Design for manufacturing
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Design for Manufacturing. Teaching materials to accompany: Product Design and Development Chapter 13 Karl T. Ulrich and Steven D. Eppinger 5th Edition, Irwin McGraw-Hill, 2012. Product Design and Development Karl T. Ulrich and Steven D. Eppinger 5th edition, Irwin McGraw-Hill, 2012.

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Design for manufacturing

Design for Manufacturing

Teaching materials to accompany:

Product Design and DevelopmentChapter 13

Karl T. Ulrich and Steven D. Eppinger5th Edition, Irwin McGraw-Hill, 2012.

Design for manufacturing

Product Design and DevelopmentKarl T. Ulrich and Steven D. Eppinger5th edition, Irwin McGraw-Hill, 2012.

Chapter Table of Contents:

  • Introduction

  • Development Processes and Organizations

  • Opportunity Identification

  • Product Planning

  • Identifying Customer Needs

  • Product Specifications

  • Concept Generation

  • Concept Selection

  • Concept Testing

  • Product Architecture

  • Industrial Design

  • Design for Environment

  • Design for Manufacturing

  • Prototyping

  • Robust Design

  • Patents and Intellectual Property

  • Product Development Economics

  • Managing Projects

Product development process

Product Development Process







Testing and





How can we emphasize manufacturing issues

throughout the development process?



  • DFX concept

  • DFM objectives

  • DFM method

  • Mfg. cost estimation

  • DFM impacts

  • DFM examples

Design for manufacturing example gm 3 8 liter v6 engine

Design for Manufacturing Example:GM 3.8-liter V6 Engine

Understanding manufacturing costs

Understanding Manufacturing Costs



  • Design for manufacturing (DFM) is a development practiceemphasizing manufacturing issues throughout the product development process.

  • Successful DFM results in lower production cost without sacrificing product quality.



  • DFM is part of DFX

  • DFM often requires a cross-function team

  • DFM is performed through the development process

Major dfm objectives

Major DFM objectives

  • Reduce component costs

  • Reduce assembly cost

  • Reduce production support costs

The dfm process 5 steps

The DFM Process (5 steps)

  • Estimate the mfg. costs

  • Reduce the costs of components

  • Reduce the costs of assembly

  • Reduce the costs of supporting production

  • Consider the impact of DFM decisions on other factors.

Estimate mfg costs

Estimate mfg. costs

  • Cost categories

    • Component vs. assembly vs. overhead

    • Fixed vs. variable

    • Material vs. labor

  • Estimate costs for standard parts

    • Compare to similar part in use

    • Get a quote from vendors

  • Estimate costs of custom made parts

    • Consider material costs, labor costs, and tooling costs

    • Depend on the production volume as well

  • Estimate costs of assembly

    • Summing up all assembly operations (time by rate)

  • Estimate the overhead costs

    • A % of the cost drives

Reduce the costs of components

Reduce the costs of components

  • Identify process constraints and cost drivers

  • Redesign components to eliminate processing steps

  • Choose the appropriate economic scale for the part process

  • Standardize components and their processes

  • Adhere the black-box component

Reduce the costs of assembly

Reduce the costs of assembly

  • Integrate parts (using the Boothroyd method)

  • Maximize ease of assembly

  • Consider customer assembly (do-it-yourself) technology driven products

Reduce the costs of supporting production

Reduce the costs of supporting production

  • Minimize systematic complexity (such as plastic injection modeling for one step of making a complex product)

  • Error proofing (anticipate possible failure modes in the production system and take appropriate corrective actions early in the development process)

Considering impacts

Considering impacts

  • Development time

  • Development cost

  • Product quality

  • External factors such as

    • component reuse and

    • life cycle costs

Design for manufacturing example 1993 gm 3800cc v6 engine design

Design for Manufacturing Example:1993 GM 3800cc V6 Engine Design

Dfm example

DFM example

  • Exhibit 13-15 on Page 274

  • Unit cost saving of 45%

  • Mass saving of 66% (33 Kg.)

  • Simplified assembly and service procedures.

  • Improved emissions performance

  • Improved engine performance

  • Reduce shipping costs (due to lighter components)

  • Increased standardization across vehicle programs.

