There are several types of material sorting devices used in the woodworking industry. Depending on the level of automation, they can be categorized into manual and mechanical sorting systems. Additionally, based on the layout of the sorting line and workshop design, these devices can be classified as longitudinal, transverse, or circular movement systems. Sorting and automatic falling systems can also be divided into single-layer and multi-layer configurations based on the number of layers involved in the sorting process. (1) Manual Sorting Devices In many domestic wood production facilities, manual sorting is still the most common method. Most use vertical and horizontal movement systems for sawn timber, while circular sorting devices are more commonly found abroad. A longitudinal sorting system is one of the simplest types of material sorting setups. It typically consists of a sorting shed located outside the main production line, where sawn timber is transported via a belt conveyor. Workers on both sides of the conveyor line sort and stack the timber based on type, size, and length before inspecting and evaluating it. The sorted materials are then transferred to a storage area using flatbed trucks or forklifts. The longitudinal sorting device allows for stacking on both sides of the conveyor. The arrangement of the stacks is usually parallel to the direction of the conveyor. As a result, finer divisions of timber lead to more piles and longer sorting areas. To make the process easier, roller conveyors are often used, with a slow speed of around 15–20 meters per minute, which keeps productivity low. This system is best suited for smaller operations with limited space and a variety of timber types. A horizontal sorting device is frequently used in larger and medium-sized enterprises. These systems typically rely on chain conveyors, with the timber moving perpendicular to the main transport direction. After being moved horizontally, the speed can be reduced to about 1/10 to 1/15 of the longitudinal speed, allowing for higher productivity. The sorting table is equipped with multiple parallel chains, each with different pitches, making it easier to handle different sizes of timber. The width of the table is designed to be less than the longest piece of timber, ensuring efficient sorting. Corridors on either side allow workers to access the timber easily, reducing physical strain. The horizontal chain sorting device includes three key parts: the receiving section, the evaluation section, and the drawing section. The receiving part takes the timber from the workshop conveyor and redirects it to the horizontal chain. The evaluation section allows workers to inspect and mark the timber, while the drawing section sorts the pieces into designated piles based on type, size, and grade. Larger pieces are drawn first, followed by smaller ones. In large-scale operations, two-tier sorting areas may be constructed to save space but require taller buildings. Circular sorting devices are designed in a disc shape, where the timber is moved in a circular path. Workers evaluate the timber from outside the circle. This system is ideal for situations with a wide variety of timber types and small quantities. However, if the timber is not arranged properly at the start, it can significantly reduce efficiency. (2) Mechanical and Automatic Sorting Devices Automatic sorting systems include falling-type and multi-layer chain sorting devices. Once the timber is inspected and evaluated, it is directed into the appropriate silo. When combined with computer control, these systems offer greater accuracy and efficiency. A falling-type sorting device uses an "L" or "J" shaped hook to transport the timber into a silo, where it drops from a height. To prevent damage, various silo designs are used, such as tilting silos, sling silos, and self-propelled trolleys. The process begins with manual inspection and specification testing, after which the timber is fed into a sorting machine that arranges it neatly. As the timber reaches the correct silo, a microcomputer triggers the release mechanism, allowing the timber to fall into the designated silo. Once filled, the silo is emptied onto transport equipment for further processing. A multi-layer chain sorting device is commonly used in planing workshops. It offers advantages such as minimal surface damage, fewer mechanical failures, high speed, and stable operation. It also allows for accurate counting of different sized boards, enabling better separation between them. Modern systems generally consist of a feeder, roller conveyor, accumulation section, storage area, and unloading device. Timber is fed into a specific layer, slides along the conveyor, and is counted as it accumulates. Once enough pieces are gathered, the timber separates and moves into the storage area, where it can be unloaded efficiently. (3) Stress Grading Devices Most traditional sorting systems rely on visual inspections to assess defects, geometry, and dimensional accuracy. However, this approach has limitations, including subjective evaluations, inefficiency, and labor intensity. It also fails to account for the mechanical properties of the wood, leading to potential waste and inaccuracies in classification. Stress grading devices, on the other hand, assess the strength and stiffness of the timber. They determine the grade based on the relationship between the wood’s elastic modulus and flexural strength. Non-destructive testing methods allow for accurate prediction of the timber's strength, providing valuable data for engineering applications, especially in structural uses. As shown in Figure 3-1, the timber is supported by two sets of rollers and a pressure roller that creates a constant deflection. The bending force is measured using a sensor, and the strength is calculated accordingly. Some systems use a fixed bending force with variable deflection, resulting in a more complex structure. Despite ongoing research, stress grading technology is still in its early stages in many countries. Establishing national standards and promoting its adoption will be essential for future development. Balanced Flowmeter,Balanced Flow Meter,Balancing Valve Flow Meter,Throttling Device Jingsu Huaerwei Science and Technology Group Co.,Ltd , https://www.hewflowmeter.com