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REJECTION / DEFECTS / DEFECTIVES
Any output (Articles, Semi finished products, parts, and so on) that does not correspond in quality to
standards, technical specifications, and other technical norms is called rejection.
Now reject s can be further understand with two terms.
Defect and Defective
Defect means the parameters which are not as per the specification. Like in plastics injection
molding it can be short mold, Black spots, burn mark etc. or in press parts dent marks, Sharp edge,
Scoring mark etc. or in casting parts it can be blow holes, pitting marks, unfilled etc. So the defect can be
present in one part or in many parts. Or multiple defects can be present in one part.
So the parameter which is not confirming the requirement is defect. And the product which is having one
or multiple defect is called defective. So defective can be one or more and in defective there can be one or
more defects.
So just do not get confused with defect and defective.
The product which is having defect in it called defective or reject. The process of defining reject is called
rejection.
A distinction is drawn between reparable and irreparable production rejects. It is technically possible
and economically advisable to repair the defects in reparable rejects at the enterprise. Irreparable rejects
are products whose defects are technically impossible or economically disadvantageous to eliminate.
Such products may be considered as waste.
Quality rejects may be result of incorrect adjustment of a machine tool, malfunctioning of equipment
and tool, error in technical specifications, disruption of production discipline or parameters, or the worker‘s
low level of skill. Characteristic of production rejects is a discrepancy between the quality of the product
and current requirements (e. g. incorrect dimension or failure to follow a standard formula)
Why is it important to clearly define and classify quality defects for your products?
Imagine you‘re manufacturing shirts in Indonesia. A product inspection report from your QC partner shows
about one third of the shirts have untrimmed threads.
Would you classify this quality defect as ―minor‖ or ―major‖? You might say untrimmed threads are
a ―minor‖ defect that doesn‘t affect the salability of the product. Or you might consider them a ―major‖
defect if you distribute your product to a high-end retailer with a lower tolerance for quality issues.
Defect classification is a vital step for determining if goods should pass or fail inspection. And
considering the quantity and severity of different types of defects found helps you make an informed
shipping decision.
A professional inspection company often has established standards for classifying various types of
defects for a particular product type. But it‘s ultimately your responsibility as the buyer to decide your
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tolerance for different defects; often using a system like AQL (Acceptable Quality Level)Here we‘ll help
you get started by explaining the most common ways to classify defects in different products.
3 Types of Defects Every Manufacturer Needs To Know
Quality control professionals typically classify quality defects into three main
categories: minor, major and critical.
The nature and severity of a defect determines in which of the three categories it belongs.
Quality professional have the power to specify how many of each type of defect they‘re willing to
accept in their finished goods. This tolerance, in turn, impacts how many units per SKU an inspector would
check during inspection—the sample size.
Professionals commonly set these quality tolerances using a statistically valid acceptance
sampling method known as acceptable quality limits, or acceptable quality levels (AQL)
An tolerance for minor defects tends to be greater than that for major or critical defects, given their relative
severity. Let‘s look at each of these defect types in detail.
Minor defects
Minor defects are usually small, insignificant issues that don’t affect the function or form of the
item. In most cases, the customer wouldn‘t even notice a minor defect on a product. And the customer
wouldn‘t likely return an item due to a minor defect alone.
Quality Professionals often set the highest tolerance—or AQL, if applying that standard—for minor
defects in their inspected sample size. But an item can still fail inspection if the number of minor defects
found exceeds the limit set by their tolerance.
Major defects
Major defects are more serious than minor defects. A product with a major defect departs
significantly from the Customer‘s product specifications.
Major defects are those which could
adversely affect the function, performance or appearance of a product.
These defects are readily noticeable by the customer. And these defects would likely cause a customer to
return the product, lodge a complaint or request a refund in
response.
Most quality professionals set a lower limit for major
defects than minor defects in their inspected sample size. They‘ll
often accept an order with zero major defects. And they‘re likely
to reject an order, or ask their supplier to hold or rework it, if the
goods fail inspection due to an excessive number of major
defects found.
Critical defects
Critical defects are the most serious of the three defect types. Critical defects render an item
completely unusable and/or could cause harm to the user or someone in the vicinity of the product.
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These defects put businesses at serious risk of product liability issues, lawsuits and product recalls.
Many customers have a ―zero tolerance‖ policy for critical defects in their orders commensurate with this
risk. An item will often fail product inspection if a single critical defect is found within the order.
EXAMPLES OF QUALITY DEFECTS IN DIFFERENT PRODUCTS
Different quality defects can appear in different products depending on materials, production
processes and standards used. Below are some common examples of minor, major and critical defects in
different product types.
Some common defects in fabrics include:

