Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

PowerPoint to accompany

Krar • Gill • Smid

Technology of Machine Tools6th Edition

Milling Machines Section 12

59-2

Milling Machines

• Used to produce one or more machined surfaces accurately on workpiece– One or more rotary milling cutters

• Workpiece held on work table or holding device and brought into contact with cutter

• Vertical milling machine most common

• Horizontal milling machine handles operations normally performed by other tools

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

PowerPoint to accompany

Krar • Gill • Smid

Technology of Machine Tools6th Edition

The Vertical Milling Machine

Unit 59

59-4

Objectives

• List four main uses of a vertical milling machine

• Describe how angular surfaces can be machined

• List three types of vertical milling machines

• State the purposes of the main parts of a knee and column machine

59-5

Vertical Milling Machine

• Developed in 1860's• Combines vertical spindle of drill press with

longitudinal and traverse movements of milling machine

• Milling process may be vertical, horizontal, angular, or helical

• Can be used for milling, drilling, boring, and reaming

• Can machine in one, two, or three planes– X, Y, Z

59-6

Vertical Milling Machines

• Equipped with variable speed spindle drives– Permit wide range of speeds

• Spindle head housing swiveled as much as 90 degrees right and left, as well as limited backward and forward for angular operations

• Longitudinal and crossfeed movements of table operated by hand or automatic feeds

59-7

Variety of Operations

• Face milling

• End milling

• Keyway cutting

• Dovetail cutting

• T-slot and circular slot cutting

• Gear cutting

• Drilling

• Boring

• Jig boring

Many facing operations done with fly cutter

(cost reduction).

59-8

Types of Vertical Milling Machines

• Ram-type– Most common because of simplicity and setup– All features of plain horizontal milling machine– Cutter spindle mounted in vertical position– Spindle head may be swiveled allowing

machining of angular surfaces

• 2-axis control– Step between standard milling machine and

CNC machining center (PC control)

59-9

Heavy-Duty Vertical Milling Machine

• Used for machining operations that require larger cutters and good rigidity

• Adapted to operations with end mills and face mills– Profiling interior and exterior surfaces– Milling dies and metal molds– Locating and boring holes in jigs and fixtures

59-10

Ram-Type Vertical Milling

Machine

59-11

Parts of Ram-Type Vertical Mill

• Base made of ribbed cast iron– May contain coolant reservoir

• Column often cast with base– Machined face provides ways for vertical

movement of knee

– Upper part machines to receive turret where overarm mounted

59-12

Parts of Ram-Type Vertical Mill

• Overarm round and may be adjusted toward or away from column

• Head attached to end of ram– Made to swivel head in one plane– Universal-type machines allow swivel in 2 planes

• Motor mounted on top of head– provides drive to spindle through V-belts

59-13

Parts of Ram-Type Vertical Mill

• Spindle speed changed by variable-speed pulley/crank or by belt changes and reduction gear

• Knee moves up and down on face of column– Supports saddle and table– Does not contain gears for automatic feed

• Automatic feed is external device and controls longitudinal and crossfeeds of table