Nathan Airchime Case Study

Die casting

About Nathan Airchime 

Robert Swanson founded Nathan Airchime in 1948 when he created custom steam whistles in his home. Since then, the company has manufactured air horns for trains, boats, dams, logging camps, and more.  

Presently, Nathan Airchime holds 95% of the market share for air horns in the world. So, if you’ve heard a horn blow as a train chugs down a track or as a ferry disembarks from a dock anywhere in the world, there’s a very good chance Nathan Airchime manufactured it.  

In 2006, Micro Precision acquired Nathan Airchime. Airchime is now a 100% subsidiary of MPI LLC, and still continues to lead the world in audible signalling device manufacturing. 

Die casting

Die Cast Challenge 

When Nathan Airchime manufactured their air horns in the mid-1970s, they used sand casting for their moulds.  

Sand casting is metal casting process that uses sand as the moulding material. Although this accomplishes the manufacture of train horns in a similar way to die casting, the sand casting part price tends to be more expensive. The high cost comes from the need to create a new sand mould for each cast—and with a need to manufacture some 500 horns of varying sizes at a time, the cost of materials and labour can get overwhelming. 

At the time, die casting was not very popular—even in Southern BC, there were only about three major players. However, we set ourselves apart from them and the rest of our competitors across North America by designing an innovative mould that could cast each of the five horn sizes Nathan Airchime needed. This mould design and build was enough to entice Nathan Airchime to pivot from sand casting to die casting. 


How We Helped 

For over 50 years, we have die cast 100% of Nathan Airchime’s horns. We’ve kept up this fruitful relationship by consistently delivering a top-tier product. 

Mould redesign 

We created mould inserts for each of the horn sizes and have continued to improve upon their design to make a better product in less time. 

For example, we redesigned the mould and the changeable inserts within it so they could be swapped out more quickly with every horn size change we needed to accommodate. We also improved the mould design to last longer so we could cast more without the interior cores breaking in the mould. We now have a top-of-the-line mould with inserts to create six different sized horns, which has helped Nathan Airchime expand their product line. 

New cleaning techniques to increase the lifespan of each die 

We used to clean out the moulds manually, and a little bit of damage from scraping out aluminum buildup was inevitable.   

To reduce wear and tear on the moulds, we formulated a new chemical cleaning method to clear the aluminum buildup in the cavities and cores without damaging the moulds.   

Competitive pricing for small-to-medium-size production runs 

What makes Simalex unique from other die casters is we have the capability to take on smaller production runs than our competitors. Where most casters work with minimum production runs with units numbering in the tens of thousands, our plant is set up to manage small-to-medium runs without sacrificing care or quality. 

Our offer for smaller size runs has worked out marvellously for Nathan Airchime, whose orders for parts tend to be in the 500-1000 range. 


Since the 1970s, our continued drive to improve our designs and deliver consistently high-quality products (whether it’s part 1 or part 1000) for Nathan Airchime has resulted in the creation of at least 50,000 horns. You’ve surely heard at least one of them.