Hot-Dip Galvanized Nuts For Chemical Industry

In the fastener products we use daily, bolts generally have no burrs, while most products with burrs are nuts. This is because bolts only have their heads formed in one step, and the subsequent screw shanks and threads need to undergo secondary or tertiary processing. After these processes, the burrs on the bolts are basically removed naturally.

Some nuts are produced by forging process, which has certain inherent limitations, resulting in many burrs on the finished nuts. The processing of internal threads is different from that of external threads: external threads are rolled out using two thread rolling dies without generating any burrs, while the internal threads of nuts are tapped using thread forming taps. During the tapping process, the taps will produce a lot of burrs, which can only be partially carried away when the taps are retracted and cannot be completely removed. Therefore, nuts tend to have relatively more burrs.

For ordinary standard nuts, these burrs will gradually fall off during subsequent tumbling treatment, or be squeezed off by external threads during installation, so the burr phenomenon itself does not cause much trouble. However, if it comes to hot-dip galvanized nuts for chemical industry, this problem will become quite tricky. Because chemical industry-specific nuts are basically not subject to thread hole enlargement. After hot-dip galvanizing with the original size, burrs will definitely form, making the nuts almost impossible to screw in during installation. Therefore, the only way to solve the installation problem of chemical industry-specific nuts is to retap the threads with oversized taps after hot-dip galvanizing.

After hot-dip galvanizing, the originally loose burrs on the nuts will fuse with the threads under high temperature and the action of zinc liquid. When installing such hot-dip galvanized nuts with burrs, they will get stuck and cannot be screwed in at all. Therefore, the presence of burrs on hot-dip galvanized nuts for chemical industry is a very troublesome issue.

So how should we solve this problem? Of course, we cannot wait until the nuts are hot-dip galvanized to find a solution. We must completely remove all burrs before hot-dip galvanizing, and then carry out the galvanizing process. Below we analyze several methods to remove burrs from nuts.

Using machining methods to remove burrs is obviously not feasible. Not only is the cost relatively high, but the output cannot meet the demand. What's more, it may damage the square edges of the nuts. Therefore, we can only solve this problem from the perspective of cleaning treatment. Through experimental verification, we can use soluble liquid mixed with a small amount of water and some fine sand. Put the mixture and nuts into a centrifuge, separate them after centrifugation, and the burrs can be easily removed.

We can also mix alkaline cleaning solution with salt. This method is relatively economical with low cost and good burr removal effect. It only needs to be put into a centrifuge for spin-drying. Industrial detergents can also be directly used for cleaning. If the burrs are particularly severe, we can also purchase acid-base solutions for polishing treatment. Only after all burrs are completely removed can the nuts be subjected to hot-dip galvanizing treatment.