FRIMO PURe Seal - It`s all a matter of sealing

10 / 2016 - The quality of foam components owes a lot to optimal sealing and degassing in the foaming tool. Particularly for the manufacture of high-quality and complex interior parts such as instrument panels or door trims, this is a key issue. With PURe Seal, FRIMO offers a one-of-a-kind sealing system for polyurethane foaming tools which provides both technical advantages and economic benefits. For two years now, FRIMO has been working with PURe Seal end pieces. The system has also been filed for patent. Before serial production, a comprehensive test phase was conducted during which customers were able to test the new end pieces thoroughly. Users include, in addition to BMW as OEM, also leading Tier 1 suppliers such as Faurecia, Grupo Antolin, SMP and Yanfeng.

In order to meet the automobile industry’s strict quality requirements, the choice of the right sealing system is a key factor for the foaming process. Inserting the fluid polyurethane triggers a chemical reaction in the closed mold during which gas is released. If this is unable to escape, gas bubbles form in the material. This so-called entrapped air must be absolutely avoided due to a negative impact on component quality. Unintentional and uncontrolled leakage of the foam system during this process must also be prevented. In order to let the gas escape during the foaming process in a controlled manner, seals are integrated into the foaming tool. For this, the sealing is carried out circumferentially around the foaming areas. The choice of the right sealing system is therefore crucial for optimally filling the cavity, and also decisive for optimal foam homogeneity.

There are a variety of different sealing systems on the market in order to meet the multiple customer demands as well as specific requirements depending on component and project parameters. For many years now, FRIMO has offered a pneumatically inflatable sealing system which enables ideal compensation of potential tolerances in the components undergoing the foaming process. For a long time, a patented carding end piece was used which placed stricter requirements on handling. In order to design handling optimally and comfortably for customers, the new flexible PURe Seal end piece, inflatable over its entire length, was developed and introduced onto the market after comprehensive series of tests were performed by various customers. All PURe Seal sealing components are made of silicone, which in itself ensures lower foam adhesion. The pressurized air is inserted here through the tool seating, as was the case for the conventional end piece. Using a sealing lip, the end piece seals itself inside the core drill hole during this process. An additional sealing lip ensures a seal between the hose and the end piece, for which the sealing lip is pressed against the hose exterior. Consequently, internal pressure may rise, causing the hose and seal to expand. Using compressed air, the required lifting movement and contact pressure is achieved between skin and carrier. The seal expands over its whole length without interruption and ensures an outstanding sealing effect. Complete contraction, as required in the original position, is of course also possible.

Make new from old: the dimensions of the new end pieces are designed in such a way that customers can also easily rework existing tools which are still outfitted with carded end pieces. No modifications of any kind are required for this, a simple exchange is sufficient. Furthermore, FRIMO PURe Seal offers additional advantages: significantly decreased cleaning costs for foaming tools, less material use for skin and carrier and highly increased durability of the seals. Rosemarie Spanner-Heigl (as process technician for PU foams) guided the test phase at BMW for the new PURe Seal sealing system, and has drawn a positive conclusion: “We were able to install PURe Seal end pieces on multiple existing tools from various model series and directly compare concepts with the predecessor over an extended period of time. We assured ourselves of the stated advantages during the test phase, and in the future we will certainly convert more tools and equip systems with them directly.”

Many customers rely on electronic leakage monitoring as a standard for the manufacture of foam components. In this area as well, FRIMO has been providing support for its customers for many years and offers a reliable system for digitally monitoring seals. In this process, the PURe Seal end pieces are monitored using a flow sensor and examined with the aim of the earliest possible fault detection. If a defect should occur, this will appear directly as a notification on the sensor’s display so that a rapid exchange can be made.

Contact for further information and documentation

FRIMO Group GmbH
Martina Schierholt
Hansaring 1
49504 Lotte

Phone.: +49 (0) 54 04 / 8 86 - 1 57
Fax: +49 (0) 54 04 / 8 86 - 51 57
E-Mail: schierholt.m[at]

“Our customers value the persuasive advantages of the PURe Seal sealing system and demand is growing. FRIMO is represented in a large share of European vehicle models with tools which are outfitted with expandable PURe Seal end pieces”, says Hermann Huster, Head of the Pre-Engineering Tools department for FRIMO in Lotte. Currently, FRIMO specialists are already working on the next stage of development, an enhanced version of the PURe Seals series. Huster is confidently looking forward to this innovation: “At the moment, the modified generation is currently in the test phase. The new end pieces are smaller than their predecessors and can also be nested flexibly in even narrower angles. We are committed, therefore, to higher flexibility in handling and more efficient outlet design.”

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