Tag: Tool Cooling System

Air conditioners of various types utilized in the USA or Canada are required to meet certain safety standards with similar requirements in most other parts of the world. This is extremely important for industrial applications where they are used as enforcement but by authorities and within companies themselves is on an increasing trend.

Legal requirements governing the use of electrical equipment may sometimes appear complex, certain compliance requirements are clear and universally apply to electrical enclosure coolers.

The most important are the following:

OSHA and NEC Standards

The Occupational Safety and Health Administration (OSHA) governs safety and health in the American workplace and are used as a guide in many other countries many which have similar regulations. In 1971 the National Electric Code (NEC) was incorporated within the Construction Safety and Health Standards of OSHA and therefore all electrical equipment must also conforms to both the safety requirements of OSHA and the NEC. Vortex tube operated control panel air conditioners operate with compressed air. However, they often use electrically operated solenoid valves and thermostats, either as individual pieces or packaged together and these items themselves must meet these safety standards. If a solenoid valve for example is modified, it may be breaking a code. An example of this is drilling a hole in a solenoid to allow for some compressed air flow into an enclosure to keep it purged of environment air instead of using a separate air line for a bypass.

Local Authorities Having Jurisdiction

The Authority Having Jurisdiction (AHJ) that operates locally in the USA is responsible for enforcing local building codes and ensuring compliance. Many of the codes in force by the local authorities are based on the NEC, also known as the NFPA 70. However, others may add local addendums or use their own specific codes.

In all cases, before an installation can be energized the installation must be signed off by a local inspector mandated by the AHJ.

Increasing Importance of Nationally Recognized Testing Laboratories

To ensure that electrical equipment conforms to the relevant codes is to have the equipment certified by a Nationally Recognized Testing Laboratory (NRTL). This certification will be accepted by the AHJ. There are more than a dozen NRTLs licensed in the USA but the most well-known are UL (Underwriters Laboratory) and CSA (Canadian Standards Association).

Before selecting enclosure cooling equipment, make sure that the equipment has been certified and carries the NRTL certification mark. These testing laboratories do more than just “test”. They ensure that the materials used in the products meet a certain standard of quality. One issue with vortex cooler “knockoffs” for example is not only potentially poor quality, but also the use of below standard materials and parts that require a certain level of testing and approval. Anything below “standard” is risky with anything electrical or electronic.

Specific Canadian Requirements

Enclosure cooling systems sold in Canada must conform to the Canadian Electrical Code Part 1. The Canadian Standards Association (CSA) and certain other testing laboratories such as UL are accredited. There are some variations in test requirements and levels of acceptance between the USA and Canada to distinguish between American and Canadian certifications.  UL for example puts a prefix C next to their mark and refers to both the USA and Canada approval. Sometimes both a C and US prefix and suffix is used to identify that the product is tested to the standards of both jurisdictions. It’s important to understand this difference so as to avoid the possibility of installing equipment with the incorrect certification for your region. CSA is based in Canada and again does the same with prefix or suffix identification to indicate approval for one or both jurisdictions. Nex Flow Panel Coolers have been tested and approved by UL to meet both Canadian and USA standards and bear the appropriate mark.

Hazardous Areas

Equipment designed for use in a hazardous area must also be certified as such. Your enclosure cooler must conform to the specific hazardous area rating applicable and must be compatible with the rating of the enclosure on which it is used. Proper wiring and connections should be particularly checked.

NEMA Type Enclosure Rating for the Enclosure and Area

The enclosure cooling system used must have the same or better  NEMA Type enclosure rating than the electrical enclosure itself. These NEMA Type ratings indicate the design level of the enclosure and the cooling system. For example NEMA Type 4 enclosures are suitable for applications and environments where the panel is subject to wash down. The vortex cooler (or whatever cooking is used) needs to be same or better for that wash down environment. Europe uses IP ratings. Various sources can provide the IP rating that is equivalent to the North American NEMA Type rating. Vortex Coolers like the Nex Flow Panel Cooler have versions tested and approved for NEMA 12 (IP 54), NEMA 3R (IP 14) and NEMA 4-4X (IP 66) applications.

In the U.S. and Canada, it is mandatory for certain equipment to carry the mark of an approved testing laboratory, and an enclosure air conditioner is on the list. Verify before you buy and be safe by using properly certified parts and equipment.

The Nex Flow Difference: Why we treat our materials differently?

Nex Flow Air Products Corp. sets itself apart from its competitors by doing a few things differently with the materials that we use in manufacturing our products. While some producers are actually quite similar in product as to how they deal with material, we stand out in four specific areas as to what we do with the materials of manufacture. Differences for Nex Flow are as follows:

1. Anodized aluminum parts
2. Powder coated parts
3. No Plastic in our vortex tubes
4. We do not mix aluminum and stainless steel in our vortex tube packages

Anodized Aluminum parts

We make it a point to anodize our aluminum air knives, amplifier, air jets, air wipes and air operated conveyors.

