Why can dispensing technique be challenging?

Nearly every process requires a different dispensing technique; it is true to say that there is no system that offers the required dispensing characteristics in an all-in-one solution.

Since it is not a theoretically well-established science, challenges may occur when dispensing. This is due to the rheological complexity of fluids and adhesives, which can be difficult to study and describe in order to fully understand the behaviors of the materials to be dispensed. Insights into the characteristics of materials when static and their characteristics during dispensing are often only acquired through experiments based on trial and error.

Common challenges

Detection of air bubbles: Avoid corrosion in sealing applications

Volume control: Ensure that structural bonding withstands loads and stresses

Temperature management: Avoid summer and winter material batches

Bead shape: Avoid unnecessary rework and scrapping

Bead position: Avoid rework and ensure process quality

Air bubble detection

One of the biggest challenges is to detect air in the system or air bubbles in the material application. This can cause serious quality problems in the long-term as it is usually not visible to the eye. This problems can be classified in four classes:

Class 01

a. Connected bead
b. Surface completely
c. Error hardly recognizable

Class 02:

a. Connected bead
b. Surface completely covered
c. Error relatively easy to recognize

Class 03:

a. Weakly connected bead
b. Surface no longer completely covered
c. Error easy to recognize

Class 04:

a. Completely unconnected bead
b. Great loss of surface coverage
c. Error obviously recognizable

There are different types of equipment and methods available to detect air in the system.

Process Challenges

A dispensing system is usually a sub-process of a complete production process. Therefore the industry and the customer are exposed to process challenges in addition to the usual dispensing ones. Here we take a closer look at the challenges which may occur before or after the dispensing process.

Pre-process challenges

  • Correct material choice: To achieve the ideal dispensing process for the application, the correct choice of adhesive material is crucial.
  • Correct substrate surface treatment:
    The surface treatment must match the material adhesion requirements, otherwise this may negatively impact the quality
    of the application. 
  • Precise substrate positioning: The wrong placing of the substrate may influence the bead positioning.

Post-process challenges

  • Correct curing time: The curing time of the adhesive material may be adapted according to the overall process, thus avoiding waiting time for curing.
  • Handling of substrate: The substrate should be handled carefully after the adhesive material has been dispensed onto it to allow for curing time.

For more information and solutions for above problems, please contact GLUDITEC:

Hotline: (+84) 969 469 089