Shanghai Jiao Tong University 1 Quality Function Deployment ME 250: Design & Manufacturing I School of Mechanical Engineering

Shanghai Jiao Tong University 2 Outline Objectives of QFD QFD Structure The General Process of QFD Project Plan Gantt Charts

Shanghai Jiao Tong University 3 QFD (Quality Function Deployment) QFD originated in 1972 at Mitsubishi’s Kobe shipyard site. The “house of quality” is the basic design tool of the management approach. The “house of quality” is a kind of conceptual map that provides the means for interfunctional planning and communications.

Shanghai Jiao Tong University 4 Quality Function Deployment “Let the customer be heard” QFD is a tool to help understand the design problem and to translate customer requirements into a technical description of what needs to be designed. QFD focuses and coordinates skills within an organization, first to design, then to manufacture and market goods.

Shanghai Jiao Tong University 5 Effect of using QFD

Shanghai Jiao Tong University 6 Objectives of QFD Identify exactly what the design goals are and how they are going to be achieved I.e., translate “customer requirements” into workable “engineering solutions” Forces “fresh eyes” on the design problem; prevents getting stuck prematurely with preconceived concepts Reduces risks of delay in new product introduction due to poor specifications, unrecognized interdependencies of specifications, etc… Provides formal record of conceptual design process for documentary, legal, management, benchmarking, etc.

Shanghai Jiao Tong University 7 CAs and ECs Customer Attributes(CAs) : Customers use to describe products and product characteristics. What do customers want? Engineering Characteristics(ECs): Engineers use to describe the products. How can we change the product?

Shanghai Jiao Tong University 8 The General Process Customer requirements Part characteristics Manufacturing operations Production requirements Design requirements

Shanghai Jiao Tong University 9 Building the House For a car door Customer Attributes(CAs) Good operation and use Good appearance

Shanghai Jiao Tong University 10 Customer Attributes(CAs) Good operation and use Easy to open and close door Isolation Arm rest …… Good appearance Clean Fit ……

Shanghai Jiao Tong University 11 Customer Attributes(CAs) Easy to open and close door Easy to close from outside Stays open on a hill Easy to open from inside …… Isolation Doesn’t leak in rain No (or little) road noise ……

Shanghai Jiao Tong University 12 Customer Attributes (CAs) Two problems Which CAs are important? What does the customer really mean? quiet easy

Shanghai Jiao Tong University 13 QFD Structure 6. Cross correlate specifications 5. Correlation matrix for requirements & specifications 4. Engineering specifications 7. Specification targets 2. Weights for requirements 1. Customer requirements3. Benchmark evaluations

Shanghai Jiao Tong University 14 Steps of QFD 0. Identify the customers. 1. Determine the customer requirements 2. Determine Requirement Weights 3. Benchmark the competition 4. Convert requirements to quantifiable eng. specs. 5. Correlate customer requirements to eng. specs. 6. Cross-correlate engineering specifications 7. Set the engineering targets with units.

Shanghai Jiao Tong University 15 Step 0: Identify the Customers Every design must serve a practical need of one or more end-users or “customers”. There may be several levels of customers/stakeholders with very different interests. It is the desire of the customer that drives the development of the product, NOT the engineer’s vision of what the customer should want. Some questions to be asking: What is the target market for the product? Who is the consumer for the product? Who will buy the product (and tell other consumers about the product and its quality)? Who are the stakeholders in the product? What roles will management, SPONSORS, manufacturing personnel, sales staff, service personnel hold? Are they also customers?

Shanghai Jiao Tong University 16 Step 1: Determine Customer Requirements These requirements commonly expressed in qualitative” terms and are determined by consultation in some form with the customer (Market surveys, focus sessions, customer feedback, etc). Types of Requirements: Functional Performance Spatial Appearance/Aesthetic Time Cost Manufacturing/Assembly Safety Environment and Environmental

Shanghai Jiao Tong University 17 Where to Gather Data Interviewing Customers or Focus Groups. Observing the product in use. Surveying customers. Searching patent and other information sources and benchmarking the competition.

Shanghai Jiao Tong University 18 How to Gather Data Be receptive; avoid confrontations. Express what the product has to do, not in terms of how it might do it. Set targets ( the machine must weigh no more than 10 lbs). Set value curves or slopes. Express the need as an attribute of the product. Prepare interview guide to structure dialogue such that all info. is gained. Avoid the words must and should ( We will rank importance later). Go with the flow. Use visual stimuli and props. Suppress preconceived hypotheses about the product technology. Have customer demonstrate product and/or task related to the product. Be alert for surprises and the expression of latent needs and follow up. Watch for nonverbal information.