Untrimmed thread

Missing stitches

Needle found in item
Some common defects in plastics products include:

Short mould

Flash on part

Burn mark
Some
common
defects
in
electronics include:

Removable mark on item

Non-function or malfunction –

Damaged wiring
Now these defects are
generated or occurred during process or manufacturing of the
product. These defects are called process rejection. Mainly the
reason for the rejection is some alteration in process, malfunctioning of the equipment, faulty material or
lower skill of the manpower.
The
process
rejection
can
be
identified
during
manufacturing or during final inspection or during usage of
product. But we need to understand the impact of process
rejection where the mass production or a bigger batch
production is taking place. Because the defect due to the
process variation can affect the entire lot and this defect if not
identified during manufacturing or even at final stage then it
will reach to customer and this can give a severe impact to
business. So it is advisable to identify the defects during
manufacturing only so that immediate corrective actions can be taken as soon as possible without much of
the loss.
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PPM
Do you know how the rejection level is calculated in automobile industries? Or what are the quality
indicators for an organization or process?
There are different ways to indicate the rejection of the process or the entire organization. Like
showing rejection percentage indicates that out of 100 parts how many parts are ok and how many are
rejected. Similarly rejection values can be calculated and ratio of value of OK parts and value of NOK
parts indicate the rejection of organization or process.
In automotive industries there is another parameter which is very popular and gives a clear picture
of the performance of the process. And it is PPM- Parts per Million
PM defectives is a measurement used today by many customers to measure the quality
performance of their suppliers. There was a time when a provider with the 10,000 PPM defectives was
considered as an outstanding supplier. A PPM defectives rate of 10,000 means the defect rate is less
than 1%. However; with the passage of time, the expectations increased to 1,000 PPM and now, the
expected PPM rate, especially in the manufacturing
industry across the globe, is close to zero PPM. One
PPM defectives mean one defect, error, or event in one
million. It is a value that represents the part of a whole
number in units of 1/1000000.
Let us have a look at an illustration for how to
calculate PPM. We are talking about the business of
manufacturing car tires. The production capacity of the
company is 535,000 tires per annum. The plant operates
around 5 days a week, 50 weeks per year or 250 days a
year. Around 70% of the customers of the business requires 20 parts per million defectives rate. It means
that the manufacturer would be allowed to produce 11 defective tires for every 535,000 tires. In
other words, the business would be allowed to manufacture 0.92 defective tires per month. If the
manufacturing capacity of car tires reaches to 1 Million tires per annum, then the manufacturer would be
allowed to produce 20 defective tires.
Let‘s look at PPM defectives from a different angle. Another car tire manufacturing company can
produce 10 000 000 parts per year for its customers. The company makes tires 5 days per week, 50
weeks per month, and 250 days per year. If the customer requirement is 25 PPM defectives. That means
that the company can manufacture 25 defectives for every 1 000 000 tires or 250 defective tires per year.
That means the company is allowed 1 defective tire for the entire plant per day. This is the way of how to
calculate PPM.
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Measuring Parts per Million defectives mean that you have physical proof of whether you conform
to your customers‘ demands. It also means that you can have a solid idea of the quality that your company
produces as well as the extent of waste that is being created.
PPM defectives may seem like a small, insignificant metric. That‘s not true. It is the one metric that
customers‘ demand of their suppliers to conform with. Parts per million defectives is the one metric
that companies can look towards for a real understanding of the quality of their products or the
lack thereof. PPM defectives guide Six Sigma practitioners to improve upon processes until the best
possible quality standards can be sustained. One of the reasons why PPM defectives are so important is
that it looks at DEFECTIVES as opposed to defects.
PPM counts the quantity of defective parts per million parts produced. As noted above, it does not
account for the fact that multiple defects may affect a single part. One defective part, even with multiple
defects, counts as a single defective among other defectives in the population. It uses 1,000,000 as a
constant, regardless of the actual number of parts produced. The formula is:
Rejected parts
PPM =
Total parts produced
X 1000000
If one part is rejected out of 1000 parts then the PPM will be
1
PPM =
1000
X 1000000
PPM = 1000
Similarly, if 50 parts are rejected out of 1000 parts then PPM will be
50
PPM =
1000
X 1000000
PPM = 50000
Now if customer allows only 20 PPM then
0.02
PPM =
1000
X 1000000
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Only 0.02 parts is allowed to reject in a lot of 1000 parts. And now customer is asking for 0 PPM
which means no rejected part is allowed to produce in 10 million (1000000) parts. This type of process is
called zero defect process or operation.
ZERO DEFECT OPERATIONS
Zero Defects refers to one of the concepts in the book ‗Absolutes of Quality Management’by Philip B.
Crosby. Zero Defects is a management tool and is aimed at halting production defects through prevention.
