Q. When using FSH and SPH type cold pressed nuts, can the bolt be screwed in from both ends of the cold pressed nut, or only from the end of the cold pressed nut?

A: Does the situation you are talking about mean that the reserved hole of the plastic part is a through hole?

Whether the reserved hole of the plastic part is a blind hole or a through hole (although this application scenario is very rare), the screw is screwed in from the "big head" direction of the FSH and SPH nuts.

Q. Rusting of stainless steel fasteners:

A: Stainless steel is not rust-free, it is just not easy to rust. When the protective film on the surface of stainless steel is damaged, it will rust. For example:

①.Dust or foreign metal particles containing other metal elements are deposited on the surface of stainless steel. In humid air, the condensed water between the attachment and the stainless steel connects the two into a micro-battery, triggering an electrochemical reaction. When the protective film is damaged, electrochemical corrosion occurs.

②.Organic juice (such as vegetables, noodle soup, sputum, etc.) adheres to the surface of stainless steel. In the presence of water and oxygen, it forms organic acid and corrodes the surface protective film.

Substances containing acids, alkalis, and salts (such as alkaline water and lime water splashing for wall decoration) adhere to the surface of stainless steel, causing local corrosion.

③.In polluted air (such as an atmosphere containing a large amount of sulfide, carbon oxide, and nitrogen oxide), condensed water forms sulfuric acid, nitric acid, and acetic acid liquid spots, causing chemical corrosion.

④.In coastal areas, due to the proximity to the sea, the air contains a lot of salt, which will corrode stainless steel, etc.