MTI® process

MTI® (Membrane Tube Infusion) is a registered trademark that describes the most advanced composite manufacturing method developed by German engineers to optimize and improve the vacuum infusion process.

The functionality of MTI® is based on a high-tech textile membrane that is permeable to gases but not permeable to resin. Built-in spiral hose provides efficient airflow for maximum performance even in difficult circumstances. The self-adjusting MTI® process has a positive effect on reliability, reproducibility, product quality, material and labor costs in the vacuum manufacturing process.

Say goodbye to post-processing

MTI® offers technology "in one go"! Reduce overall costs by eliminating post-processing. This means no more sanding, primer, paint or any other post-treatment that you have to do now. With MTI®, you have the ability to infuse at one time to produce quantities that will result in a significant competitive advantage.

No more resin waste

It's right; With MTI®, you no longer need the resin trap, which means you can calculate the exact amount of resin you need. Thanks to the semi-permeable membrane, the infusion process is self-regulating. It maintains a uniform resin content across the entire cross section of the laminate. The blocking effect of the hose ensures that the resin flows throughout the product with the exact amount absorbed each time. Complicated resin flow calculations are now a thing of the past.

Maximum reliability for your process

By using the MTI® Self-Regulating Hose, the reproducibility of the infusion process is greatly improved. The risks you traditionally face in composite manufacturing, including dry spots, are reduced with MTI®. Last but not least, when you have the ability to produce a product correctly in one go, post-processing and other product and labor costs are eliminated altogether.

Reduced effect of air bubbles

As if the consumption of resin was not enough. The low-pressure MTI® process offers clear advantages in terms of minimizing the formation of air bubbles. Consistently high-quality structural components result in increased dynamic load capacity, providing you with a winning formula for success.

Flexible and soft for easy operation

MTI® tubing is incredibly easy to work with! It is flexible and soft, which allows it to follow the contours of the most complex parts; it does not deform. The built-in spiral tube allows for easy operation and at the same time provides efficient airflow for maximum air extraction performance. This is evident even in challenging environments, including boat hulls and wind turbine blades, and other incredibly large or complex matrices.

The features of MTI® tubing, including air permeability and no resin permeability, ease of handling and integrated spiral tube is simply unmatched.

 

Vacuum Infusion Process (VIP)

The vacuum infusion process is a process used in the composite industry to produce fiberglass or carbon fiber. The manufacturing process consists of laying out a vacuum film on top of the laminate.
During the process, dry materials are laid out on a die, and then a complete seal is created with the help of a vacuum film and a sealing tape. Vacuum is then applied to remove air and apply pressure (atmospheric) to compress dry materials and create the necessary vacuum cavity in which strategically placed resin lines direct the resin into the product. In order to completely impregnate the part with resin, a pressure differential is created between atmospheric pressure and the cavity, pushing the resin through porous materials during the vacuum infusion process. To ensure that the vacuum is maintained until the part is cured.

Elements that determine the time to fill the part with resin in vacuum infusion

Viscosity - The viscosity of the resin determines the time it takes to impregnate the product. The ideal resin viscosity is between 100 - 300cps, with higher viscosity the impregnation time will be longer.

 

Permeability - The permeability or porosity characteristics of reinforcing materials affect resin flow. The use of a conductive layer is an essential part of proper infusion.

Pressure Differential - The higher the pressure difference, the faster the resin will flow. Optimum pressure is below 0.15 psi absolute (full vacuum).

Distance – The distance of the flow is also a factor that affects the soak time. If the flow distance is more than 1.4 meters, more feed points must be added.

Benefits of Vacuum Infusion

The vacuum infusion process is the leading technology for the production of composite products. This method creates stronger and lighter products, and even reduces costs. Part quality and reproducibility becomes easier to achieve compared to traditional methods.

Transition to MTI® technology from hand molding technology (with or without vacuum bagging)

If you are still working with hand molding technology, our experience makes it easy to upgrade with MTI® tubing technology.

