All coating thickness meter gauges are required to calibrate the zero position before measurement, which can be calibrated on the zero calibration plate accompanying the instrument or on the uncoated workpiece. The stability of the zero position of the instrument is the premise to ensure accurate measurement. After a good thickness gauge is zeroed, it can keep the zero position without drifting for a long time to ensure accurate measurement.
1. No need to calibrate
In addition to zero calibration, most thickness gauges also need to be calibrated with standard sheets. To measure the thickness of a certain range, the principle of the laser range finder needs to be calibrated with a certain range of standard sheets. The main reason is that it cannot meet the linear accuracy in the whole range. Not only is the operation cumbersome, but also the failure of the standard sheet due to the rough surface increases the system error.
2. Temperature compensation
The measurement of coating thickness is greatly affected by temperature. The measurement of the same workpiece at different temperatures will give a large error. Therefore, a good digital coating thickness gauge should have ideal temperature compensation technology to ensure measurement accuracy at different temperatures.
For example, when it is used for ultrasonic measurement, there is often no good acoustic reflection surface due to the compatibility between the coating and the substrate, resulting in measurement failure or serious deviation of readings. If it is used for wedge cutting method measurement, it is often used in places where it is inconvenient and difficult to read.
Therefore, at present, manufacturers in the portable electronics industry generally use the transfer method to measure coatings in the plastic industry. Professional digital coating thickness gauge manufacturers have summed up a set of methods after years of practice on coating thickness meter gauges, that is, first cover a number of small strips of polyester film with a standard thickness on the plastic industry, and then press it with paper-based masking tape. Cover both ends and leave the middle. Put the industry into the spraying line for normal spraying and baking.
After the industry is completed, remove the polyester film with the paint film left, use an iron zero plate (or aluminum zero plate) as the substrate, and use a magnetic induction (or eddy current method) film thickness meter to measure the coated part and the uncoated part respectively. Part, the difference between the two is the coating thickness. Since the same zero board is used, the reference point of electromagnetic induction will not change, thus ensuring the same measurement reference and accurate measurement. In addition, especially because of the difference method, the errors of the coating thickness meter gauge instrument and the zero plate will be canceled by subtraction. This greatly reduces the requirements on the zero plate and instrument accuracy. There are also some factories that still use the method of pasting iron sheets and aluminum sheets. It should be noted that the surface roughness, convex and concave deformation, and thickness changes of each iron sheet or aluminum sheet will cause changes in the electromagnetic induction reference point, which may cause measurement errors. Increased error and poor repeatability need to be avoided.