Design for Excellence Assignment Sample

Introduction to Design for Excellence

Design for Excellence also called DFX is a systematic process for process and product engineering that is applied for product or process designing taking into consideration the entity ‘X’. Here ‘X’ represents some attribute or characteristic feature of the process or product under development.

In real world, DFX can be defined as Design for ‘x’ where ‘x’ can be used interchangeably for multiple terms depending on the desired goals and objective of the project. Some of the mostly used alternatives for x are: DfS or Design for Serviceability, DfR or Design for Reliability, DfM or Design for manufacturability, DfC or design for Cost, DfL or Design for logistics, DfA or Design for Assembly.

Design for X varies depending on the priorities of the attributes and degrees of focusing on the attainment of objectives. To become successful and prevail in continuously changing market conditions, the companies should meet the expectations of the customers and their needs. These needs are taken into consideration for the process or product design.

In this report, we will discuss about Design for Reliability or DfR. Design for Reliability is a process that give assurance that certain product or process will perform a specific function effectively and efficiently for a certain predefined period.

Design for Reliability (DFR) is certainly not new concept, yet it has started to get a lot of consideration these days. What is DFR? What are the elements for structuring for dependability, and what is associated with executing DFR? Ought to DFR be a piece of a Design for Six Sigma (DFSS) program, and is DFR equivalent to DFSS? Right now, will attempt to respond to these questions and, simultaneously, we will propose a general DFR process that can be received and conveyed with a couple of adjustments across various enterprises such that will fit well into the general Product Development Process. The Synthesis applications can be utilized together dependent on the DFR approach.

Design for Reliability (DfR)

Design for reliability or DfR ensures that products and systems perform a specified function within a given environment for an expected lifecycle.

Technically, Design for Reliability is a process that provides an assurance that certain product or process will perform a specific function effectively and efficiently for a certain predefined period. Design for Reliability or DfR is an important stage in the system design and development process that has a huge impact on the success of the process or product and its overall efficiency.

Design for Reliability is performed before developing the physical prototype, at the designing stage of the system development. It forms an integral part of the overall Design for Excellence or DfX process. One of the most important objectives to fulfil the operating requirements for a system is achieved from design for reliability (Blanchard, Fabrycky,1990).

Reliability

Reliability is important and needs to be considered at all levels, as evidenced by the Challenger disaster and its aftermath. It is defined as the probability of a system that it will operate satisfactorily and efficiently exactly as it is expected to, under predefined conditions for a specified time period.

One of the most important methods to measure reliability is to measure the failure rate. Failure rate of a system can be defined as the total number of failures encountered in a given operating time of the system. Technically,

Determination of Reliability

Determination of Reliability of a system is as much important as other steps in the designing phase of System development. Failure rate is an important factor in determining the reliability of a system. Understanding the failure rate of components of any system helps a lot to achieve this.

Reliability of any component of a system comes out to be very useful in the life cycle of system. It determines the probability of the component to operate perfectly as expected for a given period and after that I can fail anytime. Determining the reliability involves examination of different factors from different angles. Some are:

• Reliability determination of individual components
• Reliability determination of different combinations of different components
• Reliability determination of system as a whole.

In order to determine the probability of failure of a system component over a period of time, there is a need to understand the probability distribution function (PDF) . that a component will fail within a given time period requires knowledge of how the time to failure is distributed over time (the (pdf) and not just the failure rate.

Reliability Function

The reliability function is complementary to the cumulative distribution function. The cumulative distribution function determines the probability of failure of a component while the reliability function determines its probability of survival. Hence, with every increase of x, the value of cumulative distribution function increases, and the value of reliability function decreases.

Mathematically,

the reliability function is calculated as the integral of the probability density function from x to infinity.

In series networks, the failure of one component can lead to the failure of the whole system. To achieve this, all components must operate properly without any fault. For a system having serially connected components, the reliability of the system is calculated as:

R =R_x. R_y. R_z

where x,y,and z are the subsystems or the components of the system.

Parallel Networks

In parallel networks, failure of a component does not affect the operation of the whole system. For these systems, the reliability is calculated as:

R= 1-(1-R)ⁿ,

Where n is the number of components or sub systems.

Reliability Requirements in the System Life Cycle and Importance of Design for Reliability (DfR)

In a complex technological world, the significance of Design of Reliability can not be ignored. It has been more valuable and important than it was ever before. The reasons of why the Design for Reliability is so significant are:

Differentiation of product:

With the passing time, the products developed reach the maturity stage. In such cases, the traditional metrics like product performance and product price fail to differentiate the product from others in such a competitive world.

Assurance of Reliability:

The reliability assurance is one of the most important thing demanded while product development. The sophisticated circuits, high power requirements, robust and advanced components, and other complex technologies make the providence of reliability assurance very difficult.

Costs Controlling:

Approximately the seventy percent of the total budget passed for the product development is allocated to the product design phase.

Profit preserving:

The market share and sales erosion in todays’ competitive market is preserved by the introduction of developed product earlier and hence preserving the profit.

The Design for Reliability Process

Design for Reliability (DfR) has different key that form the base for the product or process design phase.

These six steps exist in whole product lifecycle ranging from conceptual design phase till the end of the product. Each stage of the process includes different focal sets and tools. Each step is described below:

1. Identify

The first step is the identification of objectives, goals, requirements, and specifications and expectations. This first stage provides the base for the remaining process. Understanding and documenting the customer expectations for reliability performance includes:

• Use case description
• Performance requirements
• Functional requirements
• Environmentaldescriptions
• Expectations of durability
• Expectations for Probability of Success

Tools include:

• System Reliability Modeling
• Risk AssessmentStudies
• Risk AssessmentStudies
• Quality Function Deployment(QFD)
• Environment and use studies
• Benchmarking

2. Design

This stage involves Creating a draft solution for the process of development.The decisions during the design and development stages involve:

• Software/Firmware development
• Electrical and Mechanical drawings
• Human factors design
• Industrial design
• Component selection
• Material selection

The choice bound the potential future dependability execution.

