machining and machine tool (Types of milling machine)

Milling Machine

Contents

• Basic functions & purposes

• Classifications

• Kinematic system & working principle

• Applications

Functions of Milling M/c

• Producing flat surfaces at any orientation

• Inclined surfaces

• Special contours on m/c elements

Principles

• Up milling:

– More clamping forces

– No effect with back clash in screw-nut systems

• Down milling

– Proper clamping is ensured

– back clash affects the process & product

Major uses

• Making flat surfaces (diff. orientations)

• Slots and steps

• Slitting

• Rotary turning

• Threads

• Helical surfaces

• Gushing in drills

Classifications

• Purpose

• Configuration

• Spindle orientation

• Automation

• CNC

According to purpose

– General purpose :

• most versatile, non-automated

• Low vol. of production

– Single purpose :

• specific operation , automated to some degree

• Lot production

– Special purpose :

• Making special features using attachments

• Batch production (automatic)

According to configuration

• Knee type :

– Non-automated

– Piece production

– Small size m/c

-contd.

• Bed type :

– Rigid & robust

– Vertical spindle

– Depth is given to cutter

– Batch wise production

- contd.

• Plano miller:

– Many cutters simultaneously can work

– (for large jobs having many plane surfaces)

– Fast production

Contd.

• Rotary table type:

– Open / closed type

– Work table rotates

– High productivity

– More than 1 spindle

According to spindle orientation-Contd.

horizontal Vertical spindle Universal head

Base

Ram

Arbour Speed chain

Feed chain

Over running clutch

Milling cutters

classifications

• Profile sharpened cutters – surface geometry doesn’t depend on tool shape

– Slab or plain milling cutter

– Side milling cutter

– Slitting cutters

– End milling cutter

– Face milling cutter

Plain or slab milling cutter

• Hollow straight HSS cylinders

• 4 to 16 straight or helical flutes

Feed

Side milling cutters

• Large cutting teeth on periphery

• Each tooth has peripheral cutting edge

– Single sided milling cutter

– Double sided milling cutter

Slitting cutters

• Only one peripheral cutting edge

• Cutter is larger in φ & thin

• Large nos. but smaller in size

• Only for slitting

End mills & shell mill

Face milling cutter

• Larger φ:80 to 800 mm

• Coated or uncoated carbide inserts

• For larger jobs like lathe bed, planer beds

Contd.

• Form relieved cutters – surface generated is the replica of the tool shape

– Form cutters

– Gear milling cutter

– Spline shaft cutter

– T-slot cutter

– Thread milling cutter

characteristics

• Flank surface is Archimedean spiral shape

• Tooth are sharpened by grinding the rake face

• To make 2D or 3D contours

Form cutters

• Made of HSS or carbides

Gear teeth milling cutter

Disc type cutter End mill type form cutter

Spline cutter

• To make spline shaft

• The cutter has the same shape to be produced

• Indexing helps to generate the spline over the circumference

Thread milling

• Short thread

• Long thread