Milling 2


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  • The horizontal boring mill or HBM actually predates the milling machine. The boring mill was invented in 1775 by John Wilkinson. The milling machine, on the other hand was invented in 1818 by Eli Whitney. The boring mill was originally designed to do nothing more than bore deep holes through large workpieces. The HBM was eventually converted to enable it not only to mill, but to drill and even tap holes. Since it is typically much bigger than its milling machine counterpart, it can easily handle the larger workpieces. At the same time, it can be used to machine workpieces that are very small. In fact, it is not uncommon to have two or three different small to medium sized jobs on the HBM table at the same time.The size of the spindle and its accompanying drive motor is typically much bigger than a milling machine and this in itself results in a tremendous increase in horsepower availability. <number>
  • This is a medium sized Boring Mill equipped with an indexable rotary table. With the rotary table, four sizes of a cube-shaped workpiece could be machined in one set-up. It would also enable the operator to bore a hole from two opposite sides and have the hole meet at a precise location.<number>
  • This large behemoth is designed to machine workpieces too large to mount on a machine table. The work piece is mounted to a base and the machine moves back and forth past it on floor rails. Hence the name, floor-type boring mill.Notice the operator just to the right of the control pendant. The head of the Boring Mill moves up and down the face. A ladder is attached so as to allow the operator to climb down if the machine head has been raised. Not your typical Bridgeport.
  • Milling 2

    1. 1. Milling Machines Session 13 1
    2. 2. Vertical Milling Machine • Developed in 1860's • Combines vertical spindle of drill press with longitudinal and traverse movements of milling machine • Milling process may be vertical, horizontal, angular, or helical • Can be used for milling, drilling, boring, and reaming • Can machine in one, two, or three planes • X, Y, Z 2
    3. 3. Vertical Milling Machines • Equipped with variable speed spindles • Permits wide range of speeds • Spindle head housing swiveled as much as 90 degrees right and left, and limited backward and forward for angular operations • Longitudinal and crossfeed movements of table operated by hand or automatic feeds 3
    4. 4. Variety of Operations • Face milling • Gear cutting • End milling • Drilling • Keyway cutting • Boring • Dovetail cutting • Jig boring • T-slot and circular slot cutting • Many facing operations done with fly tool 4
    5. 5. Types of Vertical Milling Machines • Ram-type • Most common • Features of horizontal milling machine • Cutter spindle mounted in vertical position • Spindle head may be swiveled allowing machining of angular surfaces 5
    6. 6. Types of Vertical Milling Machines • Ram-type 6
    7. 7. Parts of Ram-Type Mill • Base • Made of cast iron • May contain coolant reservoir 7
    8. 8. Parts of Ram-Type Mill • Column • Machined face provides ways for vertical knee movement • Upper part machined to produce turret for overarm mount 8
    9. 9. Parts of Ram-Type Mill • Overarm • Round base • May be adjusted toward or away from column and rotated • Locked into position 9
    10. 10. Parts of Ram-Type Mill • Head • Attached to end of ram • Universal-type machines allow swivel in 2 planes 10
    11. 11. Parts of Ram-Type Mill • Motor • Mounted on top of head • Provides drive to spindle through V-belt 11
    12. 12. Parts of Ram-Type Mill • Spindle speed • Speed changed by variable- speed pulley/crank or by belt changes and reduction gear 12
    13. 13. Parts of Ram-Type Mill • Knee • Moves up and down on face of column • Supports saddle and table • Does not contain gears for automatic feed 13
    14. 14. Heavy-Duty Vertical Milling Machine • Used for machining operations that require larger cutters and good rigidity • Adapted to operations with both end mills and face mills • Profiling interior and exterior surfaces • Milling dies and molds • Locating and boring holes in vises and fixtures 14
    15. 15. Heavy-Duty Vertical Milling Machine 15
    16. 16. Horizontal Boring Mill • The Horizontal Boring Mill (HBM) is classically a large machine. Although small items can be machined on them, they are usually reserved for the large to very large workpieces. 16
    17. 17. Typical Boring Mill Operation 17
    18. 18. Typical Boring Mill Operation 18