Cost appendices

Cost Appendices

  • Materials costs

    • Exhibit 13-17 on page 279

  • Component mfg. costs

    • Exhibits 13/18-21 on pages 280-283

  • Assembly costs

    • Page 286 for common products

    • Page 287 for part handling and insertion times on Ex. 13-23

    • Cost structures for firms on Ex 13-24.

Design for x design principles

Design for X – Design principles

  • Part shape strategies:

    • adhere to specific process design guidelines

    • if part symmetry is not possible, make parts very asymmetrical

    • design "paired" parts instead of right and left hand parts.

    • design parts with symmetry.

    • use chamfers and tapers to help parts engage.

    • provide registration and fixturing locations.

    • avoid overuse of tolerances.

Design for x design principles1

Design for X – Design principles

  • Standardization strategy

    • use standard parts

    • standardize design features

    • minimize the number of part types

    • minimize number of total parts.

    • standardize on types and length of linear materials and code them.

    • consider pre-finished material (pre-painted, pre-plated, embossed, anodized).

    • combine parts and functions into a single part.

Design for x design principles2

Design for X – Design principles

  • Assembly strategies 1

    • design product so that the subsequent parts can be added to a foundation part.

    • design foundation part so that it has features that allow it to be quickly and accurately positioned.

    • Design product so parts are assembled from above or from the minimum number of directions.

    • provide unobstructed access for parts and tools

    • make parts independently replaceable.

    • order assembly so the most reliable goes in first; the most likely to fail last.

Design for x design principles3

Design for X – Design principles

  • Assembly strategies 2

    • make sure options can be added easily

    • ensure the product's life can be extended with future upgrades.

    • use sub-assemblies, especially if processes are different from the main assembly.

    • purchase sub-assemblies which are assembled and tested.

Design for x design principles4

Design for X – Design principles

  • Fastening strategies 1

    • use the minimum number of total fasteners

    • use fewer large fasteners rather than many small fasteners

    • use the minimum number of types of fasteners

    • make sure screws should have the correct geometry so that auto-feed screwdrivers can be used.

    • design screw assembly for downward motion

    • minimize use of separate nuts (use threaded holes).

    • consider captive fasteners when applicable (including captive nuts if threaded holes are not available).

Design for x design principles5

Design for X – Design principles

  • Fastening strategies 2

    • avoid separate washers and lockwashers (make it be captivated on the bolt or nut so it can still spin with respect to the fastener)

    • use self-tapping screws when applicable.

    • eliminate fasteners by combining parts.

    • minimize use of fasteners with snap-together features.

    • consider fasteners that push or snap on.

    • specify proper tolerances for press fits.

Design for x design principles6

Design for X – Design principles

  • Assembly motion strategies

    • fastened parts are located before fastener is applied.

    • assembly motions are simple.

    • Assembly motions can be done with one hand or robot.

    • assembly motions should not require skill or judgment.

    • products should not need any mechanical or electrical adjustments unless required for customer use.

    • minimize electrical cables; plug electrical sub-assemblies directly together.

    • minimize the number of types of cable.

Design for x design principles7

Design for X – Design principles

  • Automation handling strategies 1

    • design and select parts that can be oriented by automation

    • design parts to easily maintain orientation

    • use parts that will not tangle when handled in bulk.

    • use parts what will not shingle when fed end to end (avoid disks).

    • use parts that not adhere to each other or the track.

    • specify tolerances tight enough for automatic handling.

    • avoid flexible parts which are hard for automation to handle.

Design for x design principles8

Design for X – Design principles

  • Automation handling strategies 2

    • make sure parts can be presented to automation.

    • make sure parts can be gripped by automation.

    • parts are within machine gripper span.

    • parts are within automation load capacity.

    • parting lines, spruces, gating or any flash do not interfere with gripping.

Design for x design principles9

Design for X – Design principles

  • Quality and test strategies

    • product can be tested to ensure desired quality

    • sub-assemblies are structured to allow sub-assembly testing

    • testing can be performed by standard test instruments

    • test instruments have adequate access.

    • minimize the test effort spent on product testing consistent with quality goals.

    • tests should give adequate diagnostics to minimize repair time.

Design for x design principles10

Design for X – Design principles

  • DF Maintenance strategies 1

    • provide ability for tests to diagnose problems

    • make sure the most likely repair tasks are easy to perform.

