Basic knowledge and industry status of special screws

     Special screw, Screw manufacturers in our industry are generally called non-standard screws, also known as special screws and custom screws. Literally, it is a unique screw. In other words, there is no ready-made non-standard screw that is different from the national standard screw, or it can be said to be a special-shaped screw or an odd-shaped screw.

A screw is a tool that uses the physical and mathematical principles of circumferential rotation and friction of the inclined surface of an object to gradually tighten the utensils. The installation names of screws are: machine screws, self-tapping screws, drill tail screws, wallboard screws, fiberboard screws, wood screws, hexagonal wood screws, non-stick screws, combination screws, mini screws, furniture screws, electronic screws, chain screws. However, these screws are not suitable for special occasions, and a special screw needs to be designed to cooperate with them.

A bolt is a fastener composed of a head and a screw. It needs to be matched with a nut through a threaded connection to fasten and connect two parts with through holes. In the process of tightening and loosening the bolts, it is often necessary to cooperate with the bolts. However, in long-term use, the rotating holes on the bolts are easy to wear, and the worn bolts cannot be used, causing waste. From this aspect, the emergence of special screws is inevitable.

Special screws are divided into iron and stainless steel according to the screws and wires produced; according to the strength grade of iron wires, there are 4.8, 8.8, 10.9 and 12.9 special screws. Stainless steel special screws include stainless steel SUS201, stainless steel sus304 and stainless steel SUS316. According to the types of screws, special screws include external hexagon screws, internal hexagon screws, Phillips pan head screws, cross recessed countersunk head screws, stud bolts, carriage bolts, pan head combination screws, external hexagon combination screws, machine screws, etc.

Special screws are usually some national standard screws, with different models and sizes. Special screws are produced and become non-standard screws. For example, some screws have a GB head size of 8, while special screws may be 7 or even 10. Therefore, if the length dimension, tolerance range, material grade strength and other national standard screws do not meet the national standard screw length dimension, it will become a special screw. Generally do not provide special screws, that is to say, the general screw manufacturers will not have inventory. This special screw needs to be customized, and customers need to provide screw drawings or screw samples before production and processing. After the customer provides the screw drawing or screw sample, our manufacturer can order one mold and tooth plate for grinding teeth according to the screw drawing or screw sample. Even if there is no screw material, we have to order screws and wires.

In general, the unit price of special screws will be higher. And if there is no large order, it is not good for production. Because the cost of ordering molds is more expensive, some special screws, such as step screws, need 3000-5000 yuan or more to order molds, so it is difficult to manufacture without a large number of orders.