At the same time, it is also aimed at motivating and convincing people to identify and prevent mistakes by
constantly encouraging them to perform their job well.
Zero Defects is a philosophy that asserts that the mistakes an employee makes are irrelevant.
After all, these mistakes will be identified by inspectors before the product/service reaches customers.
Zero Defects focuses on conditioning the employee to ensure a personal interest serves as motivation in
everything they do. This is done by convincing the employee that his work is important for the success of
the organization.
As mentioned, Philip B. Crosby is credited with developing the concept of Zero Defects. Philip B.
Crosby was a quality manager at the Pershing rocket program of Martin Company. Especially during the
Cold War, Zero Defects gained a lot of traction. Eventually even NASA benefited from its Zero Defects
operations. For instance, reports on failed missile launches increased the pressure to eliminate defects.
The concept would later also be applied in the automotive industry. This resulted in drastic cost reductions
and higher quality vehicles, especially in terms of safety. Ultimately, a Zero Defects standard was created
and implemented in many organizations around the world.
Zero Defects, a term coined by Mr. Philip Crosby in his "14 Step Quality Improvement Process"
through his different books, has emerged as a popular and highly-regarded concept in quality management
– so much so that Six Sigma is adopting it as one of its major theories. Unfortunately, the concept has
also faced a fair degree of criticism, with some arguing that a state of zero defects simply cannot exist.
Others have worked hard to prove the naysayers wrong, pointing out that ―zero defects‖ in quality
management doesn‘t literally mean perfection, but rather refers to a state where waste is eliminated and
defects are reduced. It means ensuring the highest quality standards in projects.
How much do quality failures cost your company?
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Quality defects have significant costs associated with them – some of the most obvious being
money, time, resources, and lost reputation. And programs to eliminate quality defects can be expensive
and time consuming.
So,do you insist on eliminating defects entirely no matter the cost? Or, do you accept that a
certain, albeit very small, percentage of defects is acceptable, and just accept the costs and learn to live
with them?
His position was that where there are zero defects, there are no costs associated with issues of
poor quality; and hence, quality becomes free.
Thequality manager must be clear, right from the
start, that zero defects is not a motivation program.
Its purpose is to communicate to all employees the
literal meaning of the words 'zero defects' and the
thought that everyone should do things right the first
time.
"Quality Is Free" by Philip B. Crosby (McGraw-Hill
Books, 1979)
Let me explain the idea of ZERO DEFECT…
Zero defects is a way of thinking and doing that reinforces the concept that defects are not
acceptable, and that everyone should "do things right the first time." The idea here is that with a
philosophy of zero defects, you can increase profits both by eliminating the cost of failure and increasing
revenues through increased customer satisfaction.
"Zero defects" is referred to as a philosophy, a mentality or a movement. It's not a program, nor
does it have distinct steps to follow or rules to abide by. This is perhaps why zero defects can be so
effective, because it means it's adaptable to any situation, business, profession or industry.
The question that often comes up when zero defects is discussed, is whether or not zero defects is
ever attainable. Essentially, does adopting a zero defect environment only set users up for failure?
Zero defects is not about being perfect. Zero defects is about changing your perspective. It does
this by demanding that you:
1. Recognize the high cost of quality issue.
2. Continuously think of the places where flaws may be Introduced
3. Work proactively to address the flaws in your systems and processes, which allow defects to
occur
Zero defects is a standard. It is a measure against which any system, process, action, or outcome
can be analyzed. When zero defects is the goal, every aspect of the business is subject to scrutiny in
terms of whether it measures up.
When you think about it, we expect zero defects when we are talking about items or services that we
use. If you buy a fancy new plasma TV and your pixels start burning by the thousands, you demand
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satisfaction. When you take the car in for brake service, you expect that the mechanic will install the parts
exactly as the manufacturer prescribes. No defect is an acceptable defect when it affects you personally
So why then, is it so easy to accept that "defects happen" when you are the one producing the
product or providing the service? This is the interesting dichotomy that presents itself. Zero defects is one
of the best ways to resolve the discord between what we expect for ourselves and what we can accept for
other.
Quality Management and Zero defect
Some argue that a state of zero defects simply cannot exist. Others have worked hard to prove the
naysayers wrong. They have pointed out that ―zero defects‖ in
quality management does not literally mean perfection. Instead, it
refers to a state where waste is eliminated, and defects are
reduced. It means ensuring the highest quality standards in
projects.
Let's begin by taking a look at Quality Management itself.
Quality management ensures that an organization, product, or
service is consistent. It has four main components. These include:

