1. Non-corrosive fertilizers are selected. For example, ammonium bicarbonate and ammonia water are volatile and corrosive. They are easy to smear seeds and seedlings. Superphosphate contains free sulfuric acid and phosphoric acid, which can cause damage to seed germination and seedling growth. It is generally not suitable for seed fertilizer. Such fertilizers can be applied under the seeding ditch or separated from the seed by a certain soil layer, or mixed with superphosphate and soil fertilizer. 2 , do not choose toxic fertilizers such as urea often contain a small amount of biuret components, toxic to seeds and seedlings. In addition, urea molecules with high nitrogen content penetrate into the protein molecules of the seeds, denature the proteins and affect seed germination. 3. Fertilizers that do not contain harmful ions such as potassium chloride or ammonium chloride contain chloride ions, which will produce water-soluble chlorides when applied to the soil, which is detrimental to seed germination and seedling growth. The nitrate ions contained in fertilizers such as ammonium nitrate and potassium nitrate also have an effect on seed germination. 4 , do not choose unfertilized farmyard manure in rural areas commonly used manure, human waste water to do seed fertilizer, if not mature, release a lot of heat in the fermentation process easy to burn root system, release ammonia gas to burn seedlings. Therefore, the unfertilized organic fertilizer should not be applied. After the high temperature fermentation of the pile, it can be used to make the fertilizer after fully decomposing.
Although there are many types of tapping screws, they all have the following similarities: Round head Tapping screw,hex tapping screw,flat head tapping screw,pan head tapping screw,truss head tapping screw Shenzhen Lanejoy Technology Co.,LTD , https://www.ccls-vaccine.com
(1) are generally made of carbonized carbon steel (accounting for 99% of total production). It can also be made of stainless steel or non-ferrous metals.
(2) The product must be heat treated. Carbon steel tapping screws must be carbonized and stainless steel tapping screws must be solution hardened. In order to make tapping screws to meet the requirements of the standard of mechanical properties and performance.
(3) The product surface hardness is high, the core toughness is good. That is, "soft inside strong outside". This is a major feature of tapping Screw performance requirements. If the surface hardness is low, it can not be screwed into the matrix; If the core toughness is poor, a twist will break, can not be used. So "inside soft outside steel" is self-tapping screw to meet the use of performance, very important requirements.
(4) The surface of the product needs surface protection treatment, generally electroplating treatment. Some product surface must be treated by phosphate (photostatting), such as wall panel self - tapping screws for photostatting.
(5) Production by cold heading process. It is recommended to use high-speed cold heading machine and high-speed wire rolling machine or high-speed planetary wire rolling machine. High speed is emphasized here to ensure product quality. Only the head of tapping screw produced by high-speed machine is well formed and the thread quality is high.
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