How to remove a rusted drain plug
In daily life, we often encounter the situation that the oil drain plug is rusted, perhaps because the threaded hole is rusted and the entire component is dead, it is often very troublesome to remove the oil drain plug and unscrew it. So, do you know what's causing it to rust? How should we deal with this problem?
There was once a case of rust failure analysis of threaded holes, and the reasons for rusting of threaded holes were analyzed from a professional point of view. This threaded hole is machined by tapping. During machining, workpiece data is removed by continuous cutting. After the product was stored for 20 days, the threaded holes started to rust, apparently there was something wrong with the sample. After slice analysis of the threaded hole section, it was found that the reason for the rust was that the processed tapping oil contained S and Cl elements. These holes allow the substrate to be directly exposed to air. When Cl absorbs water, it forms an electrolyte, leading to autocatalytic electrochemical corrosion of Cl- ions. In addition, Cl- will not be consumed in the whole corrosion reaction, which further promotes the development of corrosion in depth.
In this case, the manufacturer's production process causes rust, and other factors can also cause rust. So how to prevent and deal with it?
1. Derusting: The derusting process is not only a general pretreatment method before painting, but also targeted. This is because some workpieces are high-strength bolts and nuts and high-strength stamping parts, and hydrogen embrittlement will occur after pickling, which affects product quality. (Note: In the case of disregarding hydrogen embrittlement, pickling can be used for rust removal pretreatment, especially for cabinets and control cabinet panels, etc. But in the process, special care should be taken not to bring the pickling residue into the plating tank, so as not to damage the zinc chrome plating solution.)
2. Coating: refers to the method of applying the coating evenly on the surface of the workpiece. According to the different quality requirements of workpieces and products, different coating methods are used. Generally, there are three methods: dip coating, spray coating, and brush coating.
