The fixed revolving broach toolholders for internal broaching with cylindrical shank are broach-holding devices designed to produce regular internal profiles on lathes, machining centers and drilling machines using dedicated broaches with the correct H dimension. They are intended for producing internal profiles in through or blind holes, such as internal hexagons, internal squares, slots, grooves, shaped profiles and geometries generated by a dedicated broach. This version, with H 25 mm, D 44 mm and F 12 mm, is suitable for more demanding internal broaching operations where higher tool stability, machine rigidity and correct broach compatibility are required.

The operating principle is based on rotary broaching. The broach is mounted in the toolholder with a slight controlled inclination relative to the axis of the broach holder body. This inclination allows the broach to cut progressively into the material, removing the required section without engaging the entire profile at the same time. The rotation and axial feed provided by the machine tool transfer the front shape of the broach into the hole, producing a regular and repeatable internal profile.

The operating principle remains the same even when the machine configuration changes. On a lathe, the workpiece and the broach normally rotate while the broach holder body remains stationary. On a machining center, the workpiece and broach may remain stationary while the body of the broach holder rotates. On drilling machines or similar equipment, use is possible only when the structure provides sufficient rigidity, controlled feed and correct centering. In every configuration, broaching quality depends on centering, workpiece clamping, system rigidity and correct broach selection.

These toolholders are intended for internal broaching and must be used with broaches having the H dimension specified in the table. The H dimension is essential because it defines the correct coupling between broach and toolholder. A broach with an incorrect dimension may alter the working inclination, generate abnormal friction, overload the bearings, produce out-of-size profiles or cause tool seizure. For this reason, broach, shank, machine and required profile compatibility should always be checked before use.

Correct workpiece preparation requires a suitable pre-hole. The initial hole must be sized according to the profile to be produced, the material and the amount of stock to be removed. A pre-hole that is too small increases feed force, overloads the broach and may cause rapid wear or tool seizure. A correctly dimensioned pre-hole reduces cutting resistance, improves finish and allows the broach to generate the profile more regularly. This is particularly important for larger internal profiles, tough materials or blind-hole operations.

Centering is one of the most important factors in rotary broaching. The broach must work as closely as possible on axis with the hole and the workpiece. Misalignment may cause eccentric profiles, out-of-size seats, irregular finish, premature wear of the broach and bearings, or a helical broaching effect. Before machining, it is advisable to check machine concentricity, workpiece clamping quality, absence of play in the toolholding system and correct broach position relative to the hole.

The feed rate must be selected according to material, stock removal section, profile size, machine rigidity and clamping stability. Spindle speed is important, but feed has a more direct effect on the load applied to the broach. Softer materials such as aluminum and brass allow smoother cutting conditions, while steels, cast irons or tougher materials require reduced load, better pre-hole preparation and suitable lubrication.

The initial contact phase between broach and workpiece is critical. At the beginning, the broach may tend to rub on the material before fully engaging. When the machine cycle allows it, a progressive entry should be used, with parameters that help the tool reach full cutting engagement quickly and avoid prolonged rubbing. Once the initial contact phase has been completed, parameters can be stabilized according to the operation. This helps reduce localized wear and improves internal profile quality.

Broaches used with these toolholders must be selected according to profile, material and required depth. Cutting edges should be inspected regularly for chipping, burrs, wear or machining residues. A damaged broach can immediately compromise the quality of the internal seat, increase feed force and reduce the service life of the broach holder. Lubrication should also be selected according to the material, as proper lubrication improves sliding, reduces heat and limits wear.

In workshop applications, these broach holders are used to produce internal seats on turned components, bushes, rings, hubs, fittings, small shafts, transmission parts, tooling components, special mechanical parts and items intended for maintenance or industrial production. On CNC lathes and multi-spindle lathes, they allow broaching to be integrated directly into the production cycle, reducing secondary operations and transfers to dedicated machines. On machining centers, they allow internal profiles to be produced without moving the workpiece, provided that centering, rigidity and broach compatibility are respected.

For correct use, contact surfaces, broach seat and cylindrical shank should always be kept clean, bearing condition should be checked periodically, toolholder clamping should be verified and the process should not be forced in case of an irregular profile or tool seizure. In the event of out-of-size slots, non-straight broaching, vibration or abnormal wear, the pre-hole, feed rate, centering, machine rigidity, broach condition and H dimension compatibility should be checked in sequence.

The fixed revolving broach toolholders for internal broaching with cylindrical shank are intended for CNC operators, turners, tool setters, CNC programmers, precision machine shops, industrial maintenance technicians, machine tool builders and production departments that need to produce internal profiles with accuracy, reliability and repeatability. Selecting the correct model according to diameter d, H dimension, machine, broach and required profile helps improve machining quality, reduce tool wear and optimize the production cycle.