The countersunk head self-tapping screw refers to a self-tapping screw whose head is not higher than the flat surface after being tightened, and can keep the surface flat and beautiful.

This kind of screw has different notches such as slot, cross slot, and plum slot, and the slot should be extended to the center of the screw, so as to effectively avoid cutting chips from blocking the slot.

Cross countersunk head tapping screws

The difference between countersunk head tapping screws and flat head tapping screws

① Different appearance

The hat of the countersunk head self-tapping screw is flat on one side, but tapered on the other side; the hat of the flat-head self-tapping screw is flat;

②The contact surface is different

The contact surface of the countersunk head self-tapping screw and the workpiece is a cone surface, and the flat-head self-tapping screw is indeed on the plane;

③ Different partners

Countersunk head self-tapping screws can only be used in combination with gaskets with a certain taper, while platform self-tapping screws can be used in combination with flat gaskets;

④ Different effects

The countersunk head self-tapping screws will not be higher than the flat surface after use, and remain flat; the flat-head self-tapping screws can be sunk into the plane or exposed.

⑤ Different stress

The countersunk head self-tapping screw has a lower force than the flat-head self-tapping screw.

About the material, type and purchase of self-tapping screws

Self-tapping screws are one of the more widely used screws. Understanding the materials and types of self-tapping screws can make us more handy and more effective when purchasing.

1. Material of self-tapping screws

Self-tapping screws are generally made of carbon steel and stainless steel. Everyone should understand the difference between the two.

Generally speaking, carbon steel self-tapping screws do not intentionally add alloy elements, while stainless steel self-tapping screws contain high alloy content. The difference is that carbon steel is easier to rust than stainless steel, but its price is far Lower than stainless steel; carbon steel is stronger than stainless steel, but its corrosion resistance is not as good as stainless steel. Therefore, the two have advantages and disadvantages compared with each other. As the so-called "Mei Xuxun Xue three points white, but snow loses Mei incense".

2. Types of self-tapping screws

In addition to the above material, self-tapping screws can be divided into carbon steel self-tapping screws and stainless steel self-tapping screws. Self-tapping screws can also be classified in terms of shape and function.

Generally, it can be divided into: Phillips pan head tapping screws, Pan head tapping screws, Phillips countersunk head tapping screws, self-drilling tapping screws, flat tail tapping screws, pointed tail tapping screws, triangular thread locking type tapping screws and many more.

The following types of self-tapping screws are mainly made of stainless steel:

1. Stainless steel self-drilling screws: Stainless steel self-drilling screws are also called self-tapping self-drilling screws, and can be divided into cross pan head stainless steel self-drilling screws and cross countersunk head stainless steel self-drilling screws.

2. Stainless steel cross countersunk head self-tapping screws: the materials are SUS304 and SUS316, which are generally used for the connection of various profiles.

3. Stainless steel cross pan head self-tapping screw: no need to make bottom holes and tap internal teeth when using, directly screw in with a tool to lock. The cross-head self-tapping screw made of stainless steel is different from the ordinary thread. The head tip and tooth spacing are large. After drilling into the substrate, there will be no tooth swarf.

3. The purchase of self-tapping screws

Material purchase

As mentioned above, carbon steel self-tapping screws and stainless steel self-tapping screws have their own advantages, and need to be purchased according to different situations. If the budget is not large and there is no special demand for the duration of use, you can choose carbon steel self-tapping screws; if you are more fancy-resistant, corrosion-resistant, and not easy to rust, you can choose stainless steel self-tapping screws.

Feature purchase

Self-tapping screws with different functions have different practical applications. For example, the self-tapping screws mentioned above are mostly used for the connection and fastening of color steel plates; the cross pan head self-tapping screws can be used for the connection between metal and plastic; the cross countersunk head self-tapping screws are often used for the connection of various profiles.

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