How to Ensure a Fair Glass Test
Evaluating the capabilities of different x-ray systems is essential to determine which system offers the best solution for a specific application.
When testing x-ray inspection equipment, it’s common to use a range of pre-prepared test samples. However, glass test samples come in many varied forms and compositions which can affect x-ray absorption and consequently glass detection sensitivity.
Glass Test Samples
Some x-ray inspection system suppliers produce glass cubes for test samples. However, as the cube rotates in the x-ray beam path, it will present a constantly varying thickness. This means the detectability of the cube can vary between passes, depending upon its orientation, and doesn’t lend itself to a repeatable result.
To avoid this ‘orientation effect’, the majority of x-ray system suppliers produce and use glass spheres (balls) which present the same thickness regardless of orientation.
Low and High Mineral Glass Test Pieces – Which is Best?
A number of different glass composition test pieces are used by x-ray system suppliers and are described by their type and density.
Depending on the customer’s risk assessment, and the potential source of glass-in-glass contamination, it may be applicable to use either ‘low’ or ‘high’ mineral glass. In tests, ‘high’ mineral glass has proven to display higher x-ray absorption, making it more easily detectable at smaller sizes, compared to other types of glass, including ‘low’ mineral glass.
At Safeline X-ray, however, we believe it’s important to use a glass test piece that’s made of the closest possible glass type to that of the glass jar material itself. This is because glass jars pose the biggest risk of glass-in-glass contamination. For example, it’s possible for empty glass jars to arrive at the factory with glass jar fragments already inside. In addition, certain production processes increase the risk of glass-in-glass contamination, such as the lidding (or capping) process where there’s a risk of damage to the neck of the jar, resulting in glass fragments falling inside the jar. For this reason we strongly advise using ‘low’ mineral glass, which is Soda lime equivalent glass, with a density of 2.5g/cm3.
To avoid inconsistency and ensure a fair and accurate comparison of the performance of different x-ray inspection systems, it’s crucial to use the same glass test samples, preferably inserted into the same pre-prepared product.Leave a reply →