Shanghai Jiao Tong University 19 QFD Structure 6. Cross correlate specifications 5. Correlation matrix for requirements & specifications 4. Engineering specifications 7. Specification targets 2. Weights for requirements 1. Customer requirements3. Benchmark evaluations

Shanghai Jiao Tong University 20 Customer Requirements

Shanghai Jiao Tong University 21 Step 2: Determine Weights for Requirements Different customers have different priorities! Identify the customers. Identify all the requirements that are "absolute must". In the weighting column of the QFD indicate these requirements with a value. All the remaining requirements are considered “wants” The goal is to have as many wants as possible, but we can’t have everything we want!

Shanghai Jiao Tong University 22 Example of Establishing Weights 1.Make a chart with all of the requirements. 2.Compare two requirements at a time. Give the more important requirement a 1 and the less important requirement a 0. 3.Compare all requirements. 4.Sum totals for each requirement. 5.Divide totals for each requirement by number of combinations resulting in a percentage. This is the weight of the requirement. 6.Enter weight of requirement into QFD chart.

Shanghai Jiao Tong University 23 Proposed Ranking System (Ulrich, 1995)

Shanghai Jiao Tong University 24 QFD Structure 6. Cross correlate specifications 5. Correlation matrix for requirements & specifications 4. Engineering specifications 7. Specification targets 2. Weights for requirements 1. Customer requirements3. Benchmark evaluations

Shanghai Jiao Tong University 25 Weight

Shanghai Jiao Tong University 26 Step 3: Benchmark Competition How well do any existing competitive designs serve customer needs & how can they be improved upon? Identify one or more “benchmark” designs that serve identical or similar customer requirements. Evaluate against each requirement (customer and engineering) as follows (rather subjective): 1 = doesn’t satisfy requirement at all 2 = satisfies requirement “slightly” 3 = satisfies requirement “somewhat” 4 = satisfies requirement “mostly” 5 = satisfies requirement perfectly Identifies area for improving current on practice; best suited to establish mass-market products

Shanghai Jiao Tong University 27 QFD Structure 6. Cross correlate specifications 5. Correlation matrix for requirements & specifications 4. Engineering specifications 7. Specification targets 2. Weights for requirements 1. Customer requirements3. Benchmark evaluations

Shanghai Jiao Tong University 28 Custom perceptions Our car A’s car B’s car competition Benchmark Competition

Shanghai Jiao Tong University 29 Step 4: Engineering Specifications Market survey: what to do? Engineering: how to do it? We need to describe the product in the language of the engineer. Easy to close from outside CA Energy to close door EC “-” Hope to reduce the energy required

Shanghai Jiao Tong University 30 Step 4: Engineering Specifications Quantifiable parameters that design engineer may specify/control to address the customer needs. Every specification must have appropriate units If you can’t quantify a specification (find appropriate units) it’s not a valid parameter and you’ll have to rethink it. Example -- customer requirement quantifiable parameters: average life to failure (years); fraction that survive > 10 years (%); max. drop onto hard floor without breaking (ft); failure load (lb)….

Shanghai Jiao Tong University 31 Step 4: Engineering Specifications One or more engineering specifications addressing each of the customer requirements will be needed (the more, the better) -- if you can’t find them, try re- formulating the customer requirement. If a EC affects no CA, it may be redundant to the EC list on the house. Any EC may affect more than one CA. Door seal resistance ECEasy to close from outside Doesn’t leak in rain No road noise CA

Shanghai Jiao Tong University 32 QFD Structure 6. Cross correlate specifications 5. Correlation matrix for requirements & specifications 4. Engineering specifications 7. Specification targets 2. Weights for requirements 1. Customer requirements3. Benchmark evaluations

Shanghai Jiao Tong University 33 EC

Shanghai Jiao Tong University 34 Step 5: Correlate Customer Req. and Engineering Specifications How much does each engineering specification influence the customer requirements? Make a systematic pairwise comparison of the specifications & requirements; enter correlation value for each pair as follows: 9 = strongly related 3 = somewhat related 1 = weakly related = totally unrelated

Shanghai Jiao Tong University 35 QFD Structure 6. Cross correlate specifications 5. Correlation matrix for requirements & specifications 4. Engineering specifications 7. Specification targets 2. Weights for requirements 1. Customer requirements3. Benchmark evaluations

Shanghai Jiao Tong University 36 EC

Shanghai Jiao Tong University 37 Importance Weighting Importance Weighting identifies which technical requirements are most important to achieve. In this chart, each weighting is calculated by multiplying the “importance to customer” rating times the value, assigned to a relationship totalling the column.

Shanghai Jiao Tong University 38 EC

Shanghai Jiao Tong University 39 Step 6: Cross Correlate Specifications The chosen engineering specifications are not always independent of each other -- we need to express the fact that changing any one can influence the others. Use diagonally-oriented cross-correlation matrix in QFD area 6 (the “roof” of the “house of quality”) to express interdependencies of the specifications. If you can’t do diagonally-oriented arrays, use a separate square array with both axes labeled with the specifications -- fill out the upper-left triangular matrix. Use blank system for correlation strengths. The cross-correlation matrix helps reveal indirect dependencies of requirements upon specifications.

