Sleeping Soundly on Tempered Springs

Posted: Mar 16, 2018 | Categories: Manufacturing

If you slept like a dream on your mattress last night, it may in part be due to the heat treatment of the springs in your mattress. Mattress springs are tempered during their manufacturing process. For this month’s blog we will start by discussing the history of the mattress and how it developed into using springs for comfort. Then we will talk about why springs are tempered and how the tempering process effects the steel.

Sleeping on the cold, hard ground has always been terribly uncomfortable. People began sleeping on primitive beds about 10,000 years ago, during the Neolithic period. The word “mattress” comes from the medieval Arabic al-matrah, which means “large cushion or rug for lying on.”

Until the 1800s, people made their beds from natural materials, such as straw, feathers and horsehair. While fluffy, these fillers tended to clump together to make for a lumpy bed. The natural fillers would break down quickly, resulting in uncomfortable pits of mushy material. The fillers were also attractive to bugs and other unwanted bedmates.

The industrial revolution forever changed the way people slept through the introduction of coil springs. First patented for use in chair seats, steel coil springs soon found their way into mattresses. The first coil spring for bedding earned a patent in 1865. It did not take long for mattress manufacturers to realize that placing a set of uniform springs inside layers of cushiony upholstery created a comfortable bed with a firm, resilient, and uniform texture. Bedsprings provide the right balance of support and “give” to create a comfortable night’s sleep. In the blink of an eye, the dream of sleeping on the perfect mattress became a reality.

Tempered Springs for a Good Night’s Sleep

There is more to making a comfortable bed than simply wrapping upholstery around any old set of springs, though. The springs and other materials must undergo certain manufacturing processes to improve their quality. For example, manufacturers may add flame-retardant chemicals to mattress upholstery and filling. They must also temper the springs to enhance the quality of the metal in the spring.

The steel used in mattress springs is quite hard, especially after undergoing hardening processes of heating and quenching during manufacturing. While hardened steel is strong, it is also quite brittle. Internal strains caused by sudden cooling in the quenching bath can compromise the integrity of the steel. Tempering reduces the brittleness in the hardened steel of mattress springs, and removes internal strains associated with the quenching bath.

Tempering is a manufacturing process that involves heating steel to a certain temperature and then cooling it to improve toughness and decrease brittleness by reducing the hardness of the steel. The exact temperature achieved during the heating process determines the amount of hardness removed. Manufacturers will temper very hard tools at low temperatures. They temper springs, like those used in mattresses, at roughly 450F (232C). The tempering process gives mattress springs the flex that you feel when you lay down and the durability to withstand years of sleep filled nights.

Wisconsin Ovens offers a variety of tempering ovens used for many applications including manufacturing the perfect mattress springs for a good night’s sleep. Available in both batch and conveyor configurations, our tempering ovens can be designed to meet your specific requirements. For more information on our tempering ovens contact our sales team at For more great information like the above, follow Wisconsin Oven on Facebook, LinkedIn and Twitter and check our blog monthly!

Tags: Heat Treating, heat treating solutions, tempering

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