Jigs & Fixtures

Design for Manufacturing:Jigs & Fixturesin Aircraft Industries

HNC Year 1

Boeing 767-400 Case Study

© Leicester College 2009. This work is licensed under a Creative Commons Attribution 2.0 License.

Author: Leicester CollegeDate created:Date revised: 2009

Abstract;The use of jigs and fixtures plays a major role in modern production engineering. The basic methods for determining the requirements and configuration of these devices is described . Examples of common practice are also given.

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Jigs & Fixtures in Aircraft Industries

Contents Design for Manufacturing Principles of Producibility Design Tools and Manufacturing What is a Fixture? What is a Jig? Jigs & Fixtures’ Advantages Jig & Fixture: Construction methods and materials Jig & Fixture: different types Jigs & Fixtures: Step by Step Using jigs to build the Boeing 767-400 Credits

These files support the Edexcel HN unit – Design for Manufacture (NQF L4)

File Name Unit Outcome Key Words

FMS 2.2 Models, work cycles, volume, machine utilisation, automation, flexible, systems

Industrial Robots 2.2,2.3 Robot, industrial, robot arm, Cartesian, polar, cylindrical, jointed arm

Jigs and Fixtures 2.1,2.3 Efficiency, production, jigs, fixtures, tooling, production,

Kinematics 2.1,2.3 Machines, kinematics, Degrees of freedom, configuration, space, work space, robot, joints, forward, inverse

For further information regarding unit outcomes go to Edexcel.org.uk/ HN/ Engineering / Specifications


Design for Manufacturing Design and manufacturing are successive phases of a single operation, the ultimate objective: an acceptable final product. In aerospace context, such acceptability has several components: – Market viability, – Operational efficiency, – Capability for further development, – Structural integrity.


Design for Manufacturing (Cont.)Other Maintainability: Civil airliner, Military aircraft Producibility: A structure must not be so complex

or difficult in concept that its realisation will

– Create great difficulties or

– Increase the cost of the manufacturing process; Tooling: Low cost production is possible only

by accounting for every possible manufacturing

advantage.


Principles of Producibility Design(1) General Configuration

(2) Major breakdowns

(3) Structure and Equipment


Principles of Producibility Design General Configuration:

– Rectangular vs. tapered wing sections, flaps and

control surfaces,

– Minimum number of major structures,

– Cylindrical, straight, or conical surfaces vs.

compound curvature,

– Extend of fairing and filleting required; Interchangeability is difficult because of tolerance

accumulation, should be used only when essential!


Principles of Producibility Design (Cont.) Major breakdowns

– Adequate access for assembly,

– Ease of handling and transportation,

– Completeness of master breakdown units,

– Assembly joints,

– Effectiveness: Improved producibility does not necessarily

follow an increase in degree of breakdown!e.g.; Centre wing-box assembled as a single part rather than more subsections


Principles of Producibility Design (Cont.) Structure and Equipment:

– Simplicity: Adequate access for fabrication and subassembly, etc.

– Parts Multiple use and Min. number of different parts Min. total number of parts Min. amount and types of attachments Effective use of standard parts, material shape

and sizes– Detail design:

Interchangeability, Adjustment, Tolerances, Adequate clearances and fastener edge distances, Machining economy, etc. ...


Tools and Manufacturing An aircraft is conceived as a complete

structure, but for manufacturing purposes

must be divided into

– Sections, or main components ==> split into

• Sub-assemblies of decreasing size,

resolved into

» Individual detail parts. To build every single part, special tools are

required!


What is a Fixture? A Fixture is a special tool used for

– Locating the work,

– Clamping the work,

– Supporting the work,

– Holding all the elements together in a rigid unit during a manufacturing operation.

The most important considerations are:

Accuracy and rigidity, followed by ease of

use, and economy in construction.


What is a Jig? A Jig is a type of Fixture with means for positively

guiding and supporting tools. For both Jigs & Fixtures:

– Origin: traced back to Swiss watch and clock industry!

– Objective: to provide interchangeability, reduction of cost, and accuracy of the manufactured Individual detail Parts, Sub -assemblies, Sections, or main components, and finally the complete structure.


Jigs & Fixtures’ Advantages Ensure the interchangeability and accuracy of

parts manufactured, Minimize the possibility of human error, Permit the use of medium-skilled labour, Reduce the manufacturing time, Allow the production of repeat orders

without retooling.


Jig & Fixture: Constructionmethods and materials Cast in iron, Fabricated from steel plates, sections and

machined parts by

– welding,

– Built-up by bolting etc. Materials such as

– Magnesium,

– Resin, Wood,

– Plastics and Composite materials, are also used.


Jig & Fixture: different types Assembly Fixtures, Machining Jigs & Fixtures, Drilling Jigs, boring Jigs, etc. Welding Fixtures, Trim Jigs, Control or Master Jig, Apply Jig; attaching to a larger jig or an

assembly of parts, etc. ...


Jigs & Fixtures: Step by StepFor every part of structure, A mockup is first designed and is made from

material such as wood, plaster, etc.,… The mockup is used to design and to build the

fixtures ensuring the contours and the externalform of the structure,

The Master Jig is then designed in order tocomplete the fixture providing the importantreference points, Jig and pin points, and to providea Reference for the regular checks of the fixture,

Thermal expansion of fixtures is important!


Design for Manufacturing:Jigs & Fixturesin Aircraft Industries

HNC Year 1

Boeing 767-400 Case Study

Shane Payne


This resource was created Leicester College and released as an open educational resource through the Open Engineering Resources project of the Higher Education Academy Engineering Subject Centre. The Open Engineering Resources project was funded by HEFCE and part of the JISC/HE Academy UKOER programme.

© 2009 Leicester College

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Jigs & Fixtures

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