It is actually much easier (and certainly less costly) to produce these items without anodizing due to the importance of efficient aerodynamic design. When the products are anodized the surface changes, even if the change is very small, it makes it more difficult to keep a flat part flat (i.e. air knives). But, we CAN do and we do it because of the value the anodizing adds benefits to the products.

Anodizing helps guard against the effects of the factory environment on the aluminum. Unprotected aluminum will form a powdering while oxide over time. Anodizing keeps the product looking better and longer even when using dissimilar metals in assembly, stainless shims, stainless screws, with aluminum bodies, it protects the accessories from even minor effects of cathodic corrosion.


Cathodic corrosion can occur in a highly humid environment or if the parts get wet. Dissimilar metals can act like a battery where the more active metal can corrode unless there is some form of protection. You can see this effect, for example, with rust around screws used on some buildings or machines because the screws are of one material while the metal it is screwed into is another. When paint wears away, it leaves unprotected metal that is more electrically “active” than the metal in the screw. By anodizing and protecting our product, Nex Flow ensures that our accessories will last longer and look better over time.

Powder Coated parts

Some of our cast zinc parts, specifically our Air Edger flat jet nozzles and cast Fixed X-Stream Air Amplifier, also have powder coating. It provides a much better finish and look to the product and again, extra layer of protection from the factory environment. Powder coating is an excellent protection in a factory environment. Powder coating parts adds intrinsic value to the products to the betterment of the customer providing a product that is longer lasting look better through time.

No Plastic in Vortex Tubes

Most manufacturers of vortex tubes use injection molded plastic “generators” which are used in the unit to initiate the compressed air spinning effect. Nex Flow machines their “brass” generators for that purpose instead of plastic. While plastic would be much less costly, brass offers a few advantages. Injection molding plastic will have some variations in production, especially as the mold wears out. By machining the metal generators we have much greater consistency with the parts which translates into much greater consistency in performance from one vortex tube to the next. Vortex tubes consist of several parts and of course, each part has a certain tolerance in manufacturing. Nex Flow has very tight tolerances on each part and the generators especially require very tight tolerances. The more pieces involved in assembling a part, the more the cumulative effect on the overall variation in tolerance and therefore performance since the operation of all Nex Flow products are based on aerodynamic shapes.

As the generator is such a critical component in a vortex tube, we recognize the need to use metal instead of plastic. Another advantage of using metal, in our case brass, instead of plastic is that plastic can possibly crack over time. If the compressed air supply is dirty the generator can also build up dirt and engrain itself, hence requiring replacement. The metal ones we use are easily cleaned. Sometimes vortex tubes or their packaged versions are used in very hot environments so the parts must be able to hold up in high temperature areas, especially when not operating. In these cases even competitive units replace their plastic generator with metal. Nex Flow vortex tubes and many of their packages are therefore more flexible in the environments where they can be used. While competitors would charge extra for a special product, our standard product can generally be used instead.

We do not mix Aluminum and Stainless Steel

Our vortex tube packages include tool coolers, mini coolers, adjustable coolers, panel coolers, etc. Of particular importance is the materials used in a panel cooler used for cabinet enclosure cooling and camera cooling. Many manufacturers will use a stainless steel vortex tube packages as a control panel cooler using aluminum housing and attachments. While not a problem in relatively benevolent factory environments, it can become an issue in very humid area or in applications where they are used in wash down conditions. Cathodic corrosion can occur described earlier with dissimilar metals with air knives. On one visit to a customer there was actually a competitive vortex tube cooling system with a big hole on the side of the assembly. Cabinet cooling applications are very critical because you do not want any possibility for moisture getting into the control panel. This is the reason vortex coolers should have the proper approvals to insure this does not happen (such as Underwriters Laboratory testing and approval).

Cabinet Coolers are essentially vortex tubes with a cover and some system to prevent moisture from getting inside of the cover and possibly then into the cabinet. This cover was aluminum and the vortex tube another material. The environment was a relatively wet environment, so over time cathodic corrosion cause the aluminum to corrode and create a hole in the protective cover. Thus, creating a potential risk for water to get into the electrical cabinet. It is for this very reason (preventing cathodic corrosion) that Nex Flow only has stainless steel covers for their stainless steel vortex tubes.

Similarly with all other packages systems, whether they are tool coolers or adjustable coolers, the packages are made with stainless steel only and not a mixture of stainless steel and aluminum.

It’s a Wrap

These are some of the reasons why Nex Flow treats their materials differently. While some of these “differences” in material handling and treatment can be more costly from a manufacturing point of view, they do offer significant added value to the products and a benefit to the customer, and still with a very competitive price.

When Should I Consider Using Vortex Tubes for Spot Cooling?

Vortex tubes create a stream of cold air from compressed air.  When discussing spot cooling we want to specify that it is a “small spot”, and not a large area such as would be addressed by a big fan for example.  We want to focus on a small area from a tiny “spot” to a few square inches, or to an enclosure which can be much larger to a maximum of around 10 square meters, although there are exceptions.

Such “spot cooling” is needed when heat at that spot is either causing a problem in production or, if production can be improved by cooling. The most common “enclosure cooling” is the cooling of electrical and electronic control cabinets that have potential overheating issues and/or where there are dirt problems due to an unfriendly factory atmosphere inside the enclosure negatively affecting performance and potentially the life of the electrical equipment.

