Detail design is the phase where all design details are finalized before releasing the design for production. Key activities in detail design include making make/buy decisions for components, completing the selection and sizing of components, engineering drawings, bill of materials, verification prototype testing, and a final cost estimate. A final design review compares the design to requirements to determine readiness for production release. Computer-based tools like CAD, CAE, PLM, and ERP help streamline design and manufacturing.
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Detail Design - Introduction
Detail design is the phase where all of the details are
brought together, all decisions are finalized, and a
decision is made by management to release the
design for production.
Detail design is the lowest level in the hierarchy of
design abstraction.
Detail design is a very specific and concrete activity.
Poor detail design can ruin a brilliant design concept
and lead to manufacturing defects, high costs, and
poor reliability in service.
• THE REVERSE IS NOT TRUE!
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9.2 Activities and Decisions in Detail
Design
What are the tasks needed to be accomplished in Detail Design?
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Make/Buy Decision
• This type of decision will be made chiefly on the
basis of cost and manufacturing capacity, with due
consideration given to issues of quality and reliability
of delivery of components.
• The decision to manufacture a critical component in-
house is based solely on the need to protect trade
secrets concerned with a critical manufacturing
process.
• An important reason for making this decision early is
so you can bring the supplier into the design effort
as an extended team member.
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Complete the Selection and Sizing of
Components
It is necessary to complete these activities before the
design can be complete.
If the product design is at all complex, it most likely will
be necessary to impose a design freeze at some point
prior to completion.
• Design Freeze: Beyond a certain point in time no
changes to the design will be permitted unless they
go through a formal review by a design control
board.
With a design freeze, only those last-minute changes
that truly affect performance, safety, or cost are
approved.
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Complete Engineering Drawings
• A major task in the detail design phase is to
complete the engineering drawings.
• Drawings of individual parts are usually called detail
drawings.
• Detail drawings show the geometric features,
dimensions, and tolerances of the parts.
• Assembly drawings show how the parts are put
together to create the product or system.
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Complete the Bill of Materials
• The bill of materials (BOM) or parts list is a list of
each individual component in the product.
• BOM is used in planning for manufacture and in
determining the best estimate product cost.
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Revise the Product Design Specification
In detail design the PDS should be updated to include all current
requirements that the design must meet.
There is difference between the part specification and the
product design specification.
For individual parts the drawing and the specification are often
the same document.
When a part specification is issued it contains information on:
• Technical performance part.
• Dimensions.
• Test requirements.
• Materials requirements.
• Reliability requirement.
• Design life.
• Packaging requirement.
• Marking for shipment.
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Complete Verification Prototype Testing
Once the design is finalized, a beta-prototype is built
and verification tested to ensure that the design meets
the PDS and that it is safe and reliable.
• Beta-Prototype: It is made with the same materials
and manufacturing processes as the product but not
necessarily from the actual production line.
Depending on the complexity of the product, the
verification testing may simply be to run the product
during an expected duty cycle and under overload
conditions, or it may be a series of statistically planned
tests.
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Final Cost Estimate
• The detail drawings allow the determination of final
cost estimates.
• Knowledge of the material, the dimensions,
tolerances, and finish of each part are needed to
determine manufacturing cost.
• Cost analysis also needs specific information about
the particular machines and process steps that will
be used to make each part.
• Note: Cost estimates will have been made at each
step of the product design process with successively
smaller margins for error.
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Prepare Design Project Report
• A design project report usually is written at the
conclusion of a project to describe the tasks
undertaken and to discuss the design in detail.
• A design project report is a vital document for
passing on design know-how to a subsequent
design team engages in a product redesign project.
• A design project report may be an important
document if the product becomes involved in either
product liability or patent litigation.
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Final Design Review
Many formal meetings or reviews will have preceded the
final design review.
These meetings include:
• An initial product concept meeting to begin the
establishment of the PDS,
• A review at the end of conceptual design to decide
whether to proceed with full-scale product development.
• A review after embodiment design to decide whether to
move into detail design.
The final design review results in a decision by
management on whether the product design is ready for
production.
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Release Design to Manufacturing
• The release of the product design to manufacturing ends
the main activity of the design personnel on that product.
• The release may be done unconditionally, or under
pressure to introduce a new product it may be done
conditionally.
• The increasing use of the concurrent engineering
approach to minimize the product development time blurs
the boundary between detail design and manufacturing.
• It is common to release the design to manufacturing in
two or three “waves,” with those designs that have the
longest lead time for designing and making tooling being
released first.
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9.3 Communicating Design and
Manufacturing Information
How can we communicate the design into another party?