Quality planning,

Quality assurance,

Quality control and

Quality improvement.
Quality management talks about a set of procedures that ensures that the deliverables produced
are "fit for purpose". At the very outset of laying out a Quality Management Process involves setting
quality targets, which are agreed with the customer. Generally, the lesser the defects the better the
quality. With this, you will understand the concept of Zero Defects in quality management
Adopting Zero Defects
There are no step-by-step instructions for achieving zero defects, and there is no magic
combination of elements that will result in them. There are, however, some guidelines and techniques to
use when you decide you are ready to embrace the zero defects concept.
Management must commit to zero defects. Zero defects requires a top-down approach: The bestintentioned employees cannot provide zero defects if they are not given the tools to do so.

When you decide that zero defects is the approach you want to take, recognize that it likely
represents a significant change to the way people do things. Manage the introduction using the
principles of change management.

Understand what your customers expect in terms of quality. Design systems that support zero defects
where it matters, but don't over-design if the end-user just doesn't care.

Zero defects requires a proactive approach. If you wait for flaws to emerge you are too late.
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
Create quality improvement teams. Zero defects must be integrated with the corporate culture. Zero
defects needs to be accepted as "the ways things are done around here‖.

Learn poka-yoke (POH-kay YOH-kay.) Invented in the 1960s by Shigeo Shingo of Japan, it translates
to "prevent inadvertent mistakes." It's an approach that emphasizes designing systems that make
defects almost impossible or, if they can't be avoided, easy to detect and address. To implement zero
defects, you have to have strong systems in place

Monitor your progress. Build mechanisms into your systems and methods of operating that provide
continuous feedback. This allows you act quickly when flaws do occur.

Measure your quality efforts. It is important to express your progress in terms of the bottom line. Take
baseline measurements so you understand the cost of defects in your organization, and can measure
the benefits you're achieving in eliminating them.

Build quality into your performance expectations. Encourage members of your team to think about
how they can achieve zero defects, and reward them when they're successful.

