What are the design considerations when selecting a spring pin?

What are the design considerations when selecting a spring pin?
Some design considerations to keep in mind when selecting spring pins include finish, fit, material, and material grade.
Finish
Spring pins are available in a variety of finishes, each with their own benefits. Common surface treatments include lightly oiled, phosphated, galvanized, cadmium and passivated stainless steel.
A lightly oiled surface protects the hardware from oxidation during shipping and storage. It should not be considered a permanent finish. Some common alloy steel spring pins have a light oil coating.
Lightly oiled spring pin
Phosphate coating Made from a thin crystalline layer of a phosphate compound. Phosphate coatings have good corrosion resistance and are a suitable base for painting. Further corrosion protection is provided when sealing oil is used over a phosphate coating. Phosphate coatings are used on low alloy steel and high carbon steel and should not be used in marine or highly corrosive environments.
Phosphate coated spring pin
Galvanizing has good corrosion resistance and is a popular choice for protecting carbon steel fasteners from corrosion. Because galvanizing is so popular, its application costs are relatively low compared to other plating solutions. It is also highly malleable and can withstand temperatures up to 120°. While galvanizing provides better corrosion protection than phosphate coatings, it should not be used in marine applications or other highly corrosive environments.
galvanized spring pin
Cadmium plating is a strong gold coating applied to high carbon steel spring pins. Cadmium plating enhances lubricity, protects against wear, and provides excellent corrosion resistance. Therefore, cadmium plating is the coating of choice for saltwater and aerospace applications.
Cadmium plated spring pin
Passivation Surface Treatment is a passivating oxide layer on stainless steel that provides additional protection from corrosive elements. While stainless steel is naturally resistant to corrosion, this oxide layer provides additional protection against surface corrosion of stainless steel components.
Passivated spring pin
furnish
Fitting refers to how the spring pin fits into the required hole. Interference fit and clearance fit are two forms of fit. An interference (friction) fit provides the highest level of alignment accuracy. However, it should not exceed a light press fit used for retention, nor should it be confused with the press fit experienced by solid pins. A clearance (free) fit is ideal for ease of assembly because the pin surface contact pressure is much less than an interference fit. Clearance fits are ideal when spring pins are used in hinge applications that require unbuckling movement.
Material
The material a spring pin is made of is always an important consideration. Spring pins are made of alloy, carbon and stainless steel. Carbon steel and alloy steel are common economical materials. However, without supplemental plating or other surface treatments, their corrosion resistance is poor. Spring pins made of stainless steel offer excellent corrosion resistance and require no additional plating. However, they are weaker than spring pins made of high carbon steel.
material cube
Material grade
Material grade is an important factor when evaluating application requirements. If the spring pin is to withstand extreme temperatures, alloy steel may be suitable. However, if the pin will be exposed to corrosive elements, stainless steel should be considered. The following is a list of common spring pin materials:
Series 1070 to 1095 carbon steel spring pins are considered high carbon steel spring pins. 10xx series carbon steel is cold drawn with carbon content ranging from 0.70% to 0.95%. High carbon steel spring pins offer high strength and wear resistance as well as extreme hardness and moderate ductility. High carbon steel spring pins require the addition of plating or other protective coatings to protect against corrosive elements.
300 Series Stainless Steels are austenitic stainless steels that can only be hardened by cold working. 300 series stainless steel provides the best corrosion protection. However, because it is not heat treated, it is not as strong as 400 series stainless steel.
400 series stainless steel is a martensitic stainless steel that is hardened by heat treatment. It has high strength and high wear resistance comparable to high carbon steel, but is more susceptible to corrosion than 300 series stainless steel.
6150 alloy steel spring pins have high tensile strength and toughness, as well as high resistance to vibration stress and high torque strength. To improve corrosion resistance, 6150 alloy steel should be coated with a phosphate coating or zinc plating.