Definition
The Wire Bar Squeegee Automatic Coater is a type of laboratory equipment used to prepare uniform coatings on flat substrates. It drives the coating rod or scraper through an automated control system to move across the surface of the substrate at a set speed and pressure, resulting in a wet film coating with a controllable thickness. The equipment is mainly used for sample preparation and process research in the fields of coatings, inks, adhesives, electronic materials and functional films.
Principle
The core principle of the equipment is based on mechanical scraping technology. The surface of the coating rod is wrapped with metal wires of a specific diameter, forming gaps; Or use a precision-machined scraper with a set gap between the cutting edge and the substrate. When the equipment is started, the motor drives the coating head to move at a uniform speed along a straight track to scrape and coat the fluid to be applied in front of the substrate. The thickness of the wet film is mainly determined by the wire diameter or scraper gap of the coating rod, and the relationship can be approximately expressed as:
Wet film thickness = k × gap height
where k is the correction factor related to the rheological properties of the fluid. The automated system precisely controls the coating speed, pressure and environmental conditions to ensure the reproducibility of the coating process.
Measurement method
The evaluation of coating quality usually involves the measurement of wet film versus dry film. Wet film thickness can be measured at multiple points immediately after application using a wet film thickness comb gauge to calculate the average. The thickness of the dry film needs to be measured by contact or non-contact instruments such as magnetic thickness gauges or eddy current thickness gauges after the coating is cured. Coating uniformity can be analyzed by observing the surface topography by optical microscope or surface profiler, combined with thickness distribution data. Adhesion, gloss and other properties need to be further tested according to relevant standards, such as ASTM D3359 or ISO 2813, using special instruments.
Influencing factors
The coating quality is affected by multiple factors. In terms of fluid properties, viscosity, leveling and thixotropy directly affect the spread and final uniformity of the coating. In the equipment parameters, the stability of coating speed and scraper pressure are the key variables. Too fast speed can lead to discontinuous coatings, and uneven pressure can cause thickness fluctuations. Environmental conditions such as temperature and humidity can affect the volatilization rate of solvents and fluid rheological behavior. The surface energy, flatness and cleanliness of the substrate also have a role in the adhesion and appearance of the coating. The technical proficiency of the operator and the maintenance status of the equipment are also part of ensuring the reliability of the results.
Application:
The device has a wide range of uses in a variety of industrial and scientific research fields. In the coatings industry, it is used to prepare test samples to evaluate weather resistance, color and coverage. In the field of printed electronics, it can be used to prepare conductive ink coatings and study their electrical properties. In adhesive development, it helps to form a uniform adhesive layer and analyze bond strength. In the research of functional materials, it is used to prepare samples of new materials such as optical films and waterproof coatings. In addition, in standard conformity testing, the equipment can prepare samples in accordance with ISO, ASTM and other standards to ensure the consistency of test conditions.
Selection
Choosing a suitable wire rod scraper automatic coating machine requires comprehensive consideration of technical requirements and operating conditions. First, the coating width and length range should be clarified to ensure that the equipment stroke covers the sample size. The coating speed range and speed regulation accuracy need to match the fluid characteristics, for example, high viscosity materials may require lower speeds and higher drive torques. The equipment should have a stable pressure control system and a flat substrate platform. Functionally, consider whether a temperature control module or a vacuum adsorption platform is needed to accommodate special materials. Compatibility with multiple coating stick or scraper types helps expand the range of applications. In addition, the convenience of equipment operation, safety protection design and after-sales technical support are also aspects worth paying attention to in the selection.