EXAIR’s E-Vacs are a great solution for many applications including pick and place, chucking, surface mounting, lifting, and vacuum forming. When selecting which is the right model for you, there are several points you need to consider. Although selecting the right vacuum cup size is important, and knowing the size and weight of the part is necessary, one of the main considerations is evaluating the nature of the material you are working with. Specifically, is the material porous or non-porous?
Porous materials, as the name suggests, have many holes in them. This will allow air to flow through them when trying to pull a vacuum. This can be a challenge when trying to use an E-Vac. To overcome this, you need a high vacuum flow. Non-porous materials, on the other hand, will not allow air to flow through them, so a higher vacuum level can be achieved with a low vacuum flow. If you know which category your material falls into, we can select the correct E-Vac.
If you are working with porous materials such as paper, cardboard, or some fabrics, we would recommend one of our vacuum generators that produces a low vacuum level and high vacuum flow. With vacuum levels up to 21” Hg and vacuum flows up to 18.5 SCFM, this style generates more vacuum flow to overcome the porosity and leakage. An additional benefit is that they can also be used to lift or hold delicate materials and prevent any warping or disfiguring of the surface due to excessive vacuum.
Alternatively, if your material is non-porous, like glass, steel sheet, or plastic, you will need a generator that produces a high vacuum level with lower vacuum flow. EXAIR’s non-porous high vacuum units can achieve vacuum levels of up to 27” Hg and vacuum flows up to 15.8 SCFM. These vacuum generators offer maximum holding capacity for heavy materials. Sizes are available with compressed air requirements as little as 2.3 SCFM at 80 PSIG and up to 30.8 SCFM for the largest and heaviest materials.
If you would like to talk to an Application Engineer to help you determine the best option for your application, give me a call!
EXAIR Intelligent Compressed Air Products incorporate several distinct principles of fluidics into our engineered designs. To be clear, these principles aren’t exclusive to making quiet and efficient compressed air products. I personally have used them all for business and pleasure over the years. In the Navy, for example, the air ejectors that pulled vacuum on the main condensers where our turbines dumped their ‘used’ steam were basically great big Venturis – they restricted the diameter through which a fluid (steam, in this case) flowed, gradually increased that diameter, and doing so, changed the velocity so that a low pressure area (or vacuum) developed in the throat:
Here are a few examples of Mr. Venturi’s discovery, implemented in modern industry.
I first learned about the Bernoulli principle on a grade school field trip to the National Air Force Museum at Wright Patterson Air Force Base, about an hour from where I grew up. See, this Bernoulli guy discovered that when there is an increase in the speed of a fluid, a simultaneous decrease in fluid pressure occurs at the same time. That’s why airplane wings are shaped like they are – flat on the bottom and curved on top…when the air flowing that extra distance over the top speeds up to get to the back of the wing as fast as the air that’s simply flowing underneath the wing does, the decrease in pressure on top causes the wing (and the plane it’s attached to) rise in the air.
Bernoulli’s Equation: this is the math that proves it works.
The Coanda effect is the third fluidics principle that’s incorporated into the design & operation of many EXAIR engineered compressed air products. Its namesake, Henri Coanda, was an early 20th Century aeronautical engineer who discovered that if a jet of fluid exiting an orifice flows across a surface, it’ll tend to not only adhere to and follow that surface (even if it curves or bends), but also entrain fluid from the surrounding area.
EXAIR Intelligent Compressed Air Products such as (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier all use the Coanda effect to entrain enormous amounts of air from the surrounding environment.
There are a couple of easy – and interesting – experiments that demonstrate the Coanda effect, both of which I used when I was a Cub Scout leader and our Pack’s Webelos den was earning their Science Activity Pin:
Turn a faucet on and let the running water flow over the convex ‘bottom’ of a spoon. Everything we know about the laws of gravity say that when the water reaches the ‘bottom-most’ point on the spoon’s convex surface, it ought to fall straight down…but it doesn’t:
Another experiment that defies everything we think we know about gravity can be performed with a ball, and a source of air flow. Here’s a short video, showing how the air flow from an Air Amplifier ‘wraps’ around a ball and holds it in that jet of air:
The Webelos den did this with a leaf blower and a playground ball. Unlike a lot of things I’ve done, I DEFINITELY encourage you to try THAT at home.