One major “spot cooling” application is the cooling of cutting tools during cutting, drilling, or routing process.  Traditionally cutting fluid is used in machining but there is a slow but steady movement to “dry” or “near dry” machining because of the increased safety and especially environmental concerns involved with cutting fluids. Cutting fluids need to be properly disposed of, so there are costs of not only buying the fluid but also the disposal of the fluid.  One of the reasons progress is somewhat slow in adapting to dry machining is that cutting fluid not only cools, but also lubricates and cleans the machine tool as it operates. This is where mist cooling systems can come in handy because it is not completely dry allowing lubrication but limits the need for cutting fluid. That being said, dry machining is actually necessary for some materials such as glass, plastic, ceramic and titanium. Vortex Tubes produce the cold air which is blown onto the cutting tool to keep heat down and actually produce a better cut and speed up the machining operation.  Often these vortex tubes are packaged with an easy to mount system such as the Nex Flow Tool Cooler. 

In some machining application, as when a hole must be drilled deep into a part, some lubrication is required.  Nex Flow developed the patented Mist Cooler to provide the necessary lubrication by misting lubricant “cooled” by the vortex tube.

There are of course many other systems developed and being developed to spot cool for machining and eliminate coolant using inert gas for example but the vortex tube is also an integral part in many of developments because they only use “air” and cost in comparison is usually much lower.  Cooling gas samples in gas analyzers is another good application for vortex tubes. Industrial camera and all sorts of sensors are used in production more and more, and many of these devices are in very hot areas on a production line. Vortex tubes are compact enough to be used to cool these products and keep them functioning effectively and with no maintenance compared to any other alternative.

Other spot cooling applications addressed by vortex tube technology are numerous and limited only by imagination. Some applications for vortex tubes include cooling the nip roll in a plastic converting process for example to prevent sticking, cooling the head of lasers to prevent heat buildup, setting hot melt adhesives so the glue dries faster and to maximize throughput.

Alternatives in such applications can be much larger in size but vortex tubes are very small. Larger size also typically  translates into larger capital cost. As vortex tubes have no moving parts, their maintenance is virtually zero and as long as the compressed air is filtered, their life is as long, or even longer than the equipment they are used with. Compact, zero maintenance and low cost are the key advantages of using vortex tubes for spot cooling over other alternatives.

Utilizing vortex tube technology for cooling enclosures is another major application.  There are many ways to cool electronic enclosures and other enclosures with traditional air conditioners.  However, factory environments can range from quite benevolent to very harsh. A carbon producing facility will be very dusty.  This dust can easily get into control cabinets and cause havoc to the electrical components inside. The limitation on the use of vortex tubes is the amount of compressed air available in any facility.  The cost is also a major consideration as compressed air is costly. Where vortex tube based products such as the Nex Flow Panel Cooler become an advantage is when the increased energy cost offsets the cost savings in equipment maintenance costs in both material and time, and in offsetting damage to the controls.  It is for very hot, humid or harsh factory environments, that increased energy cost of vortex tube cooling systems can be offset by the savings in maintenance time, materials, disposal of filters and improved control life because they keep out the nasty environment from the cabinet enclosures.

Vortex tube controlled cabinet coolers, like the Nex Flow Panel Cooler, have proper electrical certification to assure that no moisture can enter the cabinet. For example, the Nex Flow Panel Cooler models are available to mount onto cabinets with NEMA 12 (IP 54), NEMA 3R (IP 14) and NEMA 4X (IP 66) classifications.

Vortex tubes for these small “spot” and such “enclosure” applications are both a cost-effective and simple solution where cooling is required.

Vortex tubes are ideal for spot cooling and enclosure cooling.  Typically one vortex tube is used for one “spot” and for “one” enclosure.  But there are some situations where one vortex tube can be split into multiple “spots” as long as one important criteria is kept in mind.  Once the compressed air exits the vortex tube it needs to be directed to the area that needs the cooling.  When the vortex tube is out in the open, this is achieved by adding a delivery tube, usually flexible tubing to direct the cold air to that spot.  When cooling an enclosure, the cold air is sent directly into the enclosure from inside the enclosure. Once the air exits inside the enclosure it can be further distributed around the enclosure thru tubing but all the cold air is input into the enclosure.

Two factors that must be considered when using the cold air produced in a vortex tube: conduction and pressure drop.  The general rule it to keep any tubing on an open space vortex tube as short as possible, preferably under 8 inches. One example where a vortex tube has been used in open space for multiple locations is on routing a plastic part.   Once Nex Flow Model 50030H vortex tube had the cold air split into two directions and delivered to cool two routers. Rather than using one vortex tube for each router, one larger capacity vortex tube was utilized. If two separate units were used, they could have been smaller capacity units (Model 50015H), each which is ½ the capacity of what was used.    What made this work was delivering the air with large (10 mm) tubing to offset pressure drop and keeping the distance as short as possible (under 8 inches to each router). Also, the tubing was insulated to minimize the effect of conducting heat from the surroundings into the tubing, heating up the cold air. There was consideration for using two vortex tubes but there were also space issues with the application.

