Horizontal Milling Machines and Accessories Session 12

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

Manufacturing-Type Used primarily for quantity production of identical parts Distinctive features Automatic cycle of cutter and work approach Rapid movement during non-cutting cycle Automatic spindle stop

Manufacturing-Type Two common types Plain manufacturing type Small plain automatic knee and column type

Plain Manufacturing Type Milling Machine

Special-Type 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

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 Anti-backlash ball screws

Machining Centers

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

Universal Horizontal Milling Machines 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

Universal Horizontal Milling Machine

Milling Machine Parts Base Column face Knee 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

Milling Machine Parts Saddle 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

Milling Machine Parts Table Rests on guideways in saddle and travels left and right Supports vise and work Crossfeed handwheel Used to move table in and out Table handwheel Used to move table left and right

Milling Machine Parts 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

Milling Machine Parts 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

Backlash Eliminator Eliminates backlash (play) between nut and table lead screw Permits operation of climb (down) milling 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

Machine Backlash Eliminator

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

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

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

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

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

Arbors Arbors Shell-end mill 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

Collets and Adapters Collet adapters Quick-change adapter 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

Arbors, Collets, and Adapters

Milling Machine Vises Plain vise Jaws parallel or 90º to axis of spindle

Milling Machine Vises Swivel base vise Can swivel through 360º in horizontal plane

Milling Machine Vises Universal vise Can swivel through 360º in horizontal plane and tilted from 0º to 90 in vertical plane

Fixturing Systems Easy-to-adjust Stop

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

Horizontal Boring Mill

Horizontal Boring Mill