Recognize that although zero defects is a destination, circumstances keep changing. Monitor,
evaluate, and adapt in a continuous, never-ending cycle.
Where is Zero Defects used?
Manufacturing organizations use it to tackle and improve quality issues. Zero Defects is referred to
as a philosophy, a mentality, or a movement. It aims to minimize the number of defects in manufactured
products and services as much as possible. It does not have distinct steps or rules to follow.
This leaves companies open to customizing how they want it to work for themselves. This is
perhaps why Zero Defects can be so effective- it is adaptable to any situation, business, profession, or
industry. It is used in Six Sigma for reducing the variation and standard deviation. This indirectly will
reduce the defects and bring it close to zero.
Principles of Zero Defects
According to Philip Crosby, the principles of Zero Defects are as follows:
Quality is the conformance to requirements:
Every product or service has a requirement. It is a description of what the customer expects to see.
Hence, a certain product is said to have achieved quality when it meets those requirements. This should
not be confused with higher standards of products. For Instance, it will be unrealistic to say that a basic
mobile phone is of low quality compared to the latest iPhone.
They both must meet different quality standards to pass the quality test. Based on this, Zero
Defects means the basic mobile phone is a quality product if it meets the initial requirements set for it.
That is, if it can make and take phone calls clearly, send and receive text messages. Then it is only
realistic to say it conforms to quality and has (close to) Zero Defects.
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Preventing defects is better than quality Inspection and Correction:
The focus is on product quality management here. It is preferable that defect prevention is
made a part of manufacturing or company practice. It should be in the process rather than in quality
inspection and correction. This is simply because Zero Defects management is almost always less
troublesome. It is more certain, and less expensive, as it aims to prevent defects rather than to
discover and correct them later.
Quality Standards Means Zero Defects:
The third principle of Zero Defects is based on the nature of requirements. A requirement
expresses what is genuinely needed by the customer or the product itself. Any product or service unit
that does not meet the requirements will not satisfy the need and is nowhere near as good as
expected. Yet, in some cases, some units that do not meet requirements could still satisfy the need.
This means the requirement should be reviewed and changed to reflect reality.
Quality Is Measured in Terms of Money (i.e. The Price of Non-conformance
(PONC)):
Philip Crosby believes that every defect represents a hidden cost. This includes the costs of
inspection time, reworking, and revenue. Furthermore, there is the cost of wasted material, labor, and
customer dissatisfaction. When properly identified and brought to light, the effects of these costs can
be made clear.
This will help provide a cost justification for steps to improve quality. Businesses should find a
way to measure a Zero Defects management progress. This will help maintain management
commitment, rewarding employees, and ensuring company goals are made measurable. With this,
the actions can be made concrete. It will also help in making decisions based on relative returns.
Zero Defects: Advantages & Disadvantages
Advantages

Cost reduction caused by a decrease in waste. This waste could be both wasted materials and wasted
time due to unnecessary rework

Cost reduction due to the fact that time is now being spent on only producing goods or services that are
produced according to the requirements of consumers.

Building and delivering a finished article that conforms to consumer requirements at all times will result in
increased customer satisfaction, improved customer retention and increased profitability.

Possible to measure the cost of quality
Disadvantages
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
A process can be over engineered by an organization in its efforts to create zero defects. Whilst
endeavoring to create a situation of zero defects increasing time and expense may be spent in an attempt
to build the perfect process that delivers the perfect finished product, which in reality may not be possible.

For example, a consumer requirement may be a desire to buy a motor car that is 100% reliable, never
rusts and maximizes fuel consumption. However, in this instance, in practice, if an organization doesn‘t
have some kind of built in obsolescence it will have a more limited life.
Conclusion: Strive to Be Better and Better, Not Perfect
Since the slogan zero defects implies immediate compliance to a defect-free standard, it may not
leave time for the continuous improvement process to occur. In fact, it may even slow down the
continuous improvement process because of the massive resources that inspected-in quality entails.
Zero defects is a message that can carry with it confusion and misinterpretation, mixed with
technical impracticality. It may be appropriate that the idea of zero defects be replaced with a po licy of
zero escapes, since the latter has limited interpretation. As a company is doing all it can to improve the
product and business using continuous improvement techniques, it also needs to consider what it can do
to prevent a random, low-level defect from reaching the final customer. In this regard, zero escapes of
defects may be a complimentary activity to continuous improvement.
A logical strategy is to employ continuous improvement methodologies everywhere in the business
and manufacturing process to improve quality and yield, and reduce cycle time and costs. Then, at the
point of shipping the final product to the final customer, employ a zero escapes methodology to help
ensure that a randomly defective unit does not reach its final application. The tools and techniques
developed and employed at this final gate should be arrived at through a team effort of the various
suppliers and interim customers. Expecting individual suppliers in the supply chain to produce zero
defects, in an effort to eliminate or minimize the final gate, is likely to be an impractical strategy.
It is technically not possible to have no defects. However, an acceptable quality level can be
determined for the products and services. This level is determined on the basis of quality goals and
customer requirements. We need to measure quality in financial terms. Measure the cost of conformance
and non-conformance to quality.
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