What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The flange nut and the general hexagon nut are basically the same in size and thread specification, but compared with the hexagon nut, the gasket and the nut are integrated, and there are anti-skid tooth patterns on the bottom, which increases the nut and the workpiece. Compared with the combination of ordinary nut and washer, it is stronger and has greater tensile force. In some equipment with large vibration amplitude, due to the action of huge vibration force, the flange nut is prone to loosening, which often occurs. If the flange nut falls off the equipment or even damages, the staff also needs to install the flange nut repeatedly, which increases the labor intensity and brings great inconvenience to the use. Now a split type tightening nut is proposed.
The quality of the combination screw should start with the screw wire of the combination screw manufacturer. The wire of the screw is the first hurdle to determine the quality of the combination screw. Even if the wire is not good, even if the production equipment is advanced and the staff is skilled, it is impossible to produce high-quality combination screws. In the second look at the quality of the combination screw products, from the overall aesthetics of the combination screw. A combined screw is formed, the size of the screw head, the superior appearance of the flat washer, whether the screw thread can pass the stop gauge, etc. These are all things that need to be detected. A good combination screw, its overall standard can meet the national standard requirements, or customer requirements. Finally, the quality of the combination screw product is seen from the color of the plating. Of course, the iron combination screw needs to be plated, but the stainless steel combination screw does not need it. Some of them are passivation at most, in order to increase the salt spray resistance of stainless steel combination screws. In the electroplating color of the combination screw, some of them are not well controlled, which will produce a great color difference. That doesn't look good.
With the popularization of electrical equipment, the door cover that integrates the panel, the controller, the sealing and waterproof function and the appearance decoration has gradually been required for equipment matching. The head directly affects the appearance, and for kitchen equipment such as dishwashers, the fixing screws of the door cover are easily rusted in direct contact with the washing water, which urgently needs a door cover structure that is easy to disassemble but does not affect the appearance.
Inspection method There are two types of screw surface inspection, one is the inspection before the screw is produced and not plated, and the other is the inspection after the screw is plated, that is to say, after the screw is hardened and the surface of the screw is treated. . After the screws are produced and before electroplating, we inspect the screws in various aspects such as size and tolerance. See if there are national standards or customer requirements. After the surface treatment of the screws, we will inspect the plated screws, mainly to check the color of the plating and whether there are any broken screws. In this way, when we deliver screw goods to customers, customers can successfully pass the customs when they receive the goods. Inspection of screws after treatment: 1. Appearance quality requirements The inspection of the appearance of screws is carried out from the aspects of appearance, electroplating layer and so on. Second, the inspection of the thickness of the screw coating 1. The measuring tool method uses a micrometer, a vernier caliper, a plug gauge, etc. 2. Magnetic method The magnetic method is used to measure the thickness of the coating layer, which is a non-destructive measurement of the non-magnetic coating layer on the magnetic substrate with a magnetic thickness gauge. 3. Microscopy Microscopy is called metallographic method, which is to magnify the etched fasteners on a metallographic microscope with a micrometer eyepiece to measure the thickness of the coating on the section. 4. Timing flow method The timing flow method uses a solution that can dissolve the coating to flow on the local surface of the coating, and calculates the thickness of the coating according to the time required for the local coating to dissolve. There are also coating drop method, anodic dissolution Coulomb method, etc. 3. Inspection of the adhesion strength of the screw coating There are many methods for evaluating the adhesion between the coating and the base metal, usually the following. 1. Friction polishing test; 2. File method test; 3. Scratch method; 4. Bending test; 5. Thermal shock test; 6. Extrusion method. 4. Inspection of corrosion resistance of screw coatings The corrosion resistance inspection methods of coatings include: atmospheric exposure test; neutral salt spray test (NSS test); acetate salt spray test (ASS test), copper accelerated acetate salt spray test (CASS) test); and corrosion paste corrosion test (CORR test) and solution spot corrosion test; immersion test, inter-dipping corrosion test, etc.
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