But this is not a common application.  If the distance they had to cool was much longer from the vortex tube, we would have recommended two of the smaller capacity vortex tubes.  There is another consideration when considering the use of vortex tubes for multiple location cooling. Let’s take the example above. If the distance from the vortex tube was only a few inches more, to get the same cooling effect at the router, we would have had to use a larger capacity vortex tube, a Model 50040H.  That extra 10 SCFM of compressed air use costs energy. That extra energy cost would more than pay for the extra vortex tube in a very short time, and even if used sparingly, certainly in under a year. The increased operating cost, even with minimal use, can easily be equal to or more than the capital cost of one additional unit.

Concerning enclosures, more than once we had to address an issue with cooling when a Nex Flow Panel Cooler, instead of being attached directly to the control panel. Was for some reason mounting off to one side, and a tube was attached to the bottom of the Panel Cooler and then put into the control panel.   Needless to say, the unit did not cool as was expected because the cold air heated up several degrees before it reached the control panel. The Panel Cooler has a built in vent to exhaust the displaced hot air inside the cabinet and of course was not used at all when mounted outside. If you are facing any difficulties with installation – please do not hesitate to contact one of our engineers.

Another thing to remember when installing a vortex tube or a vortex tube operated device like the Panel Cooler, onto an enclosure that it must be installed at the top, or if space is lacking, near the top using a side mount.  The reason is that cold air falls and hot air rises. The reason a distribution tube is used at the end of a Panel Cooler is to distribute the cold air faster to isothermalize the cabinet (even out the temperature) more quickly.  If the vortex tube device is mounted too low, the hot air will tend to stratify at the top of the inside of the enclosure.  

When considering any vortex tube operated device – cabinet enclosure cooler, tool cooler, spot cooler, mini cooler or the vortex tube itself, it is best to keep any attachment at the cold end as short as possible when the product is in open space.  When attached to an enclosure of any type, the cold air should be directed directly into the enclosure, near or at the top.

Galvanic Corrosion – What it is and how to prevent it?

Galvanic corrosion (also called bimetallic corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte.  This occurs in batteries for example where the cathode stays whole and the anode corrodes as the battery is working. Contrary to some believes – Galvanic corrosion does not only occur in water. Galvanic cells can form in any electrolyte, including moist air or soil, and in chemical environments. As an example, Over 200 years ago, the British naval frigate Alarm lost its copper sheeting due to the rapid corrosion of the iron nails used to fasten copper to the hull. The electrolyte in this case was salt water creating a galvanic cell.

In the case of the Alarm, the iron acted as an anode and was corroded at the expense of the copper which acted as the cathode. Just two years after attaching the copper sheets, the iron nails that were used to hold the copper to the ship’s underside were already severely corroded, causing the copper sheets to fall off.

Metals and metal alloys all possess different electrode potentials. Electrode potentials are a relative measure of a metal’s tendency to become active in a given electrolyte. When in the same environment, the more active a metal is likely it is to form positively charged electrode (anode) and the less active metal is more likely it is to form a cathode (negatively charged electrode).

The electrolyte acts as a conduit for ion migration, moving metal ions from the anode to the cathode. The anode metal, as a result, corrodes more quickly than it otherwise would, while the cathode metal corrodes more slowly and, in some cases, may not corrode at all.

 

The Nex Flow Difference Allowing Products to Last Longer than Competitors

While products such as air knives, air nozzles, air amplifiers, vortex tubes, etc. are not necessarily immersed in any electrolyte, if the environment is humid, or if the equipment is subject to wash down procedures, it is very possible that this type of corrosion can occur.  One example is mixing stainless steel and aluminum. There was one example where a competitive cabinet enclosure cooler was observed with a big hole on its side after some years of use. The stainless steel vortex tube inside combined with the aluminum housing, and the factory environment, over time caused the aluminum to act as an anode and started to corrode.

Nex Flow® takes certain steps and actions to prevent this from happening in their products allowing the products to last longer.  The first is to protect aluminum that is used, especially if combining it with steel or stainless steel. Our aluminum air knives for example – are anodized and as such have a protective coating to prevent an “electrical circuit” with the stainless steel shims used inside and the stainless steel screws used to hold the air knife together. In addition, the aluminum would tend to act as an anode anyway in an electrolytic environment and being so large compared to the stainless steel shim corrosion would be minimized. Regardless of whether galvanic corrosion would occur, the anodization also protects the air knife from any environment which bare aluminum is unprotected.  Similarly, Nex Flow anodizes all their aluminum parts – air knives, air jets, nozzles, air wipes and air operated conveyors such as the Ring vacs. Air amplifiers and flat jet nozzles which are aluminum zinc-cast are powder coated for longer life and also look better.

