Wednesday, February 12, 2020

What is Quality? | QSQTECH.COM


Quality

Hello friends, 
Today, We are going to study on quality concept.
First of all, we are very thankful to you that you are visiting this website.
Now,
Main topic is that,

QUALITY: 

INTRODUCTION: 
In today's era, competition in the field of business has increased a lot, due to which the focus is on quality in business sector. 
By the way, there can be a lot of quality definitions, some of the important definitions that we will talk about.

DEFINITION
Quality is meeting the requirements of customers which is not restricted to the functional characteristics of the product and services. 
Quality means different things to different people and in different situations. This list gives some informal definitions of quality:
  • Quality is not a program; It is an approach to business. 
  • Quality is a collection of powerful tools and concepts that are proven to work. 
  • Quality is defined by the customers through their satisfaction.
  • Quality involves continuous improvement and success events. 
  • Quality tools and techniques are applied in every aspect of the business. 
  • Quality increases customer satisfaction, reduces cycling time and cost. and eliminates errors and rework.
  • Quality isn't just for businesses. It works in non-profit organizations such as schools, health care and social services, and government agencies. 
The above definitions show that quality is difficult to define, and no definition can be all-inclusive. The word 'Quality' is highly subtle, and allows for many inter-prepositions. For example, a popular online dictionary defines quality as "an inherent or distinguishing characteristic" (http://dictionary.reference.com/search?q=quality); This definition is only the first of ten distinctly different definitions from the same authority. 

Quality: The totality of the features and characteristics of a product or service that depend on its ability to satisfy perceived or implied needs. Not to be mistaken for "degree of excellence" or "fitness for use" that meet only part of the definition. (ISO 8402)

Below points shows that this definition is actually quite interesting: 
  • It is published by ISO, an international standards organization. 
  • It specifically contradicts the definition that Joseph M. Juran used throughout his career, "Quality- fitness for use." 
  • In contrast, Philip Crosby used the definition, "quality conformance to specifications," which is also narrower than ISO 8402. 
In short, "Meeting the customer's requirements".
Sometimes, some people consider the quality and reliability to be the same. But it is different from the quality. It's definition is as follows,

Reliability: It is the ability of product and service to continue to meet the customer's  requirements. It describe the long term impact.
A quality product is one that meets the customer's requirement and if the product is continuously meeting the customer's requirement, then that product is said to be reliable.

According to ISO 9001:2015, Quality is the degree to which a set of inherent characteristics which fulfills customer's requirement.
According to Phillips B. Crossby, Quality is conformance to requirements.
According to W. Edward Deming, Quality is a predictable degree of uniformity and dependability at low cost and suited to market.
Quality commitment

In simple words, 
 Quality is a relative term and it is used with reference to the end use of the product.
It represents the property of the product that are valued by the consumers. 

For example :  A gear used in the sugarcane juice extracting machine may not posses a good quality, tolerance and accuracy as compared with the gear used in head stock of a lathe, still it may be considered of good quality if it works satisfactorily in the juice extracting machine. 

We hope you will understand this topic.
We have given a example to understand this.

Thank you

Some of related question that help to improve your basic knowledge.

Thursday, February 6, 2020

MSA | Measurement System Analysis | QSQTECH.COM

MSA

MSA (Measurement System Analysis)

MSA is one important core tool in our quality management system. Like we have done consider of the four core tools in the previous concepts. 
Well today, we are going to talk about MSA, a core tool of quality management system. 
So lets start, 
Today, we are covering following points in this topic: 
  • INTRODUCTION 
  • SOURCE OF VARIATION 
  • FUNDAMENTAL PROPERTIES OF A GOOD MANAGEMENT SYSTEM 
  • ACCURACY & PRECISION 
  • GAUGE R & R 
  • BIAS 
  • LINEARITY 
  • STABILITY 
  • REPEATABILITY 
  • REPRODUCIBILITY 

Training on MSA.pdf in hindi click here to download

INTRODUCTION: 

IATF 16949:2016, which is an important part of quality management system for automotive industries. According to its clause no. 7.1.5.1.1 measurement system analysis, statistical studies shall be conducted to analyse the variance present in the results of each type of inspection, measurements, and testing equipment system. 


