Fine boring head with R429 bars

The versatile 391.37A/B system can be used for both fine boring and face grooving applications. It allows precision adjustment in microns in order to achieve close hole tolerances. Build modular assemblies with Coromant Capto^® or HSK for increased tooling flexibility.

Fine-adjustable heads and sleeves

Benefits

Choose between conventional (.37A) and high speed (.37B) fine-adjustable head
Flexible solution for a broad diameter range
Excellent surface finish with wiper inserts
Close hole tolerances of IT6

Features

Diameter adjustment by 0.002 mm (0.00008 inch) for high accuracy
The high speed fine boring heads have an adjustable counterweight, which enables runs at 20 000 rev/min
Reduction sleeves available from size 20 to 16
Internal coolant supply/Cutting fluid through the tool

Application

Fine boring for small diameters from 3 mm (0.118 inch)
For conventional fine boring and face grooving

ISO application area

R429U boring and face grooving bars

R429U bars	Boring	Face grooving
Diameter range	3–36 mm (0.118–1.42 inch)	14–50 mm (0.551–1.97 inch)
Insert choice	3–11 mm solid carbide bars 8–36 mm CoroTurn 107 indexable inserts	CoroCut MB-09FA
Application	Flexible solution for a broad diameter range. Three length ratios available in a clear and structured assortment based on CoroTurn^®107 Boring bars with increased performance dedicated to its length/diameter ratio	Optimized bar length for each diameter for excellent chip evacuation. Excellent for small O-ring grooves, for example found on water- and hydraulic pumps

Recommendations

Choose a light-cutting insert with a positive geometry for best surface finish and close hole tolerance.

Recommended first choice is the light cutting knife edge geometry (L-K) with nose radius 0.2 mm (0.008 inch)

Choose a small nose radius to minimize vibrations and cutting forces.
Choose a nose radius smaller than depth of cut
Wiper inserts can be used with small L/D ratios at high feeds under stable conditions to increase workpiece quality and productivity levels.

Product range


	With adjustable counterweight	Solid carbide bar	Steel bar	Carbide bar with brazed steel head
Boring range mm (inch)	14–50 (0.551–1.97)	3–11 (0.118–0.433)	8–36 (0.315–1.417)	8–32 (0.315–1.260)
Hole tolerance	IT6	IT6	IT6	IT6

Precision adjustment

Single-edge fine boring tools have adjustment possibilities to accurately
pre-set the cutting edge within microns.

One full turn of the scale will move the insert 0.25 mm (0.010 inch)radially.
Adjustment with nonius scale (0.002 mm (.00008 inch) on dia.)
One full turn of the scale will change dia. by 0.5 mm (0.020 inch)
Each division of the dial has 50 divisions, representing 0.010 mm (0.0004 inch)/ diameter. The vernier has 5 divisions, making it possible to adjust the diameter by 0.002 mm (0.00008 inch).

Sleeves

Sleeves are available in order to decrease the diameter range from 20 to 16 mm (0.787 to 0.630 inch)

Example: From diameter 16 mm (0.630 inch) bars in heads to dia
20 mm (0.787 inch) bars

Start recommendations fine boring

Material	Designation	V_c m/min (ft/min)	R_a 0.8 µm (31 µinch)			R_a 1.6 µm (63 µinch)
Material	Designation	V_c m/min (ft/min)	Insert	a_p mm (inch)	f_n mm/rev (in/rev)	Insert	a_p mm (inch)	f_n mm/rev (in/rev)
Steel	46MnVS6	180 (591)	TCEX 110302-L-F 1125	0.2 (0.008)	0.25 (0.010)
Steel	46MnVS6	180 (591)	TCMT 110304-PF 4325	0.4 (0.016)	0.09 (0.004)	TCMT 110304-PF 4325	0.4 (0.016)	0.13 (0.005)
Super Duplex	F55	130 (427)	TCMT 110304-MF 1125	0.4 (0.016)	0.07 (0.003)	TCMT 110304-MF 1125	0.4 (0.016)	0.13 (0.005)
Titanium	Ti6AI4V	50 (164)	TCGX 110204-ALH10	0.4 (0.016)	0.10 (0.004)	TCGX 110204-ALH10	0.4 (0.016)	0.13 (0.005)
Aluminium	ALAS9U3Y40	270 (886)	TCGX 110204-ALH10	0.4 (0.016)	0.09 (0.004)	TCGX 110204-ALH10	0.4 (0.016)	0.13 (0.005)
Cast iron	K3.2.C.UT	225 (738)	TCMT 110304-PF 4325	0.4 (0.016)	0.03 (0.001)	TCMT 110304-PF 4325	0.4 (0.016)	0.13 (0.005)

