Introduction to Machine Tool Systems

( This and other pictures are from "Manufacturing Engineering" April - September 1996 magazines)

Drilling Machines: The cutting action results from the rotary movement of the cutting tool or workpiece, with a feed motion of the workpiece or tool, in the direction of the rotating axis. Drilling machines are used for drilling, boring, counter-sinking, reaming and tapping operations.
Vertical Drilling Center

Milling Machines: Similar to drilling. In the case of milling, both the tool and the workpiece can move horizontal or vertical direction. Milling machines are used to produce flat surfaces, sink, and slot.
Milling Machine

Turning Centers

Machining Centers (Horizontal / Vertical)

Transfer Machines: A number of work stations (turning, drilling, milling, etc.) aranged behind each other, linked by the means of an automatic work transportation unit, which governs their positions and the timing cycle.
Transfer Machine

Grinding Machines: Basicaly, the cutting tool provides the cutting movement on grinding machines. The contact between the workpiece and the grinding wheel is either on the wheel periphery or on the wheel face.
Grinding Machine

Honing Machines: The fundamental difference between honing and grinding techniques, is that when honing, the aim is only for an improvement in surface finish and dimensional accuracy.
Horizontal Machining Center


to Primer Menu

Construction of Machine Tool

Slides and Rails: Guildeways are frame elements that carry the workpiece table or spindles. There are two way types: box ways and roller ways.
Picture of way and frame

Box way: This oldest and simplest of the two. It has high stiffness, good damping characteristics, a large surface contact area, and resistance to high cutting and shock load. The rail for this design is cast or welded onto the frame or bolted in place. Cast ways are diffcult to repair and virtually impossible to replace.
Box Way

Roller ways: This way type consists of a rail and a slide, but has a rolling-element bearing between the two. Roller ways are lighter weight and operate with less friction, so they can positioned faster and with less energy. Roller way, however, take more space and is usually more costly.
Roller Way

Spindles And Motors

Electric motor are the prime movers for most machine tool functions. They mostly use 3-phase ac power supplied at 220 or 460 V. Today's spindles generally operate around 10,000 rpm or higher, ranges from 5-150 hp (3.7-112 kW).

Spindle motors: A spindle is a motor-driven shaft that both positions and transmits power to a tool or holds a workpiece. Spindle motors are the major motors on a machine tool, drive the spindle shafts.
Spindle Motor

Feed motors: Positioning motors drive the ballscrews that move the sildes carrying spindles or worktables. Today's most popular positioning motor is technically called a dc brushless motor, more commonly known as an ac servo motor.

Linear motors: A linear motor is essentially a "straightened out" rotary motor. The rotor is the slide and the stator is a row of windings. It is very lightweight relative to the conventional motor, but less accurate in positioning.
Linear Motor

Controls

Controls are the brain of all machine tool operation. Earily machine tool relied on operators to turn the wheels and pull the leverthat moved cutting tools and the workpiece. Today's machine tool are mostly relied on numeric control (NC), computer numerical control (CNC), programmable logic controller (PLC) and/or microprocessors.
CNC Display

Today, engineers create both parts design and the manufacturing programs to make them on a computer. First, an enginner designs a part using computer-aided design (CAD), then the design goes to a computer-aided manufacturing program (CAM). CAM will generate the tool-paths. Finally, the CNC on the machine tool will execute the tool-paths commands.
CNC Diagram

to Primer Menu

Tools and Holders

Cutting tools remove metal from a workpiece are usually made of tungsten carbide which is form into inserts that are clamped onto a holder. In more recent times, high-speed steel are used for makeing tools. These steels are alloyed with chromium, tungsten,and cobalt to make them hard, strong, and resistant to mavhing heat at the cutting edge.
Tool (Inserts)

A tool holder is a device that holds the cutting tool. On milling and drilling machines, almost all toolholders are derivatives of Morse taper designs developed in the early 1900s. Despite the diversity in today's design, all tooholder have these common elements: a retention stud or threaded hole on one end, an external taper that nests in an internal spindle taper, a keyway on the front that drives the toolholder, and a means for holding a tool shank.
Tools (Inserts) & Toolholders