Deep Drawn Cartridge Heater Minimizes Electrical Short-to Ground Risk


The Challenge
While cruising at 30,000 feet, a flight attendant heard a loud pop from the coffee maker in the airplane’s galley.  The plane was forced to land and was grounded pending an investigation. The problem was the cartridge heater in the coffeemaker. Some cartridge heaters, such as this one, are constructed with a heli-arc welded end disc where small pin holes can form and lead to failure. This can cause a minor inconvenience, or a catastrophic problem, as it was in this case. The challenge was to design and build a cartridge heater without any welds.

The Solution
Chromalox worked directly with the customer to develop a cartridge heater utilizing deep drawn technology. The deep drawn tube cartridge heater has no welded end disc or welded seams.  The strict specifications for uniform wall thickness insure a superior cartridge heater.  Because the deep drawn cartridge heater is also electro-polished it is highly corrosion-resistant.

Chromalox engineering and manufacturing used their experience to solve a persistent problem by looking at technologies never applied to this type of product before. By doing this Chromalox was able to develop a new and unique cartridge heater using deep drawn technology.  Chromalox was able to prove a concept and take it to production in a relatively short period of time.


  • No failures in two years of robust use in the field.
  • Fast response and thermally efficient.
  • Since there are no weld joints in the sheath the customer enjoys a high degree of confidence that no moisture can enter the heater through the sheath while immersed in water.  The deep drawn technology now is being used in new product development.