DFM/CE - What's It All About Anyway?
Make no mistake, this is not about POD (my personal handle) but what it means. This is about DFM/CE. Don't make another mistake thinking it is possible to have one without the other. It isn't. My job is to prove it through all of you as the best possible DOE.
You all know how I feel about designing it right the first time, every time, on time, at an acceptable cost. Some of you have experienced this as being much more than rhetoric. You all know, or think, how difficult that often is, but shouldn't, for various reasons we've all pronounced. Simply, I as you abhor poor quality anything and continue finding ways to correct it. That's not good enough. Poor quality must be prevented. Many others do it, in other industries, so why not us?
It is just that simple. I know you all agree and would do better jobs avoiding, correcting, or otherwise preventing defect - if only you could. You may not be able, but someone must become responsible and it's my job to assure someone signs up. This doesn't let any of you design, process development, manufacturing engineering, or quality types off the hook. It makes you partners in the effort. Through you, our future management types, my goal is to see DFM/CE become a positive plague upon the earth - assuring defect is not designed into anything we seek to build or buy.
NOTE: While writing this, I've been watching (out the corner of my nearly one good eye) the series rerun of "From The Earth To The Moon" on HBO. What great stuff! In this one, Allan Sheppard gets his chance to "do it" (make the "BIG" trip) though having to "tap" on a switch counsel possibly to loosen a SOLDER BALL or something making an abort landing warning light illuminate. DFM/CE had not been formally coined as yet, but synergism was key and embodied most all the newer term's requirements and the all the events before and during the "moon shots" pointed to its effectiveness as incredible success. One lousy solder ball?
Damn, what a commentary on our profession! What important significance! How often do such defects affect all our lives let alone being within one thousand feet of the moon's surface only to be launched back in failure after traveling 250,000 miles from earth to reach it - if the abort mechanism is activated? It affected mine in a very emotional and objective way back to those days when the most exciting thing on earth, or far from it, was really going on - not on some "Star Wars" movie screen. Enough!
Proof Of Design meant, in the time of our first space explorations and times thereafter in the aerospace community, ensuring the design met intent (proposed, specified requirements). It required, absolutely, DFM first (producibility then). It meant assuring all responsible individuals provided critical input to the design process, and all those following. This meant concurrence. You just can't get there from here without it.
CE is required first to evaluate process capabilities and to determine what changes to a process, or a design, or both must be made to ensure producible, acceptable product. This requires design, process, manufacturing, quality, management, customers, and all other cognizant, responsible experts being able to clearly communicate exactly what is required and what is available to make it acceptable.
No one individual or function can know, presume to know, be responsible for knowing, or do it all. Designers cannot be expected, as too many are today, to know everything about fabricating or assembling PCB's. Process or manufacturing engineers cannot know all design requirements as electrical performance or other critical factors involved in a design or product. Therefore, CE makes DFM possible. More on this later, but for now we will deal with basic elements and requirements as a functional quality system and DFM/CE elements.
Today's ISO 9000 world evolved from MIL-Q-9858 (only nine pages and still at a REV "A" just as it was in 1965 at introduction) - its self-proclaimed foundation. The following ISO design requirement shall be met while noting there are 137 ISO shall statements that must be turned into "we are" statements to ensure compliance and registration - but you already know that:
4.4 DESIGN CONTROL
Summary of Requirements:
Compliance requires demonstrated effective control over the entire product design/development process including identification of customer needs and expectations, preparation of a marketing/technical specification, and plans for the development project, the development process, the provision of adequate resources and qualified personnel to the project, and regular product design reviews. It also requires the control of design output as in technical data sheets, product applications, and specifications, identification of regulatory requirements, and design verification and validation. Formal procedures are required for subsequent improvements or modifications.
