Pay attention to details when using fasteners. Performance is very important. Regular maintenance is the key to ensure the normal operation of the machinery. In order to prevent some problems with fasteners, you must pay attention to the following points when performing daily maintenance of fasteners.
1. Pollution generated during rinsing
Fasteners need to be cleaned with silicate cleaning agent after quenching, and then rinsed, so be very careful when rinsing to prevent residues.
2. Improper stacking of fasteners
The fasteners will show signs of discoloration after tempering, and there may be oily residue after soaking in ether, indicating that the fastener surface is not clean. Analysis showed that the fasteners were stacked unreasonably when heated, resulting in slight oxidation of the fasteners in the quenching oil.
3. Surface residues
There was white residue on the high-strength screws, which was analyzed with an instrument and confirmed to be phosphide. This reaction occurs because an acid cleaner cleaning was not performed and the rinse tank was not inspected thoroughly enough.
4. Alkali burns
High-strength screws are blackened by the residual heat of quenching and have a uniform and smooth oil-black outer surface. It was determined to be caused by alkali burns. Therefore, the alkaline substances on the surface of steel fasteners cannot be removed in quenching oil, thus causing surface burns at high temperatures and aggravating the damage during tempering. It is recommended to thoroughly clean and rinse fasteners before heat treatment to completely remove alkaline residues that can cause fastener burns.
5. Improper rinsing
For large-sized fasteners, polymer aqueous solutions are often used for quenching. Before quenching, they are cleaned and rinsed with an alkaline cleaning machine. After quenching, the fasteners have rusted on the inside. Therefore, the rinsing water should be changed frequently to ensure that the fasteners will not rust during rinsing.
6. Excessive rust
High-strength fasteners often see some black stripes. These black stripes are pollutants remaining on the surface, which are dried quenching oil and the evolution of gas phase substances during the quenching process. Because the quenching oil is excessively aged, it is recommended to add new oil.
