Cutting out the human touch

Originally used in automotive factories, it took a long time for robotic technology to be transferred to packaging lines. But, increasingly, the introduction of robotic solutions is making sense on all levels. Demographic trends are resulting in reduced levels of available unskilled or semi-skilled labour for repetitive packaging roles. In addition, there is often a high level of volatility in these jobs, making it difficult to maintain the required staffing levels and efficiency. In Western Europe and the USA, wage levels have risen dramatically, often artificially hiked by government-specified minimum wages. Payback times for robotic installations are reducing, and continual technological development is resulting in systems that have low maintenance requirements and operate at the same speed as today’s processing lines.

Flexible features in robotic applications are critical, enabling suppliers to account for demand shifts and market changes. If a flexible solution is to be cost-effective, it must facilitate quick changeover in product flow, product characteristics and packaging line configuration. For example, end-effectors can be used to pick-and-place almost any item, whether using vacuum suction cups or mechanical grippers. Furthermore, modular machines that can be arranged in numerous different configurations for specific applications offer a high level of flexibility.

Flexible and gentle

ABB develops and manufactures robotic technology for picking, packing and palletising applications. The company has recently developed its second-generation FlexPicker IRB360 robot. This is said to be faster, stronger and smaller than its predecessor, being able to handle large loads and fragile products. The FlexPicker is controlled by ABB's PickMaster software, designed to model applications and optimise multiple robot installations. The IRC5 controller is an integral element of the FlexPicker robot, now available in a panel-mounted version. It is said that this can be integrated with machines and production lines.

Robots are also becoming more intelligent. ABB's PickMaster software employs vision techniques and integrated conveyor tracking capabilities. The vision system can communicate with any external sensor-line scanners, colour vision, 3D or other systems. The software can handle products coming in at random, or on guided conveyors.

Machine vision systems can also provide other functions, including automatic inspection. For instance, a vision system can inspect the product itself, detecting visual defects. It can also recognise missing or illegible data stamps and labels, in addition to incorrectly filled packs. In most cases, inspection can be accomplished with the same vision system that is used for control purposes.

Automation made easy

Exhibited at this year’s Taropak exhibition, Soco System has introduced the plug-and-play ‘Robot-in-a-box’ flexible, compact palletising concept, said to be capable of lifting weights of 20–25kg This is supplied complete with a universal vacuum gripper head and pallet-positioning device, and it is claimed this can realise up to 10 transfers per minute. It is delivered with a control system comprising Socologic self-programming software, designed to realise complex pallet configurations. When the case to be palletised is led to the robot, the case dimensions are registered. The control system then calculates the optimal pallet position and begins the palletising process. Preferences are entered in the software, prior to putting the robot into operation. These include such factors as the number of layers and pallet patterns, and it is possible to change these parameters at any time.

In September, Paal became part of Bosch Packaging Technology. It has developed a new automatic tool-change system for its Elematic 6000 F Series six-axes top-loaders, including a new interface that is claimed to increase flexibility. A tool magazine of size-change parts can now be incorporated within the machine. When undertaking size or format changeover, the robot automatically ‘parks’ the current tool in the magazine, picks up the new tool and returns to full operation. Paal claims that tool-changeover is completed within 20 seconds. This ensures that tools are safely stored, eliminating manual carrying and handling errors.

Delicate product handling

El Dulze, a producer of lettuce, based in San Javier, Murcia, Spain, has recently installed 68 Fanuc robots in its packaging plant. Lettuces taken from the ground are delivered to the plant in plastic containers, stacked on a euro pallet. These stacks are located in a robotic depalletising area, where the Fanuc Robotics R2000iB removes one tray at a time, pouring its contents on a packaging line conveyor. The input conveyor orientates the lettuces so that they travel longitudinally on the system conveyors. Positioned centrally on the input conveyor, and spaced individually, the lettuces are directed to the robotic cutting stations.

Each LR Mate 200iB robot performs the same task, whereby sensors on the conveyor direct lettuces to the next available station. The lettuce is then orientated lengthwise on the conveyor, but the root end is randomly positioned.

At this point, a vision system weighs and measures the diameter to assess the lettuce density. If product falls outside the acceptable parameters, they are rejected. The vision system also identifies the root position for the robot, which then picks up the lettuce with a specially-designed pneumatic gripper.

