Boring Bar Deflection

Boring Bar Deflection, Cutting Forces, and Horsepower Requirement

These calculations are based upon theoretical values and are only intended for planning purposes. Actual results will vary. No responsibility from Kennametal is assumed.

Conversion of Workpiece Material Rockwell (Optional)

Skip this step if you already know the Brinell hardness number(HB)

Hardness HRB OR HRC into Brinell Hardness (HB)

Rockwell HRCRockwell HRB

Boring Bar Dimensions

D_o Outside diameter

inmm

D_i Inside Diameter / Coolant Hole Size If bar does not have a coolant hole use 0

inmm

L Unsupported length

inmm

Boring Bar Material Properties

Em_c Modulus of elasticity

psiN/mm2

Workpiece

d Bore diameter

inmm

BHN Brinell Hardness

p Power Constant

Workpiece
Workpiece			"p" Values (hp/in.³/min) for machining conditions:			"p" Values (kW/cm³/min) for machining conditions:
Type of material	Designation	Calculate Hardness	Finishing	Roughing	General	Finishing	Roughing	General
Carbon steel	AISI 1018	141	0.70	0.66	0.62	0.03322	0.03094	0.02867
Carbon steel	AISI 1045	195	0.74	0.70	0.72	0.03458	0.03140	0.03276
Alloy steel	AISI 4140	194	0.79	0.74	0.73	0.03777	0.03322	0.03367
Alloy steel	AISI 4340	214	0.76	0.72	0.73	0.03822	0.03322	0.03367
Alloy steel	AISI 4140	258	0.85	0.77	0.79	0.04004	0.03504	0.03595
Alloy steel	AISI 4142	277	0.84	0.77	0.75	0.04050	0.03504	0.03595
Alloy steel	AISI 4340	485	1.31	1.00	1.05	0.05961	0.04687	0.04869
Tool steel	AISI H11	205	0.78	0.73	0.76	0.03822	0.03367	0.03504
Stainless steel	AISI 316L	147	0.81	0.73	0.73	0.03822	0.03185	0.03322
Stainless steel	AISI 410	243	0.81	0.71	0.74	0.03868	0.03367	0.03413
Stainless steel	AISI 17-4 PH	294	0.99	0.70	0.72	0.04551	0.03367	0.03458
Gray cast iron	SAE G3000	195	0.53	0.48	0.47	0.02730	0.02184	0.02184
Ductile cast iron	ASTM 65-45-12	165	0.58	0.55	0.51	0.03003	0.02366	0.02366
Titanium alloy	AMS Ti-6Al-4V	287	0.64	0.62	0.62	0.03094	0.02776	0.02867
Nickel alloy	Inconel 718	277	1.20	1.01	1.02	1.05961	0.04596	0.04733
Aluminum alloys	AMS 2024	139	0.31	0.29	0.30	0.01547	0.01320	0.01365

hp/ln.³/min. kW/cm³/min

Machining Conditions

a_p Depth of cut

inmm

f_n Feed rate

iprmm/rev

V_c Cutting speed

sfmmm/min

E Machine tool efficiency factor

Machine Tool Efficiency Factors

Direct Belt Drive	.9
Back Gear Drive	.75
Geared Head Drive	.7-.8
Oil - Hydraulic Drive	.6-.9

Your Results

L/D_o Ratio of unsupported length to outside diameter:

I Moment of inertia of the boring bar cross section:

inmm⁴

n Spindle speed:

rpm

Q_z Metal removal rate:

in.cm³/min

Dynamics of Boring

F_t Tangential force:

lbN

F_f Radial force:

lbN

F_r Resultant force:

lbN

Y_t Maximum deflection:

inmm

Horse Power Calculation

P_s Horsepower at the cutting tool:

hpKW

P_m Horsepower at the motor:

hpKW

T Torque:

ft-lbsNmm

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Boring Bar Deflection