OTEC Präzisionsfinish GmbH Food industry: Conveyor screws benefit from a uniformly smooth surface

Conveyor screws are used in almost every area of the food industry. They are turned and milled from blanks with the desired material properties. During production, milling grooves and rough surfaces arise, which significantly impair the conveying process. Therefore, the screws are currently subjected to laborious grinding and polishing by hand.

Screw conveyors are used for a variety of materials. Not only bulk materials, but also viscous masses such as dough are transported. It is logical to assume that a rough surface is helpful for better "gripping" and conveying the material. However, the opposite is true. Firstly, a rough surface encourages the buildup of food residue and microorganisms, which makes surface cleaning significantly more difficult. Secondly, sharp, unstable edges are a disadvantage: Under stress, edges can repeatedly break off, resulting in fragments in the food. To avoid this, smooth, even surfaces down to the smallest angles as well as rounded, stable edges are essential, as only this can ensure ongoing production processes and food purity.

Components used in the food industry are typically reworked in several steps. First, the surface is smoothed with a belt sander, where possible. Then, hard-to-reach areas are painstakingly smoothed manually, and the edges are rounded. Because screw conveyors can be heavy and unwieldy, this manual process takes several hours. Due to their sharp edges, the risk of injury to the operator is high.

Schaaf Technologie GmbH manufactures extruders with screw conveyors. Previously, manual post-processing of the parts after turning and milling required approximately four hours of manual labor. The workpiece underwent three steps: In the first step, the milling marks along the longitudinal axis were manually removed using a belt grinder. After hardening, the screw was ground along its outer diameter using a cylindrical grinder, which again resulted in unwanted sharp edges. In the final step, these edges had to be rounded, and finally, the surface was smoothed and freed of the scale layer that forms during hardening using finer sandpaper. With the switch to OTEC's efficient Streamfinish process, all manual post-processing at Schaaf Technologie is a thing of the past.

Ron Hanke, Production Manager at Schaaf Technologie, reports:
“With the OTEC Streamfinish process, we have the opportunity to