The robot then positions the lettuce in the cutting machine, where the root is removed. A second check is made on the size of the lettuce as the robot again holds the lettuce beneath the camera. The lettuce that passes this final inspection is then conveyed to an operator working at the robot station, being placed in a plastic tray. Full trays are repositioned on the conveyor and sent to the packing area. It is said that the plant is capable of packaging 550,000 lettuces, although it currently produces 400,000 per day.

José Sánchez, Managing Director, El Dulze, explained: “The need to invest wasn't a difficult decision to make. This business has traditionally been labour-intensive, but labour is now increasingly unavailable. This region has a major labour shortage – many workers in the industry are immigrants, but this hasn't solved our problem. As minimal skill is needed, we have a real problem with labour and turnover of these workers is high." He also outlined how a workforce of 500 would be required to manually achieve current production levels, creating a major management problem. However, the robotic installation makes it possible to produce this output level with 100 people. José commented: "Reducing the amount of people has made everything more hygienic, and there is now minimal damage to the lettuces. The robots have reduced rejects from 20 to 5 per cent."

An embedded concept

The new Elau Robot P3+ is an embedded delta 3 robotic concept, claimed by the company to assist with the implementation of robotic packaging machines. Intelligent servo modules are used to permit integration, whilst the use of stainless steel enclosures and IP 67 protection serves to support sanitation requirements. The Robot P3+ provides three axes for pick and place solutions. An optional fourth axis is possible by integrating a rotary axis at the tool centre point. The system comprises all the mechanical, electronic and software components required for integration with a packaging machine.

The intelligent servo modules replace conventional servo-motors and drives. Connected with a single quick-connect hybrid cable drop between servo modules and a common power supply, this is a plug-and-play robotic solution. The single cabinet-mounted power supply can handle multiple robots, together with the various servo drives in the packaging machine. Using I/O option modules, up to 24 distributed I/O points can be supported at each robot.

Elau has also developed an IEC 61131-3 compliant software structure, designed to control all kinematics, logics and motions in a single program, operating from a single processor. The system is said to determine the optimal robotic motion profiles, ensuring high machine cycle rates and tool centre point programming, thereby maintaining gentle product handling. The robotic solution facilitates integration with vision systems that, like the robot itself, can be embedded by OEMs into programming as a configurable software module.

The standard Robot P3+ now has a payload capacity of up to 2.5kg, which Elau states is more than double that of its predecessor. The work envelope has also been expanded, with diameters up to 1200mm. This permits conveyor tracking on wide conveyor belts. Recent wiring innovations make it possible to bring cables up to the gripper with hardly any loops, avoiding product contact, even if there are several cables for multifunctional grippers.

Checking and packaging

Sigpack Systems (a Bosch Packaging Technology company) recently installed 18 of its XR31 Delta robots at Bama, a frozen pie manufacturer located in Tulsa, Oklahoma, USA. This combines optical quality control with a specialised vision system. It acquires a detailed image of the product carpet at the beginning of the line and every pie is then evaluated for acceptability, including minimum and maximum length and width tolerances, also identifying partial, overlapping or connected products.

Additionally, the number, shape and location of the slits in the pie surface is checked, together with the quality of the topping. The position of all acceptable products is then communicated to every robot. Each robot then detects the exact position of the acceptable products with its own vision system and selects the best product for the cycle, based upon a sophisticated strategy. Sigpack claims that this centralised quality control is more effective than individual controls in each robot cell as it improves operational reliability through automatic calibration, in addition to increasing traceability for bad products.

The company has also combined the LDM MonoPacker Delta robot with the LTE tray-destacker. This automated LDM

MonoPacker is used to fill containers with various similar product types, such as confectionery and baked goods, chilled and frozen food, or non-food and pharmaceutical products. The integrated LTE tray-destacker was developed to complement the LDM MonoPacker, and can be used to destack various tray types. No changeparts are required for adaption to other common tray sizes or shapes. The system can handle rectangular and square shapes with widths between 50–300mm and 70–425mm in length, in addition to round shapes with diameters up to 300mm. This system also includes integrated vision controls, recognising the shape and orientation of containers.

Robots – here for good

Robots are increasingly becoming a standard element of packaging lines across the world. A wide range of systems is now available for numerous product types, necessitating various degrees of investment expenditure. It can be argued that the introduction of robotic solutions pays dividends for any business type, particularly as the cost of the equipment is diminishing in real terms, whereas the cost of labour is escalating.