Purchasing a used car is always risky, and one of the main markers of the condition of the machine is the quality of the paintwork. That is why the question of what is the name of the device for measuring the paint layer on the car becomes a priority for any competent buyer. This tool allows you to instantly distinguish factory painting from handicraft repairs, hiding traces of serious accidents or corrosion.
In the professional environment, this device is most often called thicknesser. This is a compact electronic device that in a fraction of a second gives accurate data on the distance from the sensor to the metal of the body. Understanding the principle of its operation and the ability to interpret the testimony can save you from buying a βdesignerβ with broken spars or hidden foci of rust under a layer of putty.
Principle of operation and types of measuring devices
The modern market offers several types of devices, and the choice depends on what kind of metals you will work with. The most common and affordable option is magnetometer. It works exclusively with ferromagnetic metals such as steel. The principle is simple: the thicker the layer of paint or putty, the weaker the magnetic field that the sensor detects. It is the ideal choice for checking out most budget and mid-priced cars, the body of which is made entirely of steel.
However, modern automakers are increasingly using aluminum, plastic and carbon fiber to reduce the weight of the car. For such materials, the magnetic method is powerless. Here comes the game. vorticular thicknesser. It generates a high-frequency electromagnetic field that induces vortex currents in the conductive material (aluminum). Changing the characteristics of these currents and allows you to calculate the thickness of the coating. It is important to understand that measuring on dielectrics such as plastic or fiberglass will require a more sophisticated ultrasonic method, although this is less common in the context of a car body.
β οΈ Note: When buying a used device, make sure that its sensor does not have mechanical damage, since even a microscopic scratch on the contact platform can give an error of up to 20 microns, which will distort the real picture.
The most universal solution is considered compositeIt combines both technologies. Such devices automatically detect the type of metal under the sensor and switch the operating mode. This saves the owner from having to manually change the settings when switching from a steel door to an aluminum hood. Professional models are often equipped with a graphical display of the layer profile, which allows you to see the structure of the coverage in real time.
Key characteristics when choosing a tool
When choosing which device to buy, you can not rely only on the price. There are a number of technical parameters that directly affect the quality of diagnosis. First of all, pay attention to the error. For household needs, a range of 3-5% is considered acceptable, while professional certified devices must provide accuracy up to 2-3% or 1-2 microns. The smaller the error, the easier it is to distinguish the factory paint from the repainted part.
The second important aspect is range. Standard factory thickness values of the paint coating rarely exceed 150 microns. However, if a car has been in a serious accident and is leveled with a putty, the layer can reach 1000, 2000 and even 5000 microns. Cheap models often βover the chartβ after 1000-1200 microns, without showing real figures, which can hide the fact of rough body repairs.
- π Type of display: for work in the dark or in poorly lit garages, a device with a screen illumination is critically important, otherwise the readings will have to be read with a flashlight.
- π Autonomy: The quality models are powered by standard AAA batteries or built-in Li-Ion batteries, providing up to 10,000 measurements without recharging.
- π‘οΈ Temperature range: If you plan to inspect cars outside in winter, make sure the device works properly in low temperatures (usually as low as -10Β°C or -20Β°C).
The ergonomics of the body should not be ignored. The device should be comfortable in your hand, and the control buttons should be large enough to press with gloves. Often, when inspecting a car in a parking lot or in winter, you have to work quickly, and an inconvenient interface can slow down the inspection process.
Thickness standards and interpretation of readings
To effectively use the thickness meter, it is necessary to clearly understand what values are considered the norm. The thickness of the paint layer in different parts can vary, but on average for European and Japanese cars it is the same. 80 to 140 microns. On body racks, sills and roofs, the layer is usually thinner (about 90-110 ΞΌm), and on horizontal surfaces such as a roof or hood, it can be slightly thicker due to the features of the application technology.
If the device shows values in the range 150 to 250 micronsThis is likely to indicate a secondary color of the part. This may be due to the elimination of minor scratches, chips or cosmetic repairs after mild grumbling. Such values are not always critical, but they should alert the buyer and encourage a more thorough visual inspection for the quality of painting.
Testimony over and above 300-400 microns It is almost guaranteed that there is a layer of putty. This is a sign of serious body repairs associated with metal richting after impact. In such cases, under the paint layer can hide not only the restored geometry, but also potential foci of corrosion, which will manifest themselves after several years of operation.
| Device display (ΞΌm) | Probable cause | Status of detail |
|---|---|---|
| 80 β 140 | Factory coverage | Norma. |
| 150 β 250 | Secondary colouring (cosmetics) | It needs attention. |
| 300 β 1000+ | Putting on a putty | Repairs after an accident |
| More than 1500-2000 | Deep Putty / Hidden Repair | Critical repairs |
Popular models and brands in the market
The segment of measuring equipment is represented by both expensive professional solutions and available Chinese analogues. The German company has been the market leader for many years. Elcometer. Their instruments, such as the series Elcometer 450The car is considered the standard of accuracy and reliability, but their cost can be unreasonably high for a one-time purchase of a car by a private person.
