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Edison Bulbs

What is Functional Test?

Functional Test, also called performance test, operates the product like an end-user.  For example:

  • Lightbulbs turn ON and OFF

  • Printers produce papers and graphics

  • Telecommunications devices communicate with each other

  • Metrology equipment makes measurements

This sounds pretty easy until it’s your product.  If you’re making light bulbs you have customers that are particular about things like:

  • How fast does it turn on?

  • What is the spectrum of light produced?

Or if you make a printer you are concerned with:

  • How legible is the text produced at the highest speed?

  • Are there discernable artifacts in graphic images?

  • Are scans successfully transmitted over connected networks?


Weren’t we talking about a printer?  Gone are the days when electronic products had only one function.  Printers often scan and almost always include Ethernet or WIFI functions.  Even lightbulbs can have Bluetooth and WIFI now, so users can put them in “Party Mode” from an app on their cellphones.  Metrology devices no longer convey the measurement only to the operator; now the operator generates reports and shares complex images with customers over network connections with the Web and other devices. 

How can a manufacturer guarantee that all of the functions in a product operate properly so the end user will have a satisfactory experience?

Do we bring customers in to test the product in unexpected ways and reveal problems we never considered?

People Walking in an Urban City

Beta user trials have their place but are not manageable in a factory.

Do we enumerate all of the features in a product and operate them in every combination?



Breaking down the product’s design, we devise a test plan to minimize the risk of a customer having a negative experience from a defective product.  This is a cost-benefit balancing exercise guarding against:

  • Manufacturing Defects

  • Design Margin Failures

  • Cumulative Conditions

Functional Tests to exercise certain functions in a product are generally necessary.  Automation increases speed and accuracy of the test.  For example a lightbulb test may include:

  • The bulb is placed in a dark box to eliminate ambient light

  • Power applied at a set voltage, with current measured

  • Measurement of light output is made at one or more locations with intensity, spectrum, and timing compared to performance criteria

But what if in your product the bulb is just an indicator lamp and a simple verification of on/off status is all that is required.   The cost of the above steps may be appropriate for a manufacturer of display lamps but not necessarily for a printer or a measurement device.  Often, a structural test (link to structural test) is adequate for many features of a given product, leaving functional test a necessity only for key features.

 Contact CAE Integration today for a test plan optimized for your specific product.

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