When it comes to vortex tube technology, such as cabinet enclosure coolers (panel coolers) and tool coolers, no aluminum is used. It is stainless steel with some brass internal parts. This works to ensure that you will not find any holes in Nex Flow Panel Coolers caused by galvanic corrosion ever. So when shopping for products to blow off, clean, move, and cool, look not only at the performance data, design and workmanship – all which are important of course – but also refer to the quality and type of material used in construction. You can also refer to this article on how to avoid galvanic corrosion. Remember that materials used and how they are put together does make a difference.

Vortex tubes are devices that take compressed air and spins it inside the unit creating a spinning air flow in one direction and spins the air flow back in the opposite direction within the first spinning air flow. Part of the air flow is out one end and gets hot, and the internal spinning flow that is let out the opposite end gets cold. It basically acts like tube in tube heat exchanger.

Air input the vortex tube is normally 80 to 100 PSIG (5.5 to 6.2 bar). The air exiting at each end of the vortex tube goes back to atmospheric or at least to a much lower pressure.  In considering what you can or cannot attach to vortex tube, you must first consider these realities:

1. You need a pressure difference between the inlet air to the unit, and the exit points.  If there is no significant difference then the system will not work.
2. The percentage of the air out the cold end is called the cold fraction. For example, if 80% of the inlet air exits the cold side the cold fraction is 80% and the hot fraction (air out the hot side) is 100-80 = 20%.  If you add anything to the cold end, there will be a back pressure. This will affect the cold fraction by pushing more air out the hot side thereby reducing the cold fraction. So there is a practical limit of how much back pressure can be tolerated by attaching anything to the cold end. The ultimate limit is a back pressure that pushes all, or almost all the air out the hot end negating any effectiveness for cooling.
3. Similarly if you attach something to the hot end there will be back pressure pushing more air out the cold end.  The limit would be if all the air is pushed out the cold end – it negates most or all of the cooling effect.
4. Because compressed air exit at both ends, and at a pressure close to atmospheric pressure, a vortex tube is intrinsically safe from over pressurizing, the ultimate supply pressure limited to material integrity (in the case of Nex FlowTM made products, to 250 PSIG).

So when attaching any other accessory to the vortex tube the concepts above need to be considered.  Rarely is any attachment made to the hot air exhaust end except for muffling accessories with minimal back pressure. Even in pre-packaged vortex tubes such as Tool Coolers or Panel Coolers, back pressure is very minimal and typically balanced at the cold end with other attachments such as hose hits or air distribution hose with similar back pressure effects, essentially balancing the system. However, if you examine more closely the cold end attachments, which tend to vary the most, there is a limit there as well. When attaching a hose kit such as locline or similar type of hose, the longer the length the more the back pressure.  Locline hose is used extensively with Tool Coolers. The general rule is to limit the locline to 12” and under and to make sure the opening nozzle has at least a 1/8” opening.  This keeps the back pressure low. Also, the longer you make this attachment, the air will tend to warm up more because of the conduction of atmospheric temperature through the plastic hose to the inside. So practically, the longer the hose, the higher the temperature (less cold air) exiting. In the case of a control Panel Cooler, there is a hose distribution kit supplied which is basically a long PVC hose with a muffler to attach to the end.  Instructions stipulate to create inside this long hose to have at minimum of four (4) holes of 1/8” diameter drilled into the hose to let the air out and blow the cold air from the vortex tube onto the hot parts inside the cabinet. This accelerates the cooling of the inside of a control panel.  Again, the minimum number of holes is required to minimize the back pressure (and also to help iso-thermalize the control panel faster). If the holes are not drilled, the cold air will exit only at the exit of hose end and with the added back pressure will restrict the flow, hence negatively affect the overall cooling rate (slows the process of equalizing the cabinet temperature). The hose addition onto a Panel Cooler also acts as a backup in case of a very remote possibility of any moisture getting into the panel in the very rare case that the filter on the inlet air fails. There are instances where a vortex tube has a hose attached to the cold end to deliver cold air at a long distance for other applications.  It is important to simply use a larger inside diameter hose, the longer the length to minimize back pressure and if possible insulate the hose from conducting heat into the hose, warming up the cold air travelling inside. Care should be taken that the cold end hose is not fully plugged because while the back pressure will force air back out the hot side, any weakness in the hose may also cause it to split and may be dangerous as a result.

The question frequently arise is if it is possible to attach a vortex tube cold air output to the inlet to a blow-off accessory like air knife or an air amplifier (or any other air amplifying or conveying device).   The answer is – it cannot be done simply because of the back pressure requirement of the vortex tube (#3 above). Any air amplifying device requires the air inlet to have high pressure.  For a vortex tube to work, the air exit pressure from the vortex tube must be low.  So attaching a vortex tube to the air amplifying product will just not work.