Shanghai Jiao Tong University 40 QFD Structure 6. Cross correlate specifications 5. Correlation matrix for requirements & specifications 4. Engineering specifications 7. Specification targets 2. Weights for requirements 1. Customer requirements3. Benchmark evaluations

Shanghai Jiao Tong University 41 EC x x 9 x

Shanghai Jiao Tong University 42 Step 7: Set Engineering Targets List benchmarks enter their performance for each of the specifications -- this may require some “reverse engineering” Set targets for each specification, taking account of customer requirements and benchmark values -- the target may be: Specific value Range of values Lower/upper bound Lesser/greater is better Targets should be reasonable -- they can’t defy laws of physics, materials properties, economic constraints, etc., If competing state-of-the-art design exist, ask yourself how to achieve better targets than them -- be realistic!

Shanghai Jiao Tong University 43 QFD Structure 6. Cross correlate specifications 5. Correlation matrix for requirements & specifications 4. Engineering specifications 7. Specification targets 2. Weights for requirements 1. Customer requirements3. Benchmark evaluations

Shanghai Jiao Tong University 44 EC x9 9 9 x 9 x

Shanghai Jiao Tong University 45 Approach to QFD

Shanghai Jiao Tong University 46 Example: Bicycle Splashguard

Shanghai Jiao Tong University 47 Sample List of Customer Requirements Riders’ and shop mechanics’ requirements keeps water off rider easy to attach easy to detach quick to attach quick to detach won’t mar bicycle won’t catch water/mud/debris won’t rattle won’t wobble Company management requirements capital expenditure of less than $15,000 developed in three months; manufacturing cost less than $3 estimated volume of 200,000 per year for five years  won’t bend  has a long life  won’t wear out  lightweight  won’t rub on wheel  attractive  fits universally  won’t interfere with lights, rack, or brakes

Shanghai Jiao Tong University 48 QFD for Splashguard

Shanghai Jiao Tong University 49 QFD for Splashguard

Shanghai Jiao Tong University 50 QFD for Splashguard

Shanghai Jiao Tong University 51 QFD A: Customer Requirements B: Technical Requirements C: Importance to Customer D: Relationship Matrix A B C D

Shanghai Jiao Tong University 52 QFD E: Target Values F: Importance Weighting G: Correlation Matrix H: Competitive Evaluation F H G E

Shanghai Jiao Tong University 53 Four Steps to Establishing a Project Plan Step 1: Identify the tasks Step 2: State the objective for each task Step 3: Estimate the personnel needed and the time required to meet the objective. This will help define development costs. Step 4: Develop Sequence for the task.

Shanghai Jiao Tong University 54 Step 1: Identify the tasks The first step in planning a project is to list the tasks that make up the project. Uncertainty but still need to plan. Task list should contain 50 to 200 items. Each task on average should correspond to a day or two of work for an individual. Continually update plan as more information becomes available.

Shanghai Jiao Tong University 55 Step 2: State the objective for each task Each task must be characterized by a clearly stated objective. Make it: Easily understood. Specific Feasible Defined not as much as activities to be performed but as results to be achieved.

Shanghai Jiao Tong University 56 Step 3: Develop Sequence for the task 1. Schedule tasks 2. Determine correspondences between tasks 3. Determine critical paths 4. Reduce critical paths to accelerate project. Tools: Gantt Charts Pert Charts

Shanghai Jiao Tong University 57 Gantt Charts Useful tool for representing timing of task and level of task completeness Assign a row to a task and to milestones Order task in chronological order Attach a horizontal time line Draw a bar from start to end of each task. Continually track and update the Gantt chart

Shanghai Jiao Tong University 58 Gantt Chart Example

Shanghai Jiao Tong University 59 Step 4: Estimate the Personnel and Time Who on the design team will be responsible for meeting the objective or task What percentage of their time will be required. Over what period of time will be needed.

Shanghai Jiao Tong University 60 Summary 1. Always use QFD for mechanical design. 2. The customer's requirements must be translated into measurable design targets. You can't design a car door that is "easy to open" when you don't know the meaning of "easy". Is "easy" 20 N force or 40 N? 3. QFD can be applied to problems and sub-problems.

Shanghai Jiao Tong University 61 Summary 4. It is important to first worry about what needs to be designed and, only after that is fully understood, to worry about how the design will look and work.  Our cognitive capabilities generally lead us to try to assimilate the customer's functional requirements (what is to be designed) in terms of form (how it will look); these images then become our favored designs and we get locked onto them.  The QFD procedure helps to overcome this cognitive limitation.