QFD

QFD

1. IDENTIFY AND EVALUATE THE COMPETITION

   • how the customer perceives the competition’s ability to meet each of the requirements
     • For each customer’s requirement, we rate the existing design on a scale of 1 to 5
       • shows opportunities for product improvement. If all the competition rank low on one requirement, this is clearly an opportunity.
       • . If one of the competitors meets the requirement completely, this product should be studied and good ideas used from it
       • If your organization already makes a product and you are redesigning this product, then the current product is one benchmark. If it ranks high on an important requirement, don’t change the features that helped it meet that requirement
   • studying existing products is twofold: first, it creates an awareness of what already exists (the “now”), and second, it reveals opportunities to improve on what already exists

2. GENERATE ENGINEERING SPECIFICATIONS

   • Develop a set of engineering specificationsfrom the customers’ requirements. These specifications are the restatement of the design problem in terms of parameters that can be measured and have target values.
     • Parameters of interest and targets for parameters
     • They serve as a vision of the ideal product and are used as criteria for design decisions
     • We begin by finding as many engineering parameters as possible that indicate a level of achievement for customers’ requirements
       • step count, time, part count, and tool count
         • Each engineering parameter must be measurable and thus must have units of measure
   • Carefully check each entry to see what nouns or noun phrases have been used. Each noun refers to an object that is part of the product
     • Paying attention to the objects that are part of the product is a major topic in concept generation
   • Types of engineering specifications
     • Functional performance requirements
       • Are those elements of the performance that describe the product’s desired behavior
     • Human factors requirement
       • Any product that is seen, touched, heard, tasted, smelled, or controlled by a human
     • Physical requirements include needed physical properties and spatial restrictions
       • Weight; density; and conductivity of light, heat, or electricity
       • Spatial constraints relate how the product fits with other, existing objects
     • Reliability
       • Mean time between failures.
     • life cycle
       • It is important for the design team to ensure that requirements imposed by environmental concerns have been identified
     • manufacturing/assembly requirements
       • the quantity of the design to be produced and the characteristics of the company producing it.
   • If the sense (↑ or ↓) is not obvious, then the specification is not clear.

3. RELATE CUSTOMERS’ REQUIREMENTS TO ENGINEERING SPECIFICATIONS

   • This relationship matrix is completed in parallel to "Identify and evaluate the competition"
     • Each cell of the form represents how an engineering specification
     • can vary, with some engineering specifications, providing strong measures for a customer’s requirement and others providing no measure at all
     • The relation is conveyed through specific symbols or numbers:

4. SET ENGINEERING SPECIFICATION TARGETS AND IMPORTANCE

   • Here we set the targets and establish how important it is to meet each of them
     • Specification Importance
       • determining the importance for each specification
         • The method to find importance
           • Multiply the importance weightin, with the relationship values
           • Sum the weighted values for each specification
           • Normalize these sums across all specifications.
     • Measuring How Well the Competition Meets the Specifications
       • They will be measured relative to engineering specifications; , the values obtained by measuring the competition give a basis for establishing the targets.
     • Setting Specification Targets
       • Setting targets early in the design process is important; targets set near the end of the process are easy to meet but have no meaning as they always match what has been designed.
       • For those targets that have flexibility, a more robust method for setting targets is to establish the levels at which the customers will be delighted and those where they will be disgusted
       • as a design engineer you often have to trade off one specification against another

5. IDENTIFY RELATIONSHIPS BETWEEN ENGINEERING SPECIFICATIONS

   • Engineering specifications may be dependent on each other. It is best to realize these dependencies early in the design process.
     • the roof is added to show that as you work to meet one specification, you may be having a positive or negative affect on others.
   • sometimes when you improve one thing, you either improve or hurt something else. These relationships give guidance about trade-offs
   • If the roof has many of the cells full, then the specifications are too dependent
   • If the relationship is not clear, then at least one of the specifications is not clear

6. FURTHER COMMENTS ON QFD

   • it is useful with all types of design problems and results in a clear set of customers’ requirements and associated engineering measures
   • it forces such in-depth thinking about the problem that many good design solutions develop from it.
   • This is one situation when a design notebook is important. Ideas recorded as brief notes or sketches during the problem understanding phase may be useful later