# Simple plastic welding machine

I'm doing a little hobby project where I want to weld two thin plastic sheets together, using two heated plates with a specific pattern. I was doing this manually but felt that the result was unreliable as it had too many human errors, unable to control the pressure and the welding time.

I have electric linear actuator and Arduino in mind for this. I have never used any of it before, so before investing in parts I would like to ask if I am on the right path.

This is the welding process I am looking for: I place the plastic sheets in the middle of the two heated plates and then I push a button and the two plates shall move towards each other (>15 mm/s) and meet where the plastic sheets are. They “pinch” the plastic for a short period of x milliseconds and then moves back again to its original position. The plastic sheets should now have been welded together. So basically: a) Extend the actuator on button press b) Stop at full extension (or pre programmed position?). c) Stay in that position for x milliseconds d) Go back to original position and stop.

Please, take a look at the attached image for reference.

I know very little about actuators, so here are three questions: 1. Do the actuator "know" when it has been fully extended, so that the delay()-function will start when it is fully extended? That way I can mount the actuators to the aluminium profiles so that when they both are fully extended they are in connection with each other (second image). If not, I might need actuators with position feedback perhaps?

1. Do they have built in sensors where you can adjust the force it will continue to press on as it hits resistance? For example, if the actuator hits a wall, it will stop, but if is hits a 3 kg box it will continue and move the box? I'm thinking about the situation where they hit each other in the middle, if it's possible to adjust the pressure in a fairly easy way.

2. In my case, one actuator will be pushing the weight (~7kg) up, and one will be pulling the weight (~7kg). With an actuator capable of pushing e.g. +20 kg, will this situation affect the speed which they extend and retract? So in my case, the actuators will arrive to the plastic films at different time positions (diff >0,1 sec)? So, if I use Arduino delay(1000) for the welding time when they are fully extended, it will actually only be welding 900 ms if the arrival differs 100 ms.

I am 100% new to robotics, so sorry for some basic questions.

• adjust the pressure ... put a spring between the actuator and the plate ... google pogo stick .... what do you mean by this? ... one actuator will be pushing the weight (~7kg) up, and one will be pulling the weight – jsotola Jun 8 '20 at 16:08
• @jsotola put a spring between the actuator and the plate It's a good idea. But how can I connect a spring to the actuator? Do you have any device with built-in-spring and possibility to screw onto the plate in mind? I have searched but not found any. Regarding pushing and pulling weight, I was referring to the lower actuator as lifting the weight, while the upper is holding the weight as they extend. So, question was if that impact the speed of which they will extend, hence reach the middle in different time. – user26553 Jun 9 '20 at 9:35