How to Make a Heat Sealer

Well, finally, as promised, here's my how-to.

Q. What's a heat sealer?

A. Also known as an impulse sealer, a heat sealer uses a resistive heating element to seal and/or cut thin plastic bags or sheets. Rather than using continous heat, which would turn the bag into a gooey-edged mess, it uses a timed impulse of heat - hence "impulse" sealer.

This instructable reveals to you many secrets that certain people do not want you to know! I have already received several death threats from one of the major recloseable bag companies. Please enjoy this instructable, which might be my last....

Step 1 Why would I want a HEAT SEALER, anyway?

Using a proper heat sealer, you can do a much more than making toothpaste packets!

Click on the pics below to find your reason. If you do not see it, then perhaps playing with Dremel tools and electricity is reason enough.

And dare I say, you can even store your beads with it?!

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.

[Francisco.G]

Hi, this intructable is awesome. I´m doing an automatic bag sealer as a project to collage, I have all the automatic mechanics done but I really having trouble with the actually sealer part. I already have all the components to make this instructable but I wanted to know what PIC and program environment do you use and if there is a chance you share you program?? My e-mail is [e-mail] I´m new at instructables and I´m enthusiastic about share my first instructable that will be this automatic bag sealer. Thanks a lot.

[urbanwoodswalker]

I am wondering if I can heat seal an irregular line with something that will NOT gunk up the plastic mess. (Not a straight line).

I am enjoying your humor on this instructable ...

[VadimS]

I'm thinking of building this, but using 12v and thin copper wire. I'll probably use a relay instead of a mosfet, they can handle much higher peek currents.

You can get 6 mil Polyethylene rolls for use in construction (vapor barrier). 16"X375' for about $32. Enough for a lifetime supply of bags :P
It's really good quality (I use larger rolls when insulating), should be perfect

[Peraloca]

The Photobucket pictures are in a private album and can't be seen. Also, the link to the video, is missing. Can you help with that please? Thank you.

[Peraloca]

Ok, I will answer my own request. I already found your comment about this in another section of this page. Thank you anyway.

[useful1]

I made a 555 astable circuit using stainless steel wire as the wire sealer, with the claim on this instructable, saying you can make a heat sealer using a 555.

It's currently connected to a 12V power source. It doesn't work. The wire doesnt get hot enough to melt plastic. I believe that 200mA, which is the amperage, of a 555, does not make the stainless steel wire to get hot enough.

Perhaps, it is the wire im using. But as far as making a 555 heat sealer, I believe that myth is busted. Unless someone points to me a webpage which tells me how to make one correctly.

[shinobitron]

using the 555 as a straightforward output source probably won't be enough power, what would be more effective, would be to route the output pin of the 555 to a transistor or mosfet. In this instance the 555 would only function as an adjustable signal generator (think pulse frequency modulator using a potentiometer) that triggers the mosfet which would be able to draw more power to your heating element/wire. you could either use separate power sources, or the same power source/battery, as long as the 555 signal generator part of the circuit was protected with a voltage limiter. the advantage of this over simply making an oscillator or astable multivibrator with only two transistors, is that you can control the frequency of the pulses easily and accurately with the 555.
hope that helps.

[msw100]

I think the author said nichrome wire was used not stainless steel,nichrome wire can be found in electric fire heating elements

[klee27x]

"Nichrome" is a trademark, I believe. But it's a commonly used term, sorta like calling any tissue a Kleenex. The wire I'm using isn't actually nichrome, FTR.

Stainless steel wire is generally pretty good for this kind of thing.

[msw100]

its resistance is different from stainless steel,whats so hard to ubderstand about that?

[klee27x]

Hi. The 555 IC is suitable only to make the control circuit. To deliver the power, you just use the 555 output to control a power device such as a power relay or a power transistor.

Also, you must carefully choose the wire gauge, length, resistance, and power supply to work together. Using 12V, you would probably need at least 6+ amps and a suitable matched wire to make a decent sealer impulse. This is much more than 200mA!

[ykikeg]

Hello
Is it possible to use an ac transformer 110 to 19v ac, or i can only use dc?

[shinobitron]

Like David said, technically you could rectify the ac first using a full wave (or even if desperate half wave) rectifier (diode bridge basically ,easy to find on google) and could then change the desired frequency of the DC by using a pulsed capacitor system on your output. You may ask, "frequency of DC??? but pulsed dc is fairly common depending on your rectification method. Anyway once you rectify the dc, you can control the power and speed of your pulses by using capacitors of varying sizes to determine charge/ discharge times. Variable capacitors are also an option. Additionally you would not necessarily need a separate DC source, as a voltage limiter such as LM78M05 could be used on the input of an IC to prevent any damage. However ykikeg's question i believe is if you can step AC voltage up and down, to which the answer is yes.
Step up and step down transformers do this all the time. using thicker/thinner wire, and varying combinations of turns on your primary and secondary windings of your transformer, you could change 110 vac to 19vac. hope that helps all.

[DavidRobertson]

You could just use a bridge-rectifier to convert it into DC. You would need to use a smoothing capacitor on the output of the bridge rectifier and then probably also regulate it using a simple voltage regulator IC.

[klee27x]

Well, if you want to control AC current, you can't use simple transistors. You would need to use TRIACS, relays, or SCRs. Also, you'd still need a separate source of DC to supply the uController or timer IC. Or you'd need to be much smarter than I am with electronics and design a timing circuit to run off AC.

