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How to Solve the Difficulty of Demolding?


What is mouding?

In our daily life, the molding is seen anywhere, usually relevant to the plastics, mainly divided into blowing molding, injection molding, extrusion molding etc. And some times the PTFE fabric sheet of our company will help the demolding.

One of the most typical application for blowing molding is the manufacture of plastic parts for auto motives. Usually the manufacturers install the molding onto the corresponding location, then fit the two halves together, and started the blowing of plastic raw materials treated and fixed via the blowing needles. As examplified by the fuel tanks of anto motives, there will be some treatment in the process of blowing molding so as to make sure of the hollow part at middle. Then the demolding process will start after a fuel tank is done.

Blowing Moulding
Kautex Blowing Moulding Machine

Why does the difficulty of demolding happen?

When it comes to the reason why difficulty of demolding usually happens, here I list several common reasons for it in different aspects , according to some operating workers in blowing machines.

For the machine aspect, there is insufficient top output.


For mold aspect, the reasons are more variable.

1. The difficulty may result from the unreasonable demolding structure or improper position.

2. The blowing procedure may not be under appropriate temperature or the working process is under environment which is too dry.

3. The inner surface of mold is too rough for the plastic parts to release.


For the procss aspect, here I also list two reasons.

1.The barrel temperature is too high or the injection volume is too much.

2.The injection pressure is too high or the pressure is maintained and the cooling time is long.


Four raw material aspect, there may be insufficient lubricant.

How to solve the difficulty of demolding? PTFE fabric will help.

Like I just mentioned in the above section, I would like to provide you with the solutions correspondingly.

For the machine aspect, we have to test whether the top output is sufficient via some trial tests before normal working, since every time the works operate the machines, there must be some time for testing or trial production as as to make sure of the stable production.

For mold aspect,

1. If the problem really comes from the unreasonable demolding structure or improper position, it would be easily told from careful observation. Then the further adjustment is needed by the 3D-digital mold designer for more fitness.

2. In this way, as exemplified by the fuel tanks(since I once worked in a factory that specializes in fuel tanks for over 1 year), there are usually many unshaped fuel tanks which can be seen over the workshop, usually the waste rate is 2~5%, may be under contraction or expansion. In this way, with no doubt will the plastic part be difficult to demold. And the solution is that the workers shall pay great attention to the working environment, and usually speaking, an experienced worker could help avoid it.

PTFE Fabric Solution

3. For this part, it is the most difficult to handle during all the difficulties since it is almost impossible to change the materials of molding, or the surface after it is done. Under often circumstances, the plastic part will stick to the mold, and usually the workers have to manually remove the part, which takes much time, and working under high temperature will bring about some possibility of harm to workers. Here I recommend the PTFE Teflon fabric sheet, which could stick to the surface of mold, since the Teflon fabric is non-stick and high temperature resistant, it totally consists with the working environment. Recently, there is a US consumer who require this piece of sheet to stick onto the inner side of mold surface for better demolding.

For the process aspect, the two potential difficulties all result from positive reasons of the operator, just like mentioned above, the workers in charge of the blowing machine usually have to work at extreme hot temperature and for long time continuously, in this way, the workers in charge have to be more knowledged, experienced, and flexible so as to prevent and solve the potential problems.

Four raw material aspect, if there is insufficient lubricant, just check whether it is true, if so, add some lubricants before mixing of raw materials every time or at regular intervals.

That is all for the reasons of difficulty in demolding and corresponding solutions to difficulties in demolding. By the way, for more details about the above-mentioned PTFE Teflon fabric sheet, feel free to contact us, it is sure to give all consumers a better user experience.

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