Both DFMEA and PFMEA have similar principles and follow identical steps. Both involve identifying potential failures, their impact, and corrective measures to be taken for reducing or eliminating these potential failures.
However, DFMEA and PFMEA differ in a few aspects, such as their focus and the stage in which these two analyses are done.
DFMEA focuses on potential failures related to product design changes. The main focus is on finding potential failures that can result in malfunctions and safety hazards while using the product. It is also applied to identify potential causes that may curtail the life of the product. It must be conducted throughout the entire design process, starting at the preliminary design as soon as the design concept has been selected to the production.
PFMEA focus on potential failures associated with processes and changes to them. The main focus is on finding potential failures related to a process that can affect the quality of a product or cause safety or environmental hazards and result in customer dissatisfaction. It is also applied to identify potential causes that reduce the reliability of the process.
QFD offers several benefits to organizations.
The voice of the customer (VOC) is gathered and converted into technical requirements in this phase. A business case is then established and a project charter is prepared along with milestones. A team is also formed to carry out the project. Roles and responsibilities of the team members are also set during this phase. These activities are accomplished using tools such as Quality Function Deployment (QFD); Failure Modes and Effects Analysis (FMEA); the Suppliers, Inputs, Process, Outputs, and Customers (SIPOC) diagram; the Integrated Product Delivery System (IDPS); target costing; and benchmarking.
In this phase, the concept design is developed by formulating alternative concepts and choosing the best concept after evaluating the alternatives. Risks associated with the chosen concept design are also determined. The functional requirements and their Critical to Quality (CTQ) attributes are identified by the Six Sigma team. The CTQ attributes are deployed after assessing their effect on functional requirements. Raw materials and their procurement plan with the related manufacturing plan are created during this phase. In addition, the Sigma capability is predicted. These activities are accomplished using tools such as smart simple design, risk assessment, FMEA, engineering analysis, materials selection software, simulation, DOE, systems engineering, and the capability of the process is evaluated to verify if the CTQs can be met.
The design is optimized for reliability and performance by developing detailed design elements. This helps optimize the Sigma capability and cost. These activities are accomplished through manufacturing database and flowback tools, a design for manufacturability, process capability models, a robust design, Monte Carlo methods, tolerancing, and Six Sigma tools.
The prototype is tested using formal tools to validate the design. After evaluating the performance, failure modes, and risks of the design, new requirements to be met are sent to manufacturing and sourcing units. The design is iterated until it meets the requirements of the customer. A final phase review to assess the reliability is also carried out to validate the design. The term Verify is also used interchangeably for this phase. These activities are accomplished through accelerated testing, reliability engineering, FMEA, and disciplined New Product Introduction (NPI).