Blown film machine equipment FAQs: how to deal with the problem of uneven film thickness?

Uneven film thickness is a common problem in the use of blown film machine equipment. This not only affects the quality of the product, but also may lead to a decline in production efficiency. This article will provide you with detailed answers on how to deal with this problem.

1. Reasons for uneven film thickness

1.1 Equipment problems

Wear and tear of screw and barrel: after long term use, the screw and barrel may wear and tear, resulting in uneven delivery of the plastic melt.

Unreasonable mould design: Unreasonable design of the runner of the mould may lead to uneven distribution of the plastic melt inside the mould.

Improper blowing ratio: too large or too small blowing ratio may lead to uneven film thickness.

1.2 Problems of process parameters

Improper temperature control: too high or too low temperature will affect the fluidity of the plastic melt, resulting in uneven film thickness.

Unstable traction speed: unstable traction speed will lead to uneven film stretching.

Uneven cooling speed: Uneven cooling speed will lead to different crystallinity of the film, thus affecting the thickness.

1.3 Problems with raw materials

Uneven plastic granules: Uneven size and shape of plastic granules may lead to inconsistent melt flow.

Inconsistent raw material quality: Inconsistencies in the melt index (MI) of the raw material can affect the thickness uniformity of the film.

2. Solutions for uneven film thickness

2.1 Equipment maintenance and adjustment

Regularly check the screw and barrel: regularly check the wear and tear of the screw and barrel, and replace the parts with serious wear and tear in time.

Optimise the mould design: optimise the runner design of the mould according to the actual production demand to ensure the uniform distribution of the plastic melt.

Adjust the blowing ratio: according to the film thickness requirements, reasonably adjust the blowing ratio to ensure the uniformity of the film.

2.2 Optimisation of process parameters

Precise control of temperature: use high-precision temperature control system to ensure the stability of temperature in each section.

Stable traction speed: use frequency converter and other equipment to ensure the stability of traction speed.

Uniform cooling: optimise the cooling system to ensure uniform cooling speed of the film.

2.3 Raw material management

Screening of plastic granules: screen the plastic granules using a sieve to ensure that the size and shape of the granules are consistent.

Selection of high quality raw materials: Select raw materials with stable melt index (MI) to ensure uniformity of film thickness.

3. Practical case analyses

3.1 Case 1: A plastic products factory

A plastic products factory in the production process found that the film thickness is not uniform. After inspection, it was found that the runner design of the mould was unreasonable. By optimising the mould design and adjusting the blowing ratio, the problem was effectively solved.

3.2 Case 2: a packaging materials company

A packaging material company found that the film thickness was not uniform in the production process. After analysis, it was found that the temperature was not properly controlled. By precisely controlling the temperature and using a high-precision temperature control system, the problem was significantly improved.

4 Summary

Uneven film thickness is a common problem for blown film machine equipment, but it can be effectively solved through equipment maintenance, process parameter optimisation and raw material management. I hope the answers in this article will be helpful to you.

Ruian Yunfeng Machinery Factory is located in Ruian,Zhejiang, we are specialized in designing, manufacturing and marketing series of packaging equipment ,which including plastic bag making machine,printing machine , film blowing machine etc.