By Thomas Houterman, PhD, De Grood Innovations
De Grood Innovations is a family-owned and -operated business that specializes in machining and constructing stainless steel, ferrous and non-ferrous metals and plastics into parts for the medical, industrial and food industries. Shortly after joining the business four years ago, Pascal de Grood, managing director, attended a party and spoke with a guest who was looking for a printer that could print chocolate on pastries.
De Grood had previously worked for a Dutch research institute and developed printer heads for industrial applications. With his knowledge of printing, he saw possibilities in designing a printer for food manufacturers and began working on a prototype that could digitally print custom-designed, edible, high-viscosity decorations onto mass-produced food products. This food printer would also need to quickly switch from one decoration or design to another and from one food product to another with minimal production downtime.
Initially, the design work was done in de Grood's spare time, spending a year testing and trying to develop the printer head. Once he designed a printer prototype that worked well, he spent the next two years optimizing the system. During that time, De Grood received patents for the technology in Europe and North America.
The printer's development work was entirely funded by De Grood Innovations. "We invested three years and a lot of money in this technology, which was not an easy feat for a small business," says de Grood. "But we managed, and our first machines generated a lot of interest from potential customers."
The FoodJet printer is designed to have a low maintenance requirement, ease of cleaning and low price per droplet, targeting primarily bakeries and manufacturers of ice cream and dairy products. The FoodJet printer is designed to deposit a variety of thick food materials such as frosting or yogurt onto food substrates (Figure 1). The system's series of pneumatic membrane nozzle jets deposits small drops onto the moving food products. These drops then form a digital image in the shape of a decoration or a surface fill. Decorating requires higher resolution and smaller nozzle or droplet size, while filling can be done using big drops and lower resolution.
Configurable Printing System
The FoodJet printer has a flexible, modular architecture that can be configured to any production process. This allows for a vast number of decorating and filling options. Changing the angle between the printer head and movement direction of the conveyor allows the resolution to be set. Using heads behind one another permits multicolor printing, where colors are applied in different layers on top of each other (Figure 2). Placing heads next to each other allows for a wider working area.
While the physical placement of the printer head offers a lot of possible configurations, other variables like nozzles, pressure and dispensing time also increase the printing possibilities.
The printer is controlled by two PLCs, and the mechanism to program the various dispensing-pattern options is a homegrown solution, explains de Grood. Sensors like proximity switches and photocells are used for alignment. Depending on resolution, the speed of the printer can be up to 30 m/min with resolution as high as 30 dpi. The system has a reaction time of 200 µs. And with camera, the system accuracy is better than +/-1 mm. The HMI allows the operator to choose product, pressure and shutter times of valves (Figure 3). However, the camera runs autonomously.
Typical for the food industry, many products need to be manufactured continuously, and, once a process stops, the machine needs to be shut down and cleaned because products cool down and harden or dry. "The FoodJet printer is a closed system, which prevents the product from drying or cooling," explains de Grood. "This means that it has no problem standing idle for hours or even overnight."
The traditional food decorating method is manual application or, if the process is automated, using masks and mechanical restraints. Area filling is done by applying a liquid curtain under which the food products are moved on a mesh conveyor. Another filling method involves partially submerging the products in a bath to apply the substance.