Plastic (PE) bags end use (oil) leaks

hello,

where are the leaks, from the bag pe or the seal? what is the density of the pe? are you bying the bag material, or forming it yourself? is the bag material rated for oil? what kind of oil? what does the manufacturer of the bag have to say about it?

if it is the pe itself that is leaking, then you have a porosity problem. that is usually caused by contamination in the manufacturing process. most likely the manufacturer will not be willing to change his process just for you. you could use a vendor that makes a higher quality bag. for example bags intended for hazardous waste. they would cost you more, but would be better quality. it could be that the oil itself is degrading the pe.

again a better bag, or a bag made from different materials.

i remember when i worked at a disposable glove factory. they were having trouble with the continuous chain making tight bends. before i recommended a change to a teflon product, i talked to the research engineers. they tested the glove mix with teflon sprayed into the mix (worst case), it left what they called "fish eyes" in the pe. these were weak spots in the plastic. so, needless to say, they did not start using teflon lubricants.

hi there

thanks for the follow up! in fact we are the manufacturers and the leaks are at the bottom seals where the gusset folds are!

we have looked at the machine settings such as the line speed and temperature of the sealer bar but there should be a solution for making leak-proof bags on long term basis!

however, the application of these bags for our customer is for containing margarine in liquid form when filling!

appreciate your feed-back and comments!

hello,

are you saying the leaks are at the actual folds in the plastic? have you examined the area, with out any filling, with a microscopic? looking for microscopic cracks. what is the mold temperature when the bag is formed and folded? or is it folded after it comes off of the line? in other words is the bag material continuous, then cut and sealed and folded on the bottom in one operation after it has cooled down? it might be that the plastic temperature is too cool. try putting some type of heat under the line prior to sealing, cutting and folding. it could be hot air. which would be the easiest to control, being able to dial up or down the temperature and air speed.

of course, this will not help if after getting a good fold, the bag is cold when it is filled. the act of filling and opening the folds could crack the plastic at the folds. are you also filling the bags for the customer? are the bags made, just prior to and as you fill them?

cold plastic does not like to me manipulated. it might be that you have to change the mix to increase the softness of the pe. i understand how your line is probably dialed in and set for optimum production, but you will have to investigate.

one easy test is to make a balloon out of it by closing the open end around a nozzel and check for air leaks while it is under slight pressure. you can do this just by moving your hand back and forth under the area of leaks, or have it upright so that the leak will flow onto the skin of your face. your face is very sensitive.