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Questions & Answers
What is the best vibration profile to use to test my product?
The test profile is usually based on the expected environmental conditions for the product in use, and tailored to give an insight into
product life expectation. Where the environmental data is not available directly, for use as input to the shaker, then representative profiles are
chosen from a recognised standard.
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My product will only be operated in a benign environment do I still need
to shock and vibration test it?
You would probably want to ensure that the product would survive the loadings imposed by the method of transportation to the end user, and/or
evaluate the method of packaging.
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If my product survives shock testing can I assume that it will survive
vibration exposure or do I need to have that tested as well?
Shock and vibration tests have different test objectives and are complementary. Vibration tests identify potential failures in products as
well as evaluating the life to failure in an endurance mode. Resonance searches are conducted to identify components or structural parts which have
undesirable responses in the test range, usually followed by fixed frequency
and/or random vibration testing for endurance. Shock tests are used to evaluate products under transient loading, and the pulse width and shape, as
well as the peak value, determine how kinetic energy is transferred into the
product.
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What is random vibration testing and why is it necessary?
Random vibration essentially generates broad band noise. This ensures that any resonant frequencies of the product will be excited simultaneously.
In a fixed frequency test, single resonance's would be excited but would not
identify potential problems where, for example, two adjacent components with
different frequencies may interfere under random vibration exposure. The occurrence of single frequency vibration environments is not very common and
the random test has been designed to simulate, in a more accurate way, what
we find in reality.
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If the vibration test shows that my product has one or more components
with resonant frequencies in the test range what do I do about it?
Resonance's can be changed by altering mass, stiffness or damping. The choice of what corrective action to take will depend upon several
factors, including the type of component, how it is restrained, whether it
generates heat, and how it has been mounted. We can suggest appropriate modifications and give alternatives at the time of testing.
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What do I need to submit when I send a product for testing?
For full "type testing" a sample that is largely identical to the finished product is required. In addition, any combination of the following
may be required:
- Any safety or operating instructions that will be supplied with the end
product will need to be supplied.
- Any equipment that is to be used in conjunction with the specimen. (E.g. If
the unit is intended to be supplied from a 9 V.d.c. plug-pack, then that
plug-pack should be supplied with the specimen).
- Circuit Schematics
- Test reports from a recognised test laboratory, if any parts of the equipment are pre-approved. (Mains switches or power supplies are good
examples)
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Can Underwriters do all testing required by the standards or do they sub-contract services they cannot
provide?.
If it is determined that the laboratory is able to perform the requested work, a quote or estimate (depending on the information supplied) will be
supplied to the customer. IF the laboratory cannot fulfill all of your requirements, then we may sub-contract testing only after approval form the
client.
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Are Underwriters reports recognised in South Africa?
Yes, The South African bureau of Standards (SABS) will accept EMC and Electrical safety testing performed at Underwriters Laboratories.
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Our electrical product is IP rated can Underwriters perform these tests as
well as normal safety testing?
Underwriters can test up to and including IP67 on most products. Note: that our dust chamber can only accommodate products no larger than 500mm cubed.
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We don't know whether our product needs to be tested before we can sell
it or what standards it needs to meet, can Underwriters advise what is required
for my product to be sold legally on the market?
Part of the service that we provide at not charge, is to advise you of the regulatory as well as standard requirements that your product must meet.
This can be from Type testing up to getting "Approval" for your product. This will vary depending on the country that you wish to sale into.
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Our Product is very innovative, what guarantees does Underwriters offer that
my ideas won't be passed on to my competitors?
Underwriters Laboratories treats all jobs as "Confidential" all Laboratory Staff operate under a code of ethics that state that they shall not disclose
any information relating to testing work to any persons outside the
laboratory other than the client.
Underwriters staff shall not accept any gifts, gratuities, commissions or favours from the laboratory user with an interest in the work of the
laboratory.
Staff shall declare any involvement with a customer outside of the working
environment and management shall decide if they are capable of working upon
customer products without any undue influence being applied.
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