Why mastercam do like this when i milling face contour on my lathe

G50 X250. Z250.
G0 T1000
M35
G0 X170.66 Z5.
C354.958
G97 S500 M54
Z2.
G98 G1 G112
X170. Z-10. C-7.5 F50.
G3 X185. C0. R7.5
X170. C7.5 R7.5
X155. C0. R7.5
X170. C-7.5 R7.5
G1 Z-8. F10000.
Z2.
X-170. C7.5
Z-10. F50.
G3 X-185. C0. R7.5 (this code is wrong x-axis is not move limit is 20mm)
X-170. C-7.5 R7.5
X-155. C0. R7.5
X-170. C7.5 R7.5
G113
G0 X170.66 Z-5. C174.958