INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Looking for alternative for teflon foil

Looking for alternative for teflon foil

(OP)
Hello all,

Some background: my company makes filling machines. The (PE) bags with the product are sealed by using so called sealing beams. The beams are pressed onto both sides of the bag and the bag is sealed using a heated element. To protect the bag, and to prevent that the bag sticks to the heating element, we use a teflon foil between the bag and the heating element. I will add some specification of the foil later. The heating elements are heated up, in high capacity machines, to about 600 degrees Celcius, or 1100 degrees Fahrenheit.

The problem is, that in some machines with high capacity, the telfon foil wears out too rapidly, primarily due too overheating.

My question is: is there a commercially available alternative for this teflon foil, with better heat resistance and similar non-sticking characteristics.

RE: Looking for alternative for teflon foil

(OP)
Temperatur of the sealing beams is by the way not 600 degrees Celcius. The maximum it is set to is about 220 degrees Celsius. But no one ever checked this with an temperature gauge..

RE: Looking for alternative for teflon foil

You could try a PTFE filled PEEK. Or even ordinary PEEK - it's quite low friction as is. 220C will be no problem for it.

Example: http://www.victrex.com/en/aptiv-films

H

www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.

RE: Looking for alternative for teflon foil

(OP)
Thank you Pud.

One additional requirement: it needs to be foodgraded.

I'm not sure PEEK is an option in that regard, but I will check.

RE: Looking for alternative for teflon foil

(OP)
I think not, since the heating element is just a flat copper strip. But otherwise a good suggestion.

RE: Looking for alternative for teflon foil

It can be applied to copper so take a little closer look, it's worth asking the vendors. Instead of just solving the maintenance problem, you have the opportunity to eliminate the maintenance altogether. Not saying the xylan will definitely work, but I think you are narrowing the scope of the problem too much.

Ideally the machine would last forever, require no maintenance, be infinitely fast, and free to operate. Obviously you will never achieve those targets, but you can always try to improve reliability, speed, and efficiency.

For all we know, the Teflon foil could be a "oh crap, the bags stick to our prototype and we've already completed the design, what do we do right now so we can ship these things" solution. I can buy a small bag sealer off the shelf that doesn't have sacrificial Teflon foil that requires maintenance. What does it use, how do they get away with it, and why do you feel you can't?

RE: Looking for alternative for teflon foil

Polyimide tape might work too, it has decent release properties. Or perhaps a silicone rubber sheet...I think I like that option the best, because it has both a decent release property, and good thermal conductivity.

RE: Looking for alternative for teflon foil

Have you researched other types of equipment such as ultrasonic sealing machines?

RE: Looking for alternative for teflon foil

There really is not anything better than teflon. The foil is considered a consumable. Proper operation and maintenance is essential to get decent performance, however. Impulse heat sealing is more complex than it seems. The foil is normally exposed to temperatures close to its decomposition limit. Exceed this limit and the foil will be ruined on the first sealing cycle. Some machines are more robust and expensive than others.

RE: Looking for alternative for teflon foil

We have in operation many vacuum sealing machines that use the same mechanism to close the plastic bags
The teflon foils used to be damaged after one day of operation (60 cycles aprox)

I lower the voltage applied to the heating element and the problem was solved

RE: Looking for alternative for teflon foil

(OP)
Lukin1977, lowering the coltage = lowering the temperature? I do need the temperature..

RE: Looking for alternative for teflon foil

yes. I know you need the temperature

But maybe you can lower a little the temperature and increase the sealing time and still achieve good bag closing
I am just telling you what I did and how I solved a similar problem

RE: Looking for alternative for teflon foil

Sealing is a function of temperature and dwell time. If the Teflon is overheated it will be destroyed. The heater power must be limited so that it does not overheat the Teflon, and then the heating period must be set long enough to allow the film to reach sealing temperature. In addition a cooling dwell is required so the weld solidifies before clamping pressure is released. If you are burning the Teflon you have probably also ruined other parts that will need to be replaced. Decomposing Teflon is very corrosive (and toxic). The heating ribbon will get corroded and cause a hot spot which will cause another failure in the Teflon very soon.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close