The inspection of special screws can be divided into two situations, one is the inspection of the screws before electroplating, and the other is the inspection after the screws are electroplated, that is, the surface of the screws is inspected after hardening. The following introduces the inspection methods of special screws and tips for dealing with rusty screws.
1. Appearance quality inspection and coating thickness inspection.
Measuring tool method: Use measuring tools such as vernier calipers, micrometers, and thread plug gauges.
Magnetic method: Use a magnetic coating thickness gauge to make non-destructive and accurate measurements of non-magnetic coatings on magnetic substrates.
Optical microscope method: also called metallographic method, the micrometer eyepiece on the metallographic microscope magnifies the cross section of the standard part to accurately measure the thickness of the coating.
Timed flow method: Use a saturated solution that can partially melt the coating to flow on the surface of the coating, and measure the thickness of the coating based on the time required for partial melting. There are also coating dripping method, anodizing ablation coulomb method, etc.
Stainless steel screws often have rust problems in daily use. Here are a few tips for dealing with rusty screws:
Vibration method: For rusty screws, do not tighten the wrench too hard to avoid the screw slipping or damaging the screw head. Instead, gently vibrating the handle of the wrench with a hammer can usually loosen and remove the rusted screw.
Knocking method: Use a flat-top hammer to tap the rusty stainless steel nut to loosen it. For example, for the nuts of the fixing bolts at both ends of the bicycle pedal, tap the nut appropriately according to the thickness and material of the pedal.
Barbecue method: For some severely rusted screws, if the above method still does not work, you can try using "fire attack". Use a gas welding oxidizing flame to heat the screws and nuts, then apply a drop of oil. The purpose of heating is to expand the screw, and the purpose of dripping oil is to quickly shrink the screw when it cools, increasing the gap between the screw and the nut. After the oil enters, the nut can be unscrewed.
By adopting the above methods and techniques, you can effectively deal with rusty screws, maintain their normal use, and extend the service life of the screws.
