Bar peeling is a specialist application that requires relatively high feed rates and small depth of cut applied to round bars and thick-walled tubes.
Operations include the removal of surface layers of oxides, rolled contaminants and cracks caused by hot forging or rolling. This is mostly done in carbon steel, alloy steel for heat treating, tool steel, stainless steel and heat-resistant alloys. The advantages of peeling in comparison with turning are higher productivity, less consumption of inserts, excellent roughness quality and high dimensional accuracy.
Bar peeling inserts are generally mounted in two ways, either using a screw through the centre hole of the indexable insert or via a top clamp mechanism. Using a screw through the insert distributes the forces in axial and radial directions at the same time, leaving more room for chip evacuation. Clamping from the top significantly reduces the time to flip the insert and is more user-friendly. This is because it only takes a few turns of the clamping screw to loosen it, allowing for faster indexing of the cutting edge.
Dormer Pramet provides a range of cutting tools specifically for bar peeling applications. Its inserts, within the Pramet brand, are designed and manufactured to meet the most demanding machining processes. The range includes standard and special tools that ensure high efficiency, optimal surface quality and reliability in a range of peeling operations. Dormer Pramet’s state-of-the-art production methods for cemented carbide grades and MT-CVD and PVD coating layers, reduce edge wear and increase the tool life.
Bar peeling indexable inserts have different cutting-edge geometries to create chips with the required shape necessary for a smooth removal from the inside of the cutting head. This is one of the most important factors affecting the efficiency of the bar machining process. The wide variety of materials to be machined encourages tool manufacturers to continuously improve both tool geometries and carbide grades.
In a recent addition to the bar peeling inserts, Dormer Pramet now displays on the tool, not only the geometry of the insert (PM), but also the variant of support facet on flank surfaces (S01, S02 or S03) and of course the grade. This helps the customer to recognise the difference between inserts with the same size and geometry, but a different edge preparation.
Also, accurate holding cassettes have a significant impact on the machining process. There are many manufacturers of machine tools for bar peeling around the world. Most of these use different holders in their cutting heads which are equipped with proprietary cassettes for the inserts.
Dormer Pramet can make custom-made cassettes using the highest quality tool steels that will match the machine tool specifics. Pockets on these holders are designed to utilise standard inserts, while spare parts are also now available within the assortment. Production of special indexable tooling to meet the specific needs of customers is also possible.
To showcase the wide range of tools for bar peeling, Dormer Pramet has produced a new catalog which outlines the wide range of indexable inserts and cassettes that are used on machine tools of different manufacturers. The publication includes a technical section, which features detailed information about the geometry of cutting tools, materials, calculation of machining parameters, recommended initial cutting speeds and a troubleshooting guide to help respond to the most common problems during machining.