1) Procedures to control design process
2) Design and development plans
3) Technical interfaces identified and documented
4) Customer requirements fully documented
5) Identification of Regulatory requirements
6) Design reviews
7) Documentation available to show design output meets specs
8) Design Verification
9) Design Validation
10) Control of design changes
OK! So what's new? It's not new. It's DFM/CE and how it easily is integrated into ISO's 4.4 requirement. If you really read and apply the key points, it already is. This integration is DFM/CE and continuous process improvement (CPI). ISO, unfortunately, is leaving it up to us to figure out. The following represents simple DFM/CE requirements (note how they track the key points. Note they were in use way before ISO's rudimentary introduction to the USA in 1987):
PRIMARY DFM/CE CHECK LISTS - PRODUCIBILITY ASSESSMENT
MORE COMPLETE, COMPETITIVE PROPOSALS
PRODUCTION PROBLEMS IDENTIFIED AND CORRECTED EARLY
DESIGN FOR OPTIMUM COST EFFECTIVE PRODUCTION
SUBCONTRACTOR CAPABILITIES AND DEFICIENCIES CLARIFIED WITH RESPECT TO CUSTOMER AND DESIGN REQUIREMENTS - AND THE REVERSE
PRODUCT QUALITY, RELIABILITY, AND MAINTAINABILITY IMPROVED
NEW TECHNOLOGIES NEEDED TO ACHIEVE DESIGN PRODUCIBILITY IDENTIFIED AND EXPLORED
PRODUCTS DELIVERED ON SCHEDULE WITHIN COST
MORE OPPORTUNITY FOR MORE PROFITABLE PRODUCTION
LOWER COST TO CUSTOMER
HIGHER CUSTOMER SATISFACTION
EXPERIENCED TEAM MEMBERS
RIGHT DECISIONS CONCERNING BID/NO BID
EXPERIENCE ON SIMILAR PROJECTS
MEANINGFUL PRODUCIBILITY ASSESSMENT DATA
AFTER CONTRACT - SAME TEAM TO EFFECT DESIGN FOR PRODUCIBILITY
DESIGN AND OTHER TEAM MEMBERS WORK TOGETHER
INTERACTION AND COMMUNICATION
- PRODUCIBILITY ENGINEERING
- DESIGN ENGINEERING
- SOFTWARE ENGINEERING
- MATERIALS MANAGEMENT
- SYSTEMS ENGINEERING
- QUALITY ASSURANCE AND INSPECTION
- TEST AND ANALYSIS
- OTHERS AS REQUIRED
PRODUCIBILITY ASSESSMENT TOOLS
- PRODUCIBILITY ASSESSMENT WORKSHEET AND/OR STATEMENT OF WORK (SOW)
- GOALS BASED ON SIMILAR PAST EFFORTS (DESIGN/PROCESS EVOLUTION)
- GOALS BASED ON DAY TO DAY WORK ON NEW EFFORTS (EVOLUTION, REVOLUTION, OR RAPID EVOLUTION BORDERING ON REVOLUTION)
GEOMETRIC DIMENSIONING AND TOLERANCING
NOTE: This is an important area not yet even thoughtfully considered in the PCB world. For the life of me, I cannot conceive why, as this elemental requirement is the concurrent engineering language most all other designs and products are considered and effected. PCB master drawings come closest using some of what is included herein.
- ANSI Y-14.5M
- EACH DIMENSION SHALL HAVE A TOLERANCE
- DIMENSIONS FOR SIZE, FORM, AND LOCATION OF FEATURES SHALL BE COMPLETE TO ASSURE NO MIS-UNDERSTANDING OF FEATURE CHARACTERISTICS
- EACH END PRODUCT DIMENSION SHALL BE SHOWN
- DIMENSIONS SHALL BE SELECTED AND ARRANGED TO SUIT THE FUNCTION AND MATING RELATIONSHIP OF A PART
- DIMENSIONS SHALL NOT BE SUBJECT TO MORE THAN ONE INTERPRETATION
- DRAWING SHALL DEFINE A PART WITHOUT SPECIFYING MANUFACTURING METHODS BUT SHALL CLEARLY INDICATE SPECIFIED PART REQUIREMENTS
CONCURRENT ENGINEERING TEAM WITH GD&T/DFM
- SAME TEAM AS FOR PA PREVIOUSLY INDICATED PLUS:
- TOOL AND GAGE DESIGN
- SAFETY AND REGULATORY MANAGEMENT
DESIGN LAYOUT METHODOLOGY FOR PRODUCT AND PROCESS SYSTEM DESIGN
- DETAILED ASSEMBLY LAYOUT
- IDENTIFICATION OF CRITICAL CHARACTERISTICS
- MECHANICAL SIMULATION
- DESIGN FOR ASSEMBLY
- DESIGN OF EXPERIMENTS
- PHYSICAL PROTOTYPING
DESIGN FOR ASSEMBLY
- KISS (keep it simple stupid)
- MINIMIZE PARTS
- OPTIMIZE PARTS HANDLING
- MINIMIZE WORK SURFACES
- ASSURE CLEAR VISIBILITY
- MINIMIZE FASTENER USE
- BOTTOM UP ASSEMBLY