But…. the possibility of an alternative approach does come up.  There have been a few attempted applications, where the air exiting the cold end of a vortex tube is placed near the air entraining end of an air amplifier such as an air jet or small air amplifier like an FX10, or FX20 or even an FX40.    Successful results are rare however, and not confirmed, due to how air amplification technology works. The air drawn in by an air amplifier is depends on the amplifier size. For example, an FX10 will amplify air flow about 6.5 times and consumes 4.9 SCFM at 80 PSG.  That means it will draw in a volume of 27 SCFM. (6.5-1 = 5.5 multiplied by 4.9). So if you place a vortex tube cold end “close” to the air entraining end the amplified air can be cooled. Even then, much of that cold air will already be mixed with warmer atmospheric air reducing the cold temperature.  And, at the outlet of the amplifier about another 3 times the air is entrained from the warmer atmosphere. Assuming basic adiabatic mixing the cooling effect of the vortex tube supplied air will be greatly reduced. With a larger amplifier, the overwhelming effect of the high volume of entraining atmospheric air overwhelms cooling effect of the small volume of cold air from the vortex tube. This is why mixing the two technologies rarely works.

Air amplifiers and even air knives themselves do cool however, and are used extensively (especially air amplifiers) to cool very hot materials such as castings using the wind chill effect.  It’s like driving with the window down in your car while driving on a hot day. The high velocity of the amplified air will accelerate the cooling of the hot surface because the high flow and high velocity of the amplified air cuts through the heat boundary layer on the part to remove the heat fast.  One example was from an application in Mexico where small, hot aluminum parts which normally cooled in 30 minutes from sitting on a table were cooled in under a minute using a flow amplifier alone.

Vortex tubes are designed to cool enclosures or for spot cooling and not for cooling large areas.  In those applications you are best off using air amplifiers. Therefore, combining vortex tubes with air amplifiers however is not a proven method. When using vortex tubes – it is important to understand the above 4 facts governing the operation of the technology.

Options of Dry Machining

The positive features of metalworking fluids have long been established and include friction reduction, cooling, corrosion protection, welding protection from the tool to the workpiece and the washing away of metal chips. However reducing cutting fluid use offers the chance for considerable cost savings. Tool life may even improve. The problems to address in machining involve the following: chip removal, safety, cooling and lubrication where necessary.

Today, the economic cost of using fluid has gone way up —including their management and disposal—account for 16 percent of the cost of the average job, up from under 3% two decades ago. Because cutting tools account for only about 4 percent of the total cost of a machining project, accepting a slightly shorter tool life for the chance to eliminate the cost and headaches of maintaining cutting fluids could be the less expensive choice. And tool life may not even go
down thanks to coatings which have been developed for tooling over the years. In addition, there are safety concerns to deal with in the use of cutting fluids. OSHA established the Metalworking Fluid Standards Advisory Committee (MWFSAC) in 1997 to develop standards or guidelines related to metalworking fluids. In its final report in 1999, MWFSAC recommended that the exposure limit be 0.5 mg/m3 and that medical surveillance, exposure monitoring,
system management, workplace monitoring, and employee training are necessary to monitor worker exposure to metalworking fluids.
So there is a movement to dry machining for both economic and safety reasons. One of the biggest concerns in dry machining is the removal of chips after machining. Cutting fluid not only cools and lubricate but it also washes away chips. With dry machining, alternatives must be considered and one is the use on an integrated compressed air removal
system. These systems can minimize cost of air using air amplification technology such as Nex Flow Air Mag® Nozzles and standard Air Nozzles for chip removal. Their design allows them to remove chips eve when placed at some distance away due to their laminar air flow.

Safety is immediately improved with dry machining whenever the use of coolant and/or lubricant is eliminated or at least decreased. Advances in the types of coatings applied to cutting tools have been the major factor in improving the feasibility of dry machining to improve tool life in dry machining applications. What is left is lubrication where needed and cooling. With cooling several types of systems are being developed using cryogenics, and even heat pipes, some which involve the use of costly and environmentally unfriendly refrigerants and also costly system designs. The use of vortex tubes is for cooling is a relatively low cost viable option. Tests have shown that vortex tube based air cooling provides a highly efficient heat removal mechanism for metal cutting and delivers thermal cooling performance very much comparable to traditional liquid coolants without the inherent chemical exposure risks to machine operators and harmful impact on the environment. The tool life is very much unchanged and the surface finish quality of workpiece shows no significant change in comparison to liquid cooling. The Nex Flow Tool Cooler was developed for these applications. When lubrication is required the ideal would be to minimize the amount of lubricant needed. Using a vortex tube to cool the lubricant just before it is applied can reduce the amount of lubricant used as much as 20%. The patented Nex Flow Mist Cooler which incorporates vortex tube technology was created for these applications where some lubrication is needed.

Both the Tool Cooler and Mist Cooler are low cost alternatives to use in dry machining.

In summary….

Dry Machining Options

Cryogenics and Micro Lubrication – effective but costly designs
Heat Pipe – limited in cooling effectiveness but low cost
Tool Cooler or Mist Cooler with vortex tube – effective and low cost

5 Ways a Tool Cooler is used to Improve Factory Efficiency

A tool cooler is a packaged vortex tube to make it more easily used. A vortex tube creates very cold, and even freezing temperatures from compressed air for spot cooling.  By itself, the vortex tube is quite noisy so accessories to muffle the sound of the device is usually required. The tool cooler consists of a vortex tube with a cold end muffler, and a hot end sleeve (to protect from the heat generated at the hot end) which also incorporates some muffling. In addition, a strong magnet is added onto the unit to easily attach it to any magnet accepting surfaces like a machine or steel table to secure the unit in place. So this “packaged” vortex tube is now quiet, easy to handle and more flexible to use.

