Mankind has been capable of sealing of joints and gaps for many centuries, e.g. when caulking ships’ planks. Beeswax, tree resin or tar was used.

The story of modern sealants starts with polymer chemistry in the 1930s and the development of synthetic plastics and sealants. And the history is still being written. Today a multitude of different materials and technologies is available for sealing components.

For modern industrial production, another crucial requirement has been set: the sealing process must ideally be fully automated. This automated sealing process for the application of foam gaskets is generally known as FIPFG technology (Formed-In-Place-Foam-Gasket).

Traditionally, components are sealed with pre-punched sponge rubber seals or by bonding sealing cords. Today, as the degree of automation increases, liquid or thixotropic sealing foams are applied directly to the components on site using dosing equipment. There, they cure at room temperature. Also common are the terms in-situ gasket foaming, the application of liquid gaskets to a component in situ, locally foamed gaskets or Cured-In-Place (CIP). The latter highlights the curing of the foam gasket at room temperature.

The FIPFG technology has established itself as the industry standard for a wide variety of component applications. Decisive factors for the FIPFG process are the interaction of material system and machine technology as well as the application-specific understanding of the process.

An elegant and highly efficient process:
mixing, dosing, foaming.

The foam components A and B are homogeneously mixed in the mixing chamber of the dosing unit in a specified mixing ratio. For this purpose, differently designed agitators are used depending on the formulation and requirement profile.

Immediately afterwards, the liquid or thixotropic 2-component sealing compound is precisely applied directly ("in-place") to the pre-programmed component contour via the CNC-controlled mixing head of the dosing system. The sealing bead, which is precisely deposited on the contour, foams up by more than 3 times its original liquid material volume.

After just a few minutes, a soft, seamlessly closed foam seal is formed at room temperature. In contrast to the inserted sealing cord or sponge rubber seal, there is no seam through which, for example, moisture can penetrate into the industrial part. The coupling point of the seal bead is almost completely invisible.

The FIPFG foam gasket adapts to any workpiece geometry and compensates for dimensional tolerances.

SONDERHOFF SYSTEM SOLUTIONS: Optimal interaction of material and machine for your production process as well as subcontraction solutions

As a FIPFG expert, we ensure the accuracy of the sealing processes with our SONDERHOFF mixing and dosing systems. In special machine construction, we build the dosing systems optimised to your requirements in order to integrate them into your production concepts in the best possible way.

Different automation solutions for both 2D and 3D components can be implemented. With 3-axis linear robots, a travel range for the mixing and dosing head of up to X/Y/Z 3,000 x 1,000 x 500 millimetres can be achieved. When using 6-axis robots, there are practically no limits, and when using material systems with suitable viscosity, even overhead applications are possible.

Modular design for individual configurations

For gasket foaming according to the FIPFG technology, Henkel offers SONDERHOFF mixing and dosing systems in open and closed design to optimise the space requirement for both larger and smaller components. For mixed-cell foam gaskets, we offer our customers the very successful and proven low-pressure systems. For closed-cell foam sealing, we offer the exclusive world novelty of medium pressure systems.

The dosing systems perform the tasks of material preparation, material application via the mixing head, automation and process control. Liquid, medium and high-viscosity reaction materials made of polyurethane, silicone, epoxy resin can be processed precisely with these systems.

With the FIPFG (Formed-In-Place-Foam-Gasket) technology, we meet the high demands of our customers for sealing quality and contour-accurate tightness of the components.

Our more than 1000 material formulations offer a wide range of properties. Adhesion, temperature stability, elasticity, mechanical load capacity and chemical resistance are the most frequently required properties for foam seals made of polyurethane or silicone.

In this way, components of the most diverse applications can be optimally protected against the penetration of air, gases, dust, moisture and other media.

• Fully automatic, process-safe, flexible
• Fast, economical and efficient
• Low personnel expenses due to high degree of automation
• Short production cycles and high production speeds
• Reproducible quality of seamless, contour-accurate foam seals
• Nearly invisible self-levelling coupling point
• Free application process – no forming tools required as with 2K injection moulding
• Cost-effective alternative, especially for complex component geometries

• Maximum possible material utilization
• No punching waste as with insert seal
• Maximum flexibility because it can be reprogrammed at any time
• Changes during running production up to complete model changes are possible spontaneously
• Suitable even for smallest series due to free programmability of the dosing system
• Mixed "chaotic" part production with part recognition of the dosing system
• Good integration into existing productions

With the FIPFG (Formed-In-Place-Foam-Gasket) technology, much money can be saved in comparison with the manual insertion of pre-prepared seals. Especially where high production quantities are required and the parts can be provided with a traditional rubber seal only relatively labour-intensively (like EPDM or NBR), the direct foaming of a seal – the automated FIPFG process – offers clear advantages.

With the following example calculation the cost effect can be made clear in principle. Even if it represents a simplified overview, as a first estimate it can also be adapted to other applications.

In the following example an electronics box should be considered, production quantity 2,000,000 items per year, with a sealant length of 30 cm and a sealant thickness of 4 mm.

The essential costs are material and labour.

The material costs are calculated from the necessary sealing cord quantity (2,000,000 parts x 30 cm) and the material price (EPDM cord on roll 1,000 m for 300 €). Reckoned per unit, the material costs then runs to 0.09 € for each traditional seal.

The work time per sealing cord is often not exactly known. It is estimated from the number and hours of the necessary employees. In this example, 3 workers work in each of 2 shifts, 8 hours a day, 250 working days a year, to produce 2,000,000 parts – and even then have only 21 seconds’ time to mount a seal. The hourly wage is 20 €. From this arise labour costs of 240,000 € per year, or 0.12 € per part.

Through addition of the material and labour costs we arrive at a total price for manually inserted seals of 0.21 € per seal or 420,000 € per year.

To arrive at the labour costs we have to work out the cycle time for the foaming of a part. The cycle time can be roughly approximated from the estimated robot speed. The maximum robot speed is 58 m/min. As this value, however, is never achieved during application and as certain waiting and rinsing times have to be factored in, we can realistically expect that a part needs on average approx. 7 s to be sealed.

2 shifts x 250 days x 8 h x 3,600 s/h ÷ 7 s/part = approx. 2,000,000 parts

The machine is loaded and unloaded by a single employee per shift. This means labour costs of 0.04 € per part. For additionally incurred costs for energy, water, maintenance, waste disposal and material losses an extra cost of 10% is factored in, i.e. 0.01 €/part.

The sum of the individual seal costs comes to a total per seal of 0.11 €. This means for 2 million parts a year costs of 220,000 €.

Comparing the costs of the above example calculation clearly shows the savings made possible by FIPFG.

At the same time, it is an idealised comparison. Costs for electricity, pressurised air, water, replacement parts, scrap parts etc. were only applied for the FIPFG technology, and there only with a flat rate of 10 %. In real life, every situation must be considered and compared.

In our experience, however, investment in a machine usually pays itself off after a year’s production of about 50,000 parts, and a cost comparison should be carried out.