- ASSURE PARTS IDENTIFICATION
- POSITIONING NESTS TO POSITION PARTS
- KNOW MANUFACTURING PROCESSES
- OPTIMIZE MANUFACTURING PROCESSES
- VISUALIZE DESIGN AFFECTS ON PROCESSES
- VISUALIZE PROCESS AFFECTS ON DESIGNS
INDIVIDUAL COMPONENT ANALYSIS
- SPECIFICATION OF DATUM REFERENCE FRAME (MINIMIZE - NOT MULTIPLE, BUT SINGLE WHEN POSSIBLE)
- GENERATION OF FIXTURE LAYOUT
- DETERMINATION OF GAGING AND INSPECTION REQUIREMENTS
- APPLICATION OF CONTROLS TO FIXTURE LAYOUT
- CREATION OF THE TOOLING PACKAGE
- ENGINEERING CHANGE CONSIDERATIONS
- TAYLORS PRINCIPLE
- TOOLING AND GAGE DESIGN MUST INCORPORATE TAYLORS PRINCIPLE (SIMULTANEOUS INSPECTION OF ALL INTERRELATED FEATURES ON THE COMPONENT - ANYTHING LESS CREATES MEANINGLESS INFORMATION CONCERNING ASSEMBLY OR FUNCTION)
- SINGLE DRF (datum reference frame)
- FUNCTIONAL GAGING AS MIMICKING MATING PART
NOTE: Discrete gage, as CMM, relies on statistical sampling techniques and mathematical algorithms not necessarily correct as it relies on single point probing of surfaces not always including all surface elements, nor does it duplicate multiple feature interrelationships for product function of assembly conditions, nor (without a gaging fixture) does it establish a components location based upon precedence of the datum features replicating the assembly condition - thus violating taylors principle.
GAGING POLICY NOT BASED ON CURRENT STANDARDS
SPC TO CONTROL PROCESSES, NOT TO SATISFY CUSTOMER DEMAND WHERE IT SERVES NO USEFUL PURPOSE
DESIGN FOR SERVICING
- REDUCES DIRECT PRODUCT COST
- IMPROVES RELIABILITY BY REDUCING POTENTIAL FOR FAILURE
- REDUCES ADMINISTRATIVE AND INVENTORY COSTS CONCERNING SPARES
I think you all recognize this stuff as text book. It is, and it should be clearly understood, implemented, and used in all we do as engineers. If done, we all benefit - from concept to customer acceptance. The most important thing is we all will do it right the first time, on time, every time, at an acceptable cost and profit.
I've worked in over 100 companies during the past 17 years as an "independent" consultant/contractor. I've seen DFM/CE, CPI, and TQM work about 30% of the time. It was a pleasure, but little challenge, working in those organizations. It was less a pleasure, of sorts, working in other places - but what a challenge often met with the strangest of resistance. You know the resistance types I mean. I have a list of objections to improvement (positive change) growing over 120 items. They all must be overcome, but how? In the following installments we'll work on the answers together (concurrently).
Again, OK! I invite comments early on in this column. I challenge you all to challenge not me but what can be. If you are management, challenge yourselves by seeking better results (improved quality) through more effective process management starting at the customer or design level moving throughout your entire operation. If you aren't, challenge management to ensure you have all the tools needed to manage processes instead of results as defect. This column will provide some of the justification you need. My goal, within a continuing column series, is to expand on all the above DFM/CE points and make them real for CPI - for us all.
Now you know what it is anyway and what are the basic tools required to make DFM/CE work. Next time, we'll begin breaking it down and show ways to apply it all. Enjoy and remember to just do it, but do it right, while avoiding or preventing fugarwe meetings by using clearly defined agendas based on the above.
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Current assignment: DFM/CE support at major CM