Steel Bar peeling specifically is a machining process used to take a raw forged blank to a polished bar. During the bar peeling process, the forged bars are machined to remove surface cracks, cooled layers of “skin,” and oxide. It is during the peeling process that the requested dimensions and specifications are achieved on the machined parts, such as: accurate dimensions, surface quality factors, and roundness.
There are many types of metals machinists use that respond well to the bar peeling process. The following list outlines some of the more common ones:
- tempered steel
- bearing steel
- tool steel
- high-speed steel
- spring steel
- high alloyed
- stainless steels
The semi-finished product results in a high quality piece that can be machined further into axles, gears, piston rods and shafts, as well as mandrels and other machining tools.
The Bar Peeling Process:
- Blank steel is heated in a furnace
- The hot bars are then forged or rolled
- Bars are further strengthened by annealing and pre-alignment
- Quality control tests samples; piece moves on or is scrapped
- Machined to remove surface cracks, cooled layers of “skin,” and oxide; meeting dimension specs.
- Bar is straightened in a hydraulic straightening press
- Final quality checks are performed to ensure standards are met
- Optional belt grinding can be performed.
Benefits of Bar Peeling
Peeling is most commonly used on long cylindrical pieces such as bars, diameters greater than 300mm, or shafts with a step. Because the process allows for simultaneous application of cutting tools, it means feed rates are higher and there are reduced vibrations; because the bar sits closer to the cutting tools. The peeling process is generally more stable than other turning options.
One of the risks with this process is the breaking of inserts. Especially at higher speed, if an insert breaks it can not only be a write off, it can damage the inserts and cartridges, as well as other parts of the machine. This can be avoided by attentive operators as the machine will give a noticeable sound as pressure and force increase.