1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. PowerPoint to accompany Krar Gill Smid Technology of Machine Tools 6 th Edition Horizontal Milling Machines and Accessories Unit 64

2. 64-2 Objectives Recognize and explain the purposes of four milling machines Know the purposes of the main operational parts of a horizontal and a vertical milling machine Recognize and state the purposes of four milling machine accessories and attachments

3. 64-3 Classification of Horizontal Milling Machines 1.Manufacturing-type Cutter height is controlled by vertical movement of headstock 2.Special-type Designed for specific milling operations 3.Knee-and-column-type Relationship between cutter height and work controlled by vertical movement of table

4. 64-4 Manufacturing-Type Milling Machines Used primarily for quantity production of identical parts Distinctive features –Automatic cycle of cutter and work approach –Rapid movement during noncutting cycle –Automatic spindle stop Two common types –Plain manufacturing type –Small plain automatic knee and column type

5. 64-5 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Plain Manufacturing Type Milling Machine

6. 64-6 Special-Type Milling Machines Designed for individual milling operations Used for only one particular type of job Completely automatic Employed when hundreds or thousands of similar pieces are to be machined

7. 64-7 Machining Centers Capable of handling wide variety of work all in one setup –Straight and contour milling, drilling, reaming, tapping, and boring Capable of high production rates while still maintaining high degree of accuracy –Rugged construction, reliable controls –Antibacklash ball screws

8. 64-8 Knee-and-Column-Type Milling Machines Machines in this class fall into three categories: –Plain horizontal milling machine –Universal horizontal milling machines –Vertical milling machines

9. 64-9 Universal Horizontal Milling Machines Essential for advanced machine shop work Difference from plain horizontal machine is addition of table swivel housing –Located between table and saddle –Permits table to be swiveled 45º in either direction in a horizontal plane Used for milling of helical grooves in twist drills, milling cutters, and gears

10. 64-10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Universal Horizontal Milling Machine

11. 64-11 Parts of the Milling Machine Base –Gives support and rigidity to machine –Acts as reservoir for cutting fluids Column face –Precision-machined and scraped section used to support and guide knee when moved vertically Knee –Houses feed mechanism –Attached to column face and moved vertically

12. 64-12 Parts of the Milling Machine Saddle –Fitted on top of knee –Moved in or out by means of crossfeed handwheel (manually or automatically) Swivel table housing –Fastened to saddle on universal milling machine –Enables table to be swiveled 45º either side of centerline

13. 64-13 Parts of the Milling Machine Table –Rests on guideways in saddle and travels longitudinally in horizontal plane –Supports vise and work Crossfeed handwheel –Used to move table toward or away from column Table handwheel –Used to move table horizontally (left and right)

14. 64-14 Parts of the Milling Machine Feed dial –Used to regulate table feeds Spindle –Provides drive for attachments, arbors, cutters Overarm –Provides for correct alignment and support of arbor and various attachments –Can be adjusted and locked in various positions

15. 64-15 Parts of the Milling Machine Arbor support –Fitted to overarm and can be clamped –Aligns and supports various attachments Elevating screw –Gives upward or downward movement to knee and table (manually or automatically) Spindle speed dial –Set by crank used to regulate spindle speed

16. 64-16 Backlash Eliminator Eliminated backlash (play) between nut and table lead screw –Permits operation of climb (down) milling How does it work? –Two independent nuts mounted on lead screw –Nuts engage common crown gear which meshes with rack –Axial movement of rack controlled by backlash eliminator engaging knob on front of saddle –Turning knob in, nuts forced to move along lead screw in opposite directions

17. 64-17 Cross section of a Cincinnati Machine Backlash Eliminator Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

18. 64-18 Milling Machine Accessories Wide variety of accessories greatly increase versatility and productivity Accessories classed as fixtures or attachments –Work-holding device fastened to table –Designed to hold workpieces that cannot be readily held in vise or when large quantities are to be machined

19. 64-19 Three Classes of Milling Machine Attachments 1.Designed to hold special attachment that increase versatility of machine Vertical, high-speed, universal, rack milling, slotting 2.Designed to hold standard cutters Arbors, collets, and adapters 3.Designed to hold workpiece Vise, rotary table, indexing (dividing) head

20. 64-20 Vertical Milling Attachment Enables plain or universal milling machine to be used as a vertical milling machine –Mounted on face of column or overarm Angular surfaces made by swiveling head, parallel to face of column up to 45º either side of vertical Used for face milling, end milling, drilling, boring and T-slot milling Universal milling attachment modification allows swiveling in two planes for cutting compound angles

21. 64-21 Rack Milling Attachment Used to mill longer gear racks (flat gears) than could be cut with standard horizontal milling machine –Rack indexing attachment included

22. 64-22 Slotting Attachment Converts rotary motion of spindle into reciprocating motion –Cutting keyways, splines, templates, and irregularly shaped surfaces Length of stroke controlled by adjustable crank Tool slide may be swiveled to any angle in plane parallel to face of column

23. 64-23 Arbors –Used for mounting milling cutter –Inserted and held in main spindle by draw bolt Shell-end mill arbors –Permit face milling horizontally or vertically –Fit into main spindle

24. 64-24 Collets and Adapters Collet adapters –used for mounting drills or other tapered-shank tools in main spindle of machine or vertical milling attachment Quick-change adapter –Mounted in spindle –Permits such operations as drilling, boring, and milling without change in setup of workpiece

25. 64-25 Arbors, Collets, and Adapters Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

26. 64-26 Three Styles of Vises Plain vise –Jaws parallel or 90º to axis of spindle Swivel base vise –Can swivel through 360º in horizontal plane Universal vise –Can swivel through 360º in horizontal plane and tilted from 0º to 90 in vertical plane

27. 64-27 Plain Vise Swivel Base Vise Universal Vise Vises Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

28. 64-28 Fixturing Systems Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Easy-to-adjust Stop Quick-change self-locking system

29. 64-29 Indexing, or Dividing, Head Permits cutting of bolt heads, gear teeth, ratchets Revolve work as required to cut helical gears and flutes in drills, reamers, and other tools –When connected to lead screw of milling machine