Micro Boring Bar 3mm With Through Coolant Hole Steel Machining

Micro Boring Bar 3 mm with Through-Coolant Hole – Tiny Boring Cutter for Steel Machining
Cutoutil Tool

Cutoutil's micro boring bar 3 mm is a high-precision, through-coolant tool engineered for stable, chatter-free boring in stainless steel, alloy steel and hardened mould steel. The ultra-fine 3 mm shank and internal coolant outlet make it the ideal Tiny boring cutter for medical, aerospace and micro-mould applications where space is critical and surface finish is non-negotiable.

Key Features
• Micro 3 mm straight-shank design – smallest standard bore diameter down to Ø0.4 mm
• Central through-coolant hole (Ø0.5 mm) delivers high-pressure coolant directly to the cutting edge, evacuating chips and reducing heat build-up when machining steel
• Sub-micron grain carbide substrate + TiAlN nano-coating withstands 900 °C cutting temps for long tool life
• Mirror-ground flank face (Ra ≤0.2 µm) lowers cutting forces and improves wall finish to 0.3 µm Ra in steel
• Negative 7° rake and reinforced corner (0.05 mm honing) resist micro-chipping on interrupted cuts
• h4 shank tolerance (-0.003 / -0.007 mm) for perfect fit in ultra-precision collets and micro boring units
• Balanced to G2.5 @ 30 000 rpm – runout ≤3 µm for high-speed CNC Swiss-type lathes and micro-machining centres

Specifications
Part No. Bar Ø (mm) Bore Range (mm) Length (mm) Coolant Hole Ø (mm) Max rpm Insert Screw
UB03-60-300 3 0.4 – 2.0 60 0.5 40 000 T6-Torx
UB03-100-300 3 0.4 – 2.0 100 0.5 35 000 T6-Torx
(Insert: VB03 series, 0.1 mm nose radius, PVD-TiAlN)

Applications
• Micro medical implants (316L stainless)
• Watch crowns & micro-pins in hardened 1.2767 steel
• Aluminium-bronze hydraulic spool bore finishing
• High-feed correction of ejector pin holes in HRC 52 mould inserts
• Aerospace fuel-nozzle micro orifices (Inconel 718)

Benefits for Steel Machining

Direct coolant eliminates blue-chip welding on AISI 4140

30 % higher cutting speed vs. solid bars without coolant

Extends insert life from 25 min to 42 min in continuous 316L cuts

Reduces secondary reaming-achieve IT6 hole tolerance in one pass

Compact 3 mm shank allows boring only 0.5 mm away from adjacent walls in micro parts

Installation Tips
• Use ultra-precision ER8 or SYOZ collet with ≤3 µm runout
• Minimum coolant pressure 70 bar (1000 psi); filter to 15 µm
• Pre-drill pilot hole 0.05 mm larger than programmed bore to minimise entry shock
• Program entry feed 30 % lower for first 0.2 mm, then ramp to full feed

Quality & Support
Every micro boring bar is 100 % inspected on Zoller Genius 3D for shank diameter, runout and coolant flow. ISO 9001 & ISO 13485 certified facility. Next-day technical support and custom lengths available from our Germany engineering centre.

Order & Availability
In stock for same-day despatch. Discounted 10-packs for production quantities. Request free test bar-prove productivity in your steel grade before you buy.

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