What are the specifications of self tapping screws?

Countersunk self-tapping screws (diameter length):

4 16 install hinges, feet, supports and other accessories for board installation.

4 30 external door panel or trim plate corner connection.

4 35 external door panel or trim plate corner connection cabinet ordinary hanging code and side panel connection.

4 40 panel furniture does not use the nail connection of eccentric parts, which was not a formal practice in the early days, and is still used by carpenters.

8 60 or 80 cabinet wall cabinet expansion pipe into the wall nails.

Peculiarity. 1. Generally, it is made of carburized steel (accounting for 99% of the total output). It can also be made of stainless steel or non-ferrous metals.

2. The product must be heat treated. Carbon steel self-tapping screws must be carburized, and stainless steel self-tapping screws must be solution hardened. In order to make the self-tapping screws meet the mechanical properties and service performance required by the standard.

3. The surface hardness of the product is high and the core toughness is good. That is, "soft inside and rigid outside". This is a major feature of the performance requirements of self-tapping screws.

If the surface hardness is low, it cannot be screwed into the matrix; If the toughness of the core is poor, it will break as soon as it is twisted, and it cannot be used. Therefore, the "inner flexible outer steel" is a self-tapping screw to meet the very important requirements of the use performance.

1. What are the specifications of self-tapping screws?

According to the diameter of the screw, there are 13 specifications, respectively, the user needs to decide the specification of the screw according to the actual needs when purchasing. In addition, according to the different shape of the head, self-tapping screws can also be divided into three types: round-head self-tapping screws, flat-head self-tapping screws and countersunk self-tapping screws.

Second, how to choose the right self-tapping screw.

1. Look at the type of screw.

According to professionals, there are many types of screws on the market, and different types of self-tapping screws have very different scopes of application, aesthetics and performance characteristics. For example, if the screws used to fix the aluminum alloy are used, it is generally recommended to use flat-head screws.

2. Look at the size of the screw.

From the above article, it can be understood that there are many specifications and models of screws, and the force capacity of different types of self-tapping screws is very different. In the case of the same force, the longer the screw, the better its ability to hold nails, and the stronger the load-bearing capacity, so consumers must choose according to the design standards when purchasing.

3. Look at the quality of the screws.

There are many channels to buy self-tapping screws, and users must go to regular hardware stores to buy when buying, so as to ensure the quality of self-tapping screws. In addition, when purchasing self-tapping sail screws, it is also necessary to check whether the threads of the screws are clear and whether the size is consistent with the specifications, because this is the key to determining the performance of the screws.

Commonly used are countersunk self-tapping screws (82° countersunk head), semi-countersunk (82° countersunk head) pan head, spherical cylindrical head, oblate round head, semi-round head and hexagonal head, hexagonal flange head (including cavity type) several specifications.

The large diameter of the self-tapping screw, the self-tapping screw and the machine thread of the same nominal diameter are different and therefore the bore size is also different, however, most applications only require two sets of bore sizes.

One set for extruded self-tapping screws and self-cutting self-tapping screws with organic threads, and the other set for normal self-tapping screws and self-tapping screws with self-tapping threads, suitable for the bore diameter of self-extrusion self-tapping screws and ordinary self-tapping screws, and generally also for self-cutting self-tapping screws.

All other things being equal, while the "cutting" torque of self-cutting and self-tapping screws and the "thread-forming" torque of ordinary self-tapping screws and self-extrusion self-tapping screws.