Rational iCombi Pro
Rational iCombi Pro UI
Rational Icons
Rational iCombi Pro
Rational iCombi Line B
Rational iCombi Line A

Excitingly different.

ClientRational AG

IndustryLarge and industrial kitchen equipment

CompletionJune 2020

ServiceOperating concept, Interaction concept, Visual design, Icon design, Style guide, Animations, Product graphics, Product design, Model making, Prototypes

RATIONAL AG from Landsberg has been developing combi steamers and multifunctional kitchen appliances for over 40 years, making it the world market leader. From the development of the new generation of appliances came the iCombi Pro, iCombi Classic and iVario.

Thanks to the holistic UX720° approach, close cooperation with the BUSSE Industrial Design Team was maintained during the development of the devices in symbiosis. By using animated AR models, lifelike models could be quickly created and virtually evaluated.

The aim was to create a simple and intuitive operating concept supported by a visual design that corresponds to the RATIONAL brand and consciously distinguishes it from competitor products. At the same time, it was important to preserve the history in order to ensure a smooth changeover for existing users of the system, despite a completely new development of the HMI.

To give the series a new visual face, it was important to test different design directions. The very different concepts, from conventional to unusual, were presented to the RATIONAL board and project team and then evaluated. From this intensive design phase, design features from the different concepts were worked out and defined. These elements formed the basis for the further development of the user interface.

In an iterative process the main screens were then designed and presented and discussed at regular meetings. After the final presentation and approval of the board for the visual design, the transfer to the other screens from the user concept followed. All global design features were defined and described in a comprehensive style guide.

Special attention was paid to the icons during the visual redesign. For historical reasons, there were a large number of different and sometimes complex icons. BUSSE Experience was able to define a stylistic standardization and, in addition, an individual and illustrative design. In addition, familiar and learned icons, especially those used by end customers, were sensitively revised and transferred to the new icon world.

Detailed interaction sequences were defined for different situations in the operation, and wizard animations were created. Animated device renderings give the operators a visual aid to interact with the device in the best possible way.

The user interface designed in dark mode gives the RATIONAL brand with the iCombi Pro and iVario a high-quality appearance with recognition value. In line with the holistic product development approach of BUSSE Design+Engineering, the design language of the device design was also taken up in the user interface. For example, the shape of the control panel and the glass panel is reflected in the main screen. The structured and self-explanatory user interface is characterised by clearly defined interaction elements with an individual and country-independent icon language.

In the course of the UI development, the interface for the iCombi Classic was also redesigned based on the iCombi Pro. While the former standard device still had a 7-segment display, the iCombi Classic now features a much larger 4.3 inch TFT display with 6 function keys. To ensure consistent operation across the devices, the new icons from the icon world of the iCombi Pro have been transferred to the hardware features of the iCombi Classic.


Oliver Skrabl
Project manager UI / UX
+49 (0) 7308 811 499 0