Normally a vortex tube by itself has an adjustable hot end plug to control the flow of cold air out the cold and hot ends, and to vary the temperature produced at the cold end. But there is an “optimum setting” that will give you the maximum cooling effect and at the same time keep the temperature just above zero degrees C. This is to prevent any possible freezing in the device should the dew point for your compressed air supply is not very low. For sub-zero temperature generation you should have dry air with a dew point below that of the temperature you wish to produce in the vortex tube.

1. The most common use for a Tool Cooler is of course for cooling the tool used for drilling, grinding, milling and routing especially for materials that are not allowed to have liquid for cooling for various reasons like the liquid being detrimental to the material or for reason such as avoiding contamination. This would be for plastics, glass, ceramics, titanium and other special materials.In fact there is an entire movement to replace coolant normally used as much as possible due to the high disposal cost of coolant and for environmental considerations. Much has and is being driven towards dry or semi-dry machining which involves significant machine design changes as well since liquid coolant not only cools, but cleans away the chips and waste produced in the machining operation.
   Tool coolers or variations such as our mist cooler, which offers some lubrication are becoming more popular. But for materials that have always been dry machined such as plastics, the benefits are faster machining (shortens production time and increases output) and better quality, especially with plastics as it produces less waste in the cut (a much cleaner cut). Tool life can be extended as well in carbide tipped tools because the cold air produced helps prevent micro-carbon cracking.

 

2. Setting Hot Melt Adhesives is another common use for the tool cooler. When applying adhesives, the cold temperature helps to set the glue faster and allowing for a faster throughput. In one application (which I cannot detail due to secrecy), has a continuous line of adhesive applied and required rapid cooling which several tool coolers along the length of the process was able to provide. The customer utilized adjustable vortex tubes prior but the problem was actually personnel continually adjusting. As such, some devices were adjusted for higher flow, some for colder temperature but – what slipped the mind is – consideration for the cooling effect change. Our tool cooler is set for optimum cooling and took this issue out of the equation. Nex Flow do also offer adjustable spot coolers in cases where some temperature control is needed.
3. In line slitting, is a variation in tool cooling in that you are applying the cold air flow to a cutting blade in a slitting operation. The advantage here is not for increasing output, but to have the sharpness of the blade last longer. There is a very noticeable improvement when thicker material need to be slit as the blade would have to work harder and can heat up more. The vortex tube operated tool cooler keeps the temperature down, and extends the blade life. As with the adhesive application, the tool cooler is preset to give the optimum cooling effect to prevent tampering with the unit and maintaining consistency in cooling to control the quality of the adhesive application.
4. Laser cutting is an application where the tool cooler is very effective. For the laser processing of materials, the material changes in the heat affected zone (HAZ) is an important indicator for quality in microelectronics manufacturing. In laser cutting you focus beams to heat the surface of the material up to a high temperature to melt the material and you want to minimize the HAZ. The cooling from the tool cooler decreases potential burning in the heat affected zone area thereby improving quality. As there is no refrigerant involved, there is no effect on the environment. The low temperature cooling air diminishes the HAZ in laser cutting for glass fiber reinforced composite materials for example.
5. Chill roll nip cooling is where the Tool Cooler is placed on the nip roll of a plastic film web processing line. Nip rollsor pinch rolls are powered rolls that are used to press two or more sheets together to form a laminated product. The high pressure created at the nip point brings the sheets into intimate contact, and can squeeze out any bubbles or blisters that might cause a defective bond. If the material is too warm it can stick and if the material is very thick or cooling is uneven, there could be a hot spot causing defects which is easily eliminated by using a Tool Cooler.

In all these applications there is no requirement for lubrication. However, there are applications where some lubrication is absolutely necessary.  One example is drilling a deep hole into a material.  Without some lubrication to the cutting tool, it will bind inside the material being drilled. For this reason Nex Flow developed the patented Mist Cooler which operates not by cooling the tool directly, but by cooling the lubricant applied to the cutting tool to a very low temperature. The liquid is applied as a mist to the cutting tool to provide both the lubrication and cooling it needs. The benefit is the diminished volume of liquid needed to both cool and lubricate. Reduction in chemical use can be as much as 20%, a significant savings even over a short time frame.

Tool Coolers are available in various capacities for cooling depending on the nature of the material being cooled, the rate of throughput and the thickness of the material. There is even a small capacity unit called a Mini Cooler which is used in cutting thin material, and even in sewing operations involving heavy textiles such as jeans and burlap bags where the sowing needles heat up and deform or break thread. The mini cooler keeps them cool. While it is generally a good idea to avoid any adjustable system (as the fixed systems are preset for optimum cooling), the Adjustable Spot Cooler is another packaged vortex tube, very similar to the Tool Cooler but with an easy hand adjustable knob to vary the temperature at the outlet that is available. This is usually used in laboratory applications and for testing where temperature variation is required. Tool Coolers (and other variations) can be specially made to provide sub-zero temperatures if required. The versatility of the Tool Coolers makes it an excellent packaged option for all types of spot cooling applications.

