Four criteria to consider when specifying industrial drives

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Paul Streatfield, Strategic Product Manager for industrial drives specialist Bosch Rexroth, explores four key criteria for industrial drive specification to meet the challenges of today's requirements.

Four criteria to consider when specifying industrial drivesSpecifying the right industrial drives is crucial to machine and overall process performance, but with industrial automation shaping the landscape for drive selection, it is vital to keep abreast of defining specification criteria.

It can be challenging to update your specification choices continually in line with the rapidly evolving landscape of Industry 4.0 but, in doing so, machine builders can offer their customers a wealth of financial benefits as well as better use of factory space, optimised machinery performance and improved safety.

The key to selecting an industrial drive that is compatible with autonomy is to understand how that drive has been designed and constructed to operate in conjunction with other machines and control systems. In doing so, specifiers can better establish whether the drive will not only deliver tangible results, but also whether the investment will stand the test of time against the ongoing evolution of connectivity in the industrial sector.

1 - Adaptable production space with cabinet-free drive technology

Since intelligent servo drives have become an indispensable part of modern machines, end users have enjoyed efficient format changeovers and motion profile adaptations at the push of a button. This performance-enhancing technology comes at a cost though, and with more servo drives comes larger, space-hungry, control cabinets.

These 'unproductive' cabinets essentially fill production space that would be better used for expanding a production facility through modularisation. Historically the motor and control unit have been separated from each other with a power and encoder cable running from each motor into the control cabinet. This has long been the only way to utilise servo technology, until 2014 saw the introduction of cabinet-free drive technology that retains all the advantages of servo drives but delivers up to 90 per cent lower cabling costs and a significant gain in space by eliminating the need to locate servo drives in control cabinets.

Sealed to IP65, all network access components previously located in the control cabinet are installed directly into the machine. The mains module is a single unit and connects the entire system to the mains, containing the mains filter, the mains choke and the mains contactor. The regenerative supply module with control electronics, braking resistor and braking transistor completely replaces the supply and control electronics in the control cabinet, allowing the traditional servo drive cabinet to be eliminated from the system design.

Compared with traditional automation, cabinet-free systems use a fraction of hybrid cabling with the same motor spacing. This not only cuts material costs and installation times, it also reduces the probability of faults in the cabling and delivers additional monetary savings through the direct connection of sensors, I/O and fieldbus components to the decentralised drives.

2 - Integral safety features for faster engineering

Drive-integrated safety functions offer an economical method of ensuring maximum protection for people and machines while increasing productivity, ergonomics and efficiency in engineering.

It is no secret that uncontrolled movements pose significant hazards and the more time operators have to spend inside a machine, the longer manufacturers are spending ensuring compliance with the highly stringent safety regulations outlined in the Machinery Directive 2006/42/EC and the relevant machine safety standards.

Intelligent, drive-integrated safety functions make it easier and more efficient to perform maintenance work safely and in accordance with legal requirements, offering a wealth of competitive advantages when it comes to reducing system downtime and labour costs.

Building on the in-demand integrated safety functions such as 'safe stop 1', 'safe limited speed' and 'safe direction of rotation', leading innovators of drive-integrated safety features are already bringing to market a wider range of logic functions designed to deliver maximum machine safety, even satisfying the highest safety level Category 4, Performance Level e and SIL3 in some instances.

Some of these more sophisticated functions include safe door locking and safe braking and holding systems capable of monitoring and controlling two independent brakes via redundant channels in the drive, thereby ensuring safety in the event that operatives need to spend time beneath gravity-loaded axes.

3 - Operational flexibility with open core engineering

Open core engineering puts entirely new application possibilities within reach for the first time, replacing traditional HMI devices with smart alternatives during the commissioning, operation and diagnostic phases.

The ultimate in operational convenience, open core engineering unlocks the cutting edge of machine performance by expanding access to the control core and inviting the use of mobile and digital technologies into the industrial environment.

Applications made possible with open core engineering include commissioning machinery with scannable QR codes and the visualisation of processes within the machine, plus diagnostic tools that enable data to be transmitted immediately for storage and evaluation. With new and extensive applications available using commonly used high-level languages across all standard operating systems, developing bespoke solutions to a range of complex machining requirements is far easier than ever before, making open core engineering a key specification criteria for drives moving forwards.

4 - Eliminating higher-level controllers by combining motion and PLC functionality

Some class-leading drives, such as Rexroth's IndraMotion MLD units, combine motion and PLC functionality to create a modern, open automation platform for modular machine concepts.

By decentralising the control architecture in a compact motion control system - with both motion and logic control handled directly in the drive - it is possible to eliminate the need for higher-level controllers. As well as offering financial benefits due to less hardware and cabling, this type of drive architecture also enables easier engineering, faster startup, quicker diagnostics and the added benefit of only having to back up one data source.

Scalable for a variety of process and manufacturing facilities, with ready-to-use function libraries to simplify use, this style of drive-based solution is available as a single-axis control for basic applications as well as a multi-axis control for applications with a maximum of ten axes.

Modules based on PLCopen also provide access to standardised motion control functions, while open technology and communication interfaces simplify the integration of MLD with a variety of automation concepts.


There is a wealth of further information online to further support specifiers in the drives selection process, ensuring that safety, operational and monetary efficiencies are paramount. For more information, go to

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