Service Hotline(1) The screw-in performance test is to screw the self-tapping locking screw sample into the test plate until one complete thread completely passes the test without breaking. (2) The destructive torque test is to clamp the stem of the self-tapping locking screw specimen in a thread mold or other device that matches the screw thread, and uses a calibrated torque-measuring device to measure the screw. Torque is applied until fracture, which should not occur in the clamped threaded portion. (3) Carry out a tensile test on the screw sample to check the minimum tensile load for failure. The fracture should be within the length of the rod or the unthreaded thread, and should not occur at the junction of the nail head and the rod. Before the sample breaks, it should be It can reach the minimum tensile load specified by the corresponding performance class. (4) Hydrogen embrittlement is a problem that must be strictly paid attention to in the surface treatment process of self-tapping locking screws. In the pickling process, the screw is stirred in dilute hydrochloric acid, and the amount of hydrogen absorbed by the pickling steel increases linearly with the square root of time and reaches the saturation value. Less than 100%, a large number of hydrogen atoms will be produced, which will be attached to the surface of the screw, resulting in hydrogen infiltration, and the steel will become brittle due to the absorption of hydrogen. The self-tapping locking screw takes 6~8h to drive hydrogen, and the temperature is 160~200℃ (phosphating) and 200~240℃ (electroplating). However, in the production process, the hydrogen drive time should be determined according to many production conditions such as core hardness, surface roughness, electroplating time, coating thickness, pickling time, and acid concentration. It is best to do it before passivation and just after electroplating.
Stainless steel bolts refer to bolts made of stainless steel, including stainless steel SUS201 bolts, stainless steel SUS304 bolts, stainless steel SUS316 bolts, and stainless steel SUS316L bolts. The performance grades of stainless steel bolts, studs and studs are divided into 10 grades: from 3.6 to 12.9. The number before the decimal point represents 1/100 of the tensile strength limit of the material, and the number after the decimal point represents 10 times the ratio of the yield limit to the tensile strength limit of the material.
At present, the known automatic nail feeding screws are composed of the traditional hand-held electric drill modified electric screw and the automatic nail feeding device, in which the screw head cannot be moved and the angle can be changed. It is difficult to complete the installation due to the obstruction, so a multi-directional screw with a movable and rotatable screw head is required.
Generally, the most commonly used material on the market is iron. The iron one is known as carbon steel. It is punched out or turned. After being manufactured, it is in its natural color. In order to prevent rusting, it is necessary to Electroplated. The stainless steel rivet nuts do not need electroplating. In the case of iron, the color of electroplating is generally determined by the customer, and the color of the electroplating depends on what color the customer needs. There are also some requirements for salt spray time. Some electroplating colors have a higher salt spray time, and some electroplating, less rust in a few hours. Another point is to see whether the customer needs to export the product. Generally, the export needs to be environmentally friendly, and some domestic ones also need it, but most of them are not needed.
For hexagonal nuts, the commonly used standards are: GB52, GB6170, GB6172 and DIN934. The main differences between them are: the thickness of GB6170 is thicker than that of GB52, GB6172 and DIN934, commonly known as thick nuts. The other is the difference between the opposite sides, the opposite sides of DIN934, GB6170 and GB6172 in the M8 nut series are 13MM smaller than the opposite side 14MM of GB52, and the opposite sides of M10 nuts, DIN934 and GB52 are 17MM. The opposite side of GB6170 and GB6172 should be 1MM larger, M12 nut, DIN934, GB52's opposite side is 19MM larger than GB6170 and GB6172's opposite side 18MM is 1MM larger. For M14 nuts, the opposite side of DIN934 and GB52 is 22MM, which is 1MM larger than the opposite side of GB6170 and GB6172, which is 21MM. The other is the M22 nut. The opposite side of DIN934 and GB52 is 32MM, which is 2MM smaller than the opposite side of GB6170 and GB6172, which is 34MM. (Besides the thickness of GB6170 and GB6172 are the same, the width of the opposite side is exactly the same) The rest of the specifications can be used in general without considering the thickness.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: GB52 natural hexagon nuts, combination screws and bolts, large hexagon flange nuts, eye bolts and other products, we can provide you with suitable fastening products piece solution.
