Automation escapes many small and mid-sized manufacturers due to the high cost of robotics. Particularly for unique applications, finding the right solutions to remove the barrier to entry while also finding the components to get the job done is a challenging task.

The cobot includes a 7th axis that enables robots to move along a linear guide to other workstations to perform repeatable tasks. (Photo: igus)

RHEWUM®, a German manufacturer of screening machines, discovered a low-cost solution for a collaborative robot that assists in the welding process. The company sought an automated solution that was robust enough to withstand flying sparks and higher temperatures in the welding process, but also mobile enough to reach the area of application. The company found the answer with a “7th axis” robot.

A limiting factor of a four, five or six axis robot is that it is stationary and typically bolted to a floor in a fixed position to work within a predefined workspace. Adding a 7th axis enables robots to move the length of a linear guide to other workstations to perform other tasks. That is precisely the solution required by RHEWUM®.

For more than 70 years, RHEWUM® has been manufacturing screening machines for the entire range of dry and wet screening as well as vibrating conveyors. Their products screen sugar, fertilizer, salts, plastic powders and granules and numerous other products. All machines must be manufactured and tailored to the respective movement.

In its production hall, a lightweight robot is used for the automated welding of components. A Universal Robot UR 10 has a payload of over 10 kg with a reach of 1,300 mm. To increase the range of the cobot’s working area, it moves on a 5.5 meter long seventh axis.

Components used in welding applications are required to be robust enough to withstand flying sparks and the higher temperatures associated with the process. RHEWUM® needed a low-cost automated solution, including a gearbox, articulated arm and seventh axis. The process also includes an energy chain to match the seventh axis. The energy chain, which can be opened on both sides, offers a straight run thanks to the inside/outside plate principle. The special sliding surfaces of the e-chain also ensure a long surface life.

RHEWUM® uses a metal inert gas welding process to achieve a highly reproducible quality on the weld seams. While common in manufacturing, the process carries risks. Noise, heat and fire all endanger workers, as do gaseous and particulate welding fumes. Inert gases can accumulate in the work area, displacing oxygen and generating carbon monoxide at potentially toxic levels.

In the RHEWUM® process, heavy components are placed with a crane. Workers start the program, and the robot takes over the complex welding process. Originally, workers rotated the component several times during the welding process. With the 7th axis, operating personnel can now devote time to other value-added tasks.

“Before, welding was done by hand,’’ says RHEWUM® Managing Director Sigurd Schütz. “On the one hand, the automated welding system enables us to achieve greater reproducibility of the high-quality weld seams. On the other hand, our orders from various sectors have increased since February 2021. It is now a matter of realizing this pleasing development.”

The 7th axis product is manufactured by igus, the Germany-based manufacturer of high-performance plastics. Called drylin® ZLW, the product allows for ideal positioning of the axis due to its wide structure and low installation height. The unit can work in spaces from 1300m to 5500m and glides along liners that resist dirt and heat. The energy chain in the RHEWUM® application, also from igus, allows for safe cable guidance in rough environments.

RHEWUM, an independent, family-owned company founded in 1927, has developed a full line of screening machines and continues to seek projects in which automated processes can be used to enhance, streamline, and improve safety in its industrial processes. By utilizing low-cost automation products, the company has successfully found a robotics path that is affordable and achieves its intended objectives.

“We are currently checking what is possible with the system,’’ Schütz said. “The plan is to manufacture as many other components as possible here in the future.”

This article is written by Thomas Renner, who writes on engineering, construction, architecture, and other trade industry topics for publications throughout the United States and Canada. For more info visit here .