Definition
A squeegee heated coating machine is a type of laboratory equipment used to prepare uniform coatings on the surface of substrates. It cooperates with an adjustable squeegee and a heating platform to coat liquid or paste samples into a wet film of a set thickness, which is widely used in sample preparation and performance testing in coatings, inks, adhesives, electronic materials and other industries.
How it works:
The equipment is mainly composed of a precision scraper mechanism, a temperature-controlled heating platform and a substrate fixing system. During operation, the sample is placed on the substrate and the heating platform is maintained at a set temperature to control the rheological properties of the sample. The scraper moves at a constant speed or pressure, and the gap between its edge and the substrate determines the thickness of the wet film. The heating function simulates the actual drying or curing process, helping to obtain coatings that are closer to the actual application conditions.
Measurement method
The coating thickness is controlled by setting the squeegee gap mechanically or digitally, and the common formula is:
h = k × (G - S)
where h is the thickness of the wet film, G is the scraper gap, S is the thickness of the substrate, and k is the correction coefficient related to the rheological properties of the material. The actual thickness needs to be verified by a dry film thickness gauge or microscope. Coating speed, temperature and pressure parameters are calibrated according to the corresponding standards (e.g. ASTM D823, ISO 15184).
Influencing factors
Coating uniformity is affected by multiple factors. The gap accuracy of the scraper directly affects the thickness consistency. Heating temperature affects material viscosity and leveling, and temperature deviations can lead to coating defects. The scraping speed needs to match the rheological properties of the material, too fast is easy to produce streaks, and too slow may lead to local curing of the material. Ambient temperature and humidity, substrate surface energy and sample pretreatment status also have an effect on the quality of the coating film.
Applications:
This equipment has a wide range of uses in industrial R&D and quality control. In the coating industry, it is used to prepare corrosion resistance and adhesion test samples; printed electronics for the preparation of conductive films; The adhesive industry is used to control the study of adhesive layer thickness; Used in textile processing for coating uniformity evaluation. The standardized samples prepared by it can be used for a variety of subsequent tests such as gloss, hardness, and weather resistance.
Selection considerations
When selecting a model, technical parameters and usage requirements should be comprehensively considered. The scraper adjustment range should cover the thickness requirements of commonly used coatings, and the accuracy is recommended to be better than 0.5 microns. The heating platform should have a uniform temperature field and program temperature control capabilities. The material of the equipment should be chemically resistant, and the type of scraper (such as wedge, bar) should be selected according to the characteristics of the sample. Automation features such as speed programming and pressure feedback improve operation repeatability. The equipment should comply with the requirements of relevant international standards for the preparation of laboratory coating films.