1. Introduction
In this article, we will provide information about CO2 cleaning with carbon snow for plastic parts.
Currently, with increasingly strict quality requirements, there are not many systems approved by major OEMs for cleaning plastic parts. One of these is CO2 cleaning.
Throughout our experience, we have seen and gathered countless opinions on this topic, which sometimes distort the reality, and the big question always arises: does it work? The answer is not straightforward, but if I had to decide, I would say yes, as long as the system is well-chosen and other factors such as airflow and air quality are taken into account.
As an example, with a client who used a Power Wash, we installed a dual system, and after a short period of working with both systems, over 95% of the production was permanently shifted to CO2 cleaning. The hourly cost relationship between a Power Wash and CO2 is very interesting in favor of CO2.
2. What advantages does it offer?There are several advantages it offers:
The answer is simple. Basically, cleaning occurs due to three factors:
One of the main advantages of carbon dioxide is that, upon evaporating, it leaves no residue.
4. Which product to chooseThere are primarily two types of cleaning based on the initial state of the product, both of which are carbon dioxide.
4.1 PelletsThese are small solid pellets, available in various sizes ranging from 2 to 10 mm. This type of cleaning is effective for cleaning and degreasing metals due to its high energy impact. However, it is not the most recommended for painting application lines due to the tendency to accumulate water in the nozzles. This results in microdroplets of water ending up on the part, causing other quality issues.
4.2 Carbon SnowWith less impact than pellets, it generates a gentler cleaning effect on the part. Carbon snow is stored in liquid phase in a tank and is transported in either liquid or gas phase to the application point.
This is where we find significant differences. Transporting in liquid phase requires insulation to prevent gasification, which, in extreme climates, may even require vacuum jackets. Then, in the application machine, the gas must return to the tank, and at every point of evaporation, it is susceptible to generating ice due to the product's phase change, potentially causing various issues in valves and components.
Due to all these factors, at Coapsys, we choose to integrate the gas system for simplicity, maintenance, and robustness. The gas system is transported at 15-20 bar, and once it reaches the booster or pressure releaser, it reaches 55-65 bar. This gas is cooled again to generate the snow crystals ready for application.
5. What elements make up the installation and how it is appliedThe installation of a CO2 system consists of the following elements:
The application of CO2 is another crucial factor for the success of the process; considering the application speed and angle of incidence is fundamental.
Other important points to consider relate to the painting line, such as air quality, type of booth, etc., as well as safety components. We will address this in another article.
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