Company chooses the right motor for the task

Servo Sizing Solutions offers both design consultancy and training to engineers.

When engineers find that their motion control systems perform below expectations, it is probably because poorly specified components have crept into the design.

"Most engineers are good at the machine and/or control system design", says Graham Kalko, a 25 year veteran of servo system selection and integration.

"But they are less confident when it comes to sizing and selecting the optimum servo drive components for an application".

To help address this issue Kalko has a set up new company, Servo Sizing Solutions, which offers both design consultancy and training to engineers.

"Servos started making an impact in industry in the early 1980s and naturally the technology has progressed a long way since then", he says.

"They have become easier to use, but the application requirements have become more complex, so expert specification help is as necessary as ever".

Servo Sizing Solutions' principal business is to specify electronic servo systems for industrial applications, taking into consideration both the electronic control and mechanical system characteristics.

Kalko explains that it is not only the correct specification of a motion controller that makes for a good system solution.

All the system components are equally important, including the actuators and mechanical power transmission equipment.

And this is as true for a simple single-axis point to point positioning system as to multi-axes linear and circular interpolating system.

"We involve ourselves in the complete design process, from concept to finished product", Kalko explains.

"If we stopped at the motor shaft we wouldn't be able to ensure that customers realise their expectations".

As an alternative approach Kalko will train engineers on the vital aspects of servo specification.

"Most engineers come to servos from either controls or inverters, but neither route particularly prepares them for the necessary disciplines".

The training is aimed at complementing their existing knowledge to achieve a balanced mechatronic capability.

The courses range from awareness training to computer/manual modelling techniques and basic mechanics for servo system selection.

The other discipline that Servo Sizing Solutions brings to clients is a sharp commercial awareness.

"It is very easy for servo costs to exceed the initial budget".

"During the design process creeping elegance can climb its way through the performance / price spectrum and easily over-complicate a simple application".

"Our expertise allows us to identify the core requirements and achieve a correct primary specification at the outset of the project".

"This allows the true cost, benefits and value of the additional enhancements to be properly assessed in relation to the primary objective".

"The saving in time, cost and frustration can be immense".

It is also necessary to consider the whole system from the outset so that the best mechatronic design can be achieved.

For instance, should the linear actuator be a ballscrew or belt drive; an undersized gearbox could compromise total system performance.

Often a linear motor may provide the best solution.

These issues are as important as selecting the correct control strategy/system architecture.

"Getting these details right will help to increase sales, improve profitability and performance for OEMs and manufacturers in both the short and long terms".

Another issue that engineers increasingly have to address is energy efficiency.

Correctly specified servo systems meet specific application power requirements.

The servo system only develops the required torque for that instant in the duty cycle, unlike other systems that can use 100% of their power capacity regardless of the load condition.

Where the servo system is specified correctly the bulk of the energy required will be used in driving the load and not wasted driving an oversized servomotor or inefficient transmission, minimising energy costs.

Kalko says that the majority of servo systems he currently sees in use are oversized, with an average excess energy expenditure of 50-65% in real terms.

For example Kalko quotes an instance where he replaced a 3kW system with a 500W package on an OEM repeat build machine, saving the customer GBP 1450 per machine in hardware costs plus the benefits of reduced drive size and energy costs.

When you consider there are three axes on most machines the savings can soon add up.

"Green issues are only just coming to the fore in our particular area of technology".

"To date performance and costs have been the overriding considerations with energy usage coming way down the list".

"But that will change" observes Kalko.

"I am anticipating that in addition to the new build requirement even installed servo systems due to be replaced will have energy efficiency criteria considered rather than direct replacement".

Kalko will keep Servo Sizing Solutions independent, with no allegiance to particular servo equipment manufacturers.

"We want to offer our customers best fit solutions".

"When they have expressed no manufacturer preference you have to search for the best technology and have the experience and knowledge to ask the manufacturers the difficult questions".

"This will ensure that you do not end up with less than optimum solutions".

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