Design For Assembly

Design for Assembly

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

Author: Leicester CollegeDate created:Date revised: 2009

Abstract: A major cost factor in the production of and component or assembly is its assembly. This section looks at some commonly used techniques which a designer can employ to ensure that assembly is cost effective and efficient. This is then linked to the use of jigs and fixtures for this purpose.

HNC year 1Design for Manufacture

Design for Assembly

Contents Introduction Assembly Methods Design Guidelines for Manual Assembly Using Jigs & Fixtures Design Guidelines for Automated Assembly Basic DFA Guidelines Credits

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

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

File name Unit outcome Key words

Design for assembly 1.1, 1.2,1.4 Overview, Cost, quality, reliability, assembly, guidelines

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

Geometric Tolerancing 3.1,3.2 Geometric, tolerance, system, symbols, orientation, BS, ISO, location, runout, datum

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

DFM introduction 1.1, 1.2, 1.4 design

Design for Assembly

Design for Assembly

"a process for improving product design for easy and low-cost assembly, focusing on functionality and on assemblability concurrently."

--Vincent Chan & Filippo A. Salustri

Design for Assembly

Design for Assembly

Reduce cost of assembly Improve quality and reliability Reduce part inventory Reduce production equipment

Design for Assembly

Assembly Methods

Manual assembly Fixed automatic assembly Flexible automatic assembly

Design for Assembly

Design Guidelines for Manual Assembly

eliminate the need for workers to make decisions or adjustments.

ensure accessibility and visibility. eliminate the need for assembly tools

and gauges (i.e. prefer self-locating parts).

Using Jigs & Fixtures

Hull Forming Jigs at Offshore Steel Boats Ltd.Image source: www.geograph.org.uk/photo/1230702   © Copyright David Wright and licensed for reuse under this Creative Commons Licence.

Design for Assembly

Design Guidelines for Manual Assembly

Minimise the number of standard different parts – use ‘standard parts.’

minimise the number of parts. avoid or minimise part orientation during

assembly (i.e. prefer symmetrical parts). prefer easily handled parts that do not

tangle or nest within one another.

Design for Assembly

Design Guidelines for Automated Assembly

reduce the number of different components by considering does the part move relative to other parts? must the part be isolated from other parts

(electrical, vibration, etc.)? must the part be separate to allow assembly

(cover plates, etc.)? use self-aligning and self-locating

features avoid screws/bolts

Design for Assembly

Design Guidelines for Automated Assembly

use the largest and most rigid part as the assembly base and fixture.

Assembly should be performed in a layered, bottom-up manner.

use standard components and materials.

Design for Assembly

Design Guidelines for Automated Assembly

avoid tangling or nesting parts. avoid flexible and fragile parts. avoid parts that require orientation. use parts that can be fed automatically. design parts with a low centre of gravity.

Design for Assembly

Basic DFA Guidelines

Minimise part count by incorporating multiple functions into single parts

Modularise multiple parts into single sub-assemblies

Assemble in open space, not in confined spaces; never bury important components

Make parts such that it is easy to identify how they should be oriented for insertion

Prefer self-locating parts

Design for Assembly

Basic DFA Guidelines

Standardise to reduce part variety Maximise part symmetry Eliminate tangling parts Colour code parts that are different but

shaped similarly Prevent nesting of parts; prefer stacked

assemblies Provide alignment features

Design for Assembly

Basic DFA Guidelines

Design the mating features for easy insertion

Insert new parts into an assembly from above

Eliminate re-orientation of both parts and assemblies

Eliminate fasteners

Design for Assembly

Basic DFA Guidelines

Place fasteners away from obstructions; design in fastener access

Deep channels should be sufficiently wide to provide access to fastening tools; eliminate channels if possible

Provide flats for uniform fastening and fastening ease

Ensure sufficient space between fasteners and other features for a fastening tool

Prefer easily handled parts

DESIGN FOR ASSEMBLYHNC year 1

Design for Assembly

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

This work is licensed under a Creative Commons Attribution 2.0 License.

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