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Manufacturing Scrap Reduced by 30% Annually through Data-Driven Problem Solving

May 19, 2022 - 10 min read

Key Findings

  • Complex manufacturing processes are influenced by a large number of parameters
    • In such processes, root causes for malfunctions and scrap are often only indirectly identifiable in process data
    • It is usually not known beforehand, which variables are associated with the problem
  • From this, the following requirements for modern process analysis tools can be derived:
    • Recording and processing of large amounts of historical process data
    • Flexible data visualization, adaptable for a variety of possible use cases
    • Provision of suitable tools for target-oriented data analyses
  • Using the functions of the ENLYZE platform, one of our customers was able to reduce manufacturing scrap for one of their product groups by 30 %

About our Customer

In this case study, we present how one of our customers used the ENLYZE platform and a data-driven approach to reduce its scrap for a product group by 30%, saving huge annual costs on a production line that was digitized by ENLYZE.

The company from North Rhine-Westphalia, with which we have been working together for about a year and a half, is a manufacturer of adhesive tape solutions that are used worldwide by customers in a wide range of industries, such as medical technology, automotive and construction.

If you are interested in exchanging experiences with our customer, we will be happy to establish contact with the company for you.

Compact Overview: Adhesive Tape Manufacturing Process

In simplified terms, the production of adhesive tape involves the following steps: First, a liner siliconized on both sides is unwound from a roll and coated with a liquid adhesive. The adhesive is then dried and the resulting adhesive film is then wound onto another roll. To prevent the individual winding layers of the adhesive tape from sticking together during winding at the end of the manufacturing process, the siliconized liner is coated with silicone of varying release force, so that the adhesive always adheres more strongly to the side with the higher release force.

In the production line, the adhesive tape runs over different rolls. If the speeds between these deviate from each other (so-called leading), slippage occurs between the rolls and the adhesive tape. Such a lead cannot be completely avoided due to the process and is not problematic for the quality of the product as long as it is in the low single-digit percentage range.

Normally, the so-called master roll is the point with the highest friction between the production line and the adhesive tape. The speed of the master roll thus defines the production speed.

The speed of the structured master roll normally defines the speed of the entire manufacturing process
The speed of the structured master roll normally defines the speed of the entire manufacturing process

Problem Description

During the production of thin transfer films at one of the production lines of our customer, a recurring problem was observed. Sometimes, while rewinding the adhesive tape after coating, so-called partial rewinding occurred. This is an undesired detachment of the adhesive tape from the liner material which leads to damage of the adhesive tape. The repeated occurrence of this production defect resulted in a manufacturing scrap of approx. 11,000 meters per year. Furthermore, during partial rewinding, some of the adhesive film remains on the rear side of the liner and thus contaminates the rewinding mechanism, which leads to downtimes and entails costly cleaning.

Adhesive tape without (left image) and with partial rewinding (right image)
Adhesive tape without (left image) and with partial rewinding (right image)

Through extensive investigations, our customer was already able to rule out a number of sources of error that potentially could have been the cause for the partial rewinding. Those included errors in the siliconization of the used liners or irregularities in the drying process of the adhesive. Changes to the line tension did not bring any lasting improvement either.

Why Could the Problem not be Solved without ENLYZE?

The production of adhesive tape is a complex manufacturing process that is influenced by a large number of different parameters. The complexity results not only from the number of process parameters, but also from the fact that some of the parameters interact with each other.

If malfunctions occur in such a process, the causes of the problem can often only be identified indirectly in the process parameters. The identification of problem causes is made especially difficult by the fact that it is usually not known beforehand which parameters are related to the observed problem.

In order to identify the root cause of the problem of partial rewinding, our customer would need to have the ability to examine as many process parameters as possible. The PLC of the production line (built in 2005), which was digitized by ENLYZE and our edge device, the ENLYZE Spark, continuously processes about 400 actual and target values of various measured variables. These parameters therefore represented the set of variables which needed to be investigated by our customer.

However, the problem was that the PLC with the operator terminal connected to it did not provide suitable tools to be able to efficiently examine these large amounts of data. The operator terminal does have a graphical user interface (GUI) for accessing stored process data. But neither does the GUI allow more in-depth analyses of the process data, nor does it provide functions to export the stored data so that it can be evaluated with other programs.

