Module 5 Milling Machines Dr. Salah Gasim Ahmed MET 103

Dr. Salah Gasim Ahmed MET 103 What is milling Milling is the process of machining flat, curved, or irregular surfaces by feeding the workpiece against a rotating cutter containing a number of cutting edges. A milling machine uses on or more revolving cutters to shape a work piece. Dr. Salah Gasim Ahmed MET 103

Types of milling machines: Vertical milling machines Turret (head can be tilted or swiveled) Fixed head (head can not be tilted or swiveled) Horizontal milling machines Plain horizontal milling machines (table is fixed at right angle to the knee) Universal milling machines (the table can be pivoted in a horizontal plane) Milling machines for special purposes Dr. Salah Gasim Ahmed MET 103

Vertical Milling machine Milling head Ram Spindle Table Saddle Knee Column Base

Ram Milling head Spindle Table Saddle Column Knee Base

Horizontal milling machine Spindle Ram Arbor Support Column Table Saddle Knee Base Dr. Salah Gasim Ahmed MET 103

Spindle Arbor support Ram (or over arm) Table Column Saddle Knee Base

Universal Milling machine Vertical milling attachment

Milling machine attachment and accessories There are three classes of accessories: Those which increase the versatility of the milling machine e.g.: Vertical milling attachment Slotting attachment Those which holds the cutter Those which holds the work piece Dr. Salah Gasim Ahmed MET 103

Dr. Salah Gasim Ahmed MET 103 Cutter holding devices: Arbor Used for mounting the cutter It is held in the main spindle by a draw bolt The outer end is supported by the arbor support The cutter is positioned on the arbor by collars Collet adaptor It is held in the spindle the same manner as the arbor It is used for mounting tools with taper shank Quick change adaptor Used for holding wide range of cutting tools Dr. Salah Gasim Ahmed MET 103

Arbor installation

Spring collet

Quick-change adaptor and tool holder chuck Collet chuck

Work holding devices: The most common types are: Vises V-blocks Mainly used for round works Angle plates They are used for large works or special shapes Fixtures They are made to hold a particular work piece Indexing head (dividing head) It permits the cutting of gears, ratchets, bolt heads Clamps

Vises Plain vise Swivel base vise Universal vise Jaws parallel or at right angle to the spindle axis Swivel base vise it can swivel in a horizontal plane Universal vise it can swivel in a horizontal plane,3600, and can be tilted 0 – 900 in a vertical plane

Clamps When work can not be held in a vise or a fixture it is clamped on the table. Here are some types of clamps: Straight clamp Finger clamp Double finger clamp Screw clamp U-clamp Goose neck clamp Universal clamp

Indexing head

Milling cutters Plain milling cutter Plain slitting cutter There many types of milling cutter. Here are some examples: Plain milling cutter Plain slitting cutter Shell milling cutter Side milling cutter End milling cutter Gear milling cutter T-slotting cutter Dove-tail slotting cutter

Cutting speeds, feeds and depth of cut: Factors for determining speed (rpm) Type of work material Cutter material Diameter of cutter Surface finish Depth of cut Rigidity of machine and work setup

High speed steel cutter The spindle speed (inch) (metric) The Value of CS is taken from table(1) Table (1) Milling Machine Cutting Speeds Material High speed steel cutter Carbide cutter ft/min m/min Machine steel 80 25 200 60 Tool steel 65 19 160 50 Cast iron 70 20 Bronze 90 30 300 Aluminium 750 225 1500

(High-Speed Steel Cutters) Milling feed Feed = N x cpt x rpm Where, N: Number of teeth in milling cutter cpt: chip per teeth for particular cutter, see table (2). rpm revolution per minute of the cutter Table (2) Recommended Feed Per Tooth (High-Speed Steel Cutters) Material Side mill End mills Plain helical mills Inches Millimeter Inch Machine steel .007 0.18 .006 0.15 .010 0.25 Tool steel .005 0.13 .004 0.10 Cast iron Bronze .008 0.20 .009 0.23 .011 0.28 Aluminium .013 0.33 .018 0.46

Table (1) Milling Machine Cutting Speeds Material High speed steel cutter Carbide cutter ft/min m/min Machine steel 80 25 200 60 Tool steel 65 19 160 50 Cast iron 70 20 Bronze 90 30 300 Aluminium 750 225 1500 Table (2) Recommended Feed Per Tooth (HSS Cutters) Material Side mill End mills Plain helical mills Inches Millimeter Inch Machine steel .007 0.18 .006 0.15 .010 0.25 Tool steel .005 0.13 .004 0.10 Cast iron Bronze .008 0.20 .009 0.23 .011 0.28 Aluminium .013 0.33 .018 0.46

High speed steel cutter Material High speed steel cutter Carbide cutter ft/min m/min Machine steel 80 25 200 60 Tool steel 65 19 160 50 Cast iron 70 20 Bronze 90 30 300 Aluminium 750 225 1500

High speed steel cutter Dr. Salah Gasim Ahmed MET 103 Material High speed steel cutter Carbide cutter ft/min m/min Machine steel 80 25 200 60 Tool steel 65 19 160 50 Cast iron 70 20 Bronze 90 30 300 Aluminium 750 225 1500 Material Side mill End mills Plain helical mills Inches Millimeter Inch Machine steel .007 0.18 .006 0.15 .010 0.25 Tool steel .005 0.13 .004 0.10 Cast iron Bronze .008 0.20 .009 0.23 .011 0.28 Aluminium .013 0.33 .018 0.46 Dr. Salah Gasim Ahmed MET 103

Safety precautions for milling machines Wear safety goggles Clean and dry the table before mounting the work holding device Clean and dry the holding device and work piece Mount the work piece securely Select and mount the proper cutter to revolve in the proper direction Clean and dry arbor cutter and collars Use only correctly fitting wrenches on the machine Tighten or loosen the arbor nut only with the arbor support in place (otherwise the arbor may bend) Use the proper spindle speed, feed and depth of cut

Make certain that the table holding device and work piece will clear the arbor and its support during the cut. Disengage the manual feed hand wheel when automatic feed is to be used. Make sure that unauthorized persons are outside the safety zone of the machine when it is started. Keep clear of the revolving cutter Stop the cutter to remove chips and use a brush for chip removal Release the automatic feed control when the job is completed. Keep floor free of chips , oil and grease When you finish working return all tools, accessories and brush the machine free of chips.

Dr. Salah Gasim Ahmed MET 103 Thank You Dr. Salah Gasim Ahmed MET 103