Tool holding

Bending stiffness and torque transmissions are the most important factors when choosing a tool holder for boring operations. For best stability and hole quality use Coromant Capto or the Coromant EH system.

Coromant Capto coupling is the only modular tooling system designed for all metal cutting operations, including all hole making methods. The same cutting tools and adaptors can be used in different applications and machines. This makes it possible to standardize on one tooling system for the entire workshop. Remember the following:

Choose shortest possible adaptor
Choose strongest possible adaptor
If reduction is needed, use tapered version if possible
For long overhangs (>4 x DCON), use dampened adaptors
For long overhangs, ensure rigid clamping with flange contact to spindle if possible

The Coromant EH system delivers great tooling flexibility – choose from an extensive variety of heads, adaptors and shanks.

Reduced tool inventory with standardized tools minimizing machine downtime
For boring operations requiring long reach, as in large machining centres in the diameter range of 1–36 mm (0.039–1.42 inch). Deep pockets is a typical application where the Coromant EH system offers the required reach without limiting process security

Choice of adaptors/chucks for boring

		Adaptor and chuck systems
Choose coupling/chuck first, then adaptors/chucks		Coromant Capto	CoroChuck 930	Shrink fit adaptor	Collet chuck adaptor
+++ Very good	Torque transmission	+++	+++	+++	+++
++ Good	Run-out	+++	+++	+++	+++
+ OK	Balance	+++	+++	+++	+++
Boring tool couplings
CoroBore 820	Coromant Capto	1
DuoBore	Coromant Capto	1
CoroBore XL	Coromant Capto	1
CoroBore 825			1	2	3
	Cylindrical	1
	EH		1
Fine boring head 391.37A/B	Coromant Capto
CoroBore 824 XS	Coromant Capto	1
CoroBore 824 XS	EH		1

		1	= First choice

		2	3	= Complementary choice

Coromant Capto® system - first choice

First choice should always be tools with Coromant Capto coupling, which offers excellent repeatability and the best stability characteristics on the market.
		CoroBore 820

	Coromant Capto basic holders and adaptors	CoroBore 825
	Coromant Capto basic holders and adaptors
		DuoBore

		Fine boring head

		CoroBore XL

CoroChuck™ 930 – first choice for boring tools with cylindrical shanks.

CoroChuck 930 precision chucks have a very good run-out precision and high torque transmission thanks to the latest Fulcrum technology. This technology delivers the best pull-out security on the market.
	HD version	CoroBore 825 Cylindrical shank

	Slender version

	CoroBore 824 XS EH

Complementary adaptors

Shrink fit adaptors can be used for accessibility purposes. However, CoroBore 825 with integrated dampening mechanism is preferable if accessibility is required.
	Shrink fit adaptor		CoroBore 825 Cylindrical shank

Collet chucks can be used together with CoroBore 825 cylindrical shanks. However, it is not the optimal solution due to lower clamping forces and larger run-out compared to HydroGrip. Furthermore, it is not individually balanced.
	Collet chuck adaptor		CoroBore 825 Cylindrical shank

Not signed-in

My links

Settings

{{group.Text}}

Fine boring head 391.37A/B fine-adjustable head for small-diameter boring and face grooving