GlossaryKind of term: Manufacturing termSimulation (CAM)
What is CAM simulation?
CAM simulation runs toolpaths or NC code virtually, with stock, tooling and, where modelled, machine and fixture, to find collisions before the machine runs.
What the simulation covers depends on two choices: what is modelled and what is run. Material removal simulation models stock and tool and shows where material is left or where the tool cuts too deep into the part (a gouge). Machine simulation adds the machine's kinematics, the fixture and the tool holders, and checks for collisions, axis limits and reach. If the simulation runs the post-processed NC code rather than the CAM system's internal toolpaths, it also tests what the postprocessor made of them.
What does CAM simulation depend on?
A simulation is only as reliable as its models. The machine model, tool and holder dimensions, tool overhang, fixture, work origin and stock have to match what is actually in the machine; a holder that sticks out further than in the model falls outside the check. A run time from simulation is a prediction. How close it comes to the real run time depends on whether the software reproduces the control's acceleration, look-ahead and tool changes, or only works from the programmed feed. On a program with many short segments the difference can be large.
How does CAM simulation work in practice?
Simulation belongs to manufacturing engineering and programming: it catches collisions, axis limits and forgotten stock before the spindle turns, and cuts down dry runs on the machine. That matters more for 5-axis work, tight fixturing and expensive workpieces than for a simple 3-axis part. At the quoting stage there is often no program yet, so most prices rest on an estimated time. A simulated time that reproduces the control's dynamics usually comes closer to the real run time than a CAM time, but it remains a prediction; only a time taken on the machine is a measurement.
What is CAM simulation often confused with?
A simulation predicts the run time; actuals record afterwards what the job really took. Process simulation has a different aim: CAM simulation checks geometry and motion, process simulation works out what the material does under cutting forces and heat. And the graphic simulation on the control shows the toolpaths and often a run time, but whether it includes the fixture and holders depends on the control and its options.
Frequently asked questions
Why does the CAM time differ from the time on the machine?
A CAM time often works from the programmed feed. On the machine, acceleration, the control's look-ahead, tool changes and the operator's override all play a part. With many short segments the real time can come out noticeably longer.
How do you find the program run time on the control?
Many controls have a test mode or graphic simulation that calculates a run time. If it reproduces the machine's axis dynamics, it is often closer to reality than the CAM time. Loading, unloading and in-process measuring are added separately.
Do I need a simulation for every quote?
Usually not. Simulating needs a program, which is often written only once the order is in or for a new, costly part. The quote then rests on an estimated time, labelled as an estimate.
Does simulation replace proving out on the machine?
Not entirely. Simulation catches many errors in advance, but only within what the model contains. Running the first part at reduced override, after checking the work origin and tool lengths, remains common practice.