The causes of oil needles in the production of knitted fabrics by circular knitting machines and the solutions

During the operation of a circular knitting machine, there are generally three types of oils that may be encountered: knitting oil, engine oil and air compressor oil. Except for the knitting oil, the other two oils do not emulsify when exposed to water. Although knitting oil emulsifies when it comes into contact with water and can be removed during dyeing, due to the fact that most dyeing processes currently use low-temperature dyeing techniques, it is rather difficult to remove the oil. Moreover, some fabrics (such as spandex, viscose, and other new fiber raw materials) need to be pre-shaped before dyeing, which makes it impossible to remove the knitting oil. Additionally, certain colors are highly sensitive to knitting oil. Therefore, it is necessary to have a full understanding of the generation and control methods of knitting oil. 1. The Function of Knitting Oil: During the production process of the circular knitting machine, the knitting and settling plates not only need to move up and down or back and forth at high speed in the knitting and settling plate grooves, but also move in a circular motion along with the syringe (or needle disc). Friction will occur between the knitting and settling plates and the groove wall, as well as between the heel of the needle and the heel of the settling plate and the triangle. At this time, The oil film (or oil wedge) formed by knitting oil can play the following roles: 1. Alter the friction coefficient of the object’s surface and reduce frictional resistance; 2. Reduce the wear degree of the contact surface and extend the service life of the knitting needles, sedimentation plates and triangles. Reduce the friction between each other, thereby lowering the heat generated by friction and keeping the circular machine at an appropriate operating temperature. Second, the shape of the oil needle: When the knitting oil enters the knitting area, it adheres to the yarn and is woven into the fabric. Since the oil usually appears at a certain point on the syringe, the oil needle (or oil circuit) on the fabric is generally longitudinal. Iii. Causes and Preventive Measures of Oil Needle Formation 1. Oil Needle Formation caused by Air Blowing When blowing air, in order to prevent lubricating oil and flying flowers from entering the weaving area, it is necessary to reasonably control the position and direction of the air blowing, the distance and diameter of the air nozzles, and the size of the air pressure. Blow air at the gap between the two saddles. Before spraying oil, get as close as possible to the oil spraying area. This way, the short pile fibers, lubricated and saturated oil, and heat can be blown out, and the lubricating oil can be fully utilized. When blowing air in three directions, the reverse blowing of oil towards the knitting needles and settling plates can effectively prevent lubricating oil from entering the knitting area and weaving oil needles. The distance between the air nozzles is usually 3 to 5MM from the weaving area. If the distance is too large, it will not be able to prevent the lubricating oil from seeping out. The diameter of the air nozzle is usually 2.0~. If the nozzle diameter is too large, the wind blown out will be scattered and weak; if it is too small, the wind won’t be blown in place. The wind pressure is usually maintained at (29.4±4.9) N/cm ². The wind pressure is too low to blow out the oil-containing short pile fibers, oil, etc. from the weaving area. If the wind pressure is too high, it may cause lateral oil needles. 7. Oil needles caused by inappropriate oil volume 8. Excessive oil volume can cause the lubricating oil in the knitting needles and settling plate grooves to reach saturation, that is, “excess leads to overflow”. The resulting oil needles are usually in their natural color, commonly known as “transparent oil needles”, which are manifested as moist longitudinal marks on the fabric surface. If the oil level is too low, the knitting needles and the settling plate grooves will lack oil, causing dry grinding in certain parts, increasing frictional resistance, raising the machine temperature, generating heat and causing components to expand, reducing the movement clearance, intensifying friction, and creating a vicious cycle. In this case, short fibers accumulate and clink in the knitting needles and settling plate grooves, hindering their normal movement. Even in some areas, heat generated by friction turns blue (an oxide film forms on the surface). The oil needle produced by too little oil is usually black, that is, black oil containing fine iron filings. When the large circular machine is in operation, it is strictly forbidden to run out of oil. Because when the high-speed rotating parts are dry ground without lubricating oil, it will definitely cause high temperature. The result is that the friction will cause the machine mouth to “burn out”, the failure or scrapping of the parts. Solution for the 10 circular knitting machine: Maintaining an appropriate amount of oil is a necessary measure to reduce oil needles. If the oil volume is slightly large and the air flows smoothly, the oil needle will definitely come out, but be sure not to use too little oil. The cause of the oil needle caused by “cotton droppings”