Definition
The Electric Paint Circle Tester is a laboratory testing equipment used to evaluate the adhesion properties of coatings. The instrument uses a motive-driven scribing needle to perform a scribing motion on the coating surface at a fixed pressure, and determines the bond strength between the coating and the substrate according to the shape of the scratch or the peeling of the coating. It is widely used in quality control and R&D testing in coatings, automobiles, ships, furniture and industrial anti-corrosion fields.
Principle
The core principle of the instrument is based on the mechanical scratch method. The instrument spindle drives the scribing needle to rotate at a constant speed while applying a standard pressure vertically downward to the scribe through the loading mechanism. The scribing needle makes continuous overlapping circular scratches on the surface of the coating, and as the number of scratch turns increases, the scribing needle gradually penetrates the coating to the substrate. The strength of the coating's adhesion is determined by observing the degree of peeling of the coating within the scratched area or by specific judging criteria. The mechanical relationship can be simplified as follows: the interaction between the pressure exerted by the scribing needle and the strength of the coating to resist peeling determines the final morphology of the scratch.
Measurement method
The measurement process usually follows relevant standards such as GB/T 9286, ISO 2409, or ASTM D3359. First, secure the coated sample on the instrument table to ensure a flat surface. Select the appropriate size of the scribing needle according to the standard and install it, and set the scribing load and rotation speed. After starting the instrument, the scribing needle makes at least 6 overlapping circle marks on the surface of the sample. Once the test is complete, remove the sample, apply scotch tape to the scratched area and quickly peel off to remove loose coating fragments. Finally, the attachment grade is evaluated by comparing the standard map or measuring the proportion of peeling area. The grade is usually divided into 0 to 5 grades, of which 0 represents no peeling and optimal attachment; Level 5 representatives are seriously peeling off.
Influencing factors
The accuracy of test results is influenced by various factors. The coating's own properties, such as thickness, hardness, flexibility, and curing degree, can directly impact scratch resistance. The surface treatment of the substrate, such as cleanliness, roughness, and material, can also change the adhesion interface strength. In terms of instrument parameters, the tip radius of the dicing needle, the applied load, the scratching speed, and the ambient temperature and humidity can all lead to biased results. Operational standardization is also critical, such as the stability of the sample fixation, the angle of pin installation and the tape tearing technique.
Application:
Electric paint film circle tester plays an important role in quality control and research and development in multiple industries. In the coatings industry, it is used to evaluate the adhesion properties of different formulations of coatings, guiding product improvements. The automobile manufacturing industry often tests the reliability of body coatings and parts coatings. In ship and bridge corrosion protection projects, this instrument helps verify the adhesion of anti-corrosion coatings in harsh environments. In addition, it is used as a routine inspection method in the field of furniture, electronics shells and industrial equipment coatings to ensure that the coating remains intact over its service life.
Selection
Choosing a suitable electric paint scribing tester requires comprehensive consideration of testing needs and standard compliance. First, it should be confirmed that the instrument meets the standard requirements of the target industry, such as international standards or national specifications. Core parameters include load range, scribe specifications, spindle speed accuracy, and table size, which need to match the test conditions of common samples. The structural durability and ease of operation of the instrument are also worth paying attention to, such as whether it has a digital display, load adjustment mechanism, and safety protection functions. In addition, the supplier's technical support and calibration service capabilities can ensure the long-term stable operation of the equipment. It is recommended to conduct a comprehensive evaluation based on the actual sample type and test frequency to ensure that the instrument meets the laboratory's testing requirements.