Super Air Knife to the Rescue in Machining

Home-made blow-off device

As machined parts require tighter tolerances, the surface has to stay clear during turning operations.  A customer that had a CNC machine needed to make a metal tube with a specific diameter.  The metal tube was 17 ½” (445mm) long.  They made their own blow-off “tree” to keep the surface clean from shavings.  They used five open ports to blow at the part surface (reference photo above).  When they started using their home-made device, they were not getting a consistent cleaning during operation.  They wanted to speak to an expert in this type of area, and they contacted EXAIR to see if we could improve their process.

With a series of open nozzles, it is very difficult to get a consistent force along a linear line.  The air becomes very turbulent, which has changing directions of air flow.  It creates a hazardous noise exposure to the operators, and it also wastes compressed air which costs the company a large amount of money to use.  With laminar air, the path flows in the same direction.  This creates a very consistent force with less noise.  Since air is invisible, I like to use water to show the difference.  The photo below shows turbulent and laminar flows. 

Turbulent to Laminar Water

For linear blow-offs, EXAIR offers a wide range of Super Air Knives.  They give a laminar flow pattern along the entire length.  We have stocked lengths from 3” (76mm) up to 108” (2.74 meters) in different materials.  A benefit of the Super Air Knife is the high amplification ratio of 40:1.  This means that for every 1 part of compressed air, it will entrain 40 parts of ambient air.  So, they are very efficient, safe, and effective.  For the application above, I recommended the model 110218 18” Super Air Knife Kit to cover the length of the metal tube.  It has an 18” (457mm) wide air stream that is very powerful to remove chips during the turning operation.  The kit includes a filter, regulator, and shim set.  The filter will remove contaminants from the compressed air system to keep the surface clean.  The shim set and regulator provide the ability to adjust the air to the ideal force level to remove the debris from the surface of the tube. 

Super Air Knife Kits include a Shim Set, Filter Separator, and Pressure Regulator.

One of the biggest attributes that the EXAIR Super Air Knives can offer is that they use much less compressed air than a series of open nozzles. With the engineered design, it can entrain large amounts of ambient air which means that less compressed air is required.  For the nozzle tree, it was using 105 SCFM of air at 80 PSIG.  The model 110218 only requires 52.2 SCFM at 80 PSIG. That is a difference of 52.8 SCFM; half the amount of compressed air as the home-made nozzles. 

Once they installed the Super Air Knife, the first thing that they noticed was the reduction of noise. The model 110218 Super Air Knife only has a noise level of 69 dBA at 80 PSIG, compared to a noise level of an open port which was over 100 dBA. By replacing the nozzle tree with the Super Air Knife, this company…

1. reduced air consumption

2. saved money

3. reduced noise levels

4. increased the effective blowing force

If you find yourself using a home-made blow-off device, you can be creating a hazardous, costly, ineffective method to “do a job”.  Since precision was needed for the company above, they were delighted to contact an expert in this area.  You can also improve your blow-off device by contacting an Application Engineer at EXAIR for assistance.  We would be glad to help. 

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