Historically, polyurethane foam has been classified and determined by IFD (Indentation Force Deflection) and density. The IFD test measures the load bearing property of the foam at a given deflection. However, the expectation of the automotive specifications is that these properties will also define durability and comfort of the foam when used in complete seat applications. Today’s automotive customers are asking for vehicles that last longer, with higher expectations in comfort, appearance, and durability performance. New targets are vehicles that will have satisfactory performance for 150,000 to 200,000 miles. We at Johnson Controls believe that to achieve these types of customer performance standards, new definitions of the molded foams are required.
This paper will explain how a new test measurement, called hysteresis loss, is required to meet these new customer requirements. This paper compares the hysteresis loss test, and IFD test, for gauge repeatability, time from manufacture to reliable test results and as a measure of durability. In addition, the paper will discuss how to make identical foams using different technologies, different manufacturers and locations, and modeling how to change the hysteresis loss.
The conclusion of the paper is that as we attempt to achieve the customer’s higher expectations of a better more durable seat, we need to utilize the hysteresis test method, rather then IFD and density to grade performance.