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Song Ling Chan
INSPECTION: USES AND APPLICATIONS IN QUALITY MANAGEMENT
Inspection is defined as “the process of measuring, examining, testing, gaging, or
otherwise comparing the unit with the applicable requirements” (Suntag). This essential
quality tool is used in every organization to ensure that the quality of their product is
acceptable to the customer as well as the industry. There are two primary purposes for
inspection. These are to make sure the product conforms to specifications and to
determine whether a non-conforming product is fit for use. In the following paragraphs,
we will discuss the uses, strategies, and tools of inspection.
Organizations may use different strategies for inspection depending upon the type
of process they use and the cost-effectiveness of using that strategy. Types of inspection
include operator inspection, in-process inspection, tollgate inspection, automated
inspection, 100 percent on-line inspection, and computer-aided inspection. Firms in the
U.S. and Japan do not commonly use tollgate inspection because of the need to inspect
100 percent of the product at every station before moving on.
Operator inspection involves a trained operator at one or more workstations. This
is the best position for inspecting a product given there is enough time between
workstations to complete the task and the operator is sufficiently trained. The operator
may also verify work done at previous stations.
In-process inspection is when an inspector patrols from station to station at given
amounts of time to ensure that the inspection procedures are properly executed. This
type of inspection is desired when the product has a low defect rate, when operator
inspection is not sufficient, or when there are new employees on the job.
Tollgate inspection uses a sampling station at a fixed point within the process to
evaluate the quality level of products produced in a given department before moving
them on to the next. This type of inspection is used when there is a high defect rate or
when there is a need to enforce quality levels between departments.
Automated inspection is used where human inspection would not be possible or
sufficient. Usually, automated inspection is used in mechanical or electronic industries. It
is also used when more precision is needed in the process.
100 percent inspection is done in-process and involves separating the good
products from the bad. Contrary to its name, not all of the defects are always caught since
there may be multiple products flowing through the system at any one time. Therefore,
some companies may inspect the product multiple times, in which case it is called 200 or
300 percent inspection.
Computer-aided inspection (CAI) is the most modern form of inspection. It allows
for 100 percent inspection at a relatively low cost and there is less chance of damage to
the products because the products are not physically handled.
The type and frequency of inspection can vary from firm to firm. A firm
implements its desired degree of inspection until it meets predetermined standard of
quality or the standard of the industry. Also, the best inspection strategy may change as
new technologies are introduced. The tools used for inspection include acceptance
sampling and control charts. Acceptance sampling occurs when a whole lot or shipment
is rejected from examining a percentage of the lot. The exact percentage is up to the firm
to decide. Control charts called x-bar and R charts take samples from a lot to measure a
particular characteristic. If the samples fall within the upper and lower control limits then
the whole lot is determined to be acceptable. These charts also help to determine if the
firm should implement more stringent standards for higher quality.
As you have seen, inspection is a very important part of the manufacturing and
production process. It is essential to the success and productivity of an organization as
well as cost-effective. Implementing inspection into every stage of the production process
will prevent expensive costs from rework and returns. It can be used to inspect damages
caused in-transit from one location to another, in checking that an order is correct and
that it meets conformance specifications as well as many other uses. More information
can be obtained about inspection from the reference given in the bibliography as well as
on company websites.
Juran, Joseph M. and Frank M. Gryna. 1980. Quality Planning and Analysis. New York:
Perigord, Michel. 1980. Achieving Total Quality Management: A Program for Action.
Cambridge: Productivity Press.
Suntag, Charles. 1993. Inspection and Inspection Quality Management. Milwaukee:
Hradesky, John L. 1995. Total Quality Management Handbook. New York: McGraw-