Quality control in automotive painting and coating is an essential part of the production process, as well as in any industry, as it helps ensure the best possible results for both the manufacturer and the end user.
This is especially true of the automotive industry, where multiple components are assembled into one product, the automobile.
Therefore, quality control can take place in several production units, even within a single plant.
Here we will talk specifically about quality control in the production unit for auto body painting and the coating of its components.
Painting quality control before production
For the painting production unit, it’s of vital importance to execute quality control on the materials supplied by the supplier before they are applied.
In the automotive industry, the incoming materials are not only paints for car aesthetics, but also different types of coatings that provide protection to very important parts such as the chassis, for lasting durability.
For best results, there are specific material properties that need to be verified prior to application. Let’s see some of them.
Viscosity
Determining the viscosity of the paint is essential in the automotive industry as it is applied by spraying the nebulized paint with special nozzles.
In most cases, the paint viscosity is so low that it atomises, but not so low as to create problems like coating failure. This is why it’s crucial to check this parameter. It also has an impact on different performance standards such as:
- Pressure
- Flow
- Coating speed
- Coating film build up
- Color matching
- Chemical resistance
Viscosity also has a direct impact on the paint transfer and thus on the quality of the finished surface.
In any case, the production unit dealing with automotive painting should have the right equipment to control the viscosity of the paint.
Among the most suitable measuring instruments for these applications, we must certainly mention flow cups and rotary viscometers.
PH
Although automobiles were initially made of steel to balance the cost between durability and workability, aluminum is more widely used nowadays, as it’s lighter in weight without sacrificing safety.
Specifically, the paint and coatings provide the corrosion protection of these metals. Therefore, a series of steps are employed to prepare the chassis and other car components for such protection.
In general, corrosion can be reduced through pH control and the use of corrosion inhibitors.
To check the pH in the paint production unit, manufacturers can rely on tools such as portable pH meters, thanks to which, they can test the pH anytime, anywhere, quickly and easily.
Conductivity
After electrodeposition, the accumulation of excess paint that adheres to the surface, but not bound to it is rinsed through an ultrafiltration unit, to ensure the uniformity of the surface.
However, this can create a water-stain contamination problem on the coated surface. To avoid this phenomenon, well-deionized water is used. Therefore, conductivity must be constantly monitored to ensure positive results.
For this phase, it is essential to have a reliable conductivity meter.
In photo: portable pH meters
Quality control post-production
We have seen some critical aspects of quality control before painting the body and the car components. Now it’s time to see how to ensure high quality even after the end of production.
Once the paint and coatings are applied, colorimetric measuring tools must be used to ensure high quality results. Let’s take a look at some of these tools.
Spectrophotometers
The spectrophotometer is one of the most high performing tools for painting in the automotive sector.
Two objects, which are illuminated in the same way, may have the same color, under a given light source, but a different color, under a different light source. Therefore, two objects of the same color, but produced at different times and with non-identical products, can reflect light in different ways.
Spectrophotometers use the principle of combined spectroscopy, which is to separate light according to a certain wavelength range. This way, they carry out the complete spectrographic analysis of the color, covering the entire wavelength of the painted piece, confirming the spectral curves and the metamerism. This allows one to verify that an entire production batch has the same color, guaranteeing repeatability and consistency.
If you are interested in light and color analysis, please read this article on our blog to learn more about spectrophotometers.
Color Difference Meters
This tool, also known as a colorimeter, allows you to measure color differences to check their uniformity. To find out more about color difference meters, click here.
Glossmeters
The glossmeter is an interesting tool for the automotive industry as it allows one to determine the gloss and brightness of the paint; two essential characteristics that makes the car much more appealing to the human eye.
If you’re curious about how it works, read everything you need to know about the glossmeter here.
Other indispensable tools for production include: thickness gauges for paints and coatings and hardness and cross hatch testers to check the durability of coatings. The point is that quality control is a must in this industry.
You can also learn more about this topic by reading our article about the 10 Instruments for First-Class industrial Coating.
The calibration of instruments in the automotive sector
Last but not least, we must remember about calibration. These tools must be calibrated to ensure accurate and reliable results, which is why we consider it a priority service for all our customers.
Why calibrate measuring instruments?
The calibration of the measuring instruments is absolutely necessary to be in accordance with the UNI EN ISO 9001, and more specifically with paragraph 7.6, which deals with the management of the measuring equipment.
We have already explored this important topic.
Who is responsible for the calibration of the measuring instruments?
Calibrations can be performed both by independent laboratories that offer their services to different companies and by laboratories within the company itself, as long as they adhere to the same legal requirements as external laboratories.
When is an instrument considered calibrated?
An instrument is said to be calibrated when it’s subjected to a sort of “photograph” which helps to define the metrological characteristics of the instrument itself. This service is optional when purchasing the instrument and takes place by means of comparing measurements with a reference instrument, called a sample.
S.A.M.A. Italia can assist your company’s needs, both by providing you with the measuring instruments mentioned in this article, and by providing our calibration services.
We can issue calibration reports with traceability to primary samples, or we can provide you with ACCREDIA certificates, in collaboration with the best accredited laboratories.
Do you have other questions about the differences between these two services? Don’t worry because our technicians receive dozens of requests like this every day and are always available to assist you.
If you want your instruments calibrated but you’re not sure if you need to receive a calibration report or a LAT certificate, contact us. There’s no obligation.
Many of our customers often decide to leave their feedback. Find out what they have to say about us.