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Engineering Drawings
The information on a detail drawing includes:
• Standard view of orthogonal projection - top, front, side views
• Auxiliary views - such as sections, enlarged views, or
isometric views.
• Dimensions - presented according to the GD&T standard ANSI
Y14.5M.
• Tolerances.
• Material specification.
• Manufacturing details - such as parting line location, draft
angle, surface finish.
Design layouts show the spatial relationships of all components
in the assembled product (the system).
Assembly drawings are created in detail design as tools for
passing design intent to the production department.
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Written Documents
Design engineers prepare both informal and formal
documents as part of their daily routines:
• Informal:
• Email-messages.
• Brief memoranda and daily entries in a design journal.
• Formal:
• Letters.
• Technical reports.
• Technical Papers.
• Proposals.
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Electronic Mail
No form of communication has grown so rapidly as electronic mail (e-
mail).
• Well over eight trillion e-mail messages are sent each year!
Guidelines for professional e-mail writing:
• For formal business correspondence, write as you in a business letter.
Use proper capitalization, spelling and sentence structure.
• Use information and brief subject lines in all your messages.
• Keep your messages short.
• Compress any attachments.
• Do NOT use emoticons or other informal visuals.
• In addition to an informal signature use a formal signature block.
• Delete unnecessary or repetitive information.
• Include relevant detail when you are responding to a sender.
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Memorandum Reports
• The memorandum report usually is written to a specific
person or group of persons concerning a specific topic
with which both the writer and recipient are familiar.
• A memorandum is a letter written to a colleague or group
of colleagues within the same organization.
• Memorandum reports are short (one to three pages). The
purpose in writing a memorandum report is to get a
concise report to interested parties as quickly as
possible.
• The main emphasis is on results, discussion, and
conclusions with a minimum of details unless, of course,
those details are critical to the analysis of the data.
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Design Notebook
The place where the decisions made during design are found is
the design notebook.
The design notebook should be an 8 by 11 inch bound notebook
(not spiral bound), preferably with a hard cover.
Good rules for keeping notebook:
• Keep an index.
• Entries should be made in ink and must be legible.
• Make your entries at the time you do the work.
• All data must be in their original primary form.
• Rough graphs should be drawn directly in the notebook.
• Give complete references to book, journal, reports, patents
and any other source of information.
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Formal Technical Reports
A formal technical report, usually written at the end of a project, is a completely
and stand-alone document aimed at persons having widely diverse
backgrounds.
The outline of a typical professional report:
• Cover letter.
• Title page.
• Executive summary.
• Table of contents.
• Introduction.
• Technical issue sections.
• Conclusion.
• References.
• Appendixes.
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Common Challenges in Technical Writing
Tense:
• The choice of the tense of verbs is often confusion:
• Past Tense: Use to describe work completed or in general to past events.
• Present Tense: Use in reference to items and ideas in the report itself.
• Future Tense: Use in making prediction from the data that will be applicable
in the future.
References
• References are usually placed at the end of the written text:
• Technical Journal Article: C. O. Smith, Transactions of the ASME, Journal of
Mechanical Design, 1980, vol. 102, pp. 787–792.
• Book: Thomas T. Woodson: “Introduction to Engineering Design,” pp. 321–
346. McGraw-Hill, New York, 1966.
• A private communication: J. J. Doe, XYZ Company, Altoona, PA, unpublished
research, 2004.
• Internal reports: J. J. Doe, Report No. 642, XYZ Company, Altoona, PA,
February 2001.
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Meetings
• The business world is full of meetings that are held to
exchange information and plan activities.
• At the lowest level of this hierarchy is the design team
meeting.
• The purpose of the meeting is to share the progress that
has been made, identify problem, and find help and
support in solving the problems.
• Design briefing or design review meeting for high-level
management must be short and to the point.
• If you are speaking to an audience of technical
managers, they will be more interested in the important
technical details, but don’t forget also to cover
information on schedule and costs.
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Oral Presentation
Impressions and reputations are made most quickly by
audience reaction to an oral presentation.
Oral communication has several special
characteristics:
• quick feedback by questions and dialogue;
• impact of personal enthusiasm;
• impact of visual aids; and
• influence of tone, emphasis, and gesture.
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Design Briefing
• You should know the purpose of your talk and have
a good idea of who will be attending your
presentation.
• The most appropriate type of delivery for most
business-oriented talks is an extemporaneous-
prepared talk.
• Develop the material in your talk in terms of the
interest of the audience.
• Organize it on a thought-by-thought rather than a
word-by-word basis.
• Write your conclusions first!
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Final Design Review
• The final design review should be conducted when the
detail drawings are complete and ready for release to
manufacturing.