For forty years now, EXAIR has been putting these principles of fluidics into practice by engineering & manufacturing the most efficient, quietest, and safest compressed air products on the market. If you’d like to find out how we can help you get the most out of our products – and your compressed air system – give me a call.
Russ Bowman, CCASS
Application Engineer Visit us on the Web Follow me on Twitter Like us on Facebook
Years ago I was working with a pet food manufacturer who was having issues with their bag opening machine. The problem they had with their existing setup was the dust from manufacturing processes would get sucked into the venturi and start to decrease their performance. Hence, they needed a better solution that wouldn’t need to be replaced and could be cleaned.
Adjustable E-Vac
The bags were empty, and this vacuum generator was positioned to pull the bag open. The bags were made of a non-porous material as they had a coating on them and thus the actual action of opening the bag was not difficult. Enter dust through the throat of a small venturi, and it caused several downtimes that were not scheduled. When looking at the performance characteristics of their existing system I crossed that over to an EXAIR model 840008M – Adjustable E-Vac w/ Straight Through Muffler. This unit was able to open the bag and hold it open for their machine needs. The throat passage of the unit was also larger than their existing generator and the biggest benefit, the Adjustable E-Vac could easily be taken apart and cleaned. To see how easy they are adjusted, which is the same method used to take them apart, check out this previous video blog linked in the image below.
The process changed from changing an existing vacuum generator out, scrapping the old one, and putting in a new one to keeping two on hand. One (EXAIR Adjustable E-vac) that is in operation and functioning, then after a designated amount of time (predictive maintenance), they change it out for the spare (EXAIR Adjustable E-vac) vacuum generator. The second part of the process involves breaking the used one down (without the need for any specialized tools), to clean each of the three pieces on the unit. The refurbished unit is then reassembled, benchmarked for performance, and put on the shelf for the next maintenance cycle.
While this system uses the same volume of compressed air as their previous solution, we still save money in the amount of unusable replacements they were ordering with repairable units, allowing them to keep a working spare on hand. So it saves the customer money on the life of the product. A further benefit is the customer can also get the EXAIR Adjustable E-Vacs quickly as they are standard stock item for us at EXAIR and can ship the same day on orders received by 2 PM ET.
If you want to discuss how an Adjustable E Vac makes sense for you and your team, contact an Application Engineer today!
There are a number of ways to pick something up from where it is, move it to where you want it, and put it down. If it’s on a skid, you can use a forklift. If it’s got an eyebolt – or if you can get a strap or chain around it, you can use a crane…or a forklift, provided you can safely secure the strap or chain to one of the forks. Or, if there’s enough surface area for a suction cup to sit on, you can use vacuum.
The two most popular methods of that are vacuum pumps, and venturi-type vacuum generators. Both are capable of creating a high vacuum for secure attachment of the vacuum cup to the object, and both can generate enough vacuum flow, under moderate vacuum levels, to overcome vacuum leakage when picking up objects with porous or slightly irregular surfaces. In a facility with multiple ‘pick and place’ stations or operations that are some distance from each other, vacuum generators are an inexpensive and easy solution, as they can be installed right at the point of use. If the points of use are relatively close together, though, it can make sense to consider a centralized vacuum pump from an operating cost standpoint…the electricity to run the vacuum pump’s motor is oftentimes cheaper than the compressed air to run the vacuum generators. Vacuum pumps still require a lot of maintenance, and when they break, they’re notoriously expensive to fix, so maintenance cost and reliability are important considerations as well.
