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Lightweight Materials

Efficient Production of High-Grade Carbon Fibers

Process diagram of a complete carbon fiber line
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Process diagram of a complete carbon fiber line

Process diagram of a complete carbon fiber line

With well-founded process know-how our engineers are consistently working on the optimization of the plants for manufacturing carbon fibers and on enhancing the reproducibility of the processes.

From the PAN fiber to the carbon fiber

The conversion of the PAN fiber into a carbon fiber is performed in multiple thermal process steps with subsequent surface activation.

  • In the first process step, the stabilization, the fiber is oxidized at temperatures from 180 to 280 °C.
    The critical and highly exothermal reaction requires a precise process control in terms of temperature and air flow. This is decisive for the later quality of the carbon fiber.
     
  • The second step , the carbonisation, is usually performed in a two-stage process in an inert atmosphere at temperatures of up to 1000 °C in the LT oven (low temperature) or 1800 °C in the HT oven (high temperature).
     
  • The carbonisation is followed by an electrolytic surface treatment and a sizing application.

Pollutants released during the conversion process are removed in corresponding exhaust air treatment systems.

R&D oven

R&D oven in our technology center
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R&D oven in our technology center

R&D oven in our technology center

The basis of cost-efficient carbon fiber production is a stable process control close to the limits. With the R&D oven in our technology center in Germany, Eisenmann provides extensive options for testing.

Innovative Oxidation Ovens for an effective PAN Fiber Stabilization

The requirements for the process equipment during the oxidation of different fibre types are manifold. With worldwide orders for the delivery of round about 100 oxidation ovens and Eisenmann has become the leading supplier of this sophisticated technology in the past few years. In this context, the success is based on the profound analysis of the requirements and the persistent development of innovative oven technologies with energy-efficient heat recovery systems.

Carbonization of carbon fibre

Only the carbonization process will turn a synthetic filament into a fibre with extreme properties.

Typically, this process is divided in two steps. The first process step, the so called Low Temperature Carbonization, requires a temperature just below 1000 °C. It is operated in a furnace with a stainless steel muffle.

High Temperature Carbonization is the second stage which asks for a temperature of typically up to 1600 °C, but in particular cases up to 2300 °C, depending of the required properties. Furnaces built for this application are equipped with graphite muffle and graphite heating and are operated under argon atmosphere.

Air flow concepts

Oxidation ovens made by Eisenmann set new standards in terms of temperature uniformity and air velocity distribution. Eisenmann offers the customers the optimum air flow concept for each fiber type (1k-320k):

  • Vertical Down
  • Center-To-End
  • Horizontal Cross Flow
  • Multi-Flow ventilation systems with overlaid air flows

Eisenmann is the only provider on the market who can resort to this broad range of ventilation systems.

Patented air seal system

With its new air seal, filed for patent, Eisenmann has developed a sealing system that offers significant advantages compared to all the concepts available on the market.

Project Example:

For carbonizing of PAN-Fibre Eisenmann delivered an electrically heated industrial furnace with 2 gastight muffles of about 20 m length. These industrial furnace plant serves to produce carbon fibre.

Precursors is polyacrylnitrile, which is guided through the furnace by levitation.

The carbonization furnace is designed for a temperature of max. 1000°C. Each heating zone is equipped with a hot gas ventilator. This leads to a very high transversal temperature uniformity over the complete muffle width.

The muffles are welded in a gastight way and equipped with a newly developed muffle bearing. Inside the muffles there is inert gas. Unburnt gas is led into and out of the muffle at different positions. At the inlet and outlet of the muffles there are purging sections, designed especially for this process. The oxygen content in the furnace is almost zero, due to the design.

After the carbonization furnace there can be a graphitizing furnace (high temperature furnace) – depending on the product requirements – which is also manufactured and delivered by Eisenmann.

 

Technical data

Furnace designation: electrically heated 2-muffle pull-through furnace
Rated furnace temperature: 1,000 ° C
Transversal temperature tolerance: +/- 3 K over the muffle width: +/- 3 K over the muffle width
Protective gas: inert gas (e.g. nitrogen)
Oxygen content in the muffle: < 10 ppm
Rated power of heating: 1,000 KW
Number of heating zones: 8
Furnace dimensions: length: 25,000 mm / width: 6.000 mm

 

Turnkey Carbon Fiber Lines

Layout of a complete carbon fiber line
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Layout of a complete carbon fiber line

Layout of a complete carbon fiber line

With its outstanding mechanical properties, many experts consider carbon fiber as the construction material of the 21st century. The high market potentials involved, cause an increasing demand of complete systems for manu-
facturing carbon fiber
.

