How to Make a Heat Sealer

Step 5 Now make the circuit

Here's the schemmy. If you want to really DIY, you can forego the PIC and power it with a 555 timer and potentiometer setup.

Comments

[bgroicahn]

 An incandescent light dimmer though a GFI breaker would be just a useable and a lot easier to make.

[klee27x]

That would miss the point. This isn't a foam cutter. The PIC doesn't do PWM power control. It is just a fancy way to provide a user-adjustable full-power timed pulse with a single button. (Actually 2 timers... there's an adjustable delay BEFORE the pulse starts, too, in case you want it. For instance, you might want a half second or so to readjust your hands after pushing the button, if you're sealing a bag in a way that you can't use one hand.)

You have to melt the plastic. The idea is to get the wire up to temp AS FAST AS POSSIBLE, then immediately cut power. So you could use an on/off switch, if you have good timing. But a light dimmer would do nothing to help for a heat sealer. Sure, you could set the power to the point where it would only just be able to reach the melting temp of the bag, but then it'd just take LONGER to actually reach that temp, and you'd still have to turn it off and wait for it to cool down before opening the heat sealer.

[bhushan1572]

Dear klee27x,
please let me know if the current to be passed through is AC or DC.

I have tried for both AC and DC in one of my designs where i have a grid system to pass the current through. Please answer my few quries :

10 Ni wires in series total resistance 25 Ohms with : (each piece : width 1mm, 18inch long, 2.5 Ohms )
1. Do we have information regarding plastic bag thickness and temperature needed to seal it and corresponding current required?

2. I am able to seal it with naked wire but when put behind a teflon tape(standard one used in impulse sealers), then it does not seal at all. to solve this problem, should I pass more current or should I heat it for longer duration.

I have a very simple circuit designed for the pulse.
I am not using any transformer as AC supply is 240 V, current being passed is around 10 Amp for this 25 Ohm series strip. if any one is interested.. i will post the full design details.

[Francisco.G]

Hi bhushan1572, I´m interested in see the details of you circuit for the pulse, seem quite more simple. I´ll would be very grateful. I´m making an automatic bag sealer and once if finish it i will post my instructable. My e-mail is [e-mail]

[bhushan1572]

Hello, thanks for your interest. I have actually completed and successfully implemented the circuit.
As mentioned earlier, I took 10 Ni wires of 2.5ohms/18inch in a grid based structure. We have 230 V AC supply at home. I prepared a timer - RC circuit through a relay where in i used a switch.
Once the switch is turned ON, the capacitor starts charging, within 3 seconds the capacitor is charged and the relay is cut-off (reverse action through a NOT gate to a transistor).
So actually I am passing around 9.2 A AC current through the NI grid for 3 secs. This heats up suffieciently to seal up the bags.
The said design as attached is used for packaging 25 bags in 6 seconds.
This is faster than an automated machine.
Please find attached images for the actual design

[klee27x]

1. No.
2. Dunno what your timing circuit is, but it shouldn't be too hard to increase the pulse to see what happens? Or just trip it twice, quickly?

Be careful!

[klee27x]

Well, to be fair, a light dimmer would be useful if you were running a very low resistance filament from AC power, and you had to reduce the current draw (to prevent overloading your outlet and/or circuit breaker). But timing the pulse would still need to be done with a separate method.

[Salsepareil]

Hello. In very interested in your realisation, thanks very much! Their is many time I was searching something like this for making a bag sealer home made.

I've no problems with matérials, but for electronic I'm quite bad, I'm able to solder conponents but not to understand or modifie the schem.
So I 've few questions: Will it works with an intern computer alim? (I think it is 12V), and were must it be solder in the schem? What is the "box" written:"12v/2 +amps, 20V/3+amps,24V/4+amps" ?

Also, with a 555timer, will it be conected exactly same that the custom PIC? I don't saw where to connect the potentiometer (I think it is not the tactil switch), and what potentiometer would works ?

I've not already start to serch the component because I prefer first understand well and be sure I can do it, I juste know were to find nichrome on EB.y. Maybe you steel have conponement kit? that should intéresed me to be shure they are the good ones.

In case, I prefer to talk with you, but because English is not my language and make understanding mutch difficult. But maybe, would you allow me to give a link for speeking about it in a french forum, that can help me too for understandig and making it ?

[afawcett]

can you elaborate on the 555 timer and potentiometer setup? i am looking to make a solar water heater with a 10' x 25' black polyethylene sheet folded in two. then i want to heat seal rows so that the water alternated directions with each row. this allows time for the water to heat up. i want to be able to heat a pool to a reasonable temperature, without purchasing expensive heating panels. i also like this idea because it's highly portable; i can roll it up when i am not using it, and even let a friend borrow it to heat up their pool :)

[klee27x]

Well, all you need is a "555 one-shot" circuit. If you google it you'll find websites and tutorials. It's just a timing/delay circuit. The output of the "one-shot" could power a transistor/relay to deliver the pulse power. To do something like this, I suggest you take a look at using nichrome ribbon covered with teflon tape (pressed flat side against sheets) and a much higher amperage power source. This makes a wide, strong seal and doesn't cut, so your sheet doesn't expand and twist like a bunch of sausage links when you put water through it. You probably want to use at least 3-5 mil plastic for something like this, I'd imagine.

[afawcett]

i forgot to add in that i was using 4 mil plastic. thank you so much for the quick reply and information! :)