How to Understand SAE J1960by Melissa Bajorek
To understand SAE J1960, you should know the issuing committee and the purpose of the tests, as well as some details about what it covers and its potential inaccuracies. The automotive industry uses the SAE J1960 standard to evaluate how exterior plastics on automobiles weather. SAE J1960 tests are performed in laboratories by auto manufacturers and parts suppliers. To understand SAE J1960, note that in some regions automobile exteriors will weather differently due to outdoor conditions. Know that SAE J1960 standards were developed in the 1970s and are still used for preliminary tests; but be aware that auto manufacturers conduct real outdoor testing to validate lab results and to develop new auto-exterior materials.
SAE J1960: Regulations, Equipment and Standards
The Textile and Flexible Plastics Committee of SAE International issues the SAE J1960 standard. SAE J1960 sets the protocol for the operating procedures of a controlled irradiance, xenon-arc apparatus. This device is used to mimic UV radiation and outdoor conditions, to weather samples of auto exterior (or interior) plastics or fabrics. SAE J1960 sets the standards for test duration, which is length of exposure to the xenon-arc device, and states protocol for the proper preparation of material samples prior to testing.
To understand SAE J1960 standards, you should know about the equipment used to complete the tests. There are two primary types of xenon-arc instruments: air-cooled or water-cooled. According to Weiss Gallenkamp, manufacturer of xenon-arc devices, the type of cooling used in the device has a negligible effect on the light output, but does affect overall design. Xenon-arc devices and other equipment allowed to perform SAE J1960 testing is determined within the SAE J1960. regulations. In other words, only certain approved tools can be used to perform the tests. Test equipment must also pass a verification process before it can be used in the lab. Any new xenon-arc test equipment must be verified by a contracted third party. The formal Protocol to Verify New Test Apparatus is under development as of December 2010, but it will be known as SAE J2413.
To understand SAE J1960 standards, you must be aware of its inaccuracies, as the standards do not exactly represent real world weathering of materials. Materials degrade or exhibit changes like fading, loss of luster, change in tensile strength or corrosion because molecular bonds have been broken and chemical reactions have occurred within the material. These changes can be caused by forces other than sunlight. Also, the wavelengths of UV radiation from sunlight varies at different times of the day and throughout the year. Xenon-arc equipment cannot exactly mimic the effects of true sunlight because absorption of UV radiation is absolutely wavelength-dependent. Another issue with SAE J1960 standards is that real auto-exterior materials are produced in a factory, where impurities and contaminants do exist. Unlike the small amount of exterior material sample tested with SAE J1960, even small impurities can alter the effects of UV radiation on the auto as a whole. In short, the exterior of each finished automobile is unique, and is subject to unique weather conditions, meaning that SAE J1960 is an effective guide, but not always an accurate method of testing.
- red car image by Tammy Mobley from Fotolia.com