Attaining speed and accuracy in packaging operations
05 July 2015
We take a look at Omron's approach to packaging machinery automation, including the inline monitoring of fast-moving items such as bottles and beverage cartons using integrated vision inspection systems, and the use of dynamic servo controls and fast PLCs.
Vision systems can be used throughout a production process to provide a dependable method of inspecting the exterior quality of products and packaging. As a quality control measure, they can be utilised to inspect empty containers, before the actual filling process, or for final exterior quality inspections such as the position of labels and so on. These exterior inspections are often integrated with other technologies in order to provide a complete quality control system
Vision systems are generally used for higher value products, but, depending on the process and application, there are a number of hurdles to overcome in terms of technology and cost. For example, having several inspection points on a bottle demands the use of multiple cameras; pre-processing these different camera images into a single image for evaluation can be crucial for some manufacturers.
Moreover, a degree of flexibility might be necessary to adapt the inspection according to different sizes, containers or even marketing programmes. Let’s take the beverage industry as an example.
Adopting the latest technical developments, beverage manufacturers can overcome current inspection challenges. With the advent of parallel hardware architecture, image acquisition and pre-processing speeds have been improved, and software image processing speeds have also increased thanks to new algorithms. Using features such as the ‘sparse edge’ detection and variation prediction allows fast, precise measurements to be made even if images are out of focus.
Furthermore, the EtherCAT machine control network has seen faster communication speeds between databases, PLCs and other devices. Faster networks have enabled motion control instructions to be synchronised with this communication cycle.
What’s best for your application?
With so many vision systems available, it’s important to identify what’s best for your application, matching your needs with the expected performance of the package, says Dan Rossek, Omron’s vision systems expert.
If processing speed is vital, for example, that is relatively easily satisfied, as the latest vision technologies provide an order of magnitude improvement over the performance of their predecessors (Omron’s FH vision technology being a good example).
He suggests you look for systems based on quad core processors and those offering a fast image capture rate. By choosing a system that offers speed, performance and versatility, operators can achieve shorter machine cycle times and improved their production line efficiencies.
And for the 'smart phone' generation, used to having data available at their fingertips wherever they are, inspection procedures might incorporate these devices as an extension to machine and production line monitoring activities.
Speed and efficiency
Turning from vision systems and looking more closely at packaging machine automation, a UK manufacturer of vertical form-fill-seal (VFFS) equipment reports significant improvements in its machines’ performance, thanks largely to the adoption of Omron drives and controls.
Nottinghamshire-based Line Equipment, which has specified Omron control equipment in a relationship going back some ten years, builds a range of packaging machines, from horizontal FFS to volumetric dosing, flow wrappers and auxiliary systems. But the bulk of the 37 machines it constructed and sold last year were VFFS bagging machines used by leading food brands.
“Sometimes customers ask us for other brands’ control systems, and we have to say: ‘Sorry, we only use Omron,’” says Line Equipment’s managing director, John Blashkiw. “The programme is bullet-proof. It ticks all the boxes in terms of efficiency, speed, high reliability and low maintenance.
“The majority of our sales are into the food industry - packing everything from carrots and frozen vegetables to sweets, spices or crisps. Customers will often ask about speeds before they ask about the cost.
Over the past three years or so, with our all-servo machines, throughput has risen dramatically from 70 to 100 bags per minute. That leap in speed came largely thanks to the upgrade some 18 months ago from Omron’s CJ1 PLC to the faster, next-generation CP2.” Line efficiencies have benefitted, so to has energy consumption. John Blashkiw again:
“We’ve had no problems since we’ve been using Omron components. When we install a system, it will generally have to hit at least 98 percent efficiency. That’s pretty much the industry standard now. If you look at the energy requirements of a pneumatic machine, the jaw closing mechanism on a VFFS machine, which is just one part of the cycle, needs 15 cubic feet per minute of compressed air; that’s a compressor continuously working away in the background.”
The actual savings made will depend on the specifics of an installation; the same is true for payback times. Reliability, too, is another key factor.
As well as the PLC, G5 servo drive and SmartStep servo drives, Line Equipment integrates Omron’s NS8 human machine interface (HMI) into its machine control systems. As well as the throughput speed, this reports the diagnostics and seven-day production tables, indicating the numbers of filled and empty packs. Integrating heating controls into the HMI also tidies up the design for Line Equipment, so that it doesn’t have to integrate secondary sets of controls.
“The fact that we are using an off-the-shelf PLC and HMI is a selling tool for us,” says Mr Blashkiw. “The customer does not have to come back through us. It’s a quick fix in the event of a breakdown, for example; and Omron’s backup and support is second-to-none.”
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