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Ethernet-based motion control system simplifies system building on Harland's ultra-fast linear labelling machines
Bristol, June 13, 2007 --- A switch to motion control components compatible with the real-time Ethernet Powerlink protocol is simplifying electrical system building for Harland Machine Systems, the manufacturer of ultra-high-speed linear labelling machines.
Ethernet Powerlink compatible hardware has substantially reduced the hardware and wiring on a new variant of Harland's Mercury labelling system - a system designed to apply front and back pressure-sensitive labels, with a throughput of up to 275 products per minute.
Harland's linear machines are built from two main elements: the core machine itself which has six servo motor axes for feeding, positioning and stabilising products on a conveyor; plus a modular labelling head with a pair of stepper motor axes - for applying labels to both front and back of a bottle. Four labelling heads are typically fitted, with auto-change facility for continuous throughput, which allows reel changeovers to take place without stopping the line.
The high speed of the Mercury machine, combined with its programmability for different product types, places great real-time demands on the motion control hardware. Firstly, both the main controller and the labelling heads each require several high-speed inputs for product registration. The main controller must also dynamically change the cam motion profiles required for the centring and label 'wipe-down beams', which centre, stabilise and complete label wipe-down on the product. This enables a quick changeover between product types.
This complexity, plus the fact that many motion controllers do not offer multiple high-speed inputs, meant that the previous Mercury machine needed seven discrete motion controllers for a typical dual-head configuration. Baldor's Ethernet Powerlink controller reduces this to three, saving considerable hardware costs. The technology also reduces system building complexity for Harland. All of the servo drives and I/O on the main machine is interconnected by a daisy-chained Ethernet cable, saving wiring and space, as well as eliminating dozens of assembly operations. This has also allowed the drives to be fitted on one electrical panel, rather than the several used before.
"Ethernet Powerlink technology has helped us to make our electrical system both simpler, and more modular," says Tec Wright, Product Development Manager at Harland Machine Systems. "It means that we can build systems for clients more quickly."
He adds: "The high speed Ethernet network has so much bandwidth that we now have much more flexibility to customise labelling machines, and incorporate additional features that are invariably required at commissioning stage, and after installation."
The use of this technology has additional benefits for Harland customers. The ability of the network to mix and match motor technologies such as servos and steppers provides a very cost effective platform for meeting label application requirements. And the open connectivity of the resulting automation - which allows the end user company to link to it via a factory network - improves line efficiency and productivity.
"The new Ethernet Powerlink network allows most machine builders to take a fresh look at their control system architecture: our single Ethernet Powerlink controller can handle a very large number of devices on the network, including managing up to 16 interpolated axes simultaneously," adds Baldor's David Greensmith.
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