The mold (refers to ring die and roller) plays an important role in the operation of a wood pellet mill.
Today, the technology department of Kingwood is going to talk about the ring die.
The type of ring die
The type of ring die is decided by different depth, width/angle of the ring die hole, and the material and degree of finish of the ring die.
Depth of hole: in the picture following, "L" stands for the depth of the hole. Deeper the hole is, time for heating and compacting the material is long, and the pellets are more hard and of larger density. Longer the hole is, the friction between material and ring die is larger. Therefore, more power is needed to push the material into the hole. Alternatively, you may choose low-speed conveying equippment or high power motor.
Angle of hole: in the picture above, "l" stands for the angle of hole. The angle of hole decides the deformation degree of pellets after being extruded. As to some special materials, ring die has special angle.
Width of hole: different ring die has hole of different sizes of which the range from 1mm to 10mm. Pellet fuel is generally 6mm or 8mm. 6mm pellet fuel is for furnace, while 8mm is for boiler. Larger the hole diameter is, the friction and resistance are smaller, which can improve the production efficiency but brings negative influence to the pellet quality.
Mental for making ring die.
There are various mental for making ring die. Ring die should be wear-resisting, resistant to corrosion and is of high hardness to improve the productivity.
Carbon Titanium Alloy: ring die made of cabon titanium alloy is wear-resisting and resistant to damage. But it does not do well in resisting corrosion. When carbon titanium alloy rusts, the rusts will cause block in holes, which influences productivity. Before starting production, polisher should be put inside the pellet mil, such as wheat bran and vegetable oil, to the inside of the granulator, which will help remove surface corrosion before starting production. At the end of production, put some oil crops into the granulator to maintain the ring mold for the next production.If the material remains in the ring die, as the ring die cools, it will form solid particles in the ring die. With the cooling and drying of the granulator, water enters the surface of the ring die and forms corrosion.The solution is to drill holes to remove corrosion. Production efficiency of ring die made of carbon tantium alloy is lower than other materials of metal. The surface finish of the inner wall of the die hole determines the resistance of the material when it enters the ring die.
All in all, carbon steel is at a disadvantage in terms of corrosion resistance and production efficiency, but it has the greatest hardness, the longest service life and is quite cheap.Therefore, it is suitable for the vast majority of materials, especially high abrasion raw materials.
Stainless steel alloy: it has good corrosion resistance and wear resistance. Stainless steel ring dies are divided into several types. Compared with carbon steel, its corrosion resistance is strong, so its mold hole finish is very high, and so is the production efficiency. Although the resistance of pellets decreases when they pass through the die hole, this does not affect the quality of the pellets, because the depth of the die hole is greater than that of carbon steel. The main disadvantage of stainless steel die hole is high cost.
High chromium alloy: this ring die has the strongest corrosion resistance. Its hole finish is even higher than the stainless steel ring mold. This means that it's very easy to start production, and it's very productive. Although the resistance of pellets through the die hole is not large enough, lengthening the die hole can make up for this. Due to its high chromium content, die hole depth, the cost is also very high.
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Jiangsu Kingwood Industrial Co., Ltd.
Add：No. 568 Hongsheng Road, Liyang, Jiangsu
International Website: www.kingwood-china.com