The solid carbide machine reamers with straight shank, DIN 212 / UNI 6853, K20 micrograin carbide and 6° left-hand spiral flutes form B, are precision cutting tools designed for finishing, sizing and dimensional correction of existing holes. They are used when a hole must be brought to its final size with high accuracy, good roundness, geometric stability and controlled surface finish.

A reamer is not intended to create the hole from solid material, but to finish it after drilling, boring or rough machining. The tool removes a small and controlled amount of material from the internal diameter, improving the geometry of the seat and correcting minor irregularities left by the previous tool. This allows calibrated holes to be produced for precise fits with dowel pins, pins, bushes, small shafts, guides, centering components and mechanical parts intended for precision assembly.

The solid K20 micrograin carbide construction provides high rigidity, wear resistance and cutting edge stability. Compared with high-speed steel reamers, solid carbide reduces tool deflection and helps keep the hole size stable over time. This is especially important in CNC machining, repetitive production and applications where hole quality must remain constant over many parts.

The straight shank allows mounting in drill chucks, precision collet holders, clamping sleeves and suitable toolholding systems. To obtain maximum accuracy, clamping must be rigid, coaxial and low-runout. Final hole quality depends not only on the reamer itself, but also on toolholder accuracy, machine rigidity, alignment between tool and hole and stable workpiece clamping.

The 6° left-hand spiral flutes form B support stable and controlled cutting. The left-hand spiral helps limit the tendency of the tool to self-feed into the hole and provides a more regular finish compared with less controlled geometries. Form B is suitable for through-hole reaming and operations requiring chip control, geometric accuracy, dimensional repeatability and good surface quality.

Compliance with DIN 212 / UNI 6853 identifies a technical geometry suitable for professional use on machine tools. The solid carbide version is especially recommended when machining abrasive materials, cast irons, alloys, steels and non-ferrous materials, depending on the machine, coolant, stock allowance and cutting parameters used.

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 load, heat, wear and risk of breakage, especially with solid carbide tools. 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, a stable machine, constant feed, suitable lubrication and accurate alignment between tool and hole are recommended. Solid carbide provides high performance but requires correct working conditions: vibration, misalignment, unstable clamping or impact may damage the cutting edges. Reverse rotation while the reamer is inside the hole should be avoided, and the tool should never be forced. The hole and clamping system must always be clean before machining.

These reamers are suitable for precision machine shops, CNC departments, machine building, automotive, toolrooms, industrial production, mechanical maintenance and subcontract machining. They are particularly useful when accurate and repeatable holes are required in production runs, precision components, dowel pin seats, bushes, pins, guides and parts where hole quality directly affects assembly and function.

The solid carbide K20 micrograin machine reamers with straight shank and 6° left-hand spiral flutes form B are a professional solution for producing calibrated holes with high accuracy, dimensional stability and long tool life. The combination of solid carbide, DIN 212 / UNI 6853 standard, straight shank and 6° left-hand spiral enables reliable machining on conventional and CNC machine tools.