Extrusion Blow Moulding Parison Programming and Wall Thickness Calibration
Dynamic die gap programming aligns parison mass with mould draw ratios, stripping container resin weight while locking required structural wall minimums.
Acoustic Velocity
Meaning
Physical property quantifying the rate of sound wave propagation through a polymer melt or solid part. Determining the acoustic velocity allows technicians to calculate the thickness of a wall when access to both sides is restricted. Sound travels faster through denser, more crystalline resins such as high density polyethylene than through amorphous materials.
Thickness Correlation
Non destructive testing relies on the relationship between time and speed. Because ultrasonic gauges measure the time of flight for a pulse to return, an accurate value for acoustic velocity is required to convert that time into a linear measurement of the material thickness. High precision sensors monitor the internal density changes by tracking how the pulse speed fluctuates during the cooling phase.
Process Monitoring
Ultrasonic transducers integrated into the mold or die provide real time data on the state of the material. Variations in acoustic velocity signal shifts in melt temperature or pressure that might otherwise go undetected until the part is ejected. High speed data acquisition captures these transients before they result in off specification dimensions.
Maintaining a stable temperature profile ensures the sound speed remains predictable across the production run.
Defect Detection
Internal voids and delamination act as barriers that disrupt the passage of sound. Monitoring this variable helps maintain consistency in parts where structural integrity is a priority.