In this context, Eisenmann proves to be a reliable and powerful partner covering the entire field of systems engineering. While our core competence is the delivery of oxidation ovens, carbonization furnace and related exhaust air purification systems. We also supply the entire carbon fiber line on request. Together with our renowned partners, we provide overall systems whose sophisticated plant components will meet the highest quality standards.

Eisenmann Heat Treatment Plants for Aluminum Alloys

Push-through plant exit
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Push-through plant exit

Push-through plant exit

Aluminum with its alloys is becoming more and more important in the development of lightweight materials for use in the automotive industry. To meet the strength standards required for this purpose, heat treatment of the materials is often necessary.

Eisenmann has both in-depth process knowledge and extensive project experience. As a leading manufacturer of heat-treatment plants, with over 60 customer references, Eisenmann is the partner of choice for manufacturers of aluminum structural components for cars and cylinder heads, engine blocks, transmission parts, other aluminum parts, and wheels.

Sophisticated process engineering provides for increased strength

For the heat treatment of temperable aluminum alloys Eisenmann provides solutions for the process steps annealing, quenching and aging adapted to the specific requirements.

Annealing is performed at approx. 535 °C for a period of several hours. Mixed aluminum crystals are formed, in which the alloying constituents such as silicon and magnesium are completely dissolved.

Quenching serves for "freezing" this condition. This prevents the precipitation of the alloying constituents dissolved in the mixed crystal.

The subsequent aging is performed at 140 °C to 200 °C for several hours. In this process, the required strength is achieved due to segregation processes in the crystal.

Rendering processes stable and reproducible

The conceptual and construction design of Eisenmann heat treatment plants is performed with the clear objective of accomplishing stable and reproducible processes. The design of the circulating air flow, the definition of the heating zone length (gas-heated or electrically heated), the conveyor concept as well as the design of the quench will be optimized and adapted to the requirements of the actual products before accomplishing this objective. This ensures an equal starting basis for all the products being manufactured with the objective of leaving the production plant as a "first class" end product.

 

Plant Types

Heat Treatment Plants for Aluminum Wheels

With first-class plant engineering and long-standing experience, Eisenmann has become an important partner for manufacturers of aluminum wheels. Strict compliance with the temperature profile as well as the uniform andreproducible quenching ensure tight strength tolerances of the aluminum wheels.

Fully Automatic Roller Plants for Utmost Efficiency

Due to their conceptual design it is easy to automate roller plants, which are thus ideal for the series production of large piece numbers. Intelligent detail solutions such as the A-lock minimize the energy consumption and maintenance effort and thus provide for extremely efficient operation.

These benefits combined with the high reproducibility of the described plant concept are the reason why the Eisenmann roller plant is in use at almost all notable manufacturers of aluminum wheels.

Push-through plant for high throughputs

Developed for high throughputs, push-through plants make it possible to reduce the energy consumption even further due to their compact design and the sophisticated detail solutions.

A special feature of push-through plants for the heat treatment of wheels is that for quenching after the annealing process the product carriers are not quenched together with the wheels. The energy stored in the product carrier serves as a heat source in the downstream aging oven, covering a large part of the heat required.


Heat Treatment Plants for Die Cast Aluminum Parts

Whether cylinder heads or structural parts – our engineers will find the appropriate plant type for any product. Due to intelligent systems with a high repetition accuracy for linking plant areas for discontinuous as well ascontinuous kiln systems, Eisenmann provides the customers with reliable product lines for sophisticated products.

Tailor-made plants

Plant types especially optimized for the intended application are used for the heat treatment of cylinder heads, structural parts, body parts or special parts. Depending on the requirements and the piece numbers, our engineers select the optimum concept and combine chamber or continuously operating furnaces with the appropriate material flow and handling concept.

Products

gas and electrically heated plate roller hearth furnace

Gas- und elektrisch-beheizter Platinen-Rollenherdofen
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Gas- und elektrisch-beheizter Platinen-Rollenherdofen

Gas- und elektrisch-beheizter Platinen-Rollenherdofen

Purpose

The plate roller hearth furnace is used for thermal treatment of steel sheet plates for the automotive industry. These plates undergo a thermal deformation in a connected press. These warmly formed safety components considerably contribute to absorb the shocks on the car body.