SOURCE OF VARIANCE: 

The source of variation can vary, it may come due to manufacturing process, it can also come due to process variation or product variation. There may be many reasons in the  manufacturing processes, such as machining, tooling, parameter variation, method variation, variation in materials, environment & measurement.
In all of these variations, Today, we are going to understand the variation of measurement system.

Source of variation (written image)


FUNDAMENTAL PROPERTIES OF A GOOD MEASUREMENT SYSTEM: 

  • The sensitivity of the measurement system must be adequate. It is mandatory for the instrument capturing the variation of measurement system to be sensitive. This means that 1/10th of the tolerance should be the least count of the instrument. It is also called 10 to 1 rule. 
  • The measurement system must be under statistical control. Only the presence of common causes of variation and not the special causes. 

ACCURACY & PRECISION: 

We will understand this topic from an example.

Condition- 1 
Exaple of ACCURACY & PRECISION- 1.1
Example pic. 1.1 
As shown in picture 1.1,
A shooter is shooting his target. In its shown center plus mark, which is the target value. Here the shooter has shot at various points. These points are seen far away from each other. Due to which it is neither precise nor accurate.

Condition- 2 
Example of ACCURACY & PRECISION- 1.2
Example pic. 1.2 
As shown in picture 1.2,
Here all the points are around the target, so there is accuracy but not precision.
Precision means that when all the points are located close to each other, there will be precision.
Accuracy means that when all the points are located around the target, that is accuracy.

Condition- 3 
Example of ACCURACY & PRECISION- 1.3
Example pic. 1.3 
As shown in picture 1.3,
Here all the points are located close to each other, but away from the target. So there is precision, but not accuracy.

Condition- 4 
Example of ACCURACY & PRECISION- 1.4
Example pic. 1.4 
As shown in picture 1.4,
Here all the points are both accuracy and precise.
I hope you understood this topic from example very well. Hope you like this.

GAUGE R & R: 

It is a means of assessing the repeatability and reproducibility of our measurement system.
Gauge R & R diagram

In this, we understand how much measurement system is contributing to the total variation of the process. Gauge R & R studies are done to find out how much the variation of the process is due to the measurement devices and measurement methods.
Both accuracy and precision are not the same. If there is an accuracy error in the measurement system, then the result of measurement shown the locational error.
Precision and Accuracy are not same 1.1

If there is a precision error in the measurement system, then the spread error will be shown in the result of measurement error.
Precision and Accuracy are not same 1.2


BIAS: 

It is the difference between the observed average of the measurement, and the true value. It is also called an error.
Bias diagram

True value: 

The value that is checked with a high precision instrument.

Observed average: 

Average value that is the average of multiple reading taken from an instrument.
To find the Bias, the Observed average is subtract to the true value, then the difference that comes out, is called Bias. The report noted a bias or error when calibrating the instrument.

LINEARITY: 

It is the difference in bias value over the expected operating range of the measurement gauge.
LINEARITY diagram

That is, if you have taken a vernier caliper, the vernier caliper range is from 0 mm to 300 mm. Then you will check the bias at different points in it's operating range i.e. from 0 mm to 300 mm. If the bias of the instrument is zero at every point, then you will call the instrument linear. And if bias is not coming zero, then it will be called non linear. So your instrument should be ideally  linear.

STABILITY: 

It is the variation in the average over an extended period of time using the same gauge and appraiser to repeatedly measure the same part.
If the same appraiser or inspector taking readings from the instrument at different times from the same gauge, the study is called a stability study. Stability, basically process variation; like here is the measurement process, so the variation of the measurement process tries to understand over a period of time.

REPEATABILITY: 

In this, we try to understand the difference that the same inspector check the same part, the same parameter, using the same gauge quite frequently, that study is called repeatability.

REPRODUCIBILITY: 

In this, different inspectors check the same part, same parameter, using the same gauge, quite frequently, that the study is called reproducibility.

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