TAHA Engineering Toolsby TAHA Knowledge Lab

Machining & Workshop

CNC Machining Cycle Time Estimator

Cycle time and parts per hour from cutting moves, rapids, tool changes and handling.

Inputs

Sum of all rapid (G0) moves, from the CAM report or program.

Chip-to-chip time from the machine data, if known.

Result

Estimated cycle time per part
2.60917
Parts per hour (at 100% running)
22.9958parts/h
Cutting time
79.8
Rapid travel time
3.75
Tool change + handling + other
73
Share of the cycle spent cutting
50.97%
Working
Op 1: 180 mm ÷ 400 mm/min = 27 s Op 2: 95 mm ÷ 250 mm/min = 22.8 s Op 3: 60 mm ÷ 120 mm/min = 30 s Rapids: 1,500 mm ÷ 24,000 mm/min = 3.75 s Tool changes 3 × 6 s + load 45 s + other 10 s = 73 s Cycle = 79.8 + 3.75 + 73 = 156.55 s

The estimated cycle is 2.60917 min (22.9958 parts/h); 50.97% of it is cutting.

Educational estimate — check the assumptions below.

About this calculator

A CNC cycle is more than cutting: the machine also moves rapidly between cuts, changes tools, and waits while the operator loads and unloads the part. This estimator adds these parts together. Use it for quoting, for comparing process plans, or to see where the time goes before optimising a program. Path lengths and feed rates can be taken from the CAM software report or worked out from the drawing.

Formula

tcycle = Σ (Li ÷ vf,i) + Lrapid ÷ vrapid + ntool × ttool + tload + tother

Li = cutting path length of operation i, vf,i = its feed rate, Lrapid = total rapid distance, vrapid = rapid traverse rate, ntool = number of tool changes, ttool = time per change. Parts per hour = 3600 ÷ cycle time (s).

Worked example

Three operations: 180 mm at 400 mm/min (27 s), 95 mm at 250 mm/min (22.8 s), 60 mm at 120 mm/min (30 s); rapids 1500 mm at 24 m/min (3.75 s); 3 tool changes of 6 s; load/unload 45 s; other 10 s.

  • Cutting = 79.8 s; non-cutting = 3.75 + 18 + 45 + 10 = 76.75 s
  • Cycle = 156.55 s (2.61 min) → about 23 parts per hour; only 51% of the cycle is cutting.

Assumptions and limitations

  • Machines accelerate and decelerate, so short moves take longer than length ÷ programmed rate; real cycle times are usually somewhat longer than this estimate. Feed override and CAM corner slow-downs are not modelled.
  • Parts per hour assumes the machine runs continuously. Use the OEE calculator to allow for downtime, speed losses and scrap.
  • Measure the real cycle on the machine as soon as possible and use it for production planning.

References

  • Cycle time as the sum of cutting, rapid traverse, tool-change and handling times (standard machining-time estimation practice).