Any production line involves some form of inspection; the most basic form is manual visual inspection. This type of inspection is not always the least expensive or the most reliable. For example, sheet metal is monitored visually by trained personnel, which requires a very slow production line for reliable detection and to ensure the safety of the inspector. Such systems are very expensive due to the lower production speed; they are also labor-intensive and labor-dependent and must be a separate step to avoid production line disruptions. Therefore, a less expensive and more reliable automated system is needed. Several automated inspection systems have been introduced to detect and locate defects on production lines. Due to the high cost of inspection systems, the manufacturer needs guarantees that the system works and can increase the quality of the products. Since the 1980s, several international groups have worked to introduce such systems. One of the first collaborations was between nine steel companies and three aluminum companies; called the “American Iron and Steel Institute for Surface Inspection Project,” the collaboration resulted in an inspection system manufactured by Kodak. Other systems have been introduced that include CCD cameras with a variety of image processing techniques [7]. Such systems are limited to certain defects i.e. those that include a color difference or a change in geometry, the main problems they can detect are pitting, roller marks and the presence of lubricant. [8] Such systems are usually implemented in the cold rolling stage as a precaution. Other systems propose to build 3D information on the surface of the steel sheet (Profilometer [9,10]). . Due to the small inspection area used (340 μm x 260 μm), this system is...... in the center of the paper......tear so the strip will heat up in relation to the resistance of the steel [ 16 -18]; although such systems are very promising and can detect focal and deep defects, the use of electric fields can generate some risks when working online. For both cases of IR thermography detection methods and due to the wide variety of manufacturing conditions and material processes, there is a need to determine the relationship between detectors (IR camera) and material properties. The purpose of this study is to find scalable relationships that can be used in the development of inspection systems using infrared thermography. The materials used are steel, aluminum and plastic which represent the three main materials used in common products. The scaling laws are derived from constant reflection heating at three temperatures low, intermediate and high which represent the most common heating conditions on a production line.