Annealing Lehr


Annealing lehr.

The annealing lehr is a key factor in the glass manufacturing process – this is where the tension and quality of the glass are determined. CNUD contributes its experience with over 300 annealing lehrs installed to date – perfectly complemented by Grenzebach’s expertise as a specialist in conveyor technology.

The process

More than 60 years of experience: the best basis for an accurate annealing process.

From the tin bath, the 600 °C glass moves on rollers through the dross box into the annealing lehr. The optimal cooling curve depends on the customer’s specific requirements; it is determined by criteria such as the composition, thickness and width of the glass, tonnage, and speed. In calculating this curve, CNUD EFCO GFT can rely on a program that has been established on the market for almost 60 years.

Ongoing developments will allow more flexibility on the glass ribbon speed to better fit with the glass shrinkage. Developments that will also contribute to safety improvements.

Cooling process

The right combination between the radiation process and the convection process

In CNUD EFCO GFT annealing lehrs and especially in the radiation area, ambient air is crossing a battery of heat exchangers that avoids any contamination of the glass. As a result, higher quality glass is ensured and a better control accuracy of the process.
Thickness gauge in the hot area

Precise measurements right from the start.

The thickness of the glass is measured continuously and directly at the beginning of the annealing lehr, so that we can react fast if the thickness deviates from the permissible tolerance range. An important benefit: the thickness gauge is no longer inserted from the basement, as in the past, but through the side wall of the annealing lehr, which means lower CAPEX.
Waste heat recovery

Heat is valuable. Why not make full use of it?

An intelligent solution: we transfer the heat that is discharged during the cooling process via pipelines to the warehouse area, where it serves to maintain the required minimum glass temperature during the cold season. At the same time, this reduces heating costs in the warehouse. A further development is the use of waste heat to heat water in production areas, offices, showers, kitchens and more.
Mobile pyrometer

We don’t miss a trick in temperature measurement.

A temporary temperature measurement system is used to calibrate all the permanently installed pyrometers in the annealing lehr. It allows the temperature to be measured on both sides of the glass for the first time. As a standalone piece of equipment, it can be installed anywhere in the lehr, so a basement is not needed. Retrofitting in existing lehrs is also possible.

Let us help you create a “thinking” factory.

The future of the glass manufacturing industry is digitalization, which means that all stages in the process not only deliver and process data, but also communicate with each other. That’s what we call smart production.

Thickness measurement in the hot area and two-sided temperature measurement are just two of the features involved. The measurement of the glass ribbon’s width offers an additional advantage: by combining the drawing speed of the annealing lehr with the thickness and width of the glass ribbon, it is possible to calculate the tonnage precisely. And by measuring the glass’s position, ribbon swing can be detected and corrected at an early stage. Moreover, the data from the annealing lehr generate conclusions for the entire production process, particularly the cold end. This data gathering and analysis and the resulting conclusions offer real added value for glass producers.

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Talk with a

CNUD EFCO GFT has extensive experience with the thermal processes of a glass production line upstream of the cold end, where the quality of the glass ribbon and thus the customer’s yield are determined.

Data acquisition

More and better output thanks to fully data-driven processes.

CNUD EFCO GFT’s experience and process knowledge combined with data resulting from Grenzebach’s inspection solutions to form a fully integrated approach. By using SERICY, the digitalization platform developed by Grenzebach, we will be able to record and analyze all relevant parameters of a production batch or even a single glass sheet along the entire production line and archive the information for later tracking. Glass producers can use this input for process optimization – right down to concrete recommendations for plant operators and reliable data for quality managers.

Global references

References Map

Float lines references per Region

End-user industries

A universe of variety.

Where can the glass produced on CNUD EFCO GFT and Grenzebach production equipment be used? The answer is: almost everywhere! Thanks to our extensive experience and intelligent solutions, our joint production technology can create a vast range of glass types – from thin glass for smartphones to architectural glass for impressive facades.

Joining forces for the glass industry

Grenzebach and CNUD EFCO GFT: a symbiosis that benefits you in so many ways.

The merger of CNUD EFCO GFT and Grenzebach combines all the system components that are essential for the glass pane in its final form. From the tin bath to the annealing lehr to the cold end and the transport of the finished product to the warehouse: now everything is available from a single source. As a glass manufacturer, you benefit from integrated high-tech solutions with reduced coordination effort – starting from synergies in design and engineering and extending to lifelong service and support from a single supplier.

Your advantages with CNUD EFCO GFT and Grenzebach:

  • Comprehensive technology integration
  • Strong, focused engineering
  • Reduced project management effort
  • Uniform control concepts, fewer interfaces
  • Intuitive operation of the glass plant

Overview of solutions

Tin bath

The tin bath is the heart of every float glass production line; it is a decisive quality factor. Consequently, at CNUD EFCO GFT, it is always tailored to each customer’s requirements. Using process simulation, we are able to extract the ultimate in yield and quality.

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Waste heat recovery

Environmental protection and economic efficiency can go hand in hand if the right solutions are used. With our innovative systems for waste heat recovery, you can make your glass production more energy-efficient while creating a new source of energy for your company – this means more profit for you and a big plus in sustainability.

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Service and support

Construction and commissioning of a new glass production line is only the first stage in a good customer relationship. Professional service in daily operation is just as important: We want your investment to be profitable without any interruption – that’s why our engineers are there for you with guidance and support over the entire life cycle of the plant.

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Since late 2019, CNUD EFCO GFT has been part of the Grenzebach Group, linked to it by common high standards of high-tech and quality. A large proportion of the flat glass produced worldwide passes through Grenzebach’s cold end – from inspection, cutting, snapping and stacking to transport. With the integration of CNUD EFCO GFT, the entire float glass production line is now available from a single source.

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