Due to the lack of analysis tools and the limited availability of process data, the tape manufacturer could not solve the manufacturing problem without ENLYZE's process data analysis. Only the process understanding from the experts at our customer with access to the functions of ENLYZE brought the desired result.

How Could the Problem be Solved with ENLYZE?

Since the integration of ENLYZE into the production line of our customer, all target and actual values of the machine PLC are processed and made available in the web-based ENLYZE app for target-oriented data analyses.

When the error pattern described above was detected again in a batch from previous production, the head of development of the company used the analysis dashboard in the ENLYZE app to investigate whether there were any abnormalities in the measured values from the control system during the production period of the faulty batch.

Data selection with the ENLYZE app analysis dashboard: Datenauswahl im Analyse Dashboard der ENLYZE App: The production period of the batch is either entered directly or determined via the production order number.
Data selection with the ENLYZE app analysis dashboard: Datenauswahl im Analyse Dashboard der ENLYZE App: The production period of the batch is either entered directly or determined via the production order number.

In a direct comparison of some of the numerous roll speeds, the head of development noticed that during production of the affected batch there was a discrepancy of about 20% between the actual speeds of the laminating station (11 m/min, corresponding to the target value) and the drawing station (13.6 m/min), i.e. considerably more than would have been expected under normal circumstances.

Since a simultaneous display of 400 available target values and actual values on the operator terminal of a PLC would be practically impossible to implement, such a display is usually limited to a few process variables. For this reason, the two investigated roll speeds are not displayed on the terminal. That is why it was impossible to detect the speed difference without ENLYZE.

With the ENLYZE app analysis dashboard, it is possible to effortlessly compare process data of one or multiple production runs during their production intervals.
With the ENLYZE app analysis dashboard, it is possible to effortlessly compare process data of one or multiple production runs during their production intervals.

The discovery of this significant deviation was the starting point for carrying out manual speed measurements on the individual rolls of the production line. This revealed that the actual speed of the master roll was significantly higher than its target value.

The reason for the increased speed was insufficient friction between the master roll and the produced adhesive tape. In order to keep the tape tension at the setpoint value despite lower friction, the control system increased the speed of the master roll. Simultaneously to the tensile force at the master roll, the system regulates the line speed at the rewinding station. This simultaneous control of two process variables combined with the low friction on the master roll inevitably resulted in an impermissibly large speed difference between the rolls.

The resulting slippage led to severe abrasion on the thin silicone layer of the liner by the structured master roll. This damage, in turn, caused increased adhesion between the back of the liner and the adhesive surface when the adhesive tape during rewinding, which was ultimately the cause of the defect pattern.

After the slippage was identified as the root cause of the problem, it could be eliminated by adding a vacuum at the master roll. This now ensures a higher contact pressure and thus a higher friction between the master roll and the product.

What Cost Savings Could be Achieved by Solving the Problem?

Since the vacuum was switched on at the master roll, the error pattern of partial rewinding no longer occurred during the production of thin transfer tapes. Consequently, with the help of the ENLYZE platform, our customer has been able to save all costs that would have continued to be incurred in connection with the error pattern if the cause had not been eliminated.

The saved material costs alone amount to approx. 11,000 Euro per year since the implementation of this measure. The total cost savings are likely to be significantly higher, as operating costs for the plant, personnel and lost profit contributions during scrap production also have an impact.

Conclusion

The use case of adhesive tape production has shown that digitization offers enormous potential for reducing costs in production processes. However, this potential can only be exploited if the large volumes of data generated in those processes can be managed.

The ENLYZE platform makes this possible by recording and systematically processing all process data on the one hand, and by providing suitable analysis tools for extracting insights from the process data on the other. Due to its compatibility with many different data sources, ENLYZE can also be integrated into older production lines and be connected to a wide variety of subcomponents of production lines.

Of course, the problem of partial rewinding in the production of adhesive tape at our customer's plant was not solved by simply having the process data and analysis tools available - they must also be used in a targeted manner. Ultimately, the use case also showed that digitizing manufacturing equipment is an effective tool for solving problems for companies, especially when combined with an innovative mindset and a deep understanding of the own manufacturing processes.