Knit line dispense techniques
Knit Line dispense techniques for cure-in-place and form-in-place gasketing
In cure-in-place (CIPG) and form-in-place (FIPG) gasketing applications, the gasket creates a seal used to protect critical components from air, dust, and moisture intrusion, and to prevent leaking and dampen vibration. Achieving a good knit line can help to eliminate voids and ensure bead fusion to deliver a reliable seal.
Knit line dispense techniques
Determining the appropriate knit line dispensing technique is an important consideration in dispense system programming and setup. Several knit line techniques include the overlap, parallel pass, butt joint, and sloping overlap.
Overlap
![A figure explaining overlap knit line technique](/content/dam/graco/aftd/images/Charts/knit_line_techniques_overlap.rgb-01.jpg)
Sloping overlap
![A figure explaining sloping knit line technique](/content/dam/graco/aftd/images/Charts/knit_line_techniques_slopingoverlap.rgb-01.jpg)
Parallel pass
![A figure explaining parallel pass knit line technique](/content/dam/graco/aftd/images/Charts/knit_line_techniques_parallel%20pass.rgb-01.jpg)
Butt joint
![A figure explaining butt joint sloping knit line technique](/content/dam/graco/aftd/images/Charts/knit_line_techniques_butt%20joint.rgb-01.jpg)
Automation techniques
Programming of the robotic dispensing system can also play a critical role in achieving bead path application requirements. Depending on part complexity and axis, adjustments to the automation motion can help optimise the dispensing process. Several automation motion techniques include the rake motion, traditional motion, reverse rake, and reverse rake and brake motion.
Traditional motion
![A figure explaining traditional automation knit line technique](/content/dam/graco/aftd/images/Charts/knit_line_techniques_traditional_motion.rgb-01.jpg)
Rake motion
![Rake automation technique](/content/dam/graco/aftd/images/Charts/knit_line_techniques_rake_motion.rgb-01.jpg)
Reverse rake motion
![Reverse rake automation technique](/content/dam/graco/aftd/images/Charts/knit_line_techniques_reverse%20rake_motion.rgb-01.jpg)
Reverse rake and break motion
![Reverse rake and break automation technique](/content/dam/graco/aftd/images/Charts/knit_line_techniques_reverse%20rake%20and%20break_motion.rgb-01.jpg)
Summary
In CIPG and FIPG, knit line dispense techniques and automation motion techniques play a critical role in proper bead dispense and achieving the desired knit line. In addition, here are some other important considerations:
• The rheological properties of the material
• Material viscosity
• Temperature
• Bead profile and functionality
• Dispense valve sealing technology
• Dispense parameters
• Equipment fixturing
• Substrate design and complexity
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