Transient Entanglement Disentanglement Kinetics in Deep Draw Thermoforming under Multiaxial Strain Gradients
Matching plug speed to polymer disentanglement kinetics prevents corner thinning and optimizes wall thickness in deep draw thermoforming.
Non-Destructive Thickness Testing
Meaning
Quality control evaluation of polymer wall dimensions without damaging or altering the test sample ensures the structural integrity of moulded parts. This evaluation approach, known as non-destructive thickness testing, relies on ultrasonic or magnetic sensors to gauge the barrier layers of coextruded or blown containers. It verifies that the protective layers in a bottle or film remain within the specified tolerances.
Measurement Technology
Ultrasonic wave propagation provides the primary means of measuring thin polymer layers during continuous production runs. Transducers send high-frequency sound waves through the material, which reflect off the boundaries between different polymer layers or the back wall. Using the known speed of sound in the specific resin, the sensor calculates the distance travelled.
This technique of non-destructive thickness testing enables real-time monitoring of thin barrier films without needing to cut the sample.
Processing Benefit
Coextrusion blow moulding systems use real-time thickness data to make immediate adjustments to die positioning and preform extrusion. If the thickness falls below the minimum limit, the operator can adjust the parison programming before defective parts are produced. Implementing non-destructive thickness testing reduces the amount of regrind generated during startup by detecting drift early.
This rapid feedback loop keeps the process within a tight capability index.
Economic Impact
Material cost reduction represents the primary commercial driver for adopting modern scanning methods on the factory floor. Since polymer resins account for a large portion of the total part cost, manufacturers try to run as close to the lower tolerance limit as possible. Precise measurements from non-destructive thickness testing allow the line to operate with a smaller margin of safety, reducing average part weight.
This saving directly increases the profitability of high-volume runs by preventing over-moulding of expensive virgin resin while ensuring the mechanical performance meets the client’s specifications.