Sumitomo U101172 Screw Machine Drill Bit 0.4531in Carbide

Product Description

The SUMITOMO U101172 is a screw machine length drill bit engineered for precision drilling in ferrous materials. Built from solid carbide with a coated finish, this bit delivers consistent performance in demanding production environments. It features a 135-degree split point for reduced walking and self-centering entry without a pilot hole. The straight-cylindrical shank seats securely in standard drill chucks and tool holders. At 0.4531 inches (29/64 inch) in diameter, it covers a wide range of close-tolerance hole applications. Machinists, tool and die technicians, and CNC operators are the primary users of this bit in shop and production settings.

This bit is designed for drilling cast iron and steel in screw machine, turret lathe, and CNC drilling applications. The screw machine length profile — shorter than jobber length — provides added rigidity and reduced deflection when drilling in these materials. With a flute-to-diameter ratio of 2xD and a tapered web configuration, it handles moderate depths efficiently. The maximum drilling depth is 1.1707 inches, making it well suited to through-hole and shallow blind-hole work in production runs requiring consistent hole geometry and finish quality.

Key Features

• Solid carbide construction for hardness and wear resistance in ferrous materials
• 135-degree drill point angle for self-centering entry and reduced thrust force
• Coated finish extends tool life and improves chip evacuation
• Screw machine length design increases rigidity and reduces deflection vs. jobber length
• Tapered web configuration supports strength at the cutting edge
• Straight-cylindrical shank fits standard drill chucks and tool holders

Compatibility

Designed for use in cast iron and steel workpieces. Fits standard straight-shank drill chucks and tool holders accepting a 0.4531-inch shank. Part of the Sumitomo MDW-GS series drill bit family.

Installation Notes

Installation and use should be performed by qualified machinists or CNC operators familiar with carbide tooling. Ensure the tool holder or chuck is clean and properly torqued before operation to prevent runout. Carbide is brittle — avoid side loading, interrupted cuts beyond the tool rating, or dropping the bit on hard surfaces. Follow machine manufacturer guidelines for spindle speed and feed rate recommendations appropriate to the workpiece material and hole depth.