What is Quality by Design (QbD)?
Quality by Design (QbD) is a structured process for designing and launching new products. Products include goods, services, information, or internal processes. A high-quality product meets specific customer needs so effectively that they will buy or use more of the product in preference to other sources for meeting the need.
Why We Need QbD
Traditional new product introduction or process design usually suffers from a number of gaps, including:
- A gap between what the producer thinks the customer needs and what the customer really needs
- A gap between what the producer thinks the customer needs and what is actually designed
- A gap between the design and the actual production or execution.
Quality by Design applies proven methods to close these gaps. Because of these gaps, traditional design work is usually plagued by a number of problems, including:
- Cost and time overruns
- Failures to reach sales and profit targets
- Dissatisfied customers
- Even abandonment of the effort
The QbD Approach
QbD methods have been shown to prevent most of these failures. QbD is a companion to traditional quality improvement such as Lean and Six Sigma. It incorporates many of the same principles and tools, but its focus is delivering a new product (good, service, information, or process) that meets customer needs without defect from the moment of launch. While Lean and Six Sigma focus on correcting the flaws that were designed into an existing product, QbD is preemptive. It anticipates and prevents flaws that might require later improvement, and it builds quality into the product such that customer loyalty is enhanced.
QbD is applied in a team framework. The team includes subject matter experts from all disciplines required to design and deliver the intended product. Traditional product development tends to proceed in sequential fashion with multiple handoffs from one set of specialists to another. The lessons of QbD are that all disciplines must be integral to the effort from the beginning applying a strategy that has been called concurrent engineering. While there is still a definite need for precedence and linearity in much of the design process, concurrent work by multiple specialties ensures both better designs and more timely delivery.
The QbD Process
QbD is organized into five major activities, with multiple steps in each. As we have just noted, the design process has definite elements of linearity, but the specific tools applied ensureensure and facilitate collegial work in parallel. The five major activities are:
The first step is to describe in general terms what the product is and what set of customers it is intended to serve. There may be multiple different target customers. The project charter includes not only this description of the product and target customers, but also the specific measured goals for the product. The specific goals adopted will depend on the product and its role in the enterprise strategy. These goals usually include:
- Market share
- Price point
- Lead times
- Launch date
- Performance in terms of quality, cost, cycle time, or the like
- Customer loyalty
QbD requires the discipline to discover the exact needs of the customer – expressed in terms of the benefit that the customer is seeking. The needs must be specific and measurable so that we can design to them and measure our success in meeting them.
There are usually multiple customers – both internal and external – and some of them are hidden from our usual view of the business.
QbD incorporates robust science into the measurement and analysis of needs. In some cases this will be rather straightforward, but many cases will require the application of advanced survey and statistical techniques.
At this point, the project begins the completion of a series of planning worksheets that directly tie:
- Customer to …
- Customer need to …
- Functional feature and goals to …
- Detailed design features and goals to …
- Process features and goals to …
- Control features and goals.
This systematic structure ensures that we meet all-important customer needs and that every feature in the design, production, and control of the delivery has a useful role and can be related unambiguously to the customers’ needs.
Once we know what the customer needs, we must design the product that will meet those needs better than competitors’ and preceding products. Design, of course, encourages creativity and insight to meet needs in new and exciting ways that will appeal to the customer.
While it may seem contradictory to insist on structure to achieve creativity, that is exactly what is required. The proper structure encourages creativity and provides a safety net that allows the team to push the limits of creative ideas without running unnecessary risks.
QbD encourages multiple approaches to designing, including:
- Creative thinking techniques
- Competitive assessment
- Multiple alternative evaluation
The designs are solidly tied to reality through the application of …
- Market competitive analysis
- Deconstruction competitive analysis
- Salability analysis
- Multiple tools to assess failure modes and probability of failure
- Explicit trade-off analysis
- Design reviews at several stages
- Advanced techniques when needed, such as design of experiments, including non-linear response surfaces
- Value analysis to ensure that every dollar spent brings a return on the investment
Once the product is designed then the designers turn to the equally important job of developing the process for delivery. Process design is strongly rooted in a full understanding of the effects of variability and the need to measure and optimize process capability.
Finally, no design is complete without a rigorous control plan that will assure that the process will continue to run free of defects indefinitely.
The job is not done until the product is in production, meeting all the goals set out in the charter, and delighting the customers. Effective delivery relies on strong planning from transfer to operations, a scale-up strategy, and validation of the transfer.