Design of Experiment (DoE)

Design of Experiment (DoE) is a structured, organized method that is used to determine the relationship between the different factors (Xs) affecting a process and the output of that process (Y). This method was first developed in the 1920s and 1930, by Sir Ronald A. Fisher, the renowned mathematician and geneticist.

Design of Experiment involves designing a set of ten to twenty experiments, in which all relevant factors are varied systematically. When the results of these experiments are analyzed, they help to identify optimal conditions, the factors that most influence the results, and those that do not, as well as details such as the existence of interactions and synergies between factors.

DoE methods require well-structured data matrices. When applied to a well-structured matrix, analysis of variance delivers accurate results, even when the matrix that is analyzed is quite small. Today, Fisher's methods of design and analysis are international standards in business and applied science.

Experimental design is a strategy to gather empirical knowledge, i.e. knowledge based on the analysis of experimental data and not on theoretical models. It can be applied whenever you intend to investigate a phenomenon in order to gain understanding or improve performance.

Building a design means, carefully choosing a small number of experiments that are to be performed under controlled conditions. There are four interrelated steps in building a design:

   1.     Define an objective to the investigation, e.g. better understand or sort out important variables or find optimum.
   2.     Define the variables that will be controlled during the experiment (design variables), and their levels or ranges of variation.
   3.     Define the variables that will be measured to describe the outcome of the experimental runs (response variables), and examine their precision.
   4.     Among the available standard designs, choose the one that is compatible with the objective, number of design variables and precision of measurements, and has a reasonable cost.

Standard designs are well-known classes of experimental designs. They can be generated automatically as soon as you have decided on the objective, the number and nature of design variables, the nature of the responses and the number of experimental runs you can afford. Generating such a design will provide you with a list of all experiments you must perform, to gather enough information for your purposes.

Design of Experiments (DoE) is widely used in research and development, where a large proportion of the resources go towards solving optimization problems. The key to minimizing optimization costs is to conduct as few experiments as possible. DoE requires only a small set of experiments and thus helps to reduce costs

SPC

Statistical Process Control (SPC) can be applied to software development processes. A process has one or more outputs, as depicted in the figure below. These outputs, in turn, have measurable attributes. SPC is based on the idea that these attributes have two sources of variation: natural (also known as common) and assignable (also known as special) causes. If the observed variability of the attributes of a process is within the range of variability from natural causes, the process is said to be under statistical control. The practitioner of SPC tracks the variability of the process to be controlled. When that variability exceeds the range to be expected from natural causes, one then identifies and corrects assignable causes.

SPC is a powerful tool to optimize the amount of information needed for use in making management decisions. Statistical techniques provide an understanding of the business baselines, insights for process improvements, communication of value and results of processes, and active and visible involvement. SPC provides real time analysis to establish controllable process baselines; learn, set, and dynamically improve process capabilities; and focus business on areas needing improvement. SPC moves away from opinion-based decision making.

These benefits of SPC cannot be obtained immediately by all organizations. SPC requires defined processes and a discipline of following them. It requires a climate in which personnel are not punished when problems are detected, and strong management commitment.

SPC Concept

• All processes vary.
• The aim of SPC is to minimise variation.
• Variation is expressed in "sample standard deviations" (SD)
• SD is a mathematical term, based on probability theory.
• Consider the process of driving a car along a dry, straight, level road.
• Look at your hands on the steering wheel - they move as you make slight adjustments.

If you draw a graph of the movements you will have a "normal distribution curve"

In a normal distribution, most of the time your hands are in the middle

(In the secret language of SPC the "middle" is called the "average" or "mean" or "x-bar")

But sometimes your hands are a little to the left, at other times they're a little to the right

And on rare occasions they're on the extreme left or extreme right.


Taken from www.iso9001help.co.uk

SPC - statistical process control

What is SPC:

The method of SPC was discovered by Walter Shewhart during the 1920s

SPC is an informative inspection technique that uses control charts to determine when shifts or changes are likely to have occurred in a process.

• Makes no assumptions on performance
• Simple graphical representation of current process performance
• Helps to understand the potential of achieving targets
• Focuses on detecting and monitoring process improvement

Roadmap FMEA

Procedure of FMEA

The process to lead a FMEA is direct.
The basic steps are:

1. It describes producto/proceso and his function. An understanding of the product or the process under consideration is important to have articulated clearly. This understanding simplifies the process of the analysis helping to the engineer to identify those applications of producto/proceso that lower within the predicted function and that they lower outside.

