Solving Static Problem in PET Plastic Thermoforming Application

PET plastic entering thermoforming machine to make cups

The image above shows a PET plastic sheet which is fed into a thermoforming machine. During thermoforming the plastic is made into drinking cups.  But, if the plastic enters the thermoforming machine with static present, the forming process cannot occur properly which results in defects.

The company in charge of thermoforming these cups reached out to the Application Engineering department at EXAIR in search of a solution to their problem. They had considered using Ion Bars, but were unsure if Ion Bars were the right solution.  So, we examined the process and the variables at play to determine the best path forward to remove this static.

The static in this application was present throughout the travel of the plastic sheet into the thermoforming machine. At EXAIR we always recommend to install any static eliminating solution at the last possible point before the static is causing a process disturbance, to ensure no static is regenerated.  Yes, a static charge has the potential to regenerate with friction, spearation or even simple contact with another surface. In the above example separation from the roll and friction upon the additional rollers could be a source of static. This meant finding a way to eliminate the static just prior to the sheet entering the thermoforming machine.

As it turns out, the thermoforming in this application can occur between 180-260°F, and this heat permeates from the machine to the area immediately outside of the plastic feed entrance. So, placing Ion Bars just outside of the machine, while potentially possible, would place them near temperatures at the high end of their operating temperature limits (maximum temperature for an EXAIR Ion Bar is 165°F).

However, just a couple of feet away from the machine this temperature dissipates significantly. So, if we could find a way to mount our solution 2-3 feet away and effectively eliminate static, we would have a viable solution.

That solution came in the form of Super Ion Air Knives. The Super Ion Air Knives provide the same static eliminating capabilities of an Ion Bar, but with an added benefit of transferring the static eliminating ions via a smooth and laminar air profile.  This allows for us to mount the Super Ion Air Knives a few feet away from the machine entrance, but to still effectively eliminate static.  At a distance of 12” away, the Super Ion Air Knife can eliminate a 5kV static charge in 0.18 seconds at an operating pressure of 80 PSIG, and in 0.60 seconds at an operating pressure of 5 PSIG.

Based on the width of 486mm, this customer opted for (2) 18” Super Ion Air Knives, model 111018, and (1) 230VAC power supply with (2) outlets, model 7907. By installing one Super Ion Air Knife on top of the plastic sheet, and one on the bottom, the static problem in this application is solved.

If you have an application in need of a static solution, contact an EXAIR Application Engineer. We’re here to help.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR.com

Replacing Unsafe Open Pipes with High Pressure Air Nozzles

Open pipes present unsafe working conditions and continuous pressure drops in compressed air systems

Let’s talk for a minute about pressure drops. Normally when the topic of pressure drops is raised, it comes in a context related to proper plumbing and volume supply.  (If there are significant pressure drops within a compressed air system, especially those which reduce volume flow, problems will arise with compressed air driven devices.)

But, there is another important aspect of pressure drops which relates to open pipe blow-off, a common homemade remedy for blow-off applications. This aspect has to do with the available compressed air pressure at the exhausting point from the pipe or nozzle.  In the case of an open pipe, it requires so much compressed air volume that, there can be a continuous pressure drop from the compressor to the open pipe.  However, when a nozzle is installed onto a compressed air pipe, there is a restriction to the flow and the entire pressure drop takes place across the nozzle.

What this means for the blow-off solution is a higher velocity blow-off and a more powerful force from the airflow, with less compressed air consumption.

To think of it another way, imagine the flow of water from your garden hose. If the hose is open-ended and the water is fully on, the flow will be high and the force will be low.  But, when you install a nozzle onto the end of the hose the flow reduces and the force increases.  This is because the pressure drop in the system is taking place across the nozzle rather than the entire system.

This type of a scenario was taking place in the image shown at the top of this blog. The plastic lines connected to the aluminum manifold were fully open on the end, providing a continuous pressure drop and poor blow-off performance.  This, coupled with the maximum operating pressure of similar types of hose being 35 PSI, led to a poor performance in this application.

The solution for this customer was to replace these open pipe blow-offs with EXAIR model 1126 Flat Super Air Nozzles and 12″ Stay Set Hoses, model 9262. The flat airflow of the 1126 Super Air Nozzles provide a highly efficient and forceful blow-off, and the Stay Set Hoses allow for articulation of the nozzles into any position needed.

By replacing these open pipes this customer saved compressed air, added safety (open pipes present an operating hazard per OSHA Standard CFR 1910.242(b)), and improved the performance of their operation.

