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’s Flat Super Air Nozzles Serve a Variety of Applications

EXAIR’s line of 1” and 2” Flat Super Air Nozzles are rugged, efficient, and ideal for applications that require a wide forceful stream of airflow. The patented design utilizes a special shim to maintain the critical position of the component parts. The result is a laminar, high velocity blast of air with minimum air consumption and sound level.

The Flat Super Air Nozzles are available in a wide range of configurations. With both the 1” and 2” sizes you have the ability to select either Zinc Aluminum alloy or Type 316 Stainless Steel for higher temperature or corrosive applications. They’re also available installed at the end of our Safety Air Guns. The 1” Flat Super Air Nozzles are ideal for our VariBlast Compact Safety Air Gun while the 2” is suitable on either our Soft Grip Safety Air Gun or the Heavy Duty Safety Air Gun. With extensions ranging from 6”-72” and Chip Shields also available, you have the ability to tailor a blowoff gun to your exact application. Since the design of the nozzle prevents any chance for it to be dead-ended, all configurations will be compliant with OSHA directive 29 CFR 1910.242(b). This means you’re able to operate at pressures in excess of 30 PSIG without risking harm to your operators.

In addition to two different sizes and materials, there’s also a wide range of shims that can be installed. Just like the Super Air Knife, the thickness of the shim installed (in addition to the input compressed air pressure) will dictate the force and flow through the nozzle. For both the 1” and 2” Flat Super Air Nozzles, shim thicknesses are available ranging from .005”-.030”. Thicker shims will increase the force and flow, thinner shims will reduce it while also reducing the air consumption. To allow you to experiment with different flows, we make shim sets available that’ll allow you to test out a few different sizes in order to determine the best solution for your application.

EXAIR 1″ and 2″ Flat Super Air Nozzles can be fitted with a variety of shims for variable performance.

New to EXAIR in 2018, the Model 1144 2” Super Air Scraper is a patent pending nozzle used to remove stuck-on debris from work or machine surfaces. It incorporates a strong corrosion resistant scraper blade to add necessary leverage to allow you to get underneath and scrape away debris. The strong airflow from the 2” Flat Super Air Nozzle then is able to get underneath and blow away the material. The scraper nozzle is great for applications involving the removal of tape from floors, gaskets, adhesive, labels and stickers, grease, paint and sealant. It’s also available on the end of our Soft Grip Safety Air Gun with durable ¾” air extensions in lengths ranging from 6”-72” and Chip Shields.

You may have seen (or used) the plastic flat nozzles that come in a variety of different colors. EXAIR’s Flat Super Air Nozzle is a safe, efficient replacement that will maintain a similar airflow pattern at a dramatically reduced operating cost. EXAIR’s flat nozzles also offer a reduced sound level compared to these styles of nozzle. Reducing sound is another directive that OSHA 29 CFR 1910.95 outlines. If you’re using an unsafe nozzle in your facility, OSHA can quickly begin assessing fines for each violation. They don’t announce their visits beforehand, so make sure you do your due diligence and assess your compressed air usage yourself!

All of these possibilities are available from stock with same day shipments. EXAIR’s wide-range of solutions allow you to customize the product to your exact specifications. Stop wasting time and money replacing cheap plastic air nozzles, get yourself a nozzle that’s Built to Last by EXAIR!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_td

Benefits of Air Nozzles Replacing Coolant Lines used for Air

Over the years, EXAIR has come across many different types of blow-off devices.  We have seen copper tubes, pipes with crushed ends, fittings with holes drilled into them, and modular flex lines.  For compressed air use, these are very dangerous and very inefficient.

A plastic machining center was looking for a better way to blow compressed air.  They were using modular flex lines, similar to Loc-line, which are mainly designed for spraying coolant.  They had 14 blow-off lines in their plant that were about 18” (457mm) long and operated 8 hours a day at 40 PSIG (2.8 bar).  They liked the positioning feature of the flex line, but they could tell by the loud noises that they were wasting compressed air.  So, they contacted EXAIR.

When EXAIR started to manufacture compressed air products in 1983, we created a culture in making high quality products that are safe, effective, and very efficient.  With our Super Air Nozzles, we engineered a way to entrain the ambient air to add mass to the air stream to use less compressed air with a strong force.  This is done by the Venturi method.  We create a high velocity which will make a low pressure at the exit.  The surrounding air is drawn into the compressed air stream increasing efficiency.  We also engineered fins to support OSHA compliance in noise levels and dead-end pressure.  So, if your skin comes in contact with an EXAIR nozzle, the end will not be able to be blocked and allow air to penetrate the skin membrane; even above 30 PSIG (2 bar).  I went over the cost savings and safety solutions that EXAIR’s products could give.

EXAIR Super Air Nozzle entrainment

Since the modular flex lines had a ¼” (6mm) opening, I recommended the model 1100 Super Air Nozzle with a Stay Set Hose.  This recommendation is from experience with these types of blow-off devices.  The Stay Set Hoses will give them that possibility of manually adjusting and re-adjusting the Super Air Nozzles.  The hoses have a “memory” function and will not creep or droop until you physically move it.  They work well to direct air flows at specific target areas like the flex lines above.  For the company above, I recommended the model 1100-9218 which is a model 1100 Super Air Nozzle with an 18” (457mm) long Stay Set Hose.  It was easy to remove the flex line and replace it with a safer and more efficient product

Model 1100-9218

Now, let’s look at the savings.  The Super Air Nozzle with the 18” Stay Set Hose cost $92.00 each.  The flex line is generally around $10.00 each.  But this is not the total cost of ownership.  As an efficiency comparison, the model 1100 Super Air Nozzle will only use 8 SCFM (227 SLPM) of compressed air at 40 PSIG (2.8 bar); and, the noise level is reduced to 70 dBA for each nozzle.  At 40 PSIG (2.8 bar), the flex line had a noise level of 97 dBA and an air usage of 19 SCFM (538 SLPM).

For the annual savings and the payback period, I will look at the electrical cost.  (Since the Super Air Nozzle is using less compressed air, the maintenance and wear on your air compressor is reduced.)

  • The air savings is calculated from the difference in air usage; 19 SCFM for flex line – 8 SCFM for Super Air Nozzle = 11 SCFM savings per blow-off device.
  • With 14 flex lines, the total compressed air savings will be 11 SCFM * 14 = 154 SCFM.
  • To get into the cost, an air compressor can produce 5.36 SCFM/KW of electricity at a cost of $0.10/KWh.  For an annual savings, we have the figures from the information above; 8 hours/day * 250 days * 154 SCFM * $0.10/KWh * 1KW/5.36 SCFM = $5,746.27/year.
  • For a payback period, the model 1100-9218 has a price of $92.00 each, or $1,288.00 for 14 systems.  The flex lines were $10.00 each, or $140.00 total.  The payback period will be ($1,288 – $140) / ($5,746.27/year) * (12 months/year) = 2.4 months.  Wow, what a savings!

Not all blow off devices are the same.  With the customer above, they were able to cut their noise levels, remove the dead-end pressure concerns, and save $5,746.27 a year in compressed air.  If your company decides to select an unconventional way to blow off parts without contacting EXAIR, there can be many hidden pitfalls; especially with safety.  Besides, if you can save your company thousands of dollars per year as well, why go with a non-standard nozzle?  If you are using compressed air for blowing, cooling, cleaning or moving material; you should contact an Application Engineer at EXAIR.  What do you have to lose?

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