What is the key to selecting lubricating grease for automotive coating and conveying equipment?
July 03, 2023
In automotive coating equipment, conveying equipment, as the artery of the coating workshop, runs through the entire coating process. It is particularly important to ensure the stable operation of the conveying system and reduce equipment failure rate. Due to the long-term exposure of conveying equipment to humid, acidic, and high-temperature environments, these external environments inevitably affect the stability and lifespan of the conveying equipment, ultimately leading to a decrease in the overall efficiency of the enterprise. Therefore, good lubrication is an important condition to ensure the stable operation of the conveying equipment. Environmental requirements for use The environment of the coating workshop is special. The pretreatment electrophoresis area is a high humidity acid-base environment. The electrophoresis drying, intermediate coating drying room and finishing paint drying room are high humid and hot environments containing high concentrations of Volatile organic compound (VOC). The selected lubricating grease must meet the environmental requirements before the next selection. Match with the selected paint Silicone is the root cause that affects the quality of coating, so the prerequisite for selecting lubricating grease is that it does not contain silicone, and on this basis, the selection of lubricating grease model can be carried out. All lubricating greases used for conveying equipment in the painting workshop need to be matched with corresponding paint materials for testing before use to ensure that they do not affect the quality of the paint film, especially to prevent shrinkage on the surface of the paint film. Shrinkage can seriously affect the appearance quality and delivery of the vehicle body, and is the most important reason for quality defects. Low volatility, less carbon deposition, and less coking In the painting workshop, the temperature inside the drying furnace is relatively high. The circulating air temperature of the electrophoresis drying furnace can reach up to 250 ° C, and the temperature of the vehicle paint surface can reach 180 ° C. Lubricating grease will evaporate at high temperatures and form black oily particles, which are carbon deposits or coking. Coking and carbon deposition will remain on the chain, and too much carbon deposition will increase friction and wear of the conveying equipment, and even lead to bearing jamming. This requires low volatility of lubricating oils and reduces the adhesion of volatile substances to the paint film. Therefore, low volatility and less coking and carbon deposition are also important characteristics to measure the quality of lubricating oils. The selection is generally based on the mass loss of lubricating grease after baking test, and the mass loss after baking at 220 ° C for 48 hours is required to be ≤ 4%. The coking performance of lubricating grease is evaluated by the color change after baking. A small amount of yellowing is allowed after baking at 260 ° C for 48 hours, but visible coking blocks or carbon deposits are not allowed.
Good extreme pressure resistance, wear resistance, and corrosion resistance
It is inevitable to have Sliding friction and rolling friction between parts during chain operation and bearing rotation. Good lubrication can reduce friction between components. Excessive friction can exacerbate the wear of parts and generate heat, causing them to overheat and become damaged. These are important factors that affect the lifespan of chains and bearings. Therefore, the selected lubricating grease needs good lubrication performance and extreme pressure wear resistance. The load-bearing capacity and extreme pressure performance of lubricants are measured using the four ball method, and specific indicators can refer to relevant national standards. The electrophoretic conveying equipment for pre-treatment in the painting workshop is exposed to temperature, humidity, acid, and alkali environments for a long time, which can cause severe corrosion. The drying room is in a high-temperature environment, so it is required that the lubricating grease has good water resistance, corrosion resistance, and stability.
Appropriate adhesion
The selected lubricating grease needs to have a suitable viscosity, and its viscosity will not change significantly due to temperature changes in the usage environment. If the viscosity is too high, the lubricating grease is not easy to penetrate and cannot provide lubrication; If the viscosity is too low, the lubricating grease cannot adhere well to the metal surface and may drip due to equipment operation, vibration, etc. When selecting a lubricant, it is necessary to fully communicate with the merchant and select a lubricant with good viscosity temperature characteristics. For mineral oils with stagnant flow characteristics, the recommended viscosity is 3~220 mm2/s (within 100 mm2/s at room temperature).
The conveying system is an important component of the painting workshop, and lubrication is a key maintenance program in the conveying equipment. The quality of lubrication directly affects the lifespan of conveying equipment and ultimately affects the quality of automotive coatings. Therefore, selecting appropriate lubricating grease is particularly important.
