The KraussMaffei Vario nozzle features a wide processing window, high mixing quality and low maintenance when used in polyurethane processing

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kraussSmall nozzle with a large impact
The KraussMaffei Vario nozzle features a wide processing window, high mixing quality and low maintenance when used in polyurethane processing
(Munich, February 4, 2015) The Vario nozzle is a flexible, powerful solution for processing polyurethane (PUR) developed by KraussMaffei that keeps the pressure in the mixing head constant even when the output rates of the PUR components change quickly. This means it is possible to produce components of various sizes and hardnesses with consistently high quality.

Constant mixing pressure

Processors benefit above all from high flexibility in the system assignment with large and small components, which require correspondingly large and small discharge capacities. This adaptability is made possible by the large adjustment range—the nozzle keeps the pressure in the mixing head constant up to a quantity ratio of 1 : 5. This way it ensures a high mixing quality and a constant mixture ratio. During the process, the Vario nozzle also features high repeatability and particularly good consistency in pressure and quantity.

Even compared to conventional, spring-loaded nozzles, the Vario nozzle from KraussMaffei has numerous advantages. Instead of a spring, it operates with a pressure cushion, which counteracts the component pressure. This air cushion has approximately 160 bar of pressure and sits in a gas compartment in the rear part of the nozzle. It acts upon the nozzle needle via a membrane, eliminating the need for moving seals, which are used in the case of the spring-loaded nozzles. These, in turn, are wear-prone and more sensitive to aggressive media and contamination. Moreover, in certain cases the spring and nozzle needle system can begin vibrating.

By contrast, the design of the Vario nozzle without moving seals significantly reduces the cleaning and maintenance expenses, because the needle can no longer get stuck and become jammed. Thanks to its compact dimensions, the new Vario nozzle is also easy and inexpensive to retrofit into existing systems. This requires neither additional control elements nor changes to the control system. The Vario nozzle is compatible with all KraussMaffei mixing heads and systems.

Very wide application range

Thanks to its flexibility, the Vario nozzle is particularly suitable for what are called multi-hardness products made of PUR, in other words, applications with various hardness zones. For example, if you want to manufacture automotive seat cushions with different output rates and molds on one system, you need a wide processing window for shot weights and quantity flows. The automotive seats generally consist of zones of different hardness. Usually the seat and back surfaces are soft, while the side parts need more rigidity to provide the occupants with more support. This means that when foaming the various component areas, the output rate of the PUR components changes from shot to shot. In order to avoid a loss of quality, pressure differences from these fast and very substantial quantity changes must be kept as close to zero as possible. The mixing head provides the solution; the Vario nozzle is able to compensate for these changes reliably. This guarantees that the components have consistently high quality.

The Vario nozzle’s range of applications is not limited merely to soft-foam applications. The new Vario nozzle has also already proven itself in the realm of major appliances—such as inserting the insulating layers of refrigerators—and when manufacturing fiber-reinforced parts with resin transfer molding (RTM).

 About KraussMaffei

The KraussMaffei product brand is internationally recognized for its groundbreaking, multitechnology system and process solutions for injection and reaction molding technology and factory automation. With its standalone, modular or standardized machinery and systems, and a wide, customizable service offering, KraussMaffei is a full-system partner for customers in many industry sectors. KraussMaffei bundles many decades of engineering expertise in plastics machinery and is headquartered in Munich, Germany. For more information:

About the KraussMaffei Group
The KraussMaffei Group is among the world’s leading suppliers of machinery and systems for producing and processing plastics and rubber. Its products and services cover the whole spectrum of injection and reaction molding and extrusion technology, giving the company a unique position in the industry. The KraussMaffei Group is innovation-powered, supplying its products, processes and services as standard or custom solutions which deliver sustained added value along the customer’s value-adding chain. The company markets it’s offering under the KraussMaffei, KraussMaffei Berstorff and Netstal brands to customers in the automotive, packaging, medical, construction, electrical, electronics and home appliance industries. Continuing a long tradition of engineering excellence, the international KraussMaffei Group currently employs around 4,000 people. With a global network of more than 30 subsidiaries and more than 10 production plants, supported by around 570 sales and service partners, the company is close to customers around the world. KraussMaffei has been headquartered in Munich since 1838. For more information: