MRC Awards Research Contract to Knoble Design to Develop Innovative Process for Recycling Pocket Coils

Pocket coils are one of the most challenging components to process in mattress recycling operations. Pocket coils (also known as Marshall Coils) are a common construction type for inner spring mattresses because they isolate the transfer of movement to individual coils.  About 20% of all discarded mattresses contain pocket coils which contain between 250 and 1,000 individual spring coils. These metal coils are individually encapsulated in either polypropylene or woven cotton fabric.

When a mattress is deconstructed, the pocket coil layer is easily separated from other components. However, it is impractical to manually separate the individual coils from their sleeves. Since most metal recyclers will not tolerate fabric contamination, the pocket coil units are often sent to landfills. Successful implementation of an alternative solution for separating pocket coil metal from fabric would significantly improve overall mattress recycling rates and create added revenue for recyclers.

In response to a request for proposals, Knoble Design, a Wisconsin-based custom engineering company, conceived a novel process which would quickly, affordably and efficiently separate the springs from their pockets without destroying either component. In their research, Knoble Design will design, test and optimize individual components of the process. If successful in meeting the design criteria, they will proceed to develop a pilot scale demonstration device.

The project is already underway and should be completed in early 2020. At that time, MRC and Knoble Design will determine if there is a good business case to develop a commercial scale machine.

For more information about MRC’s research efforts, visit