I am having to write a procedure to perform calibrations on a Dino-Lite USB microscope using a glass scale (Klarmann Rulings KR814 to be exact). I was wondering what is a typical calibration/verification frequency for these by which you have them verified by an external lab? The way we have been doing it at my job is we buy the scale and set a 10 year calibration on it and once that is up, we scrap it and buy a new one, however these are in controlled lab settings. I dont know if an auditor would be okay with this, but I wanted to ask here. Also would it be required to document the temp and humidity at the time of this calibration?
Calibration frequency for glass scale
- Thread starter Jayfaas
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At the places where I have worked glass scales are considered to be inherently stable for their use, so we designate them as Initial Calibration Only. You obviously must retain the original calibration documents. We also set a policy that they be reviewed for damage or wear, and that they are replaced whenever there is evidence.
You may want to purchase this study on the long-term stability of glass scales as well as the previous study that is mentioned. This is the abstract of the study:
Abstract
Line scales are commonly used as a working standard of length for the calibration of optical measuring instruments such as profile projectors, measuring microscopes and video measuring systems. For high-precision calibration, line scales with low thermal expansion are commonly used. Glass ceramics have a very low coefficient of thermal expansion (CTE) and are widely used for precision line scales. From a previous study, it is known that glass ceramics decrease in length from the time of production or heat treatment. The line scale measurement method can evaluate more than one section of the line scale and is capable of the evaluation of the longitudinal uniformity of the secular change of glass ceramics. In this paper, an arithmetic model of the secular change of a line scale and its longitudinal uniformity is proposed. Six line scales made of Zerodur®, Clearceram® and synthetic quartz were manufactured at the same time. The dimensional changes of the six line scales were experimentally evaluated over 2 years using a line scale calibration system.
Abstract
Line scales are commonly used as a working standard of length for the calibration of optical measuring instruments such as profile projectors, measuring microscopes and video measuring systems. For high-precision calibration, line scales with low thermal expansion are commonly used. Glass ceramics have a very low coefficient of thermal expansion (CTE) and are widely used for precision line scales. From a previous study, it is known that glass ceramics decrease in length from the time of production or heat treatment. The line scale measurement method can evaluate more than one section of the line scale and is capable of the evaluation of the longitudinal uniformity of the secular change of glass ceramics. In this paper, an arithmetic model of the secular change of a line scale and its longitudinal uniformity is proposed. Six line scales made of Zerodur®, Clearceram® and synthetic quartz were manufactured at the same time. The dimensional changes of the six line scales were experimentally evaluated over 2 years using a line scale calibration system.