Page 239 - The Jet Engine

22: Manufacture

Contents Page

Introduction 229

Manufacturing strategy 230
Forging 231

Casting 233
Fabrication 234

Welding 235

Tungsten inert gas (T.I.G.) welding
Electron beam welding (E.B.W.)
Electro-chemical
machining (E.C.M.) 237

Stem drilling
Capillary drilling
Electro-discharge
machining (E.D.M.) 238

Composite materials and

sandwich casings 240
Inspection 240

INTRODUCTION 3. No manufacturing technique or process that In
any way offers an advantage is ignored and most
1. During the design stages of the aircraft gas available engineering methods and processes are
turbine engine, close liaison is maintained between employed in the manufacture of these engines, In
design, manufacturing, development and product some instances, the technique or process may
support to ensure that the final design is a match appear by some standards to be elaborate, time
between the engineering specification and the man-
ufacturing process capability. consuming and expensive, but is only adopted after
confirmation that it does produce maximized
2. The functioning of this type of engine, with its component lives comparable with rig test achieve-
high power-to-weight ratio, demands the highest ments.
possible performance from each component.
Consistent with this requirement, each component 4. Engine components are produced from a variety
must be manufactured at the lowest possible weight of high tensile steel and high temperature nickel and
and cost and also provide mechanical integrity cobalt alloy forgings. A proportion of components are
through a long service life. Consequently, the cast using the investment casting process. Whilst
methods used during manufacture are diverse and fabrications, which form an increasing content, are
are usually determined by the duties each produced from materials such as stainless steel,
component has to fulfil. titanium and nickel alloys using modern joining

229