When choosing a used vehicle and assessing its condition, great attention should be paid to the condition of the bodywork. As practice shows, almost every car has some kind of external damage, but they are often skillfully hidden behind a layer of putty and painted over exactly to the tone of the car.
With the naked eye, it is almost impossible to determine the true condition of the body in most cases - however, later such undetected defects can become a serious problem. In addition, an incorrectly defined technical condition of the car leads to an incorrect price setting - every damage, even if not visible to the eye, allows you to reduce the cost of the car. To detect such defects, a special device should be used - a thickness gauge, which determines the thickness of the paintwork. With its help, it is possible with almost 100% accuracy to determine whether the car got into an accident and how serious the damage was.
What is the thickness gauge for the paintwork of a car
The thickness gauge for the paintwork allows you to quickly and accurately measure the thickness of the paint layer on certain body parts car. The vast majority of modern models of thickness gauges use the ultrasonic measuring principle. The sound pulse travels at a precise speed from the device to the metal base of the part and returns back. The device registers the return time of the signal and, multiplying it by the value of the ultrasonic velocity, obtains the value of the thickness of the paintwork.
The main components of such thickness gauges are:
- generator of ultrasonic pulses with a given duty cycle;
- ultrasonic emitter;
- module-receiver of the reflected pulse;
- a pulse delay time matching module;
- digital converter;
- LCD display for total thickness reading.
With such a complex design, ultrasonic thickness gages are compact and lightweight. At the same time, they operate on batteries, which allows measurements to be taken directly at the inspection site of the machine.
There are also magnetic, electromagnetic, eddy current, mechanical thickness gauges on the market, but they are characterized by a large operating error. Therefore, they are used much less frequently than ultrasound models.
Using such a device, it is possible to identify various types of defects and repairs:
- thinning of the factory coating;
- applying a second paint coat;
- puttying and subsequent painting of damaged areas of the body.
The measurement accuracy is a few micrometers, so even minor damage can be detected with such a device. In addition, unlike all other types of thickness gauges, ultrasonic models are suitable for examining not only metal parts, but also plastic ones. In particular, they can be used to determine whether bumpers, decorative trims, etc. have been repaired.
How to use the paint thickness gauge
In some cases, before measuring the paint thickness directly, it is necessary to properly calibrate the device. To do this, use special calibration plates, one of which plays the role of a metal base, while the others imitate layers of paint of various thicknesses. According to them, the accuracy of the device change is set. However, not all models require such a setting - self-calibrating models can also be found on sale.
Next, you need to decide what thickness of paint for your car should be considered normal? After all, each manufacturer for each model can use a different color intensity. You can find such information in the technical documentation for your car. On average, a layer of factory paint has a thickness of 70 to 150 microns.
However, a number of nuances must be taken into account:
- In different parts of the body, the thickness of the paint layer may be different, due to technological features. In particular, a thicker layer is usually applied along the edges of the body.
- On the front and rear fenders, the base paint thickness can be different, but on symmetrically located elements it is always the same by default.
- The factory setting range for the thickness of the paint layer on different parts should not differ by more than 50 microns.
- The internal surfaces of the body parts are covered with thinner layers of paint, the difference here is about 40-60 microns.
In order to change the thickness of the paintwork evenly and firmly press the working plate of the device to the surface of the investigated part and, if necessary, press the start button (many modern models automatically turn on when it comes into contact with the inspected element)... Literally immediately, the thickness gauge will display data on the thickness of the paintwork at a given point.
For greater accuracy and reliability of measurements, divide the investigated part of the body conditionally into 5 parts - 4 corners and a center. For each such point, take 3-5 measurements, recording the results in writing - this minimizes the error. Moreover, the measurements must be repeated not exactly in the chosen place, but at some distance from it. For example, take measurements within a radius of 15-20 cm, so the objectivity of the results will be much higher.
If there are strong deviations from the norms or a large measurement range in some area, then such an element can be examined more carefully. Take measurements not at 5, but at 8-10 different points, this will allow you to accurately determine the relief of the metal and the change in the thickness of the paintwork.
When all the necessary measurements have been made, you need to determine the arithmetic mean values for each part. Further, if necessary, you can calculate the average value for the entire machine.
See also : What you need to know when buying a used car.
What the thickness gauge should show on the whole car
If the car is not damaged, not repaired or repainted, then the thickness gauge should show the thickness of the paint layer not more than 200 microns... In general, as already mentioned above, the average values are from 70 to 150 μm. Accordingly, such readings indicate that everything is in order with the car body. If the average values are higher, then this can already be regarded as a sign of a broken car. And the thicker the paintwork layer, the more serious the damage was.
For example, we give a table with the values of the thickness of the paintwork on some popular car models.
|Manufacturer||Car model||Paint thickness, μm|
|Audi||A1, A3, A4, A5, A7, A8||100-140|
|Q3, Q5, Q7||110-165|
|BMW||1-series, 2-series, 3-series, 5-series, 7-series||100-165|
|Chevrolet||Lanos, Aveo, Cruze, Captiva, Lacetti, Niva||80-135|
|Citroen||C5, C -Elysse||110-140|
|C4, C3, Picasso, Berlingo||75-125|
|Hyundai||Accent, IX35, I30, I40, SantaFe, Elantra||70-110|
|Tucson, Solaris, Sonata||90-130|
|KIA||Sportage, Sorento, Cerato, Cee'd, Picanto||100-145|
|Soul, Rio, Venga, Optima||120-150|
|Lexus||RX, ES, LX||140-160|
|CT, GX, LS||120-150|
|CX-7, CX-5||90 -120|
|Mitsubishi||L200, Outlander XL, ASX||70-95|
|Nissan||X-trail, Patrol, Juke, Qashqai, Murano, Tiida, Pathfinder||80-120|
|Opel||Astra, Corsa, Mocca, Zafira, Insignia, Vectra||110-160|
|Peugeot||208, 308, 508, 3008||100-120|
|Fluence, Duster, Megane, Sandero||100-140|
|Skoda||Octavia, Yeti, Superb, Fabia, Roomster||100-145|
|Suzuki||Grand Vitara, SX4, Swift, Splash||85-115|
|Toyota||LC200, Camry, Highlander, Auris, Verso||95-130|
|Avensis, Corolla, Prado, Prius, RAV4||80-110|
|Tiguan, Passat, Caddy, Multivan, Amarok||105 -140|
|Volvo||S40, S60, XC90||100-150|
|Lada, VAZ||Kalina, Priora||60-100|
Remember, that different parts and their different areas in most cases, by default, have a different thickness of the paint layer. Therefore, small deviations from the center to the edges are acceptable. However, they should be really small - within 50 microns. At the same time, symmetrically located parts at the factory are always painted the same way - therefore, if the thickness gauge on the left wing shows a higher value than on the right, then this can be regarded as evidence of repair.
Of course, the thickness gauge should not be considered a panacea for detecting absolutely any damage - modern body shops allow you to restore parts with almost factory accuracy. However, such cases are still rare, so in most cases such a device will be really useful.
Read also : What is liquid glass for a car and how to apply it.