Some manufacturers will resell the returned products after repair. If it is a reputable manufacturer, the repaired products will have their parts replaced or undergo high-precision repairs to maintain consistent product performance. However, some units may only require high repair standards for other reasons Actually, the differentiation method is not very difficult.

1. Make the machine vibrate as much as possible. If the machine has been used before, the crushed material will stick to the corners of the machine, and simple cleaning cannot clean it completely. With vibration, the dried material will scatter out;

2. Check the edges of the screws. Repeatedly disassembled screws will leave marks, including cross screws;

The crushing process of solid drugs generally utilizes external mechanical force to partially break the cohesive force between material molecules, causing the large particles of the drug to become small particles and increase the surface area, that is, the process of converting mechanical energy into surface energy. Polar crystalline substances such as gypsum and borax have considerable brittleness and are relatively easy to crush. When crushed, it usually breaks into small crystals along the bonding surface of the product. Non polar crystalline substances such as camphor and borneol have poor brittleness. When a certain mechanical force is applied, they are prone to deformation and hinder their crushing. Usually, a small amount of volatile liquid can be added. When the liquid penetrates into the cracks between solid molecules, it can reduce the cohesion between their molecules, making the crystal easy to separate from the cracks. Amorphous drugs such as resins and gums have a certain degree of elasticity. During crushing, a portion of the mechanical energy is used to cause elastic deformation, which is then converted into heat energy, thereby reducing the crushing efficiency. Generally, reducing the temperature (around 0 ℃) can increase the brittleness of amorphous drugs to facilitate crushing. Plant medicinal materials have complex properties and contain a certain amount of water (usually about 9% -16%), with toughness. The less water they contain, the more brittle the medicinal materials are, which is more conducive to crushing. Therefore, they should be dried appropriately according to their characteristics before crushing. Thin walled medicinal herbs, such as flowers, leaves, and some rhizomes, are easily crushed. Medicinal herbs with a woody and keratinous structure, as well as those with high viscosity or oil content, and animal tendons, bones, and nails that are difficult to crush, can be processed using a wind selective traditional Chinese medicine grinder.