Design for Manufacture and Assembly ME 475/476 Some slides in this presentation have been provided courtesy of Emeritus Professor, Dr. Perry Carter, School of Technology at Brigham Young University

Schedule

Assignments

What Would you Like to Learn About Design for Manufacture & Assembly (DFM/DFA)?

Important Considerations in Product Design Functionality Safety Appearance Weight Maintainability Recyclability Reliability Manufacturability ….

What is the Cost of a Product? Bulb Boss Costs   Cost Remaining: Selling Price: $5.00 Retail Store Gross Profit: $2.50 Distribution: $0.75 $1.75 Overhead of Manufacturing: $0.50 $1.25 Development Cost: $0.10 $1.15 Warrantee Cost: $0.05 $1.10 Advertising: $0.40 $0.70 Packaging: $0.20 Assembly: Materials: $0.35 Manufacturing Profit: $0.00

Reduced Production Costs

Four Activities of Manufacturing Changing the shape of materials Changing the properties of materials Assembling materials (as component parts) Creating or organizing the tools, machines and systems to make the first three mf’g. activities happen

We can Make Anything, Right?

Engineering is a People Profession

Harvard Business Review “Nowhere in a company is the need for coordination more acute than between the people who are responsible for product design and those responsible for manufacturing.” Harvard Business Review

Clint Eastwood

A Very Helpful Book

The Cost of Design Changes… Time of Change Relative Cost During Concept selection and early stages of product & process design During design testing During process testing During test production During final production $1 $10 $100 $1,000 $10,000

Improving Manufacturability The single most important principle to improving manufacturability is to want to The second most significant principle to improving manufacturability is to do it in the early stages of design A third important principle is to seek to learn from others A significant additional guideline for improving manufacturability is to strive for Simplicity! Reduce the number of parts Reduce tolerances Use standard parts whenever possible Reduce number of fasteners & adjustments

Manufacturability (Cont’d) Seek to learn about the capabilities and limitations of manufacturing processes, equipment, and materials before you design the product. Consider preferred vs. nonpreferred processes and materials Consider manufacturing cost targets for the different parts of the your product

The Importance of Seeing Things in New Ways: "I had an immense advantage over many others dealing with the problem inasmuch as I had no fixed ideas derived from long-established practice to control and bias my mind, and did not suffer from the general belief that whatever is, is right." - Sir Henry Bessemer inventor of the modern Bessemer Steel making Process

What is DFMA? DFMA (Design for Manufacturability and Assembly) is a structured method for comparing alternative product designs with respect to manufacturability Back in the 70’s there were no DFM classes in engineering. Now every program has one. Why is that? These comparisons are usually based on cost or time…

What are the benefits of DFMA? Improved communication and decision making Earlier and fewer design changes Improved Quality Reduced production costs Shorter time to market Increased market share and profits…

One Example… Plastic intake manifold from Porsche SUV. Following the success of the GM experiment.

Three principle parts of the Porsche manifold Two A’s and one B make up one C

Designing for the Process

Mf’g. Processes Reference Guide Breaks 125 mfg. processes into three categories: - Knowledge - Application Development Defines, explains each process Encourages integration of design and manufacturing to yield better designed products

What Mfg. Process Should I Use? Preferred Methods Nonpreferred Methods   Castings or plastic Completely Machined Near net-shaped casting Casting Screw Machine Lathe Turning Milling Jig bore Turning Standard Materials Nonstandard Materials Tolerances > +/- 0.005 Tolerance < +/- 0.001 6061 Aluminum Steels, stainless steels 303 Stainless Steel Other types of stainless steels Thermoplastics Thermosets Hardness < or = 41 Rc Harness > 41 Rc

Tight Tolerances Cost Money! Ken Forester has prepared a nice handout to get you started…

Designing for the Process: Example Ford Air filter cover, initial release

Designing for the Process

Designing for the Process Ford air filter cover after redesign

Design for Assembly What does DFA accomplish? What are the basic assembly tasks? What are the cost drivers associated with these assembly tasks? - Reduce cost!