If you have a similar application or would like to speak with someone about increasing the efficiency of your compressed air applications, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Proper Plumbing Means Proper Performance

36″ Aluminum Super Air Knife being used in a monofilament extrusion line

An EXAIR customer recently contacted me about the application shown above, using an aluminum Super Air Knife model 110036 as a component to a blow off application in a monofilament extrusion line.  The extrusions from this line are used in one of the end user’s main product lines, a personal health device used by over a billion people around the world.

The original problem of drying the extrusions can certainly be solved with the setup shown, but the output force from the knife was less than what the customer expected, and below the EXAIR published data.  We take great care in the collection and verification of our performance data, so this prompted a deeper dive into the application to determine what could be the cause.

Immediately upon seeing the application photos, there were two things which stood out.  The first was the angle of attack of the knife, and the second was the compressed air plumbing.  The angle of attack in the original setup was ~90°, nearly perpendicular to the extrusions passing through the airstream from the knife.  EXAIR always recommends an angle of attack of ~45° to increase time in contact between the airstream from the knife and the materials passing through the airstream.  Although a small adjustment, this angle significantly contributes to overall blow off performance.

5mm ID x 8mm OD tubing used to supply compressed air to the knife

But, the real issue with this application was in the compressed air supply.  The tubing for this knife was shown as having a 5mm ID and an 8mm OD, which will allow a compressed air flow of ~40 SCFM at 80 PSIG, maximum, without consideration to pipe length from the compressor.  The 36” aluminum Super Air Knife will require 104.4 SCFM at 80 PSIG operating pressure.  So, it was clear that there was a significant plumbing problem, leading to the reduced performance from the knife.

In order to prove this out, we first had to take a pressure reading directly at the knife.  When this was done, the operating pressure dropped from ~85 PSIG at the main header to less than 20 PSIG at the knife.  By taking this pressure reading directly at the knife we were able to gain valuable information as to the true operating pressure of the knife, which was far below what the customer expected, but which made perfect sense given the performance output.

The remedy in this case was to increase the size of the supply line to at least 15mm ID (approximately equivalent to a ½” schedule 40 line), and preferably to something in the range of 19-20mm (~a ¾” schedule 40 line).  Once this was done the knife operated flawlessly, and after adjusting the angle of attack this application was optimized for the best possible results.

Being able to find the source of the problem for this application was a great service to the customer.  Our engineers are well-versed in compressed air system requirements, and we’re available for help in your application if needed.  If you’d like to contact an EXAIR Application Engineer we can be reached by email, phone (1-800-903-9247), or Twitter.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Keeping Sensitive Equipment Cool with an EXAIR Cabinet Cooler

The image above shows a sophisticated microscope used in a highly controlled environment to monitor living cells.  The end user of this microscope recently contacted the Application Engineering department at EXAIR in search of a method to cool the internal temperature of the microscope chamber from 22°C (72°F) to 14°C (57°F).

The small space of this application made the use of a typical refrigerant based air conditioner an impossibility.  But, near to this microscope is a source of very dry, clean, oil free compressed air – perfect for operating a Cabinet Cooler.

The internal heat load of this application was known by the end user, but the effects of external heat load on the application were still unclear.  In order to determine the full heat load of the application a Cabinet Cooler Sizing Guide must be used to perform heat load calculations.  This document, once complete, allows EXAIR to determine both internal and external heat loads, which in turn allows us to determine the required Cabinet Cooler model number.

This application was served by the model 4325 Cabinet Cooler, which allowed for a cooling solution in tight spacing where a traditional air conditioning unit wouldn’t work.  The small and compact design of the Cabinet Cooler was the perfect fit for this customer and application need.  If you have an application in need of a cooling solution, contact an EXAIR Application Engineer.  We’ll be happy to help.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Camera Lens Cooling with EXAIR Vortex Tubes in a High Temperature Environment

Connection side of camera lens housing. Dimensions shown are in cm.

A customer in Russia contacted our distributor in Moscow about an application to monitor the flow of melted glass.  In their application, the end user had installed (4) camera “eyes” with thermal insulation to instantaneously measure the melted glass flow.  But, the high ambient temperatures would cause the temperature of the camera lens to slowly increase during operation, eventually resulting in an overheating condition.  This overheating condition rendered the cameras inoperable until they were cooled below a temperature of approximately 40°C (104°F).

What this end user (and application) needed was a suitable solution to cool the lens of the camera to a temperature below 40°C (104°F).  A typical refrigerant based air conditioner wouldn’t work for this application due to space and temperature constraints, as the cameras are located close to the furnace with ambient temperatures of 50°C (122°F) or higher.

