Precision Linear Drives for Safe and Fast Production Processes

To enable economical and efficient working with maximum production volumes, Riehle Maschinenbau GmbH & Co. KG in Aalen has developed new lye application equipment for bakeries, which can be operated by a single person. Precision linear drives in the feeding station constitute the core of these systems. Here, the dough pieces are transported into the fully automated lye application machine. The linear drives, the materials and protection category of which are specifically adapted to the relevant hygiene requirements, ensure precise movement of the lift table as well as a high throughput of 200 trays per hour.


With its innovative lye application technologies, Riehle integrates traditional, manual tasks in electronically-controlled bakery processes. The lye application machine developed for this utilizes a fully automatic infeed. Carriers are simply docked and the dough pieces—pretzels, for example—are automatically transported from the feeding station into the lye application machine. 

The carts carrying the dough pieces are recognized by initiators in the feeding station and locked in place by means of pneumatic cylinders (Figure 1). A light barrier checks the position of the dough piece carriers and the operator releases them for transport once the correct alignment has been achieved. A lift table, driven by two electrical linear drives, moves vertically to the upper level of the cart (Figure 2). For the automatic transfer of the dough pieces, the lift table is extended horizontally by means of two pneumatic linear drives (Figure 3). The conveyor belt then starts up and takes on the dough pieces from the first carrier. Once all pieces have been transferred, the pneumatic linear drives retract again. The lift table is then lowered by the electrical linear drives to the transfer position for the lye application machine, the dough pieces are conveyed, and the unloading process continues with the next cart level. At the same time, the lye and optional salt is automatically applied to the dough pieces, which are then deposited onto a baking tray. This fully automated system, which is operated by just one person, processes more than 200 trays per hour. 

Exact Positioning, Even Under Difficult Operating Conditions

The heart of this automated system is the feeding station, which transfers the dough pieces from the carriers to the lye application machine. Two Parker ORIGA electrical linear drives with ball bearing guidance are used for the vertical movement and control of the lift table. Linear drives are ideal for situations where precision and operating speed are paramount, particularly when outstanding running properties are required. Furthermore, the linear drives are sealed by a metal strip and have a protection rating of IP54. Particularly in dusty environments, this decisive advantage contributes to a long service life, good cleanability, minimum maintenance efforts, and thus optimized economy. The integrated guides of the electrical linear drives minimize the risk of rotation while ensuring smooth operation. The parallel electrical linear drives for the lift table are synchronized by means of a connecting shaft. 

The horizontal movement of the lift table is carried out by two pneumatic, rodless Parker ORIGA linear drives. Despite their small dimensions, these linear drives are powerful enough to bring the lift table with the dough pieces into the correct position quickly. Since both pneumatic linear drives are fitted in tandem in the lye application machine, no separate guides are necessary. Furthermore, the rodless, pneumatic linear drives are an ideal attachment point for the lift table.

The German Federal Ministry of Economics and Technology awarded the lye application machine with its automatic feeding and transfer station for dough pieces the Federal Award for Outstanding Innovation in the Craft Trades. It enables economical and efficient work with maximum product volumes, even in small and medium-sized bakeries. The high performance of the system is ensured by the precision and speed of the linear drives employed. Thanks to the early involvement of the drive specialists at Parker ORIGA in the development of this machine, as well as the excellent specification of operating parameters, this sophisticated drive solution has been a great success.