Furnace Description

The roller hearth furnace is a continuous furnace with a production roller conveyor on which the steel sheet plates are heated up. The furnace enclosure consists of a U-shaped body with layed on cover. The furnace ceiling, the furnace walls and the furnace bottom are lined with ceramic fibre in form of sheets and mats as well as lightweight refractory brick. The furnace enclosure and the top cover are welded gas-tightly and are joint gas-tightly with an intermediate sealing.

The production roller conveyor is equipped with ceramic rollers and the roller drive system is divided into 4 segments. On this roller conveyor the steel sheet plates are run through the furnace and are heated up to the forming temperature. In front of the furnace inlet there is a roller inlet track on which two steel sheet plates each one after another are placed directly onto the rollers. Per quick entry the steel sheet plates are run into the furnace. After the throughput the steel sheet plates are run onto the roller outlet track at the furnace output per quick discharge. They are also centered at this place. From this exact defined position the unloading robot takes up the warm steel sheet plates and puts them into the press.

In order to avoid a strong oxydation (scaling) protective gas is inserted into the furnace by means of hazes at the furnace inlet and outlet and at further feeding positions. To the protective gas max. 5% combustible components can be added (e.g. 1 % CH4) in a mixer unit.

The complete control and regulation of the heating unit is programmed by a PLC which is also delivered by Eisenmann. Apart from the heat treatment plants Eisenmann offers its customers also the individually designed corresponding periphery equipments as handling, cooling, drive and transport systems, process control and protective gas and process gas equipments.

Advantages in heat forming plants, proved Eisenmann roller hearth furnace concept

  • maintenance free drive
  • low-wear self-lubricating drive
  • worn and broken ceramic rollers can be changed during operationn
  • gas-tight rollers drive by upright shaft and screw gears
  • drive of each roller by screw gear
  • negligible slipping in quick and revers operation
  • gas-tight enclosure with good heat insulation
  • gas steel tube burner and electrical heating can be combined for optimal temperature control
  • With car body parts produced by Eisenmann roller hearth furnaces drivers all over the world drive more safely.

Technical data

Furnace designation: gas and electrically heated plate roller hearth furnace
Rated furnace temperature: 950 °C
Number of heating zones: 5
Net output: 1.000 kg/h
Cycle time: 20 s
Furnace dimensions: 3.800 x 2.300 x 13.500 mm (w x h x l)
Width of channel: 2.050 mm
Protective gas: e.g. nitrogen N2
   

 

Plant Types

With comprehensive know-how and innovative technology, Eisenmann has been a reliable partner in the pretreatment and coating of aluminum, steel and non-ferrous metal strips. In this context, our engineers resort to a broad range of plant types and combine proven modules with innovative systems to form tailor-made solutions for our customers.

In doing so, our engineers adapt the plant concept optimally to the customer requirements and the conditions on site. To achieve perfect results for the wide variety of requirements, Eisenmann has a broad range of plant components available, be it for vertical applications with a feed speed of 500 m/min or for horizontal applications with thick material up to 6 mm.

The product range features the complete area for pre-treating and coating coils, including:

  • Pretreatment lines
  • Coating lines
  • Waste water treatment plants
  • Exhaust air purification plants

 

Litho Strip Pretreatment

Consistent process parameters are the key for good pretreatment of high-grade surfaces and thus a prerequisite for optimum product quality. Eisenmann is the leading supplier of pretreatment plants for litho strips, which set standards in terms of product quality.

In the production of litho strips, an effective pretreatment, in this case cleaning and activating, are indispensable requirements for the downstream coating with photosensitive material. Based on comprehensive process know-how, Eisenmann has developed the appropriate plant engineering systems to be able to implement the extraordinarily high demands on the surface properties such as roughness, uniformity and hardness in an optimum and reproducible way.

The cleaning process

The aluminum strips are cleaned by being passed through a multi-stage washing chamber in loops. An alkaline cleaning agent with pickling properties supports cleaning the strips of adherent rolling oils. Oil remains and cleaning agent are rinsed off in the downstream rinsing zones.

A nozzle system provides for an even distribution of the cleaning and pretreatment agents on the upper and lower sides of the aluminum strips. The use of spoon-type nozzles with a large bore hole minimize the risk of contamination and thus the maintenance effort.

The spray bars of the degreasing zone are combined to multiple spray bar groups that are automatically switched on or off depending on the feed speed. The media are circulated via a degreasing bath that is cleaned by means of an ultrafiltration system.

