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Coatema expertise: coating and materials handling technologies for prepregs

News International-French

18 Apr 2011

The use of coated products in prepreg production is expanding rapidly, which has prompted Coatema Coating Machinery GmbH to develop new and highly innovative machinery concepts in prepreg impregnation and coating.

(Published on July-August 2008 – JEC Magazine #42)






The worldwide trend in prepreg machinery is towards flexible, multifunctional systems for the production of a variety of products made from rovings, textiles and multiaxial structures. The use of fibres like carbon, glass and Kevlar® in combination with epoxy resins to produce reinforced plastics for lightweight products in the aerospace, sports and automotive industries is becoming more widespread. There are a number of mechanical engineering challenges when it comes to the design of specialized coating technologies and of effective treatments for the fibre materials used in prepreg products. Generally speaking, prepregs are temperatureactivated intermediate products with tailormade properties that offer a number of application advantages, such as: superior stiffness; high tensile strength; low density; corrosion resistance; high vibration resistance; low heat elongation; low weight; extraordinary fatigue resistance; easy installation; and low maintenance costs in use. Finding a machinery solution usually requires 1) testing the chemistry of epoxy or phenolic resins on substrates made of different types of material and 2) assessing potential product-handling problems for winding, material guiding, coating and drying processes. Each piece of equipment proposed for coating and impregnating lines must be assessed in detail as a function of the substrate, coating chemistry and end product.



Material types and product design

Coatema has considerable experience in handling prepreg fibre materials, mainly carbon, glass, Kevlar®, graphite and other man-made fibres. Different types of fibre products are available, such as woven fabrics, uni-, bi- and multidirectional fibre constructions, and products with more than one orientation depending on the desired strength direction.


The material structure determines the specific creel- or roll-winding handling technology used. Different creel sizes are used to wind off the rovings in parallel and feed them to the coating process, as a function of the number of rovings to be coated. Tensile strength control is essential, as rovings can cause problems if they are too tight or if they sag. The result can be an uneven coat, rendering the products unusable due to poor quality. Handling woven or multiaxial substrates can be a problem if the slippage resistance is too low. The tension must be finely adjusted, because any out-of-place fibre affects the resulting force distribution in the structural component part.



Coatema's top ten ideas for prepreg manufacturing systems

  1. From lab scale to turnkey production plants, Coatema prepreg systems provide just the automation and continuous running capability needed for the specific application and machinery budget. This can include automated roll or bobbin changes with accumulators and splicers, closed-loop monitoring and adjustment of warp and weft parameters, and loading and thickness controls for impregnation or coating.
  2. Coatema's Microsoft-based visualization hardware and software provides master stations with complete access to all machine functions, plus an interface to the manufacturing system. Satellite visualization and control stations, which access only the information needed locally, can be located at critical points in the process.
  3. Critical systems are designed to address the nature of the materials being processed for simplified and safe maintenance and cleaning. This can include special machine surface treatments and coatings, removable maintenance intensive modules, and ease of access features.
  4. Robust and flexible preparation, delivery and circulation systems for resin and epoxy materials meet the most demanding requirement for product purity and longevity. They can be equipped to continuously monitor and make automatic adjustments for fluid level, temperature and viscosity.
  5. Total web or warp management systems can include floatation-, roller-, belt- or tenter-supported transportation with precise tension control, material guiding, pre-cleaning, pre-heating and weft alignment.
  6. Temperature and air flow control systems, which can be built to explosion-proof standards, are available in Coatema-patented vertical and horizontal configurations for curing, drying, and cooling. The heated systems can function with jets of air or radiant heat from a wide range of energy sources including hot oil, steam, gas, electricity or combustion of recovered solvents.
  7. All Coatema prepreg lines include continuous monitoring for potentially hazardous situations with automatic and manual emergency shut-off and lock-out features. All guarding, alarms, safety and environmental protection systems required for compliance with international and local environmental and safety standards are included.
  8. A complete offering of built-in finishing processes is available, including calendering, slitting, slip sheeting, roll reduction, wrapping, and packaging ready for shipment to the end user.
  9. World-class service and support begins with acceptance testing before and after delivery, installation and start-up assistance with operator and maintenance training. Post-installation service includes remote help, with built-in modems and diagnostics software, plus on-site maintenance, repair and upgrading.