2. It creates a block diagram of the product or proce it to it. A block diagram of producto/proceso must be developed. This diagram demonstrates to important components or passages of process like blocks connected together by the lines that they indicate how the components or the steps are related. The diagram demonstrates to the relations logics of components and establishes a structure around which the FMEA can be developed. Establish a system of the codification to identify elements of the system. The block diagram is due to always include with the FMEA form. The head in the worksheet of the FMEA form finishes: Producto/Sistema, Subsistema./Montaje, component, lead of the design, were prepared close, date, revision (letter or number), and date of the revision. Modify these titles according to the needed thing.

3. Use the prepared diagram above to begin articles or functions of the listing. If the articles are component, enumérelos of a logical way underneath their subsistema/asamblea based on the block diagram.

4. Identify The Ways De Fallo. A failure way is defined as the way in which a component, a subsystem, a system, a process, a etc. could potentially not be able to solve the attempt of calculation.

The examples of the potential ways of failure include: or electrical hydrogen Corrosion or Fragility or Short or opened or to Fatigue Of the Effort of torsion or Deformation or cracking themselves

1. A way of failure in a component can serve as the cause as a way of failure in another component. Each lack is due to enumerate in technical terms. The failure ways are due to enumerate for the function of each passage of the component or the process. To this point the failure way must be identified if or the lack is not probable to happen. To watch similar products or processes and the lack that have been documented for them is a to begin with excellent point.

2. Describe the effects of those ways of failure. For each way of identified failure the engineer must determine itself which will be the last effect. An effect of the lack is defined as result a way of failure in the function of producto/proceso according to the perceived thing by the client. They must be described in terms of which it could see the client or experience if it happens the way of identified failure. Remember internal as well as the external client. The examples of the effects of the lack include: or Injury to the user or Inoperabilidad of the product or the process or incorrect Aspect of the product or the process or Scents or degraded Operation or Noise Establish a numerical graduation for the severity of the effect. A standard scale of the common industry uses 1 not to represent no effect and 10 to indicate very severe with the lack that affects the operation and the security of system without the warning. The attempt of the graduation is to help the analyst to determine if a lack would be an annoyance of smaller importance or a catastrophic occurrence to the client. This allows the engineer to give the priority to the lack and to treat true great editions first.

1. Identify the causes for each way of failure. A cause of the lack is defined as weakness of the design that can give rise to a lack. The potential causes for each way of failure must be identified and to be documented. The causes are due to enumerate in technical terms and not in terms of symptoms.

The potential examples of causes include:
or the incorrect effort of torsion was applied
or to incorrect Conditions of operation
or erroneous Contamination
or Algorithms
or incorrect Alignment
or excessive Shipment
or excessive Voltage

1. Incorporate the factor of the probability. A numerical weight is due to assign to each cause that it indicates how that cause is probably (probability of the cause that happens). A standard scale of the common industry uses 1 to represent not probably and 10 to indicate inevitable.

2. Identify the present controls (design or process). The present controls (design or process) are the mechanisms that they avoid that it happens the cause of the failure way or that they detected the lack before they reach to client. The engineer must now identify techniques of the test, the analysis, the supervision, and other that can or be used in such or productos/procesos similars to detect lack. Each one of these controls to determine how this, is hoped that it identifies or detects failure ways. After a new product or a process has been in the previously unnoticed use or the identified ways of failure cannot appear. The FMEA must then be updated and formulated plans to try those lack to eliminate them of producto/proceso.

3. Determine the probability of the detection. The detection is a burden of the probability that the present controls (design and process) will detect the cause of the way of failure or the way of failure itself, thus avoiding that reaches to the client. In agreement with the present controls, it considers the probability of the detection using the following table for the direction.

4, Risk Priority Numbers (RPN). The RPN is a mathematical product of the numerical degrees of severity, the probability and the detection. RPN = (Severity) x (Probability) x (Detection). The RPN is used to give to priority to articles the planning or the additional action of the quality.

5. Determine Recommended Actions (It determines Recommended Action(s)) to treat the potential lack that a high RPN has. These actions could include: Specific procedures of the inspection, the test or the quality; selection of diverse components or materials; reducing the normal capacity; limitation of environmental stresses or the rank of operation; readjustment of the article to avoid the failure way; supervision of mechanisms; execution of preventive maintenance; and inclusion of the systems or the redundancy of spare part.

6. Assign to the responsibility and a date of the completion in target for these actions. This makes responsabilidaad net and facilitates the pursuit.