EXAIR E-Vac Vacuum Generators are compact, single-stage venturi products that generate rated vacuum on demand. With no moving parts to wear, or electrical components to burn out, they address the concerns I just mentioned about maintenance costs and reliability of electric-driven vacuum pumps. E-Vacs are available in three basic configurations:
High Vacuum: These are capable of generating up to 27″Hg vacuum levels, and are specified went the object to be lifted has a smooth, non-porous surface for the Vacuum Cups to pull down on. With that kind of tight seal and high vacuum level, they’re effective, safe, and reliable.
Low Vacuum: Why would you not want the vacuum to be as high as possible? Well, if you’re picking up something with an irregular surface, or if the material is porous, you’re going to have leakage past the lip of the Vacuum Cup, or through the pores of the material, meaning you won’t be able to get that high of a vacuum in any case. EXAIR Low Vacuum E-Vacs are specified for lifting objects like this. They generate sufficient vacuum (up to 21″Hg) and enough vacuum flow at those levels to overcome the leakage for the same effective, safe, and reliable operation as their High Vacuum counterparts.
Adjustable: These offer a combination of the benefits of the High and Low Vacuum Generators. By threading the plug in or out of the body, you can control the amount of vacuum – and vacuum flow – that they generate. This can be particularly beneficial if your system needs to pick up a variety of loads. They also have a larger throat diameter, so if you’re picking up something with dust or other contamination on the surface, it won’t clog up like an In-Line model (with a much smaller throat) would. These are commonly used for work holding tables as well, since those are almost always pulling in particulate from the surface.
From a lightweight manual operation to an automated system with large or heavy objects, the EXAIR E-Vac Vacuum Generators can solve the application.
Once we’ve determined the appropriate style of E-Vac Vacuum Generator for the application, we’ll move on to specifying the correct Vacuum Cup(s). EXAIR offers a wide variety of these, from small Bellows style Cups as small as 3/4″ in diameter, to round Vacuum Cups ranging in diameter from 1″ to 6″. We use this table from our catalog to determine how many of which Vacuum Cup to use. They’re rated for the amount of weight each Cup is capable of lifting, at specific vacuum levels.
Several factors come in to play here – the number of Vacuum Cups you’re going to use, the vacuum level required, and which specific Vacuum Cup(s) are most suitable for the particular object.
For example, let’s say we need to pick up a solid object with a flat, smooth top that weighs 5 pounds. We’re going to apply a 2x safety factor, so we’re going to select a Vacuum Cup rated for at least 10 pounds, and since the surface is flat & smooth, we don’t expect a need to overcome any vacuum leakage, so we’ll use the rating at 27″Hg. In this case, we can use a Model 900764 Oval Vacuum Cup, which are rated for 10 pounds at 27″Hg.
If it’s a small-to-medium sized object with a round or square top, you can usually just use one Vacuum Cup to pick it up. For larger objects, you’ll want to use multiple Vacuum Cups to keep it balanced. Let’s say our 5 pound object is a thin plate that’s long and narrow. For that, we can use two Model 900752 1″ Small Round, or two Model 900767 1″ Round Bellows Vacuum Cups (both rated for 5.2 pounds each at 27″Hg), spaced out appropriately for the length, to safely pick and place the object.
If the object’s top surface isn’t smooth & flat, and/or if the material is porous, we’re going to select Vacuum Cup(s) that are rated for the weight (again applying a 2x safety factor) at a lower vacuum level. Let’s say our 5 pound object is a cardboard box. We know a Low Vacuum (Porous) E-Vac can create a vacuum of up to 21″Hg (with no vacuum flow) or 15″Hg with a moderate amount of vacuum flow to overcome leakage. We can use one Model 900754 2″ Round or Model 900769 2″ Bellows Vacuum Cup, which are both rated for at least 10 pounds at 15″Hg. We could also use two Model 900764 Oval Vacuum Cups, since they’re rated for 5.5 pounds each at 15″Hg.
If you’d like to find out more about generating vacuum with compressed air, or if you’d like help in specifying the right E-Vac(s) and Vacuum Cup(s) for your application, give me a call.
Russ Bowman, CCASS
Application Engineer Visit us on the Web Follow me on Twitter Like us on Facebook
