Comparison VVV-Group CM-222 vs Yunombo YNB-100

The type determines how the thickness gauge works.

— Eddy current. Devices, the operation of which is based on the fact that the sensor, using an alternating electromagnetic field, induces special currents in the metal under the paint — the so-called. vortex. Such currents create their own electromagnetic radiation, their power — and, accordingly, the power of secondary radiation — depends on the distance between the sensor and the metal, that is, on the thickness of the paintwork. Devices of this type can be used with any conductive materials, but it is believed that they work best with non- ferrous metals(in particular, aluminium).

— Electromagnetic. Devices operating on the basis of basic electromagnetic phenomena — magnetic induction or the Hall effect. Simply put, the sensor of such a thickness gauge creates a magnetic field, when a magnetic object enters the sensor’s coverage area, the field characteristics change, and these changes determine the distance to the object — in this case, this distance corresponds to the thickness of the paintwork, because the sensor is pressed tightly during measurements to the surface. Electromagnetic devices do a better job with steel and other ferrous metals than eddy current ones, however, such devices cannot work with non-magnetic materials.

— Electromag...netic / eddy current. Universal thickness gauges that combine both of the above principles of operation and are capable of using either of them. At the same time, some models are able to automatically determine the type of metal and turn on the appropriate mode of the sensor. This is the most convenient option from the user's point of view, despite the fact that it is not so expensive. As a result, universal devices are very popular today.

The maximum coating thickness that the instrument can detect when measuring on ferrous metals such as steel. With a larger coating thickness, the thickness gauge sensor simply cannot “catch” on the metal surface under the paint, and effective measurement will not be possible. This parameter is indicated in micrometers — thousandths of a millimetre; the larger it is, the more versatile the device is, the wider the possibilities for its use. On the other hand, a large maximum measurement thickness can adversely affect the accuracy when measuring small values.

For modern thickness gauges, the maximum thickness up to 1000 microns is considered small, from 1000 to 1500 microns — small, from 1500 to 2000 microns — medium, more than 2000 microns — significant. In the most advanced professional-level models, this figure can reach 20 – 30 cm.

The maximum coating thickness that the instrument can detect when measuring non-ferrous metals such as aluminium alloys. With a larger coating thickness, the thickness gauge sensor simply cannot “catch” on the metal surface under the paint, and effective measurement will not be possible. This parameter is indicated in micrometers — thousandths of a millimetre; the larger it is, the more versatile the device is, the wider the possibilities for its use. On the other hand, a large maximum measurement thickness can adversely affect the accuracy when measuring small values.

For modern thickness gauges, the maximum thickness up to 1000 microns is considered small, from 1000 to 1500 microns — small, from 1500 to 2000 microns — medium, more than 2000 microns — significant. In the most advanced professional-level models, this figure can reach 20 – 30 cm.

The maximum measurement error provided by the device, in other words, the largest deviation from the real value of the measured value that may occur during the measurement process. The smaller this indicator, the more accurate the device, the smaller the error it gives in the measurement process; on the other hand, high accuracy has a corresponding effect on cost.

Specifically, in thickness gauges, an accuracy of 10% is considered low, 5% is average, 3% is good, and less than 3% is excellent.

Support of the device of a mode of continuous measurement.

In this mode, the user does not need to press the button every time to take measurements — the device constantly scans the space and automatically displays the measurement results on each subsequent contact with the painted surface. This format is very convenient for large-scale work — for example, for a comprehensive check of the car body.

The presence of a built-in source of ultraviolet radiation in the device — usually in the form of a special LED. In accordance with the name, such an LED is mainly used as a bill detector : most modern currencies have protective elements that glow in ultraviolet light, and under UV lighting, marks and inscriptions made by special “invisible” compositions become visible. There are other, more specific ways to use such a detector — for example, searching for leaks in air conditioners and refrigerators (many freons have additives that glow in the ultraviolet).

All power sources can be divided into two categories: replaceable batteries in a standard size and built-in batteries. The former are convenient in that a dead battery can be quickly replaced with a fresh one, while the original battery will have to be charged — and this takes time and an external power source. In addition, batteries can be selected at your discretion by type (disposable/rechargeable) and capacity. Batteries, in turn, can be made more compact and at the same time capacious, besides, they do not need to constantly spend money on fresh batteries.

The main characteristic of a replaceable battery is its size; The most popular sizes found in thickness gauges are as follows:

— AAA. Elements, also known as "mini-finger" or "little finger". They have a cylindrical shape with a diameter of 11 mm and a length of 44 mm. Usually used in 2 or 3 pieces. They can be made in the form of batteries.

— AA. Elements, also known as "finger". They have a cylindrical shape with a diameter of 13.5–14.5 mm and a length of 50.5 mm. Usually used in 2 pieces. They can be made in the form of batteries.

— PP3. Batteries of a characteristic rectangular shape, with a pair of contacts on one of the ends. They have a nominal voltage of 9 V. They can be made rechargeable, however, for a number of reas...ons, this option has not received distribution; disposable “PP3” are used much more often.

— CR2032. One of the most popular sizes of "tablet" batteries. They have the shape of a disk 3.2 mm thick and 20 mm in diameter. They are used in the most miniature devices, where compactness is crucial. They are only made disposable.

— LIR2032. A rechargeable version of the CR2032 batteries described above, made using lithium-ion technology.

— A23. Cylindrical batteries with a diameter of 10 mm and a length of 29 mm. They are distinguished by a rather high voltage — 12 V. They are usually made disposable.

As for batteries, the key parameter for them is the technology by which the battery is made:

— Li-Ion. Lithium-ion technology allows you to create batteries with a good charge density — that is, compact and at the same time capacious. In addition, they are not subject to the “memory effect” (reduction in capacity when charging to full discharge) and charge quickly enough. Of the shortcomings of such elements, one can only note the likelihood of overheating and fire in case of malfunctions, however, subject to the operating rules and the use of serviceable chargers, the probability of this is almost zero.

— Li-pol. An improved version of the lithium-ion batteries described above, providing even greater charge density, but at a slightly higher cost.

The temperature range at which the thickness gauge can normally perform its functions. If you go beyond this range, the device may not break down immediately, but you won’t have to talk about accurate measurements. Note that you have to pay attention to this parameter mainly in cases where the device is planned to be used outdoors. So, for use in winter, it is worth making sure that the device is able to operate at temperatures below zero, and for hot climates, it is desirable that the upper limit of the range is +40 °C and above.