QFD Process and House of Quality

quality function deployment (QFD)

• approach to define VOC and translate it into service/product designs
• reslies of series of interlocking matrices
• result of QFD process is a House of Quality (HOQ) matrix
• at least one HOQ made in each phase of QFD

phases

product planning

customer spec turned into requirements

part deployment

requirements turned into parts requirements

process planning

process selected to meet part requirements

process control

process control, inspection and test methods developed

steps to create HOQ

1. collect VOC information/requirements
   • includes assigning priorites and ranking of competing products
2. develop list of technical requirements
   • indicate direction of improvement (i.e., target value or more, target or less or exactly target) for each requirement
   • includes filiing interrelationship matrix using numeric scale (e.g., 5:3:1)
3. measure technical values of competing products
4. calculate priority of each tech requiremet
   • priority calculated as sum(priority*interrelationship)
5. populate correlation matrix
6. analyze matrix to identify target values for requirements

HOQ/QFD Matrix

components of HOQ diagram

1. customer requirements
   • derived from customer statements
2. customer importance
   • numeric rating of customer's priority for each requirement
3. technical requirements
   • measurable specification defined by manufacturing company/project team
   • define how customer's requirements will be met
4. interrelationship matrix
   • design team's perception of relationship between customer requirements and technical requirements
   • usually rated as weak, medium, or strong
5. technical priorities
   • usually rated 1-5
   • details priorities, measure of competing product performance and difficulty developing technical requirement
6. technical correlation matrix
   • relationship between technical requirements
   • usually classified as positive, negative, strong positive, or strong negative

visual cues to validity of matrix construction in interrelationship matrix

• blank column
  unnecessary technical requirement
• blank row
  unaddressed customer requirement
• two identically weighted rows
  requirements are the same, consider combining
• strong diagonal pattern
  indicates each technical requirement fits one customer requirement
• complete row or complete column
  strongly bound requirement, needs to be closely monitored for cost and compliance