A spanner is the name given to a tool that gives grip for the purpose of loosening or tightening a fastener such as a bolt or nut.
Types of spanners
There is a wide array of different spanner types, including the open-ended spanner, ring spanner, combination spanner and adjustable spanner.
Open-ended spanners are spanners that can be opened at either end, also sometimes referred to as a D- spanner and which comes in two types, single ended and double ended.
Ring spanners have holes at either both or one end, with twelve notches often being made in the hole for the purpose of gripping the head of the bolt or nut from every side. Ring spanners are used when open-ended spanners cannot be.
Combination spanners are a combination of an open-ended spanner and a ring spanner, with both ends being the same size and able to open and tighten a bolt or nut of the same size.
Adjustable spanners can be altered to suit different nut sizes and are particularly suitable for use with nuts that are unevenly sized.
All spanners come with metal parts and these parts are provided with some type of coating in order to cut down on the chances of the metal being corroded. Aside from the rust inhibitor solution that is applied to every spanner near the close of the manufacturing process there are also a number of other coatings that spanners can be coated with, but what are they and how can you tell the difference?
Coatings
Chromium or nickel or in some cases both are used to coat some types of spanners. This is because chromium and nickel both offer greater resistance to corrosion than is the case with steel and the coating thus offers protection to the iron, preventing it from reacting with oxygen and producing rust. Another reason that chromium and nickel are commonly used to coat spanners is that they offer a very attractive finish for the tool.
Another coating that is also sometimes used to provide additional protection from corrosion is black oxide.
The spanner is placed inside of a chemical bath that causes a reaction with the iron that is situated in the outer steel layer and results in the creation of a black layer. Due to the reaction of the iron to the chemicals, this means it will no longer react with oxygen and create rust. This coating type is referred to as a “Conversion” coating due to the fact that the exterior layer of steel has effectively been converted into a different material.
How do you tell the difference?
Chromium and nickel both have a steely grey colour. This makes it very difficult, if not impossible, to tell the difference, which is one of the reasons why they are sometimes both used as spanner coatings.
Black oxide on the other hand has – as the name suggests – a black appearance and can thus be identified as such.
Coatings are vital to ensure that the spanner you use will not rust and be durable for many years to come.
