Mainly two categories: physical and chemical drying. The former is based on hot air, air flow speed and time, while the latter requires a source (typically lamps) to activate some internal components in the lacquer. There are also lacquers that need both of these methods.
There are different types of oven: in-line, vertical and UV. The first two will dry items through a physical process and differ by size, working speed and hold times of the workpieces. UV ovens, on the other hand, are based on a chemical process and their size is smaller. The choice of an oven is determined by the type of lacquer used.
The recommended type of drying depends on the type of product and is normally defined in agreement with the lacquer manufacturer, to ensure the required coating performance over time. The coating cycle, which also includes drying, is then defined with the aim of obtaining the desired final result, reducing the required investment and optimising performance.
Let's talk about the advantages of the whole finishing process, which includes lacquer application and drying. The "finished" item ends up with improved resistance and protection from external agents, as well as a better aesthetic presentation.
Excimer drying is a drying process for UV coating products, which allows surfaces to be obtained with truly outstanding deep matt finish and resistance characteristics of the coating film. Normally it is a mixed cycle, which includes the evaporation of the solvents, followed by exposure to a dedicated lamp (an excimer lamp), to end with final UV crosslinking, necessary to definitively "lock in" the obtained result. The oven Exydry-Z ensures a deep matt finish, surface resistance and soft touch effect even on shaped or raised panels.
Drying in an inert atmosphere is obtained by dramatically reducing the amount of oxygen present in the oven and replacing it with an inert gas, nitrogen. Considering that oxygen is the natural barrier preventing the crosslinking process, this type of drying allows a 40-70% reduction in the quantity of photoinitiator needed to start crosslinking of UV coatings, resulting in significant cost savings. The first inert atmosphere oven on the market is UV-I.
In addition to the dramatic reduction in photoinitiator requirements, with the resulting lower cost of lacquers, drying in an inert atmosphere ensures other advantages. The lacquer used is less harmful to the environment. The yellowing effect caused by photoinitiators is less likely. Fewer UV lamps are required to activate crosslinking, resulting in lower energy costs.
Different systems can be used to evaluate the drying quality and characteristics to be obtained from the finishing process. For example, if we want to test the final degree of resistance of the treated item, we will use destructive tests, or tests with solvents or with abrasive tools.
Normally drying ovens are rather simple machines, only a few parameters need adjustments and most importantly, these parameters remain stable even when the lacquer colours and/or the shapes of the coated pieces change. No particular skills are therefore required; it is necessary, however, to set the temperatures for the different zones (if any), the air speed and possibly the power of the lamps (if any).
It depends on the type of oven but generally speaking drying ovens are low maintenance. Only vertical ovens, due to their operating mode, require some extra care because of the loads that they have to bear, but all that's required is checking, tensioning and lubricating some of their parts.
Our international network of distributors and branch facilities is widespread globally, and most likely, you'll easily find the right contact in your own country. Otherwise, in just a few days we will send spare parts and technicians straight from our headquarters.
The entire coating process, or the drying part only, can be managed through recipes, therefore in a very straightforward way.
Ovens, just like the coating application machines, have specific characteristics. This makes some ovens specifically suitable for some processes, while others are more flexible and able to adapt to different types of application. For example, a vertical oven is specifically intended for raised or shaped doors, but it can also be used for flat ones.
Each oven is created with a specific objective in mind. Within the scope of these specifications, it is obviously possible to adjust some parameters including temperature, air speed, power of the lamps and lamp distance. The machines are therefore inherently flexible when operating within their design scope.