A kind milling machine inscribes a mix of curves and straight traces over a workpiece area. It may produce contours made entirely of curves. The curves produced by type milling cutters can be the two concave and convex. Arbor: Arbor is usually a style of tool adapter (or Instrument holder) https://milling-machines-for-sale35555.thelateblog.com/27349591/helping-the-others-realize-the-advantages-of-thresher-machine-hsn-code