• The purpose of the final design review is to compare the
design against the most updated version of the product
design specification (PDS) and a design review checklist,
and to decide whether the design is ready for production.
• The intent is to have a group comprised of people with
different expertise, interests, and agendas.
• An effective design review consists of three elements:
• input documents,
• effective meeting process,
• appropriate output.
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Input Documents
The input for the review consists of documents such as:
• PDS.
• QFD analysis.
• Key technical analyses like FEA, CFD.
• FMEAs.
• Quality Plan.
• Testing plan and results of the verification tests.
• Detail and assembly drawings.
• Product specifications.
• Cost projections.
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Review Meeting Process
• The design review meeting should be formally
structured with a well-planned agenda.
• The final design review is more of an audit in
contrast to the earlier reviews which are more
multifunctional problem-solving sessions.
• The review uses a checklist of items that need to be
considered. Each item is discussed and it is decided
whether it passes the review.
• Any items that do not pass the review are tagged as
action items with the name of the individual
responsible for corrective action.
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Output from Review
• The output from the design review is a decision as
whether the product is ready to release to the
manufacturing department.
• Sometimes the decision to proceed is tentative,
with several open issues that need to be
resolved, but in the judgment of management the
fixes can be made before product launch.
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9.5 Design and Business Activities
Beyond Detail Design
What are the design and business activities required?
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Design and Business Activities
• In this section we briefly discuss each activity
from the viewpoint of the engineering information
that must be supplied to each of these business
functions.
• These activities are divided into two groups:
• technical (manufacturing or design) and
• business (marketing or purchasing).
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Technical Activities
• Process planning.
• Develop production control plan.
• Designing for tooling and fixtures.
• Develop quality assurance plan.
• Develop maintenance plan.
• Develop plan for retirement from service.
• Manufacturing production acceptance test.
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Business Activities
• Negotiate with suppliers.
• Develop distribution plan.
• Write the user manual.
• Decide on warranty.
• Develop a plan for customer service.
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9.6 Facilitating Design & Manufacturing
with Computer-Based Methods
How can computer-based methods help design and
manufacturing?
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CAE and CAD
Computer-aided engineering (CAE) has had an
important and growing influence on:
• Reducing the product design cycle time.
• Improving the quality of the product.
• Decreasing manufacturing cost.
The ability to store standard details in a CAD system
for retrieval when needed saves much drafting labor.
CAD integrated with such powerful CAE tools as finite
element analysis (FEA) and computational fluid
dynamics (CFD).
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Product Lifecycle Management (PLM)
• Product lifecycle management (PLM) refers to a set
of computer-based tools that has been developed to
assist a company to more effectively perform the
product design and manufacturing functions from
conceptual design to product retirement.
• The software provides complete integration of
the engineering workflow from start to finish of
product design.
• PLM systems are specifically designed to
increase the effectiveness of the product design
process.
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Three Subsystems to PLM
Product data management (PDM):
• Provides a link between product design and
manufacturing.
Manufacturing process management (MPM):
• Bridges the gap between product design and
production control.
Customer relationship management (CRM):
• Provides integrated support to marketing, sales, and
the customer service functions.
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Enterprise Resource Planning (ERP)
• Enterprise Resource Planning (ERP) systems
are aimed at integrating the basic business
processes of an organization.
• Originally ERP dealt with manufacturing issues like
order entry, purchasing execution, inventory
management, and MRP.
• Today the scope of ERP is very broad and includes
every aspect of the business enterprise. This
includes human resources, payroll, accounting,
financial management, and supply chain
management.
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Summary
• Detail design is the phase of the design process where all of the details are
brought together, decisions finalized, and a decision is made by
management whether to release the design for production.
• The detail design phase also involves verification testing of a prototype, the
generation of a bill of materials (BOM) from the assembly drawings, a final
cost estimate, and decisions on whether to make each part in-house or to
obtain it from an outside supplier.
• Detail design ends when the design is reviewed and accepted by a formal
design review process. The review consists of comparing the design
documentation (drawings, analyses, simulations, test results, HOQ, FMEAs,
etc.) against a checklist of design requirements.
• While detail design is the end of the design process, it is not the end of the
product development process.
• The engineering design process, and in particular the detail design phase,
requires considerable skill and effort in communication on the part of design
team members.
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Assignments
• Prepare a final design review checklist for your design
project.
• Prepare a PowerPoint presentation for the first design
review of your team project.
• Prepare a poster for the final presentation for your design
project. A poster is a large visual display, with a series of
graphics, containing text, mounted on a large sheet of
poster board. The display should be self-contained, such
that a technical person will be able to understand what
you did.