The extra-long finishing machine reamers with straight shank, DIN 212, made of HSSE steel with 42° left-hand spiral flutes, are cutting tools designed for finishing, sizing and dimensional control of existing holes on conventional and CNC machine tools. They are used when a hole must be brought to its final size with accuracy, good roundness, controlled cylindricity and suitable surface quality for the required mechanical fit.

The function of a finishing reamer is to work in the final stage of hole machining. It is not used to create the hole, but to finish it after drilling, boring or rough machining, removing a small and controlled amount of material. This operation improves the internal geometry of the seat, corrects minor irregularities left by previous tools and produces a calibrated, stable and repeatable hole.

The extra-long version allows machining of deep holes, recessed internal seats, areas far from the entry surface and positions that cannot be easily reached with standard reamers. This feature is particularly useful for complex mechanical components, machine bodies, supports, fixtures, guides, bush seats, turned parts and components where hole depth requires extended tool reach.

The straight shank allows mounting in drill chucks, collet holders, clamping sleeves and suitable toolholding systems on drilling machines, lathes, milling machines, boring machines, machining centers and CNC machines. To obtain an accurate result, clamping must be rigid, coaxial and low-runout. With extra-long tools, system stability becomes even more important because the increased overhang makes the reamer more sensitive to deflection, vibration and misalignment.

The HSSE steel construction provides higher wear resistance than standard HSS and ensures good cutting edge stability in professional machining operations. It is suitable for steels, alloys, cast irons, ferrous and non-ferrous materials, depending on the machine, lubrication, stock allowance and cutting parameters used. HSSE is especially suitable when accuracy, tool life and repeatability are required in hole finishing.

The 42° left-hand spiral flutes are an important technical feature of this series. The pronounced spiral supports stable machining, helps control tool behavior during feed and improves chip management. This geometry is suitable when a regular finish and good dimensional control are required, especially in deep holes or operations where chip evacuation and cutting stability are essential.

For best results, the hole must be prepared with the correct stock allowance. If the pre-hole is too small, the reamer must remove too much material, increasing cutting force, heat, risk of sticking and cutting edge wear. If the pre-hole is too close to the final size, the tool may not cut uniformly over the full surface, leaving geometric defects, scoring or uneven finish.

During use, constant feed, suitable lubrication and accurate alignment between tool and hole are recommended. Vibration, misalignment, unstable clamping and reverse rotation while the reamer is inside the hole should be avoided. Proper lubrication reduces friction and heat, improves chip evacuation and helps produce a more regular surface finish and longer tool life.

Extra-long finishing machine reamers are used in precision machine shops, CNC departments, machine building, automotive, toolrooms, industrial maintenance and subcontract machining. They are suitable for finishing deep holes, internal cylindrical seats, holes for dowel pins, pins, bushes, guides, small shafts, centering components and parts intended for precision mechanical assemblies.

To preserve tool precision, the reamer should be stored in a clean and dry environment, protecting the cutting edges from impact, oxidation and accidental contact with other tools. Before use, the cutting edges should be checked to ensure they are intact, clean and free from chipping. A damaged, dirty or deformed reamer can immediately compromise hole quality, causing scoring, incorrect dimensions or unacceptable surface finish.

The extra-long HSSE finishing machine reamers with straight shank and 42° left-hand spiral are a professional solution for finishing deep and hard-to-reach holes on conventional and CNC machine tools. The combination of finishing geometry, extended length, HSSE steel, straight shank and 42° left-hand spiral enables accurate, reliable and repeatable machining when hole quality is critical to component performance.