What did provide a viable solution, however, were High Temperature EXAIR Vortex Tubes.  Suitable for temperatures up to 93°C (200°F), and capable of providing cooling capacities as high as 10,200 BTU/hr., these units fit the bill for this application.

Full view of the camera lens housing. The camera lens is the portion protruding from the far left of the housing.

After determining the volume of compressed air available for each camera, and after discussing the solution options and preferences with the customer, they chose (4) model BPHT3298 Vortex Tubes, using (1) Vortex Tube for each camera.  The cold air from the Vortex Tube will feed directly onto the camera lens, keeping it cool even in the hot ambient conditions.  This removes lost productivity due to machine downtime, which in turn increases output and reliability from the application process.

High Temperature Vortex Tubes provided a solution for this customer when other options were unable to deliver.  If you have a similar application or would like to discuss how an EXAIR Vortex Tube could solve an overheating problem in your application, contact an EXAIR Application Engineer.  We’ll be happy to help.

 

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Removing Chips from a Plastic CNC Router

These CNC routers needed a viable solution to remove and collect plastic chips and debris created during machine operation.

Our distributor in Poland recently emailed me about an application in need of a method to collect plastic chips from the CNC router tables shown above.  These machines are used for precision cutting, but face a problem when the cutting edge of the machine comes into contact with the chips and debris created during normal use.

The end user had considered a blow off device such as a nozzle or Air Knife, but this raised concerns with material collection.  Ideally, the customer wanted to be able to capture the chips and debris for recycling.

So, we looked into a method of removing the chips with a Line Vac, conveying the debris to a stationary drum for collection and recycling.  This type of solution has proven to be effective many times in the past, as shown in the image below. A Line Vac can be mounted at the cutting head to vacuum chips and debris as they are created by the cutting process.

This Line Vac provides vacuum to a drill head to remove debris.

Using the model 6081 Line Vac we can remove the plastic debris from the plotter as it is generated, and convey it to a drum located within the workspace.  And, to facilitate collection of the plastics for recycling, we can use our model 6850 drum cover to separate the conveyed chips from the air used to move the materials.

By providing a dynamic solution for this application, the Line Vac is able to lessen the workload of machine operators, allowing them more time to perform value added tasks rather than cleaning.  And, the solution is easy to install, requires little to no maintenance, and provides instantaneous vacuum only when needed.

If you have a similar application or would like to discuss problems facing your facilities, contact an EXAIR Application Engineer.  We’re available by phone, email, and online chat.

Lee Evans
Application Engineer

LeeEvans@EXAIR.com
@EXAIR_LE

Why Measure Compressed Air Use?

Model 9097-M3 Digital Flowmeter installed on 3″ compressed air line

One of the best analogies I’ve heard to explain the importance of monitoring compressed air related to banking.  With any bank account there are deposits and withdrawals, and if withdrawals exceed deposits, problems ensue.  So, most people/businesses/institutions have systems in place to monitor their banking accounts, ensuring that there is always enough of a balance in the account to cover expenses.

The same is true for a compressed air system.  If the demand exceeds the supply, problems ensue…Lowered pressure and force from compressed air driven blow offs, irregular performance within pneumatic circuits of CNC machines, and general decline of any devices on the system all begin to occur when demand exceeds supply.  So, this begs the question of how to prevent a mismatch between compressed air demand and available supply.

Enter the Digital Flowmeter.  The entire purpose of the Digital Flowmeter is to provide a method to see (in real time or over a specific period of time) what the existing demand is within a compressed air system.  This quantifies the “withdrawal” into an output that can be compared to what is produced by the compressor, allowing for analysis and proper balance of the system.

This Digital Flowmeter allows for monitoring compressed air usage quickly and easily. The USB Data Logger installed onto this unit allows for collection of compressed air flow data.

The application photo at the top of this blog shows the DFM being installed to do just that.  This unit is being set up to use a USB Data Logger to capture compressed air flows at a customer-chosen time interval.  By monitoring their compressed air flow, this customer can optimize their compressed air system (align output of the compressor with demand of the facility), determine whether there are any leaks in the system, and determine the effectiveness of the compressed air which is being used.

It is important to remember that compressed air is the most expensive utility in any industrial facility.  Failing to monitor the system is akin to blindly writing checks on your bank account.  Proper system performance starts with proper monitoring, which the Digital Flowmeter easily provides.

If you’re interested in learning more about monitoring your compressed air system, contact an EXAIR Application Engineer.  We’ll be happy to discuss specifics and options available.

Lee Evans
Application Engineer

LeeEvans@EXAIR.com
@EXAIR_LE

%d bloggers like this: