Screwed mandrel This mandrel is threaded at one end and has a collar. It is used to hold workpieces having threaded holes. Step mandrel Step mandrel has step of different sizes of holes. Collar mandrel This mandrel has two collars. Collars fit firmly into the hole of workpiece. Collar mandrel is lighter in weight. It is used for holding workpieces having larger diameter holes. MILLING FIXTURE
Location – Machine Table
Use – For Clamping Workpiece
Should be Strong and Rigid
Clearance should be provided for disposal of swarf Elements of Milling Fixture
Base
Tenon Strip
Setting Block
T – Bolts
Clamping Device
Locating and Positioning element Base Thickness 20-25mm Should be Rigid, absorb cutting forces Material used – Cast Iron Tenon Strip Locate fixture base with reference to milling cutter Fixes the base of the fixture to machine table in same relative position every time Material used – hardened and ground steel Setting block With the help of Feeler gauge(used to check positional accuracy) Use – reduces time for setting milling cutter relative to fixture Material used – hardened and ground steel T – bolts Use – binds fixture to mill table
Clamping Device Should be rigid Must not loosen by vibration caused during cutting Must not interfere during cutting operation
Locating and positioning element Cylindrical locating pins, diamond locators Different types of milling
Single Piece Milling
String Milling
Reciprocal Milling
Progressive Milling
Index Milling
Rotary Milling Dimensional Data of Milling
Dimensions of Milling Machine table
Dimensions of T – Slots
Center to Center distance of T – Slots
Length of Travel in all three fed directions Strap Clamps Used for holding the fixture bases(fixture to be used on more than one machine) Should be extremely rigid Should be tight even during more vibrations