Tips for better dispensing
Consider the following when you program your dispensing paths for optimal consistency and quality:
Distance between tip and workpiece
Robot27 recommends maintaining the distance between the workpiece and the tip to be about 2/3 the height of the bead you are dispensing. For example, to create a 1mm bead, start with the tip about 0.67mm from the workpiece.
Dispense start dwell
Make sure to allow enough time for the material to begin flowing before the robot begins moving. This setting can be adjusted from the Installation tab by clicking on the URCaps dropdown menu and then on Robot27 Dispense.
Dispense pressure and speed
Pressure and speed are directly correlated. Higher pressures allow the robot to move at higher speeds while dispensing materials. However, Robot27 recommends finding the lowest pressure and speed combination that meets your process requirements to ensure consistency and accuracy of beads.
Tip size, shape, and material
Long, small inner diameter (ID) needles require more pressure to dispense materials than shorter, larger ID needles. Tapered tips require less pressure than straight tips. If a stainless steel tip must be used, Robot27 recommends using the shortest possible tip length. Tapered tips are not well suited for applications with thin/low viscosity materials requiring retraction. Applying vacuum retraction to a tapered tip can create air bubbles in the tip leading to inconsistent dispensing.
Large collections of material at the start of the dispensing path can be reduced by reducing the Dispense Start Dwell in the URCap default settings. Thin or disconnected collections of material at the start of the dispensing path can be resolved by increasing the Dispense Start Dwell.
Closed loop abnormalities
When your dispensing path starts and ends in the same place, material can collect at that location. Reducing the Dispense Start Dwell or moving the Dispense End waypoint farther away from the Dispense Start waypoint can correct this problem.
Adjust one variable at a time
Robot27 recommends adjusting only one variable at a time when optimizing a dispense routine (tip size, robot speed, dispense pressure, etc.). Keeping track of the changes made and any observations about the results of those changes will help develop a finished product more quickly. Adjusting multiple variables at once makes it difficult to determine which changes are effective and which are not.