The rinsing area is subdivided into multiple zones, ending in a final DI water zone. An intelligent cascade provides for minimum water consumption and operating costs. The combination of squeegee rollers and pre-spraying bars minimizes the bath carry-over, thus ensuring sufficient dilution using only 3 rinsing zones; compared to traditional solutions involving 6 zones, 3 zones and the corresponding space required for these 3 additional zones can be saved.

Litho Strip Cleaning

Coated aluminum strips – manufactured by means of the coil coating procedure – are gaining more and more in importance in industrial manufacturing processes. Especially their use in the food, building and automotive sectors is achieving high growth rates. For this purpose, an effective pretreatment is indispensable for optimum coating with high quality standards.

Within coating plants for aluminum strips, Eisenmann supplies appropriate pretreatment plants. This process is decisive for the subsequent coating of aluminium strips. To achieve an optimum surface, the effective removal of surface contaminants is not enough. In addition, the existing oxide layer on the surface of the strip must be removed by pickling and a conversion layer needs to be applied.

Eisenmann even has a solution for this requirement and supplies high-quality systems to ensure the process parameters in narrow confines. To reduce the energy and media consumption to a minimum, our engineers rely on a combination of sophisticated system technology and intelligent control engineering. To learn more about this topic, please refer to the data sheet aluminum strip pretreatment for coating lines.

Layout of the aluminum strip pretreatment plant
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Layout of the aluminum strip pretreatment plant

Layout of the aluminum strip pretreatment plant

Pretreatment plants for aluminum strips coating lines typically include the following process steps:

  • Alkaline degreasing
  • Rinsing
  • Pickling Rinsing
  • Conversion treatment
  • Blow-off zone for drying and cooling

Eisenmann can also resort to varied experience in the field of pretreatment of steel strips for coating lines. Our specialists will be glad to provide you with more information on request.

Ovens for Strip Coating Lines

Example of the process technology applicable to a coil coating line
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Example of the process technology applicable to a coil coating line

Example of the process technology applicable to a coil coating line

With its comprehensive product portfolio, Eisenmann not only has the process know-how for the wet stages of a line but also for the steps involving dryers and ovens that are often located downstream.

The topic of curing ovens has always been a focal point of the engineers at Eisenmann. As a leading supplier of coating lines for the most diverse industrial sectors, our engineers have gained vast experience with all the established drying processes and can thus balance the advantages and disadvantages of alternative procedures objectively against each other.

In this way, Eisenmann can always supply the appropriate drying process, from the conventionally designed oven up to 500 °C with direct or indirect heating right up to the high-performance drying system with near-infrared technology, referred to as NIR in short.

The latter achieves an excellent curing performance due to a very high energy density despite the extremely short design. It can vaporize the solvent effectively before the crosslinking process of the paints has been completed. At the same time, the system responds to changes in the process very fast by switching on or off, virtually eliminating damage to the coating caused by overheating or too long a residence time. This application has won recognition especially in the field of inline painting in galvanizing.

Due to the integrated air rate control system, Eisenmann drying plants facilitate an energy-efficient operation as a function of the respective solvent concentration. Of cause, our engineers will take all the required monitoring facilities into consideration and suggest alternative safety concepts. For the safety requirements according to DIN EN 1539 and DIN EN 13849-1 that have been tightened recently, we can provide solutions we have already put into practice.

However, the scope of performance does not end at drying. As a supplier of overall systems, Eisenmann also offers the related exhaust air purification plants. Depending on the application, either a regenerative or thermal oxidizer and an adsorption system from the Eisenmann portfolio can be combined with the dryer.

Processes

Processes

To produce quality requires to master and control the processes! Plants made by Eisenmann are manufactured with the objective of mastering processes. Our engineers are continuously committed to achieving this goal and devise solutions to satisfy even the highest demands.

Eisenmann has experience with all the established processes in the field of pretreatment and curing ovens for strips; among others, these are:

  • Spray and dip cleaning
  • Spray and dip pickling
  • Brushing
  • Electrolytic degreasing
  • Electrolytic roughening
  • Electrolytic anodizing
  • Phosphating
  • Conversion treatment
  • Water drying
  • Paint curing

 

Contact

Contact person

Name

Monika  Kunzmann

Firm

Eisenmann Thermal Solutions GmbH & Co. KG

Telephone

work T
+49 7031 78-2177
fax F
+49 7031 78-222177
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