MTI® procedure:

• Treat the matrix with a release agent.
•  Lay dry materials on the matrix. If necessary, secure them with a layer lock.
• Lay the sacrificial tissue, perforated film, conductive layer, create a "brake zone" of about 2.5 cm.
• Lay the MTI® tube around the perimeter of the matrix on the sacrificial tissue and secure it if required. Connect one end of the tube to the vacuum line and seal the other end with a sealing tape. Check that the connections are tight.
• Use a suitable vacuum film and sealing tape to create a sealed system. Install resin line.
• Using a vacuum pump, a vacuum of less than 0.15 psi absolute pressure must be obtained for best results. The vacuum system must be 100% tight. The sealed system easily maintains a vacuum without the use of a vacuum pump. We recommend using a digital vacuum gauge for control.
• Use resin suitable for infusion and degas it for at least 20 minutes. Make sure you have prepared enough resin.
• Feed degassed resin into the system.
• The pressure differential between the cavity and the outside atmospheric pressure is the driving force that pumps the resin through the porous material. The resin fills the space between the reinforcing fibers. Resin cannot leak out of the die cavity due to the barrier effect of the MTI® tube.
• After the resin reaches the membrane, it will stop there and flow over the remaining reinforcing material until the entire product is saturated
• Finish the process and shut off the feed line according to the desired amount of fiber content. There are several ways to control this volume.
• After curing, the bag is removed and the product is removed from the mold.

Advantages compared to hand molding:

• The layer fixer (spray) fixes the stacked layers of material very securely at sharp corners, where traditional hand molding cannot cope. Laying narrow strips is no longer required. Air bubbles, especially at edges and corners, are excluded. You get a perfect surface in one go. Critical for CFRP products.
• Particularly with larger parts, the lamination process becomes much easier as you can stop the process where you want. We did not find any restrictions on the size of the matrix for infusion.
• The air-free surface offers competitive advantages due to less post-processing, less material consumption and higher component quality.

Transition to MTI® Technology with Vacuum Infusion

If your current production is using vacuum infusion, your experience will help you make the transition to an MTI® infusion process as easy as possible. Upgrading your existing vacuum infusion is incredibly easy. Simply replace your regular coiled tubing with MTI® tubing. Tightly connect one end to the vacuum line, and seal the other end with a sealing harness.

A very small change that opens up a wide range of benefits thanks to:

One step technology

• A void-free surface in one go.
• Reducing overall costs by eliminating post-processing (sanding, primer application, painting, etc.).

Maximizing Process Reliability

• The reproducibility of the vacuum infusion process is greatly improved when using the self-adjusting MTI® tubing.
• Risks traditionally associated with such processes, such as dry patches, are minimized with this tube.
• If products are produced correctly in one go, the post-processing costs associated with fastening parts are eliminated.

Minimizing the effect of air bubbles

• The low pressure MTI® process offers a distinct advantage in terms of air bubble reduction.
• The constant high quality of the structural components results in a higher resistance to dynamic loads.

Uniform component structure

• Thanks to the semi-permeable membrane, the infusion process is self-regulating. This makes it possible to maintain a uniform resin content by weight across the cross section of the entire component.
• The resin trap is no longer required as the exact resin consumption can be calculated.
• Adjustment of the amount of resin supplied to achieve the optimal volume fraction of the fiber.
• Infuse the exact amount of resin needed to impregnate the item.
• Since the resin does not need to uniformly reach the vacuum source, there is no need for complex resin flow calculations.

Convenient handling of feed tubes and vacuum tubes

• MTI® offers easy placement of resin lines where needed.
• The built-in spiral tube allows for easy operation and efficient airflow for maximum air extraction even under difficult conditions or on incredibly large or complex matrices.
• Even dies such as boat hulls or wind turbine blades are lightweight with MTI® tubing.

Easy handling

• MTI® tubing is incredibly easy to work with.
•  Very low initial investment: no autoclave or resin trap required.
• It is easy to lay out around the perimeter of very complex parts.
• Once you try it, you will love it.

Transition to MTI® from autoclave technology

If you are thinking about upgrading your manufacturing process by investing in autoclave technology, first consider that the required component quality can be achieved with MTI® technology.

MTI® is a process that, compared to an autoclave, is characterized by:

 

• Easier handling with dry reinforcing materials, with less VOC emissions.
• High quality production without voids in one go.
• There is no need to use an autoclave pressure cycle as you do not run the risk of air pockets that can occur when laying out the prepreg.
• Incredible reduction in production time as you infuse the entire full bag regardless of the transverse dimensions.
• Investment and operating costs are less than when using an autoclave.