Whether
produced after injection products meet quality standards, must be tested, a
common quality test methods are the following two.
(1) full
inspection
The
so-called full inspection is individually tested for injection products, we
have talked about "full" refers to the number of all the plastic
parts produced, rather than the entire value of the quality characteristics
tested. In determining the test items, test cost is usually lower or greater
impact on the quality of the quality characteristics of the implementation of
full inspection, such as plastic parts Dimensions test is easier and can be
fully tested, and the requirements of the position and some plastic parts
crucial, a great impact on the quality, but also the need for full inspection.
Not plastic parts for each test must be carried out in full, as it is too
time-consuming and laborious. Usually occurs when the following conditions
using full inspection.
1) found
that more unqualified plastic parts, plastic parts or the whole batch are
unqualified, the need for follow-up products for full inspection.
High single
value 2) injection products, even when a scrap will bring great losses.
3) If the
product quality problems, give people life safety or safety hazard when great.
(2) sampling
inspection
The
so-called sampling inspection,, is from a group of randomly selected plastic
part of the test conducted. By this test section of plastic parts extracted to
make the evaluation of quality of these plastic parts. Compared with the full
inspection sampling inspection, it tested a small number of plastic parts,
low-cost test, test speed. Sampling inspection and batch size of the number of
samples, volume, sample quantity; small quantities, less sampling; as long as
the appropriate number of samples, the test results have a high accuracy.
Usually by random checks in the following cases.
1) Some of
the plastic parts of the mechanical and physical properties of the need for
destructive testing, this will bring damage to the plastic parts.
2) more than
the mass production of plastic parts, plastic parts produced quantity
particularly large, want to save test time and test costs.
3) the
production of raw materials in plastic parts, there are a lot of raw material
is powdered, granular or liquid form, the raw material for these multi-use
sampling. Compared with the full inspection sampling inspection, although there
are a small number of test and low test cost advantages, but also the following
problems: First, when the second installment of the plastic parts, even after
sample testing has been considered qualified, can not believe that this batch
of plastic parts plant each plastic parts are qualified, which may also exist a
very small amount of non-conforming product. Second, the sample tests will
inevitably appear judgmental errors, this is the vast majority of qualified
products, due to sampling bias, but judged unqualified; or could have been
substandard goods, has become qualified. Therefore, in order to determine the
probability of error is controlled within a reasonable range, often need to
coordinate the use of mathematical statistics methods.
In short,
the full inspection and sampling test has its own characteristics, and
applications and problems also vary, depending on the circumstances test
methods should be chosen to adapt. Mostly due to the injection mold products
for mass production, it is more to take sample tests
more information www.chinamoldmaker.org www.cnmoulding.com
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