Most of the spanner manufacturers made tools using the drop forging process. Steel rods are been cut into shorter lengths, that called billets. Each one is been passed through an induction heating coil when it uses electromagnetism that heats the metal to about 1000 degree Celsius.
The billets are placed in particular three dies (also known as moulds) in succession. The upper die drops onto the biller, then forcing it into the shapes. The first dies provide the rough shape of the spanner, and the second step is the finished shape. The third trim the excess metal from the formed spanner.
The trim line, this is where the two halves of the die come along. It is ground down to produce a long and smooth surface using hydraulic press stamps. The tool manufactures name and some of the product description could be written or stamped there. If the spanner has some angled head, machines bend the end of the spanner and give it the required shape.
If the spanners have some ring or have flare nut head, a vertical milling machine cut a hole through the center of the head and makes it ready for shaping and sizing with some broad machine.
Tempering the spanner
Box and spark plug spanners are not made up of drop forging. These are made up of steel tubing which is shaped with forming tools that push into the ends of the tubes and create the profile. The Spanners are now tempered to increase the age of the steel, tempering is such a specific sequence of cooling and heating which could slightly be different for each type of steel. flare nuts are developed after tempering is done, by cutting into small section out of the front of the head.
The spanners are left in a constant moving tub of chemicals and ceramic stones for half a day which prepare the surface of the tool for coating. Some spanners are electroplated by being dipped in a sequence of baths that contains nickel and chromium solutions. Electricity also passes through the spanner that causes particles of metal to stick o the tool, it creates a very thin layer of metal on the surface.
The coating on raw spanners
All the spanners are been coated with black oxide is being immersed in a chemical solution that reacts with the iron in the steel, producing a covering of magnetite that protects the steel from corrosion. Spanners are being dipped into a rust free inhibitor solution for protecting it from the corrosion; it will help the tool and increase its life. If the spanner has multiple components, they are fitted all together, often by hand. For example, rivets are being fitted to hold the heads of flex-headed spanners in plastic gears and place. These are made using injection molding and are fitted into the heads of ratchet spanners. Injection molded components are also made in a mould thro the molten plastic and pushed under pressure. Once the pieces are set it could be removed and ground down to smooth it into the finished component.