What are basic assembly tasks? Handling Grasping, separating from bulk, orienting… Insertion Aligning, engaging, inspection Fastening Clamping, threading, plastic deformation, adhesive, etc.

Some Tips… Design so the Assembly Process can be completed in a layered fashion – preferably from above Consider easy part handling Design mating parts that are easy to insert and align Avoid part designs that will cause tangling with identical parts Make parts symmetrical to aid in automatic orientation If symmetry can’t be achieved, exaggerate the asymmetrical features…

Effect of Part Size on Handling Time Part Handling Effect of Part Size on Handling Time

Part Tangling

Spring Tangling

Insertion Effect of Chamfers

Insertion

Example of Obstructed Access

Alignment

Assembly Time Example

3. Fasteners

Fastener Costs… Number; type High assembly time Quality may be poor Higher quality is expensive Prone to assembly errors Cost of inventory

Other Methods of Fastening

What is the Cost of Inventory? Documentation Inventory space Inventory cost of h’wd. Shipping Incoming inspection Vendor relations Vendor qualification Part certification Failure replacement Lucent Technologies reports it costs$15,000/year to maintain one electronic part certification and $150,000 for a new part

Product Reliability Improvement Product reliability, that is mean time between failures (MTBF), is inversely tied to part count!

Proof-of Concept vs. Prototype

Watch for Over-Constraint in Design

Avoid Adjustments…

What constitutes a theoretically necessary part? Identify parts that don’t meet theoretical criteria for being separate parts…and eliminate them if possible Motion Material Access

Motion 1.  During the normal operation of the product, does this part move relative to all the other parts already assembled?

Material 2.   Must this part be of a different material than all the other parts already assembled? (Reasons should be based on fundamental, properties of the material such as electrical conductivity, thermal conductivity, vibration damping, hardness, modulus, etc.)

Access 3.   Must this part be separate from all other assembled parts to allow the assembly of other theoretically necessary parts. This could involve parts that must pass through an opening requiring a door, cover, lid etc. that must be removable to allow assembly of other internal parts.

DFMA Examples Flowserve valve GM Intake Manifold Jeep Throttle Linkage XEROX door lock Automotive “A-arm” Coat Rack

Standardized Parts… Interchangeable flanges

What Material Should I choose?

Manifold Cost Comparison Aluminum design: Sand casting process $3.53 Machining $1.70 Assembly _____ Total processing $5.23 Nylon design: Injection Molding $2.66 Assembly _____

Redesign Benefits 45% unit cost savings 66% weight savings Simplified assembly & service Improved emissions performance due to EGR mounting Improved engine performance due to reduced intake air temperature Reduced shipping costs due to weight reduction Increased part standardization

British Motors Example

Avoid Unnecessary Part Numbers

Modern one-piece A- arm

1964 Jeep Throttle Pedal 38 parts 23 fasteners 228 seconds assembly time 1 theoretically required part 1.3% assembly efficiency

XEROX Door Lock

XEROX Door Lock Original Design Redesign 62 parts Total time = 6.9 min. Assembly cost = $2.76 Parts cost = $9.80 Min No. parts = 10 Efficiency = 4.8% Redesign 17 parts Total time = 1.48 min. Assembly cost = $0.59 Parts cost = $7.44 Min No. parts = 10 Efficiency = 22.5%

Coat Rack Design for assembly analysis by MFG 572 student team 16 parts, including 9 fasteners

One single part requiring several forming operations and one weld.

Summary Observe what others have done, good and bad, in the way things are made Avoid the “us vs. them” paradigm Seek input from experts, be eager to learn Design your parts considering the mf’g. process If you can, reduce the number of parts Seek to eliminate fasteners and adjustments Keep in mind that it’s the obvious that is most often overlooked in DFMA Most importantly—consider manufacturability early in the design process…

Thank You!