Design and Application of Device for Measuring Water Absorption Thickness Swelling Rate of Wood-based Panels

The water absorption thickness swelling rate of engineered wood products is an important indicator reflecting their water resistance and dimensional stability. It is the ratio of the increase in thickness after water absorption to the original thickness. Currently, most testing methods for determining the water absorption thickness swelling rate of engineered wood products such as particleboard, fiberboard, and oriented strand board (OSB) are based on the provisions of section 4.4 of GB/T 17657-2013, "Test Methods for Physical and Chemical Properties of Engineered Wood Products and Decorative Engineered Wood Products".

According to the regulations, the surface of the test specimen must be perpendicular to the water surface, and the distance between specimens and between the specimen and the bottom and walls of the water tank must be at least 15 mm. The upper part of the specimen must be (25±5) mm below the water surface. In actual testing, due to the physical properties of the engineered wood material itself, the buoyancy force in the water is greater than its weight, causing the engineered wood specimen to float. Furthermore, the testing standard does not provide a corresponding device or method to solve this problem.

The author's organization has researched and designed a device for measuring the water absorption thickness expansion rate and has obtained a national utility model patent. This article focuses on the structure and design principle of the device for reference by colleagues in the industry.

1. Design model of the water absorption thickness expansion rate measuring device

2. Design principle explanation of the water absorption thickness expansion rate measuring device

2.1 Explanation of Device Dimension Design Principles

2.2 Equipment Material Specifications

The material of the water absorption thickness expansion rate measuring device is preferably round steel, whose weight is much greater than the sum of the buoyancy force on the device and the specimen in water, which can ensure that the test device sinks stably and does not tilt during the test.

3. Application of the water absorption thickness swelling rate measuring device

4. Conclusions and Recommendations

The device is scientifically and rationally designed and meets the standard requirements. In practical applications for determining the water absorption thickness swelling rate, it is simple and convenient to operate. The specimen remains stable and does not tilt in the water, and it meets the requirements for the position of the specimen immersed in water in section 4.4 of GB/T 17657-2013 for the water absorption thickness swelling rate test.

All testing and inspection units can refer to the design concept of this device and design their own suitable testing devices without affecting the requirements of GB/T 17657-2013 for the determination of water absorption thickness swelling rate. For example, based on this device, the inner width of the fixed small unit can be designed to be adjustable, so that one device can be used to determine the water absorption thickness swelling rate of various thicknesses of wood-based panels. Secondly, it is recommended that when revising GB/T 17657-2013, corresponding devices or methods be provided to facilitate the implementation of the standard by various units.