Understanding the problem and the Development of

Engineering Specifications

Understanding the Problem

Surveys show that poor product definition is a factor in 80% of all time-to-market delays.

Sometimes a lot of time and money can be wasted solving the wrong problem.

Quality Function Deployment (QFD)

QFD is a popular product design technique.

QFD is organized to develop major pieces of information necessary to understanding the problem.

Using QFD, Toyota was able to reduce the costs of bringing a new car model to market by over 60% and to decrease the time required for its development by 33%.

Toyota achieved the above results while improving the quality of the product.

The House of Quality (HOQ)

Applying the QFD steps builds the house of quality.

HOQ is a house of many rooms, each containing valuable information.

QFD Steps

Step 1: Identify the customers: determine exactly WHO they are.

Customers can be internal or external to the company.

For many products, the most important customers are the consumers, the people who will buy the product and tell other consumers about its quality (or lack thereof).

Step 2: Determine the customers’ requirements: WHAT do the customers

want?

Typically, as customer surveys show, the consumers want a product that works as it should, lasts along time, is easy to maintain, looks attractive, and has many features.

Typically, the production customer wants a product that is easy to manufacture and assemble, uses available resources, uses standard parts and methods, uses existing facilities, and produces a minimum of scarps and rejected parts.

Typically, the marketing/sales customer wants a product that meets consumers’ requirements; is easy to package, store, and transport; is attractive; and is suitable for display.

Collection methods for customer requirements

Observations = observing customers using the existing product.

Surveys = questionnaires through e-mail, over the telephone, or in face to face interviews

Focus groups = a specially designed meeting with a carefully chosen group of 7 to 10 potential customers.

Step 3: Determine relative importance of the requirements: WHO versus WHAT

Relative importance can be evaluated by generating a weighting factor for each requirement.

Traditionally, the customers are asked to rate each requirement on a scale from 1 to 10.

A better method, the fixed sum method, is to tell each customer that they have 100 points to distribute among the requirements.

Step 5: Generate engineering specifications: HOW will the customers’ requirements be met?

Engineering specifications are the restatement of the design problem in terms of parameters that can be measured and have target values.

Parameters are developed in this step and the target values for these parameters are developed in step 8.

Step 6: Relate customers’ requirements to engineering specifications: HOW to measure WHAT?

This is the central part of HOQ.

Strong relationshipMedium

relationshipWeak relationshipBlank = no

relationship

Step 7: Set engineering targets: HOW MUCH is good enough?

Target values are used to evaluate the product’s ability to satisfy customers’ requirements.

Two actions:1. To ascertain how the

competitors (step 4) meets the engineering specifications, and

2. To establish the targets for the new product.

Step 8: Identify relationships between engineering requirements: How are the HOWs dependent on each other?

Engineering specifications may be dependent on each other. It is best to realize these dependences early in the design process.

Negative (-1) Strong negative (-3) Strong positive (9) Positive (3)

A Reduced HOQ Form

QFD can be applied at all phases

QFD Example

Propose a HOQ for the design of a steam iron.

Conclusions The QFD technique ensures that the

problem is well understood. The HOQ automatically documents and

records the evolution of the product design.

The HOQ is an excellent communication tool for the design team.

The QFD technique can be applied at any of the design phases.