TM Robotics, the UK sales partner of Toshiba Machine, and Mey und Andress, a German systems integrator, have installed three Toshiba Machine TH-350 ceiling mounted robots at a pet food factory in Bremen, northern Germany. Richard Hill, technical manager of TM Robotics explains how the robots have improved productivity.
The pet food manufacturer in question has branches and subsidiary companies across Europe, the USA and Asia, employing 2,500 staff. Its product range includes more than 3,500 different items for feeding and caring for pets.
In order to maintain this range and improve its productivity, the company has made substantial investment in factory automation to improve productivity. Before the investment in robotics was made, the now automated functions were performed manually. Following the installation, Toshiba Machine robots now package birdseed sticks at a rate of ninety per minute. Where once there were seven people working on the application across three shifts, now three Toshiba Machine TH-250 robots achieve the same results. These people have now been re-deployed across the plant.
This is the first robot application that this factory has been involved in. “It is a brilliant experience to work with a company that is new to robot automation,” said Nigel Smith. “You begin with engineers who have a degree of uncertainty in their expressions. By the end of the project those same engineers are delighted with the results and converts to the technology.”
The SCARA robots are part of a production line that manufactures birdseed sticks that are analogous to a fat based lollypop, embedded with nuts. The birdseed sticks are channelled down three conveyors, each with a ceiling-mounted SCARA robot at its end. As this happens, the boxes are channelled down another conveyor positioned at ninety degrees, in the horizontal plane, to the first. A robot gripper then picks up the seed sticks and transfers them into boxes.
Ceiling mounting SCARA robots make the best use of the available work area. They are perfect for use at the junction of convening conveyors or other areas where space is at a premium. Ceiling mounting can also make the best possible use of the robots working envelope. “In modern manufacturing everything comes down to fixed cost,” continued Smith. “Ceiling mounting a robot saves real estate which, in turn, saved money. As a result, payback times become marginally quicker and the factory becomes a fraction leaner.
“However, the biggest challenge in this application wasn’t space but finding a gripper that can pick up the greasy seed sticks,” established Smith. “The gripper solution that we found inserts its fingers underneath the sticks like a cradle. As a result, the sticks don’t fall out despite being very slippy.”
Another significant factor in the application was cycle time. In order to match the production rates of the manual version of the line, TM Robotics worked with the pet food manufacturer to specify one of Toshiba Machine’s fastest robots. “It is still quite rare to find an end-user specifying the speed of the robot they are buying,” explained Smith. “Furthermore, in packaging applications, payload can be a significant factor when selecting a robot, yet this is also rarely end-user specified. The key is to find a robot that is fast enough for the application but also sturdy enough to provide the payload.”
TH-350 SCARAs provide better accuracy and repeatability and offer quicker cycle times and faster motion than most available models. They also feature absolute encoders as standard, dispensing with the need for a home return function, which further improves cycle time. Payloads of up to 3kg and repeatability of ±0.01mm make them perfect for handling small and delicate food items such as these birdseed sticks.
Another challenging factor in any industrial robot application is control. Although, in this instance, the TH-350s are controlled via a Plc running profibus they do feature a built in PLC, which, regardless of robot operation and program, can control I/O equipment. The robots can be programmed using a ladder sequence program and, as an option, can feature Ethernet, DeviceNet or Profi-bus connectivity. A further option is the Toshiba Machine teach pendant; an external switch pad that can be used to direct the robot through a sequence of movements.
The increased profitability that is the result of overcoming these challenges does raise the question of why automation is not more prevalent in the food industry. “On this subject, engineers are ahead of the game,” said Smith. “They already understand that automation of existing processes can increase a plant’s output and reduce its overheads. They recognise that more efficient work practices can be just as effective, in terms of output, as simply adding another production line.”