[jwu6]

The video link is dead :(

Do you think you would be able to re-upload it?

Thanks in advance!

[klee27x]

Awwww. Photobucket just nixxed all user's "remix videos." That's where you use their web-software to edit a video. So that video is really gone! Sorry. Anyways, I'll just say the vid shows me filling a bag with air, then sealing it. Then cutting it in half, and then I pop both balloon halves to trippy techno music, and it was really freaking cool. Too bad you missed it. :)

[jwu6]

awwww, that would've been freakin cool! :)

Anyway, what are your thoughts on using teflon coated nichrome vs. non-teflon coated?

Thanks again!

[klee27x]

Teflon coating the wire is probably a good idea. With a bare wire, I could run into trouble if I tried to seal a foil lined bag. (But in practice, it seems to work ok). Also, putting a strip of teflon tape over the wire would keep it from moving when it heats and expands. But the bag, itself, seems to keep the wire in place. It gets "sticky" when it heats, and the wire stays put.

So there are definite advantages to using an electrical insulator, but it can also be done with a bare wire without much issue. I chose not to cover the wire, because that would make it more likely that the plexiglass melts by the time the bag seals.

[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 ?

[wdugdale]

Great Instructable...Thanks for posting it.
I've used Heat Sealers before and repaired them...but now I need to make a big one for my project.

Do you still have some of your Kits available?  I can do the building and wiring of Nichrome, but the electronical timer and PIC I have no knowledge of.

I need to make a Heat Sealer / Cutter that has 2 - 60" seal blades...So any help on adjusting the components would be greatly appreciated.
Yes, I need 10 Feet of Sealing Length.... and don't really have the  Thousands of dollars that most companys want.

If you have some kits available, you can reach me at [e-mail]
Thanks
Bill

[forspam2004]

Great product and instruction. I'm a newbee to electronics so if you have more kits left i am interested. please e-mail pm instructions to [e-mail]

[SoftySquirrel]

Hi

I have very much enjoyed reading your Instructable and would like to have a go at building a heat sealer.  I am very much a newbie in electronics, but have managed to source all the parts (I am in the UK) except for the MOSFET.  I know enough to know that there are N Channel and P Channel MOSFETs (and others!) but not enough to know which one I should be using!

Can you either tell me the MOSFET part number you used or what sort I should look for.

Regards
SoftySquirrel

[klee27x]

To simplify things greatly, making many assumptions along the way, I'm going to assume you'd be best off with an N-FET.

Specs that are most important might be max voltage and max sustained/average current capability. (Current capability is based on on-resistance and power dissipation, so you don't have to look at and understand all the specs, just those 2). Note that the max current is only valid if the gate is set to +10V. When driven to only 5V, as I have done in my own circuit, you have to derate the part.

One other spec to be aware if is maximum gate voltage. This is most commonly expressed as +-12V, or +-20V. You cannot drive the gate higher than that number, or it will die.

The other big spec for FETs is the rise/fall time. This is not important, at all, for this particular app, since there is no high frequency switching involved.

The N-FET I used is an obsolete part and was a bulk purchase. The specs are 30V, 9A, and gate voltage +-20V.

Because power FETs can be effectively paralleled to decrease their collective resistance, they make an ideal part to stock up on. If you burn out a FET, you can replace it with 2, next time. :)

[SoftySquirrel]

Really helpful :-)
Thank you
SoftySquirrel

[socaldt]

Hi,

I am really interesting in your neat project. Are you willing to share your PIC program? Which chip did you use? I hope it would work with either the 16F84/16F628. If you do not mind, I would love a copy or some help since I barely played with some of the PIC tutorials.

Dave

[klee27x]

I used the 12F629 for this.

Perhaps you could recommend a good hosting site for HEX and assmbly files, so I could post a link?

[socaldt]

I personally don't know of a good hosting site for HEX and assembly files but I use www.fileden.com for file hosting. Maybe you can zip the files for convenience. If you prefer to e-mail the files then that is fine. My e-mail: [e-mail]

Thanks

[weaselkeeper]

Nice gizmo, I wouldn't have thought plexiglas would work. But I might try it instead of wood, a lot easier for me to work with :P

I did find an assortment of gauges of nichrome wire on ebay, for like $10, and some ribbon, when it gets here, will try building this.


I also wonder if you could do this with a sort of pizza wheel mechanism.  Might work with the ribbon.

Thanks for the instructable.

[klee27x]

FYI, my original build lasted for a good long while. But after maybe 300 seals, the wire had melted into the plexiglass.

On this one, I put a strip of teflon tape on the blade, underneath the nichrome wire. I don't have the pics, because the tape didn't arrive until after I made the Instructable. I also put a strip of tape on the base. Some 1000 seals later, it's working like new. Teflon is a great insulator.

The bigger the gauge of wire you use, the more likely you are to melt plexiglass. So keep that in mind.

[klee27x]

Also keep in mind that I had a precise timer for the pulse and only gradually increased it. If you're just messing around, you could melt the plexi in one go. :)

[incorrigible packrat]

Neat. Years ago, my mammy had a similar doodad known as the Decosonic Vacuum Bag Sealer. It had a little fan to suck air out of the bag before sealing it. It worked quite well, until I investigated what happens when you put a match on the wire... It wasn't clear, like this one, however, so it was tres difficile to get the baggie edges lined up all nice and even.

Awwwwwwwwwwwww! Sleepy Kitty!

[alpha1040]

lol matches...