I need to automate a process that involves applying hot glue to paper. I own a standard handheld hot glue gun, like this one:

hot glue gun

Sticks of room-temperature glue are fed in the right side. Pulling the trigger slightly advances the stick of glue. The orange tip on the left is heated, melting the glue stick, and the pressure of the advancing glue stick causes heated liquid glue to come out of the tip. It quickly cools once it's applied to a surface such as paper, and becomes a room-temperature adhesive within just a few seconds.

Industrial-scale machines exist to apply hot glue to surfaces, but they are very expensive. They don't involve glue sticks and hand-activated triggers; they involve glue beads and some other mechanism for forcing liquid hot glue out of the heated nozzle, and then cutting it off.

Using either the glue gun that I already own, or simply the sticks of glue with another heating-and-pressure mechanism, is there a simple way to robotically apply hot glue to paper?

EDIT: In my application, the paper will be on a flat tray. The 'bot needs to apply a line of glue around the edge of a 1" circle, or a 1" square. Once the application is complete the glue should stop emitting from the gun. There is often a "streamer" of glue after it stops emitting; I want this to be handled without a mess. The paper is then move a few inches, and the 'bot squirts out another circle or square of glue. The process keeps repeating.

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    $\begingroup$ Could you narrow the scope of the question? This is an open ended design problem. $\endgroup$ – holmeski Apr 13 '19 at 13:19
  • $\begingroup$ @holmeski Thanks for the suggestion. Does my edit help? If not, can you advise what else I could add? $\endgroup$ – CreatedByBrett Apr 13 '19 at 14:18
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    $\begingroup$ It is still an open ended design problem, you've just been more specific about the requirements. What have you tried? What is not working? What have you thought of? Demonstrate that you have thought about this problem. Tell us about the shortcomings of the design you are imagining; that is what we can help you with. $\endgroup$ – holmeski Apr 13 '19 at 14:32
  • $\begingroup$ @holmeski I guess I shouldn't have asked. I haven't tried anything. I'm new to robotics. I was hoping somebody here had already designed a 'bot that could do this, and they'd just add a diagram in their answer and say "Here's what I did." $\endgroup$ – CreatedByBrett Apr 14 '19 at 14:25

The problem I see is that after a while of holding the trigger, you have to let go of the trigger and then squeeze again. This is because the trigger has advanced the stick of glue as far as the travel allows it. So by squeezing it again, the trigger goes further up the glue stick and grips at a new location.

You can either automate this squeeze-release-squeeze-release pattern or look at adding a continuous feed solution (such as these).

You are only after 1" squares or circles so I think the trigger method would suffice. The actuation method could be pneumatic or electric, it doesn't really matter. As long as you can get the squeeze-release motion. At the the time releasing the trigger you would need to stop the motion until you are back into the squeeze part of the cycle again.

A standard X-Y gantry system would be sufficient. These can be cheeply purchased off sites such as AliExpress or Ebay. Like this one.

XY CNC Plotter

You will need stepper motors and software (such as Mach 3 or Linux CNC) to drive the stepper motors using G-code.


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