Abrasion resistant hard gold plating
Galvanic Gold plating of contacts
Abrasion resistant hard gold plating on contact pins in PTR HARTMANN rotary code switches is aprox. 1.2 µm thick, with min. thickness of 0.8 µm.
Contacts with hard gold plating show considerable abrasion after 30 000 steps, whereas on commonly used flash gold contacts gold is completely gone after 10 000 steps.
Gold plating not only serves for better conductivity of contacts, but also as an anticorrosive between operations. So if flash gold on contacts is gone, they will more likely corrode than hard gold plated contacts.
Therefore on PTR HARTMANN rotary code switches hard gold plating is a standard.