How to distinguish the quality of screw bolts?

There are dozens of different types of screw bolts. Additionally, screw bolts are available in a wide range of materials, However, up to 90% of all screw bolts are made of steel, making it the preferred choice among manufacturing companies.

• What are the differences between bolts and screws?

• How to distinguish the quality of screw bolts?

• What should be checked for screw bolts?

What are the differences between bolts and screws?

There is an assumption that screw bolts are screws that they are the same fastening hardware. While they look similar and even have similar characteristics, they are two unique fasteners with their own unique applications.

Screw bolts are used to assemble to unthreaded objects with nuts. Screws assemble objects with threads. Some objects have pre-made threads, whereas others create the thread during the installation. The screw bolt is to assemble threaded objects, while the screw is to assemble untreaded objects.

Screws must be turned to assemble a joint, while screw bolts can be secured in place using a tool. Screw bolts are typically used to make a bolted joint by using a nut to apply force while using the shank to act as a dowel. This pins the joint against sideways forces. Therefore, many screw bolts have an unthreaded shank, making them more effective for dowels.

How to distinguish the quality of screw bolts?

First of all, screw bolts have to look at the material before they are made. Quality compliance is the prerequisite for reaching the national standard. Without looking at the material, the heavier one is the better

Then look at the tolerance value between the screw bolts and the national standard. The standard is used to determine whether it is good or not. The smaller the tolerance value of screw bolts and national standards, the better screw bolts are. After screwing the nut into the screw bolt, hold the nut and shake it left and right to feel the gap between the nut and the screw bolt. The one that has the larger gap is inferior. This way can check the rib accuracy of the screw bolt.

What should be checked for screw bolts?

Inspect the adhesion strength of the screw bolt coating. There are many ways to determine the adhesion between the coating and the base metal, including conflict polishing experiment, file method experiment, scratch method, torturous experiment, thermal shock experiment, and kneading method.

Inspect corrosion resistance of screw bolt plating. The corrosion resistance inspection methods of the coating include atmospheric exposure test, NSS test, ASS test, CASS test, and corrosion paste corrosion test.

Check the appearance of screw bolts. There are two types of the appearance inspection. One is the screw bolt is produced without being electroplated. The other is after the screw bolt is electroplated.

After the screw bolts are produced, we will check the specifications, tolerances and other aspects of them before they are electroplated. After the surface treatment, we shall inspect the color of the electroplated ones.

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