What does CT Brazed mean?

CT stands for Coolant Through. A CT Brazed tool has internal coolant channels precision-machined through the steel body that deliver high-pressure coolant directly to the cutting zone at the tip. The cutting tip itself is a brazed carbide insert. This combines the economics of brazed carbide construction for larger diameters with the productivity benefits of through-coolant delivery.

What coolant pressure is needed for CT Brazed tools?

CT Brazed drills and reamers work best with coolant pressures of 20–80 bar (300–1200 psi), supplied through the machine spindle. Minimum recommended pressure is 20 bar for effective chip flushing in holes up to 5× diameter. For deeper holes (5–10×D), 40–80 bar is recommended. Below 10 bar, chip evacuation is insufficient and tool life is compromised.

What is the maximum hole depth for CT Brazed drills?

CT Brazed drills with through-coolant are typically rated for hole depths of up to 10–12×D (10–12 times the drill diameter). For holes deeper than 12×D, gun drilling or deep-hole BTA drilling processes are more appropriate. Vega Tools also manufactures extra-long CT Brazed drills for specific deep-hole requirements.

Can CT Brazed reamers achieve IT7 bore tolerances?

Yes. CT Brazed reamers from Vega Tools are designed to achieve IT7 tolerances (±0.007–0.012 mm at 20 mm diameter) in standard production conditions. IT6 is achievable with a high-rigidity CNC machining centre and controlled coolant pressure. The through-coolant delivery helps maintain consistent bore diameter by stabilizing cutting zone temperature.

What is the advantage of CT Brazed over solid carbide with through coolant for large diameter tools?

For diameters above 25–30 mm, solid carbide through-coolant tools become very expensive because the volume of carbide required is large. A CT Brazed tool provides the same through-coolant functionality at significantly lower cost because the body is steel and only the cutting tip is carbide. Tool life and performance are comparable to solid carbide TC tools in most applications.

Through Coolant Brazed Drills & Reamers: Essential Guide for Deep-Hole Machining

Deep-hole drilling and reaming are among the most demanding operations in precision machining. When holes reach depths of 5, 8, or 10 times the drill diameter, chip evacuation, heat management, and bore straightness become critical challenges that external flood coolant simply cannot address adequately. This is where through-coolant (CT) brazed tools become not just beneficial — but essential.

Vega Tools manufactures a complete range of CT Brazed Drills, CT Brazed Reamers, CT Brazed Profile Tools, and CT Brazed Side & Face Cutters from our Pune facility, serving automotive, hydraulics, oil & gas, and aerospace machining applications worldwide.

What Makes Deep-Hole Machining Different?

In standard drilling (up to 3×D), chips can exit the hole reasonably well through the flutes, and external coolant reaches the cutting zone. Once hole depth exceeds 3–5×D, three critical problems emerge:

Chip packing: Chips accumulate in the hole, are recut, and eventually jam the drill — the leading cause of drill breakage in deep holes
Heat accumulation: Without direct coolant at the cutting edge, temperatures rise rapidly, accelerating wear and causing dimensional variation
Bore deviation: As hole depth increases, small lateral forces on the drill tip accumulate into measurable bore deviation (off-centre exit)

Through-coolant tools solve the first two problems directly, and the improved cutting stability partially addresses the third.

How CT Brazed Tools Work

CT Brazed tools have two or more precision-machined coolant channels running through the steel body from the shank face to the cutting zone near the brazed tip. High-pressure coolant is supplied through the machine spindle, travels through the tool channels, and exits as a high-velocity jet directly at the cutting edges.

This direct delivery achieves:

Hydraulic chip flushing — high-velocity coolant jets force chips out of the hole continuously
Cutting-edge cooling — direct temperature reduction at the point of highest heat generation
Lubrication — coolant reduces friction between chip and rake face, extending tool life

CT Brazed vs Solid Carbide Through-Coolant: When to Choose Each

Factor	CT Brazed	Solid Carbide TC
Diameter Range	12 mm – 80 mm+	Up to 25–30 mm
Cost	Lower for large diameters	Lower for small diameters
Precision	Good (IT7–IT8)	Best (IT6–IT7)
Toughness	Better (steel body)	Lower (brittle)
Re-grindability	Excellent (steel body intact)	Yes but diameter reduces slightly

Rule of Thumb: For deep-hole tools below 20 mm diameter, solid carbide TC drills/reamers are usually more cost-effective and precise. For diameters 20–80 mm+, CT Brazed tools provide superior economy with equivalent performance. Vega Tools manufactures both ranges.

CT Brazed Drills: Configurations

Vega Tools CT Brazed Drills are available in:

Standard twist drill geometry (118° or 130° point) for general deep-hole drilling
Multi-flute step drill configurations for drilling and chamfering in one pass
Gun drill-style single flute for maximum straightness in deep bores
Custom point geometries for specific workpiece materials

CT Brazed Reamers: Achieving Precision in Deep Bores

CT Brazed Reamers from Vega Tools combine the accuracy of carbide reaming with through-coolant delivery for consistent bore size across long production runs. Key advantages over standard reamers in deep-hole applications:

Consistent bore temperature → consistent bore diameter throughout production batch
Chip flushing prevents scoring of the bore surface by chip recutting
Lower cutting force variation → better bore straightness in deep bores

CT Brazed Reamers are available from 8 mm to 100 mm diameter, with hole depth capability up to 8×D.

Machine and Spindle Requirements

To use CT Brazed tools effectively:

Through-spindle coolant: Your CNC machining centre must have a through-spindle coolant system (20–80 bar recommended)
Sealed toolholder: Use a coolant-sealed collet chuck or hydraulic chuck to prevent coolant leakage at the shank-holder interface
Correct coolant: Use a good-quality water-soluble cutting fluid at 5–8% concentration, free of particles that could block the small coolant channels
Controlled feed: Use CNC feed control — never "air cut" at a high feed rate as the tool enters the hole, to avoid shock loading

Industries and Applications

Automotive: Engine block oil galleries, transmission hydraulic bores, steering rack bores
Hydraulics / Pneumatics: Valve body spool bores, manifold passages, pressure ports
Oil & Gas: Valve seat bores, fitting bodies, control valve precision bores
Aerospace: Landing gear hydraulic actuator bores, fuel system components
Medical devices: Orthopaedic implant bores, surgical instrument bodies

Through-Coolant Brazed Drills and Reamers: Why They Are Essential for Deep-Hole Machining

What Makes Deep-Hole Machining Different?

How CT Brazed Tools Work

CT Brazed vs Solid Carbide Through-Coolant: When to Choose Each

CT Brazed Drills: Configurations

CT Brazed Reamers: Achieving Precision in Deep Bores

Machine and Spindle Requirements

Industries and Applications

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