentially, open ended blow offs just like the copper tube mentioned above.  When you let compressed air out of a hole like that, all the potential energy of the pressure is converted to force…and noise.
    • Drilled pipes are among the worst offenders; almost always well in excess of 100 dBA.  Super Air Knives generate a sound level of only 69 dBA with 80psig compressed air supply.  They are, in fact, the quietest compressed air blowing product on the market today.

This Model 110048 48″ Aluminum Super Air Knife replaced a drilled pipe for over $5,000 annual compressed air savings.

These aren’t just theoretical “for instances” either – the data, and the photos above, come from actual Case Studies we’ve performed with real live users of our products.  You can find them here, and here (registration required.)

These are two examples of EXAIR product users who only used Step 3 of our Six Steps, although BOTH of them were already practicing Step 4 (Turn off the compressed air when it isn’t in use)…they had their blow offs supplied through solenoid valves that were wired into the respective machine controls, and the Air Knife user HAD to do Step 6 (Control the air pressure at the point of use) to keep their product from being blown clear off the conveyor..

But we’ll be happy to help you with optimizing your compressed air system using any or all of the Six Steps. Give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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