ACTUATION FORCE testing allows measurement of the force required to, for example, release hair fixatives or air freshening sprays from aerosols; or liquid soap, shampoo or cream from dispensers. Manually-actuated spray pump dispensers or finger pumps rely on the consumer to generate a hydraulic pressure in the pumping engine in order to dispense the fluid. Dispenser designs may change or vary, or the ever-increasing market for child friendly products may require adaptations.
When operating a pump-type liquid soap dispenser, for example, a child may have difficulty applying sufficient force in the appropriate direction to operate the pump, which may cause the dispenser to move, tip, or otherwise fail to discharge the product toward the intended target. An actuation force test typically uses a hemispherical probe to apply the force and provides an imitative test to assess such issues.
Drug delivery can also be as a result of actuation and an actuating force test is therefore necessary. A metered dose inhaler (MDI) delivers a precise, reproducible dose of drug accurately to the deep lung. It is also well accepted by patients who depend on MDI's in their treatment and therefore it is essential to constantly improve this technology. Patients need to rely on their inhaler to provide them with the required medication which is often at a crucial time when physical strength may be very low.
The metering valve, whose performance is assessed with this test, is a critical component of a finished metered-dose inhaler. The interaction between the elastomeric components and the formulation can significantly affect product performance. A change in formulation, for example implementing a new propellant system, may necessitate a complete redesign of the valve system in order to successfully deliver the drug with the minimum of difficulty.
Measuring actuation force does not always apply to the delivery of a product as a result of the actuation but is also applicable to the testing of, for example, actuation buttons for mobile phones, cameras etc. or defining the life of a membrane switch. It is important that the switch or button under test be pressed with a force hard enough to achieve switch contact closure or the actuation of a motion.
Typical properties that can be obtained from a texture analyser graph:
Force to Actuate and/or Deliver a Product, Distance at which Actuation occurs during Compression, Switch Actuation, Button Actuation
Typical Texture Analyser graph with annotated properties of foam dispenser actuation test
Typical Probe/Fixture used for Measurement:
The above are only typical examples of actuation force measurement. We can, of course, design and manufacture probes or fixtures that are bespoke to your sample and its specific measurement.
Once your measurement is performed, our expertise in its graphical interpretation is unparalleled – no-one understands texture analysis like we do. Not only can we develop the most suitable and accurate method for the testing of your sample, but we can prepare analysis procedures that obtain the desired parameters from your curve and drop them into a spreadsheet or report designed around your requirements.
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