Machining basics: turning and milling – primary motion and feed motion
Design & TechnologyMechanical EngineeringAges 16–17
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Mechanical Engineering
Choose a lathe or a milling machine, then press Run to watch the primary motion (the workpiece spins on a lathe, the cutter spins on a mill) and the feed motion that carries the cutting edge along the workpiece length while chips fly off and a layer of thickness t is removed. Sliders change spindle speed n, depth of cut t and feed rate s; the display shows cutting speed v = πDn/1000 and the time for one feed pass.
Lesson: Cutting methods: turning and milling – cutting motion, cutting parameters (v, s, t), and machining time
What it shows
Turning and milling remove material as chips using two motions. The primary motion creates the cutting speed: on a lathe the workpiece rotates, on a milling machine the cutter rotates. The feed motion moves the tool, or the table carrying the workpiece, so the cut advances along the surface. The simulation calculates the cutting speed v = πDn/1000 in m/min, the feed speed s·n and the time for one pass T = L/(s·n). The depth of cut t sets the thickness of the layer removed, so a turned diameter shrinks by 2t.
How to use
Choose the Machine, press Run and identify which part rotates and which part feeds. Then change one setting at a time: raise the Spindle speed n, then the Feed rate s, and compare the cutting speed and pass time shown below the drawing. Increase the workpiece or cutter diameter D at constant n to see v rise. Use Switch to milling or Switch to lathe to compare the two machines with the same n, s and t.
Parameters you can change
- Machine Lathe (external turning), Milling machine (face milling)
- Spindle speed n 100–2000 rpm
- Depth of cut t 0.5–5 mm
- Feed rate s 0.05–0.6 mm/rev
- Workpiece diameter (turning) / cutter diameter (milling) 20–120 mm
- Machining length L 40–300 mm
Questions to explore
- How does the primary motion on a lathe differ from the primary motion on a milling machine?
- If you double the Feed rate s, what happens to the time for one pass, and why?
- At the same spindle speed, why does a larger diameter give a higher cutting speed?