Should I use a Mist Cooling System or go the route of Dry Machining to replace Flood Coolant?

Machine operations still commonly use flood coolant but are working on ways to replace with alternate systems.   One such system called Minimum Quantity Lubrication (MQL) attempts to reduce flood cooling.  MQL eliminates conventional flood coolant from the machining processes, lubricating cutting tools with a fine spray of oil directed exactly when and where it is needed. MQL reduces oil mist generation; biological contamination of coolant; waste water volume; costs for capital equipment; and regulatory permitting. MQL also improves recycling and transport of coolant contaminated chips.   Dry machining is also a growing trend when possible to use and is much less messy than mist cooling systems.

Dry machining has been called the machining of the future and there are many benefits to avoid the use of flood coolant, the most obvious being the increasing environmental considerations and the disposal of waste coolant. (Reference: https://www.theengineer.co.uk/the-benefits-of-dry-machining, Oct 4, 2016).    The advantages of cooling, especially to eliminate micro-carbon cracking on carbide tools, are not only for cooling but also to wash out chips from the drilling operations.  Machine designs are now taking these things into consideration as the move to dry machining continues, especially as the growth of new composite materials are adopted.

Nex Flow^® has developed two products to address dry machining applications – one completely dry and another adapting mist for lubrication.

While obviously using a liquid to cool is easier, compressed air can also be used by adopting vortex tube technology such as that used with our Tool Cooler.  A vortex tube takes compressed air and divides the air into a hot and a cold stream – capable of producing very cold temperatures.   Normally the temperatures are 0 degrees C. to 5 degrees C. at the exit to avoid condensation.   The cold air blows directly onto the desired tool.   In many cutting applications this can actually make for a better quality cut.   Applications where the vortex tube alone (usually packed in the form of a tool cooler with a mounting magnet to attach to the machine) complete with a flexible hose to deliver the cold air produced, is ideal for cutting, drilling, milling, routing of plastics, glass, and ceramics.  Titanium steel is another good application for this totally dry cooling system.

In many situations however, some lubrication is required – for example in deep hole drilling.  Without some form of lubrication, the drill can bind.  For this purpose, when attempting to eliminate flood cooling, mist cooling has been used where a “mist” is sprayed onto the cutting operation.  Nex Flow^® has developed a patented system to utilize a vortex tube to cool a lubricating mist which is syphoned up into the unit using a special nozzle.   This is their Frigid-X^® Sub-Zero Vortex^® Mist Cooling System.

As the lubricant is syphoned up, the cold air from the vortex tube cools the lubricant to about 5 degrees C.   Then the cooled lubricant is misted onto the cutting tool with volume controllable by an adjusting knob.  The liquid being cooled reduces the amount of lubricant needed significantly, up to 20% less than what would be needed with a standard mist coolant.  This reduces the environmental effect dramatically, reduces lubricant cost and cools the operation significantly.

The compressed air required for purely dry machining using vortex tube technology is about double that required for using some liquid along with the vortex tube.  In both situations it is important that the compressed air is properly filtered to keep the system clean and dry to prevent condensation and any oil clogging up the vortex tube component.  Recommendation for filters is a minimum 10 micron water removal filter and if there is oil in the air line, a 0.3 micron oil removing filter.  Without proper filtration the systems can be damaged over time and lose effectiveness.

There was a very interesting application recently on board an oil rig where either a Tool Cooler or a Sub-Zero Vortex^® Mist Cooler could be used for a particular cutting application.  The restriction was that the temperature produced by cutting metal was to be kept under 200 degrees C. due to the nature of the explosion proof rated environment.  This could be accomplished by using either system.  Lubrication was not an issue so water was used in the Mist Cooler in lieu of any lubricant.  In addition, the use of water itself was not an issue for the materials being machined.  Both systems were tested.

Both the systems were highly successful in achieving the goal of maintaining any temperature from the operation below 200 degree C limit.  In the end, the Mist Cooler was used because of limited compressed air available for the multiple number of systems required.

In most situations, when moving away from flood coolant it comes down primarily to the need for any lubrication in the process.  If no lubrication is required, for both reasons of eliminating lubricant cost and a cleaner environment in the workplace, it would be best to use purely dry machining process.  However, for dry machining system with multiple stations, care should be taken to ensure adequate amount of compressed air capacity when using a system like the Tool Cooler.   MQL systems are certainly an ideal goal to reduce flood cooling when lubrication is also necessary.  When using the vortex tube operated mist system the lubricant should be water based and after use, be thoroughly flushed from the system to keep it clear and clean for the next use.   Misting however does effect the nearby environment so reducing the amount of liquid is always a plus.  Systems like the our mist cooling system can reduce lubricant use (and cost) up to 20% by cooling the mist as it is being used.

Regardless of which system is chosen, anything to reduce and replace flood cooling offer benefits to both the owners and employees of any company both in cost and environmental impact.