Mitsubishi 388851 Micro Drill Bit 0.025 in Solid Carbide

Product Description

The MITSUBISHI 388851 is a solid carbide micro drill bit engineered for very small hole drilling and deep hole drilling applications. It features a 0.0250 inch diameter with a 135-degree split point and X-thinning geometry that reduces thrust force and improves centering at entry. The TiAlN coating increases surface hardness and heat resistance, extending tool life in demanding materials. At 1.856 inches overall length with a 0.6350 inch flute length and a 12xD flute-to-diameter ratio, this drill is suited for high-precision, repeatable work in production and job-shop environments. Installation is handled by machinists and CNC operators working with precision components.

This drill bit is designed for use on steel as its primary workpiece material, with broad secondary compatibility across alloy steel, austenitic stainless steel, brass, bronze alloy, carbon steel, cast iron, copper, copper alloy, hard materials, hardened steels, high temperature alloys, iron alloy, magnesium, nickel, nickel alloy, soft metals, and special alloys. The straight cylindrical shank with a 0.1250 inch diameter fits standard collet and chuck tooling. It is well suited to CNC machining centers, drill presses, and precision manual equipment requiring consistent micro-hole results.

Key Features

• 0.0250 inch diameter for micro and fine-tolerance hole drilling
• 135-degree drill point angle with X-thinning for reduced entry thrust and improved self-centering
• TiAlN coating for elevated heat resistance and extended tool life in ferrous and hard materials
• Coolant-through design supports deep hole drilling and chip evacuation
• 12xD flute-to-diameter ratio enables drilling up to 0.3050 inch maximum depth
• Right-hand cutting spiral flutes with parallel web configuration for consistent chip flow
• ISO standards compliance

Compatibility

Designed for use with standard straight-cylindrical collet systems accepting a 0.1250 inch shank diameter. Primary workpiece material is steel; secondary workpiece materials include alloy steel, austenitic stainless steel, brass, bronze alloy, carbon steel, cast iron, copper, copper alloy, hardened materials, hardened steel, high temperature alloys, iron alloy, magnesium, nickel, nickel alloy, soft metals, and special alloys.

Installation Notes

This tool should be installed and operated by qualified machinists or CNC technicians familiar with micro-diameter tooling. Ensure the spindle and collet are clean and within tolerance before seating the shank to prevent runout that could snap the bit. When drilling at this diameter, feed rates and spindle speeds must be dialed in carefully — consult the machine tool manufacturer guidelines for micro-drill parameters. Coolant-through capability should be used wherever possible to improve chip evacuation and reduce heat buildup at depth.