7. Indicate the taken actions. After these actions have been taken, it again values severity, the probability and the detection and reviews the reviewed RPN. Any other action

8. is required more Ponga to the day the FMEA as the changes in the design or process, the changes of the burden or the new information

Synchronization of FMEA

The FMEA is an alive document. Through development cycle of the product, change and the updates that become in the product and process. These changes often can and introduce new ways of failure. It is therefore important to review and/or to bring up to date the FMEA when:

• A new product or a process is beginning (at the beginning of the cycle).
• The changes are made to the conditions of operation of the product or it hopes that the process works inside.
• A change is made to the product or design of the process. The product and the process are correlated. When the product design changes is affected the process and vice versa.
• The new regulations are instituted.
• The regeneration of client indicates problems in the product or the process

Benefits of FMEA

FMEA is designed to assist the engineer improve the quality and reliability of design. Properly used the FMEA provides the engineer several benefits. Among others, these benefits include:

* Improve product/process reliability and quality
* Increase customer satisfaction
* Early identification and elimination of potential product/process failure modes
* Prioritize product/process deficiencies
* Capture engineering/organization knowledge
* Emphasizes problem prevention
* Documents risk and actions taken to reduce risk
* Provide focus for improved testing and development
* Minimizes late changes and associated cost
* Catalyst for teamwork and idea exchange between functions

Use of FMEA

Historically, the engineers have done a good work of evaluating the functions and the form of products and of processes in the phase of the design. They have not always done so well in designing in reliability and quality.

The engineer uses safety factors as way of making sure that the design will work and it protected often user against product or absence in the process.According to the described in a recent article:

"a great factor of safety does not translate necessarily to a reliable product. In place, it often leads to redesigned the product with problems of the trustworthiness."

FMEA provides to the engineer a tool that can attend the reliable supplying, safe, the pleasant products and the processes of the client.

Since the FMEA aid the engineer identifies the potential product or lack of process, they can use it:
* They develop the product or the process requisites that limit to the minimum the probability of these absences.
* Evaluate the obtained requisites of the client or of other participants in the process of the design to make sure that these requisites do not introduce potential absences.
* They identify the characteristics of the design that they contribute to the absences and design them out of the system or limit to the minimum at least the effects that prove.
* They develop the methods and the procedures to develop and to prove the product / process to make sure that the absences have been eliminated successfully.
* He continues and handles the potential risks in the design. To continue the risks contributes to the development of the corporate memory and of the success of the future products also.
* Make sure that any absence that might happen should not damage or affects seriously client of the product / process.

Types of FMEA

There are several types of FMEA, something is used much more often that others. FMEA must be always done whenever the lack meant damage or potential injury to the user of the article of the end that is designed.

The types of FMEA are:
* System - centers in global functions of the system
* Design - centers in components and subsystems
* Process - centers in processes of the manufacture and assemblies
* Service - centers in functions of the service
* Software - centers in functions of software

Failure Mode and Effect Analysis (FMEA)

The clients are bringing increasing suits in the companies for the high quality, reliable products. The capacities and the functionality of increase of many products are making more difficult so that the manufacturers maintain the quality and the trustworthiness. Traditionally, the trustworthiness has been reached with the extensive test and the use of techniques such as to model probabilistic of the trustworthiness. These technical are done in the last stages of the development. The challenge is to design in quality and early trustworthiness in the development cycle. The analysis of the ways and the effects of failure (FMEA) is methodology to analyze potential problems of the early trustworthiness in the development cycle where it is easier to take actions to surpass these editions, of such way heightening trustworthiness with design. FMEA is used to identify potential ways of failure, to determine their effect on the operation of the product, and to identify actions to attenuate the lack. A crucial step is anticipating what could go badly with a product. Whereas to anticipate each way of failure it is not possible, the equipment of the development must formulate so extensive a list of the potential ways of failure as it is possible. The early and constant use of FMEA in the process of the design allows that the engineer designs outside lack and produces reliable, safe pleasant products, and of the client. FMEA also captures the historical information for the use in the future improvement of the product.

Process Flow

Definition:
Visual representation of all steps and decision points in process
Purpose:
1.Evaluate process performance
2.Determine process bottle neck
3.Identify non-added value activities which should be deleted or modify
4.Identify new process steps to be added to improve overall performance
5.To breakdown big problem into smaller problem which can be handled easier

Pareto Chart

. By Kerri Simon
Vilfredo Pareto was an economist who is credited with establishing what is now
widely known as the Pareto Principle or 80/20 rule. When he discovered the principle,
it established that 80% of the land in Italy was owned by 20% of the population.
Later, he discovered that the pareto principle was valid in other parts of his life,
such as gardening: 80% of his garden peas were produced by 20% of the peapods.
Some Sample 80/20 Rule Applications
•80% of process defects arise from 20% of the process issues.
•20% of your sales force produces 80% of your company revenues.
•80% of delays in schedule arise from 20% of the possible causes of the delays.
•80% of customer complaints arise from 20% of your products or services

A pareto chart is used to graphically summarize and display
the relative importance of the differences between groups of data.

About 80% of the problems are
from 20% of the causes
differences between groups of data.