Software simplifies linear drive selection

CNC systems, metrology equipment and other types of machinery often require a linear motion component. This may be because of a need to move a cutting tool back and forth, position measuring probes, convey material or clear debris from the work area.

Selecting the right size linear drive to provide this linear motion can involve a series of complex and time-consuming calculations. Linear-drive selection involves analyzing and integrating many variables, including axial thrust requirements, weight of the tooling head being moved, desired linear speed, frequency of reversals, system component life expectancy and travel distance.

Joachim Uhing KG GmbH & Co., Kiel, Germany, manufactures “rolling ring” linear drives, which are friction drives for reciprocating or positioning linear motion. The company has equipped its distributors with proprietary software that simplifies drive selection. The Uhing UH5 software program rapidly analyzes linear motion application requirements and selects the correct size rolling ring drive.

In a rolling ring drive, the linear motion results from friction produced at the point of contact between the inner race of the drive bearings and the shaft. The amount of thrust depends on the shaft diameter and the number of bearings in the drive unit. But the thrust produced by even a large friction drive can be overcome by a payload that is too heavy or by trying to move the drive too fast. Selecting the right drive means calculating how the coefficient of friction is impacted by the weight of the load and the linear speed.

The temptation is to oversize the drive to allow for a comfortable margin of error, which increases the price. Also, it’s not always possible to oversize a rolling ring friction drive because of design limitations.

All images Courtesy of Amacoil

Tech support personnel can simplify selection of rolling ring linear drives with Uhing’s UH5 software. Application data is gathered by telephone or online, and a printout summarizes the output data and specifies the correct size linear drive.

The manner in which the payload, such as a cutting tool or pneumatic hose, is attached to the drive may cause overturning moments of force, twisting or pulling the drive unit as it travels. This works against the thrust generated at the shaft/bearing interface and increases wear on the bearings, dramatically reducing the system’s lifespan. A machine designer needs to calculate bearing life to know if the drive system is large enough and whether or not the load is properly supported.

In the time-sensitive design of CNC machinery, delving into these types of analyses and complicated calculations is not an attractive proposition. The UH5 software processes and calculates complex drive selection criteria in seconds while minimizing the possibility of human error. Engineering and design personnel can focus on other aspects of the project without getting bogged down with the myriad details surrounding drive ––selection.