Video: How Air Filters Are Made At K&N Engineering

K&N Engineering has been producing performance air filters and intake kits for the automotive and powersports aftermarket since 1969, and has since become a dominating force in the industry and a household name among enthusiasts. So it’s pretty safe to say that every automotive enthusiast has purchased an intake kit for their engine at one point or another, whether it’s from K&N or one of the many other high quality intake and filter manufacturers. But have you ever wondered how exactly it was made?

In the video above, Dave Pratte and the team from Speed Academy stopped by K&N Engineering’s manufacturing facility for an all access tour.

The Facility

K&N has an international presence, with facilities even located in the United Kingdom and the Netherlands. But the company’s central hub located in Riverside, California, consists of 10 buildings that makes up a footprint nearing 400,000 square feet of workspace.

K&N’s corporate offices are occupied by several departments ranging from engineering, and product design, to sales, customer service, and marketing. The manufacturing side includes air filter and intake tube production, a CNC machine shop, fabrication, powder coating, roto-molding, carbon fiber production, assembly, and packaging. It should also be noted that K&N also produces air filters and intake kits for other well known manufacturers such as AEM, Spectre and AirRaid, with the majority of the products being produced using in-house designed and built machinery.

The product design phase at K&N is accomplished using computer aided design (CAD) software, where after being designed is then passed along to be tested on the in-house chassis and engines dynamometers, custom filtration test stands, flowbenches, and vibration test equipment for performance and durability verification.

Equipment And Manufacturing

K&N’s air filters are made using a high quality cotton fabric material, similar to medical-grade gauze, which is then encased in an aluminum mesh to reinforce its structure. This process is completed using a machine that was designed and built in-house and was first introduced in 1972. The rolls of material are pulled together through this machine, which then pleats the material into shape.

Once through this pleating machine the finished material is then cut into large rolls and transferred to the sorting department, where employees will cut the material to the perfect length — depending on the application — by literally counting the pleats by hand before making each cut. From there the material will be rolled into shape if it’s a cone filter or the pleats will be tightened for a panel filter.

From there, a computer sorts the filter material into bins and collects the correct mold, by application, before being transferred to the molding table for cone filters or a molding machine for panel filters. For cone filters, the aluminum molds are secured to a heated table where a computer then directs a nozzle to inject the perfect volume of liquid rubber into the mold. An employee then follows behind and carefully places the filter media into the rubber and braces it before letting it cure, the process is then repeated for the inlet side of the filter as well.

For panel filters, the media is carefully placed onto an aluminum mold that is placed into a machine. Once properly seated, the machine places the mold in a heated chamber where the liquified rubber is then injected into the mold and then cured.

After having what resembles a finished air filter, it is transferred to an oiling machine that coats the filter media in a defined quantity of oil that will spread throughout the cotton material within 20 to 30 minutes, giving it the iconic red color and improved filtration.

Product Testing

K&N has a fully equipped ISO 5011 lab, where prototype air filters are tested for durability and filtration efficiency before going into production. The International Organization for Standardization (ISO) set forth the ISO 5011 standard which establishes uniform test procedures, conditions, equipment and performance reporting to measure the laboratory performance of an air filter — and was last updated in 2014. K&N is so confident in the performance of their filters, they are even used on their in-house air system for their own test benches. 

In this lab, K&N has the ability to test a filter’s efficiency by installing it into an OEM airbox or cone filter test bench, and a controlled volume of dirt is injected directly into the airstream. Any dirt that makes it past the test filter is caught by a finer filter in the main vacuum further down the line, where it is then measured to test the actual efficiency of the filter so that it can move on to production or the engineers can go back and make the appropriate changes to the design.

The nozzle used to introduce dirt into the airstream to test an air filters efficiency.

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About the author

Kyle Kitchen

Born and raised in Southern California, Kyle has been a gearhead ever since seeing his first Mitsubishi Evo VIII in 2003. He is almost entirely self taught mechanically, and as an inexperienced enthusiast always worked on his own vehicles, regardless of the difficulty, just to learn how to do it himself. Prior to becoming a freelance writer for the company, Kyle started his automotive performance career with Power Automedia as a shop technician, where he gleaned intimate knowledge of LS platforms and drag racing builds; then later joining the editorial team as the Staff Writer for EngineLabs And Turnology. Today, Kyle is an experienced EFI calibrator; hot rod builder; and motorsports technician living in the San Jose area. Kyle is a track junkie with lots of seat time. You can usually find him racing his Mitsubishi Evo X in local time attack and road race events.
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