The DfR tools during this stage center around empowering every individual from the group to settle on choices which completely think about the effect of future unwavering quality execution.

Tools include:

• Design Review Based on Failure Modes
• Design Reviews
• Degradation Protection
• Overstress Protection
• Critical to Reliability/Quality list
• Non-material failure modes
• Reviews of part, material and process selections
• Hazard and Operability Studies
• Tolerance Analysis
• Stress-Strength Analysis, Derating Analysis
• Computational Fluid Dynamics (CFD) modeling
• Mechanical and Electrical performance modeling
• Finite Element Analysis (FEA)

3. Analyze

This stage involves the examining of the developed product. During the design procedure, there might be remarkable inquiries to address. A large number of the devices utilized during the design stage additionally give a way to refine understanding concerning unwavering quality. FEA, for instance, is a basic device for material science of disappointment displaying and use.

The focus is to explore, discover, and reveal the design weaknesses in order to allow design changes to improve the product robustness. Another part of this step is to check and refine the understanding of the customer environment and use conditions. As the design takes shape the team is likely to discover potential failure mechanisms that require additional environmental and use condition information.

An output of the analysis is a refinement of the areas of focus during the verify step. Areas of high risk or uncertainty may receive additional scrutiny.

4. Verify

This step checks whether the design is meeting the design specifications? The stage verifies that the developed solution is upto the specifications developed.

If all is well executed to this stage the design and analyze steps created and refined a product that meets the set of specifications created during the first step of the process.

A couple additional tools are:

• Measurement System Analysis
• Document/Configuration Control
• Waterfall test sequencing
• Sample Size Calculations
• FRACAS

5. Validate

This step checks whether the developed solution meets the expectations of customers. The intention of thei step is to validate that the product developed performs exactly as per the customer expectations.

The same basic set of tools used during verify may take part in the validate step, yet may focus on customer specified evaluations or production variation concerns. HALT, HASS, ALT, FRACAS, etc all may play a role.

Some customers may require or expect a reliability growth or demonstration testing as part of the validation step.

6. Control

The choices during this step center around provider and creation dependability and capacity. Besides, the data returning from client gives a way to distinguish potential plan or procedure improvement ventures. The work right now as the group sets up the stock and creation forms. It comes to fruition starting during the plan step and gets refined as information and data become accessible.

Tools such as SPC, control charts, and process capability studies focus on monitoring variation and adjusting or improving to reduce or maintain an acceptable amount of variation.

Tools may include:

• Call center data analysis
• Customer Surveys
• Maintainability analysis
• Testability analysis
• ORT
• HASS
• Failure analysis of field returns or production failures
• Process FMEA
• HASS
• ORT

DfR Methods

The iterative process of framing decisions, gathering information and checking assumptions and results permit the team to evolve the design to meet expectations. Some DfR methodologies are:

FMECA

Failure Modes, Effects and Criticality Analysis (FMECA) is a methodology specially developed for identifying the factors that could cause failure of a component or system. This methodology involves risk assessment, component ranking according to the risk assessment and identification of the possible solutions in case of a failure.

FMEA

Failure Mode and Effects Analysis (FMEA) methodology is also used to identify and investigate the potential weakness of a component or the system. It can be implemented in case of failure in a component whether it is hardware or software component.

FTA

Fault Tree Analysis (FTA) is the reverse of FMEA. It is a top down approach in which a conclusion is made at first and then attempts are made to determine the possible causes that lead to that conclusion. The whole process is represented by a logic diagram and is called the fault tree. The FTA is one of the most used methods in system reliability, maintainability and safety analysis.

Conclusion on Design for Excellence

In this report, we endeavored to give a general picture concerning what Design for Reliability is, and we proposed a procedure to follow for actualizing DFR.

Most organizations apply DfR at the structure and advancement phase of a given undertaking improvement cycle. Be that as it may, this basic practice comes past the point of no return in the improvement procedure. Effective DfR requires the coordination of item structure and procedure arranging into a strong, intelligent action known as simultaneous building. The basic process is to focus on understanding the customer reliability expectations well enough to enable the creation and production of products that meet or exceed those expectations. Identifying the right set of specifications enables the team to design, analyze and verify while making decisions that shape the reliability performance. The steps of design, analyze, and verify may occur sequentially or simultaneously (or nearly so).

DfR is not one tool or analysis, it is many.More importantly, DfR is focused on enabling everyone in the organization to make decisions that support the goal of meeting customer reliability expectations.

References for Design for Excellence

Blanchard, B.S., Fabrycky, W.J. and Fabrycky, W.J., 1990. Systems engineering and analysis(Vol. 4). Englewood Cliffs, NJ: Prentice Hall.

Crowe, D. and Feinberg, A. eds., 2017. Design for reliability. CRC press.

Eastman, C.M. ed., 2012. Design for X: concurrent engineering imperatives. Springer Science & Business Media.

Kapur, K.C. and Lamberson, L.R., 1977. Reliability in engineering design. Wayne State Univ., Detroit, MI (USA). Dept. of Industrial Engineering and Operations Research.

Kuo, T.C., Huang, S.H. and Zhang, H.C., 2001. Design for manufacture and design for ‘X’: concepts, applications, and perspectives. Computers & industrial engineering, 41(3), pp.241-260..

com. 2020. Reliability Function. [online] Available at: <http://www.engineeredsoftware.com/nasa/reliabil.htm>

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