I encountered a strange calculation problem that I can not explain:
I calculate the power torque of a disc milling cutter.
cutter diameter Dc= 63mm
quantity cutting teeth Z= 5
cutting speed vc= 140 m/min
feed fz=0,1 mm
specific cuttingforce for the material Kc1= 2000 N/mm^2
exponent value for specific cuttingforce change mc=0.25
depth of cut ae= 3,4 mm
width of cut ap= 8.53 mm
surface section full depth cut = 29 mm^2
This is my calculation:
average chiptickness hm=fz*SQRT(ae/Dc)= 0,1*SQRT(3,4/63) = 0,023 mm (simplified formula)
cuttingforce for this chiptickness Kc=kc1*(1/hm^mc) = 2000*(1/0,023^0,25)=5135 N/mm^2
cuttingforce Fc=surface cut x kc = 29 mm^2 x 5135 = 148915 N
Pc= Fc x vf= (148915 x 353,68)/60x10^6 = 0,8778 kW
Mc=(Pc x 30 x 10^3)/pi x n = 0,8778 x 3000/pi x 707 = 11,85 Nm
This has all been confirmed by several calculators and should be more or less correct BUT now my problem !!!!
If I calculate the moment of torque Mc out of the cutting force : Mc = Fc x Dc/2 (Nm) = 148915N x 0,0315m = 4691 Nm
????? What will be the torque that my tool will need ????
This 4691 Nm can not be correct that is far too much but still I calculate it from the same force that I use in the other forumula.
I am really confused here. Am I mixing up different forces ?
I calculate the power torque of a disc milling cutter.
cutter diameter Dc= 63mm
quantity cutting teeth Z= 5
cutting speed vc= 140 m/min
feed fz=0,1 mm
specific cuttingforce for the material Kc1= 2000 N/mm^2
exponent value for specific cuttingforce change mc=0.25
depth of cut ae= 3,4 mm
width of cut ap= 8.53 mm
surface section full depth cut = 29 mm^2
This is my calculation:
average chiptickness hm=fz*SQRT(ae/Dc)= 0,1*SQRT(3,4/63) = 0,023 mm (simplified formula)
cuttingforce for this chiptickness Kc=kc1*(1/hm^mc) = 2000*(1/0,023^0,25)=5135 N/mm^2
cuttingforce Fc=surface cut x kc = 29 mm^2 x 5135 = 148915 N
Pc= Fc x vf= (148915 x 353,68)/60x10^6 = 0,8778 kW
Mc=(Pc x 30 x 10^3)/pi x n = 0,8778 x 3000/pi x 707 = 11,85 Nm
This has all been confirmed by several calculators and should be more or less correct BUT now my problem !!!!
If I calculate the moment of torque Mc out of the cutting force : Mc = Fc x Dc/2 (Nm) = 148915N x 0,0315m = 4691 Nm
????? What will be the torque that my tool will need ????
This 4691 Nm can not be correct that is far too much but still I calculate it from the same force that I use in the other forumula.
I am really confused here. Am I mixing up different forces ?