    • ensure repair tasks use the fewest tools.

    • use quick disconnect features

    • ensure that failure or wear prone parts are easy to replace with disposable replacements

    • provide inexpensive spare parts in the product.

    • ensure availability of spare parts.

Design for x design principles11

Design for X – Design principles

  • Maintenance strategies 2

    • use modular design to allow replacement of modules.

    • ensure modules can be tested, diagnosed, and adjusted while in the product.

    • sensitive adjustment should be protested from accidental change.

    • the product should be protected from repair damage.

    • provide part removal aids for speed and damage prevention.

    • protect parts with fuses and overloads

Design for x design principles12

Design for X – Design principles

  • Maintenance strategies 3

    • protect parts with fuses and overloads

    • ensure any sub-assembly can be accessed through one door or panel.

    • access over which are not removable should be self-supporting in the open position.

    • connections to sub-assemblies should be accessible and easy to disconnect.

    • make sure repair, service or maintenance tasks pose no safety hazards.

    • make sure sub-assembly orientation is obvious or clearly marked.

Design for x design principles13

Design for X – Design principles

  • Maintenance strategies 4

    • make sure sub-assembly orientation is obvious or clearly marked.

    • provide means to locate sub-assembly before fastening.

    • design products for minimum maintenance.

    • design self-correction capabilities into products

    • design products with self-test capability.

    • design products with test ports

    • design in counters and timers to aid preventative maintenance.

    • specify key measurements for preventative maintenance programs

    • include warning devices to indicate failures.

Design for x design principles14

Design for X – Design principles

  • Axomatic Design by Nam Suh

    • Axiom 1

      • In good design, the independence of functional requirements is maintained.

    • Axiom 2

      • Among the designs that satisfy axiom 1, the best design is the one that has the minimum information content.

Design for x design principles15

Design for X – Design principles

  • Axiomatic design- corollaries

    • Decouple or separate parts of a solution if functional requirements are coupled or become coupled in the design of products and processes.

    • Integrate functional requirements into a single physical part or solution if they can be independently satisfied in the proposed solution.

    • Integrate functional requirements and constraints.

    • Use standardized or interchangeable parts whenever possible.

    • Make use of symmetry to reduce the information content.

    • Conserve materials and energy.

    • A part should be a continuum if energy conduction is important.

Design for x design principles16

Design for X – Design principles

  • DFA Method: Boothroyd and Dewhurst

    • Apply a set of criteria to each part to determine whether, theoretically, it should be separated from all the other parts in the assembly.

    • Estimate the handling and assembly costs for each part using the appropriate assembly process - manual, robotic, or high-speed automatic.

Design for x design principles17

Design for X – Design principles

  • Three criteria

    • Is there a need for relative motion?

    • Is there a need for different materials

    • Is there a need for maintenance?

Design for assembly rules example set of dfa guidelines from a computer manufacturer

Design for Assembly RulesExample set of DFA guidelines from a computer manufacturer.

1.Minimize parts count.

2.Encourage modular assembly.

3.Stack assemblies.

4.Eliminate adjustments.

5.Eliminate cables.

6.Use self-fastening parts.

7.Use self-locating parts.

8.Eliminate reorientation.

9.Facilitate parts handling.

10.Specify standard parts.

Design for assembly

Design for Assembly

  • Key ideas of DFA:

    • Minimize parts count

    • Maximize the ease of handling parts

    • Maximize the ease of inserting parts

  • Benefits of DFA

    • Lower labor costs

    • Other indirect benefits

  • Popular software developed by Boothroyd and Dewhurst.


To compute assembly time

To Compute Assembly Time

Handling Time

+ Insertion Time

Assembly Time

Method for part integration

Method for Part Integration

  • Ask of each part in a candidate design:

    1.Does the part need to move relative to the rest of the device?

    2.Does it need to be of a different material because of fundamental physical properties?

    3.Does it need to be separated from the rest of the device to allow for assembly, access, or repair?

  • If not, combine the part with another part in the device.

Three methods to implement dfm

Three Methods to Implement DFM

1. Organization: Cross-Functional Teams

2. Design Rules: Specialized by Firm

3. CAD Tools: Boothroyd-Dewhurst Software

Dfm strategy is contingent

DFM Strategy is Contingent









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Other Images

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