Evacuated resin matrix as key factor

TARTLER supplies dosing-mixing systems including vacuum degassing for pultrusion

Pultrusion is regarded as the standard technology for the automated production of lightweight but highly resilient profiles and molded parts made of GRP and CFRP. The provision of a high-quality resin matrix for the continuous impregnation of fiber reinforcements is a decisive process stage here. The dosing, mixing and application systems of the NODOPUR series from TARTLER are perfectly matched to this process step. What’s more, material processing can be significantly optimized by the upstream connection of a degassing system of the T-EVAC type.

Maschinenbild Pultrusions-Anlage

Attractive solution for pultrusion: The Nodopur synthetic resin processing systems from TARTLER. With automatically controlled mixing ratios and outputs of 0.1 to 100 l/min, TARTLER’s Nodopur systems meter and mix meter and mix one or more components with viscosities from 1.0 to 60,000 mPas.

With automatically controlled mixing ratios and outputs of 0.1 to 100 l/min, TARTLER’s Nodopur systems meter and mix one or more components with viscosities ranging from 1.0 to 60,000 mPas. Even with these basic parameters, the system solutions of the German company are a highly attractive solution for synthetic resin processing for users of pultrusion (strand drawing). Especially since, in addition to a simple operating unit, a Siemens touch panel is available for the control system and the company’s own programmers can meet almost any customer requirement with regard to the function and operation of the machine. Even in its basic configuration, a Nodopur is mounted on a mobile frame with an integrated collecting tray and can be equipped with containers of different sizes. A wide range of accessories can then be used to make many other individual adjustments. The selection here ranges from volume flow control and a refill system to a heating system with agitator and a melting unit to an automatic vacuum control and many different mixers. A particular advantage is the possibility to feed material that has been previously freed from any disturbing air and moisture into the Nodopur dosing and mixing process. This ensures excellent mixing qualities, which in pultrusion is an important prerequisite for the realization of highly resilient composite solutions from the GRP/CFRP fabric and the synthetic resin.

Machine Pultrusion system
One of the first processing stages of pultrusion: Introduction of the fiber reinforcement into an impregnation tank or profile mold filled with liquid synthetic resin. (Photo: PulNet)
Machine Pultrusion system
In pultrusion, a glass or carbon fiber knit is impregnated with a matrix of liquid polyurethane (PU) or epoxy resin and various additives. (Photo: PulNet)

The result of pultrusion is a lightweight but highly resilient profile and molded part made of GRP or CFRP. (Photo: PulNet)

First degas, then mix

Today, pultrusion in its industrial form is a multi-stage process at the end of which lightweight profiles or molded parts made of glass or carbon fiber reinforced plastic are produced. One of the first processing steps is to guide the fiber reinforcement (nonwovens, mats, knitted fabrics, etc.) through an impregnation trough or a profile mold, which contains a synchronously generated matrix of liquid polyurethane (PU) or epoxy resin and various additives (hardener, release agent, color pigments, etc.) and dose it into the pultrusion mold via a pressure control system. Since the quality of the mixture of these components is of decisive importance for the optimum cross-linking of the GRP or CFRP fabrics with the resin matrix produced, TARTLER recommends the use of a degassing station of the T-EVAC type to users of pultrusion. This is because, apart from the manifold possibilities of positively influencing the mixing quality via the control of the Nodopur and the use of the most suitable dynamic mixers, this opens up further potential for improving product quality for the operator of a pultrusion plant. The reason for this is quickly summed up: With a vacuum <5 mbar (abs.), the T-EVAC evacuation system removes all air and moisture from the resins and hardeners intended for processing, so that the Nodopur can produce extremely homogeneous, high-quality compounds that produce the best composite results in pultrusion.

Machine Pultrusion system
With a vacuum <5 mbar (abs.), the evacuation system T-EVAC extracts all air and moisture from the resins and hardeners intended for pultrusion. This is an important prerequisite for the production of extremely homogeneous compounds for best composite results.

Measurable quality improvements

The vacuum degassing station T-EVAC was developed by TARTLER to give users of pultrusion as well as vacuum infusion, wet pressing and resin transfer molding (RTM) an additional possibility to further improve both their molding processes and their product quality to a decisive degree. The standard system, designed for epoxy resin and PU resin degassing, achieves a maximum degassing capacity of 1.000 l/h and is offered in two variants: firstly, an offline central station at which several Nodopur systems can be “refueled” with degassed material, and secondly as an inline module integrated directly into the dosing-mixing system and adapted to special process requirements. Based on its expertise as a special machine builder, TARTLER always takes care of all technical adaptations. The customer can therefore rely on a tailor-made complete solution from a single source.
The T-EVAC has a Siemens PLC control system with a 7-inch HMI screen. Their basic equipment also includes an automatic vacuum pump protection system and an automatically controlled water heating system with heat recovery. As an option, TARTLER offers an automatic water cooling system, an MX feed system with Kamlok connection for 1,200 liter IBCs and a vacuum buffer tank with a capacity of 1,000 liters. The quality improvements achieved by using the T-EVAC are measurable and have already been verified and documented in numerous applications at TARTLER customers.

Pultrusion theme day

TARTLER GROUP is a founding member of the network for pultruded lightweight structures PulNet. This interest group, based at the Fraunhofer Institute for Machine Tools and Forming Technology IWU in Chemnitz, currently comprises eight companies and is funded by the Federal Ministry for Economic Affairs and Energy. The aim of PulNet is intensive networking along the entire value chain and the further development and establishment of the pultrusion manufacturing process. On January 18, 2022, the network will host a theme day entitled “Pultrusion – Giving Lightweight Construction a Profile” with presentations and a virtual trade fair. The focus is on the three thematic blocks of Fiber and Matrix, Technology and Digitalization, and Process and Application. Interested parties can register on the website www.pul-net.de register.

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