In the middle price segment, devices from the Conrad and Etari. Model Etari ET 11P It has become a kind of folk classic due to the optimal ratio of price, speed and availability of a Russified menu. These devices are great for both private buyers and small car service providers. They are quickly calibrated and have a clear interface.
The budget segment is filled with a lot of clones and devices under various brands, often sold on marketplaces. Instruments such as ChY or unnamed series models TTMThey can show acceptable accuracy on new batteries, but often suffer from unstable readings and slow response rates. When choosing a budget option, be sure to check the equipment: the presence of calibration plates and metal substrates greatly simplifies the initial test of the device's operability.
Before leaving for a car inspection, be sure to test the device on your own car or a part known to you to remember the sensations of pressing and the speed of the numbers on the screen.
Methods of measurement: step-by-step instructions
The correct use of the device is as important as its availability. Start the check should be set with zero readings on the reference plate or just in the air (for some models) to exclude the drift of the sensor. Then you need to choose a reference body section that has not exactly been repaired - usually it is the roof racks inside the doorway or the central parts of the sills. Remember or write down these basic values.
Then move from the reference site to the periphery, checking each body part at several points: top, middle and bottom. Pay special attention to the transitions between parts, for example, from door to wing. A sharp jump in readings at the junction of elements often gives out a repainted part, even if the neighboring elements have factory values. Press the sensor tightly and perpendicular to the surface, avoiding swaying.
βοΈ Body inspection algorithm
If the readings at the edge of the door are 40-60 microns, and in the center - 120 microns, this is normal. However, if the values are flat and high along the entire plane of the door, and there is a sharp cliff or abnormally low numbers on the edge, this is a sign of repainting.
β οΈ Note: Do not take measurements on dirty, wet or coated surfaces with wax/polyre. Pollution can create an additional gap between the sensor and the varnish, which will lead to falsely inflated readings.
Limitations and possible sources of error
Despite the high technology, the thickness meter is not an all-powerful device. One of the main sources of error is surface-curvature. On strongly convex or concave areas, as well as on sharp edges, the contact area of the sensor with the body decreases, which can lead to errors. In such cases, it is recommended to make several measurements near the problem area and to derive the average value.
Another factor. metallicity. Different grades of steel may have different susceptibility to the magnetic field. If the car is made of metal from different batches or suppliers, the baseline readings on different doors of the same car can vary by 10-15 microns without the presence of paint. This is why it is so important to compare symmetrical details (left and right wing) with each other.
Effects of metal temperature
If the car has just driven from the cold into a warm box, condensate can act on the metal, and the metal itself has not yet warmed up. This can temporarily change electrical conductivity and affect the readings of eddy current sensors. Let the machine stand for 15-20 minutes for acclimatization.
Also, it is worth considering the presence of protective films, βantigraviaβ or thick layers of preservatives on the thresholds and arches. The thickness gauge will show the overall thickness of all layers, and you may mistake factory corrosion treatment for a putty. Visual inspection and tactile surface sensation will help differentiate a solid putty from an elastic protective coating.
FAQ: Frequently Asked Questions
Can a thickness gauge determine if the entire part has been replaced?
The device itself shows only the thickness of the coating. However, if the new part is installed in the factory paint (80-120 ΞΌm), and on the neighboring elements - 140-160 ΞΌm (taking into account the age of the car), this may indirectly indicate a replacement. But for an accurate diagnosis, you need to look at the labeling of the glasses, the date of production and VIN codes on the hinged elements.
Is the device lying in rusty areas?
Yes, in areas with through or deep corrosion, the readings will be incorrect. Rust products have a different density and structure than metal, which distorts the magnetic field or vortex currents. In such cases, the device may show either very high values or a measurement error.
Do I need to calibrate the device before each use?
Modern digital thickness gauges do not usually require calibration before each use unless they have been subjected to shocks or extreme temperatures. However, it is recommended to periodically check the accuracy on the reference plate, coming in the kit, especially if you doubt the readings.
Will the device show the quality of paint (acrylic, metallic, ceramics)?
No, the thickness meter only measures the physical thickness of the dielectric layer (varnish and paint) above the metal. The type of chemical composition of the coating (ceramics, liquid glass, ordinary varnish) does not matter for it, only the final micron layer is important.
The thickness gauge is just a diagnostic tool. No device will replace a comprehensive inspection of the body, geometry check and study the history of the car databases.