MFGT 124
Solid Design in Manufacturing
The Design Process
Professor Joe Greene
CSU, CHICO
Reference: The Mechanical Process, 3rd Edition, David Ullman,
McGrall Hill New York (2003)
MFGT 124
Copyright 2003 Joseph Greene All Rights Reserved
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Chap 3: Problem Solving
• Topics
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Introduction
Overview of Design Process
Designing Quality into Products
Simple Design Process Examples
Complex Example
Communication during the Design Process
Sample Design Problem
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Introduction
• The design process
– Varies from product to product and industry to industry
– Generic diagram of activities that must be accomplished for all
projects.
• Figure 4.1
– Project definition and planning
» Establish need for product
– Specification definition
» What should product do and how will it be tested?
– Conceptual design
» Build a prototype to prove concept is manufacturable
– Product development
» Build production parts and a system for mass production
– Product Support
» Provide means for product to be used
» Provide spare parts for returns.
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Introduction
• The design process
– Always have market input
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New type of part that is new to market.
Use consumer focus group testing.
Develops business case
Example,
– Stick it notes or walkman or CD burners
– Most designs are redesigns of existing products
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Cars have major design changes every 5 to 7 years.
Cars have minor changes to fascias, lighting, every 1 to 3 years.
Computers are redesigned every 6 months.
Make products less expensive and more features.
Fix problems with current designs
– Cars have changes in the first year of production.
» Often times prototype tooling is used at start of production
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Introduction
• Break part into major systems and subsystems
– Car has 6 major systems
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Designed by about 300 designers for GM.
Lowers, uppers, engine, transmission, interior, and exterior panels.
Assembly plant is laid out in order of build of 6 major systems.
Design of car is broken into 6 major systems.
– Each system is proken down into subsystems and assemblies and
subassemblies.
– Example, space shuttle, Fig 4-2
• Rocket booster, Fig 4.3
• Major systems
– Sub systems
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Major Systems
• Space Shuttle is broken down into smaller components.
– Major Systems
– Tree Diagram
• Each sub system is broken down further to major assemblies.
• Each major assembly is broken down further to sub-assemblies.
• Each subassembly is broken down further into individual parts.
– Engineers are typically responsible for a sub-assembly or two and several parts.
– Designer is given a few parts to design.
• All parts and assemblies have to be designed to fit together to form major assemblies
and systems.
– Problems can occur if a redesign in on part does not get changed in another
mating part in the subassembly.
• One designer has an older subassembly information than another designer.
• Example, GM Camaro bumper beam not fitting with rails changes,
– Solution: Use product data management to coordinate versions of parts.
• Designer is automatically sent the latest drawing information when the designer
opens the model.
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Project Planning
• Example of Redesign
– Shuttle has reusable boosters
• Before each launch
– Booster is disassembled, repacked with fuel, shipped to launch site, and
assembled in field.
– Field joints were used to fasten segments together.
– Changes in materials or design have to be updated to master design.
• Project planning
– Process- Fig 4.1
– Planning is important
• Chief engineer and product development team meet every week and major
systems groups give status report (timing, budget, performance)
• Resource requirements
– What funding and personnel are needed in near future.
• Timing and Cost
– 15 people worked on design of field joints of rocket boosters for 1 year.
– Hundreds of GM engineers work on a car program over 4 years.
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Specs Definition
• Specs Definition
– Federal requirements
• Bumpers must be 2.5 MPH for cars and 0 MPH for trucks.
• Canadian requirements are 5 MPH with some damage OK.
– Customer requirements
• Want no damage to vehicle in low speed collisions (< 10 MPH)
– Company requirements
• Bumpers must survive 5 MPH impact with no damage for cars and 2.5 MPH
for trucks.
– Specifications are written to meet the company requirements.
• Bumper must maintain defection less than 130mm and maintain a load of
8,000 pounds without breaking.
• Bumper must survive two car hits at 5 MPH and one crash into the wall at 5
MPH.
• Bumper must survive room temperature impact and one at –40F.
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Conceptual Design
• Most designs start with a conceptual design.
– Designs can start on paper with a back-of-the-napkin design or in CAD in
sketch mode.
• Brainstorming session proposes several designs.
• Designs are ranked in order of those best meeting requirements.
• Conceptual design is developed to prove that idea works and is best.
– Functional prototype is produced and tested with some of the important
functional requirements.
– Quality is estimated.
– Costs are estimated.
– Timing is estimated to produce part.
– Conceptual design will lead to a Go – No Go decision.
• Go decision- money is requested and approved, resources are identified, timing is
established, project requirements are finalized.
• No-go decision- Project is shelved and no resources are provided.
– Example, GM Camaro program was cancelled in 1985 and then restarted in
1987.
– It takes 5 years to design a car. 4 years after car program is approved.
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Product Development
• Puts concept into production.
– Develops the part into a production system.
– GM has 4 phases to develop a car or truck
• Phase 0- develop functional prototype that meets performance on a per part basis.
– Business case is developed and $$ are approved for programs, typically $300M
to $5 Billion.
– Tools are ordered. Steel stamping dies take 12 months to make; plastic molding
tools take 6 months to make.
• Phase 1- develop systems that meet performance requirements on production tools
and materials.
– Production plant is identified and production parts are produced in small
batches.
– Cars are tested for final safety testing.
• Phase 2- develop plant production system to produce car in the assembly plant.
– Layout of assembly plant is changed to new car or truck line at costs of $200M
to $800M.
– Limited cars are produced and market tested.
• Phase 3- start of production at line speed of 1 car per 60 seconds.
– Get first saleable vehicle.
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Product Support
• Support is needed for the design.
– Manufacturing and assembly support.
• Meeting quality targets like ISO 9003.
• Quality workshops and clinics.
• Design changes in production plants.
– Sales and marketing support.
• Parts are provided for early showroom and customer clinics.
– Spare parts and warranty support.
• Provide parts and design for years after production stops to supply spare
parts to customers wanting to repair or replace item.
– GM requires vendors to supply parts up to 10 years after car program
ends.
– Engineering support
• Engineering changes during production that make the part cheaper or have
higher quality.
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Product Quality
• Designing quality into parts
– Quality cannot be manufactured or inspected into a product, it must
be designed into it.
• Old school:
– Quality was to measure the quality by inspecting the parts and see what
the problems are and then make changes to production system.
• New school:
– Quality is designed into the part by having concurrent engineer where
the design is approved by a cross-functional team.
• More effective to design quality into a product than measure it later.
• Better to make design changes early in product development than later.
• Example,
– US car makers versus Japanese car makers.
– Figure 4.5
– Best practices in design.
• Table 4.1
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Simple Design Example
• Simple Design Example
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Complex Design Example
• Complex Design Example
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Communication
• Communication
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