At a time when Australian manufacturing industry is confronted with substantial challenges, an innovative custom designed automation system is delivering significant productivity benefits for an Adelaide manufacturer.
Leviathan Design, in the Melbourne suburb of Rowville, has designed, manufactured and installed an automated cell to bond metal trim and plastic columns to a glass panel to form a door outer assembly used in free standing household cookers manufactured by Electrolux Home Products in Adelaide.
The Adelaide factory, which employees some 450 people, produces around 1300 cookers per day including Electrolux, Westinghouse and Chef brand names.
Leviathan Design has in-house machining facilities capable of producing all components required for the system. These were designed in 3D CAD and the model was used directly by the company's CNC machines to produce the components. This ensured that the company had complete control from design through to the manufacturing process.
Sales engineer at Leviathan Design, Glenn Westonsmith, points out that the automated production cell designed for Electrolux is extremely compact, with seven ABB robots all working together in the one cell, which is very unusual.
"A critical requirement of the project was to achieve a cycle time of 14 seconds. A full computer simulation using ABB's Robot Studio software was used to show the proposed system capability," he said. "This simulation was continually updated and tested throughout the project to check the cycle time."
Automated system
The oven doors are constructed of three parts: painted glass sheets supplied in stacks, plastic injection molded columns provided in trays, and powder coated or stainless trim placed by hand onto the conveyor. Main elements of the automated production system are the robot oven door bonding cell, overhead link conveyor, and the robot storage buffer.
A key task of the robot oven door bonding cell is glass separation and paper removal. The glass sheets tend to stick together due to vacuum between the sheets, but this issue was solved by gripping the glass stack so that the top sheet can be removed by robot without the second sheet sticking.
Paper removal is provided by a high velocity fan creating a vacuum to suck the paper away to a hopper. Westonsmith says it is critical that glass and trim is accurately aligned for assembly of the doors, so glass and trim are placed on 'air tables' to provide a frictionless surface.
"Small holes release air to provide a flotation cushion so that friction between the glass and the table is reduced to almost zero. This ensures that the glass and trim consistently align to a datum position," he explained.
"The glass bonded doors are then stored in a curing oven for 20 minutes for accelerated curing of silicon. This double sided oven was designed and manufactured by Leviathan Design to provide redundancy and to ensure that cycle times could be met.
"The oven maintains a controlled temperature and stores 80 doors (40 in each side). The complete system can run at a reduced speed with only one side of the oven operating. Glass and trims are inspected by a vision system of Cognex ISM1050 vision cameras to ensure that the correct components have been loaded."
Task optimisation
Seven robots supplied by ABB Australia were required to assemble the doors and tasks are shared between the robots to optimise cycle time.
Tasks undertaken by the robots include:
- IRB2600: Robot 1 – Picking trim, placing trim on regrip station. Picking trim from regrip station and placing on assembly table.
- IRB2600: Robot 2 – Plasma treating trim on regrip stations for better silicon adhesion.
- IRB2600: Robot 3 – Picking glass, confirming correct glass with vision system, applying label, checking label barcode with vision system, placing in regrip station.
- IRB2600: Robot 4 – Picking columns, plasma treating columns for better silicon adhesion, placing columns in regrip station.
- IRB2600: Robot 5 – Picking glass from regrip station, applying silicon bead, placing glass on assembly table.
- IRB2600: Robot 6 – Picking columns from regrip station, applying silicon bead to columns, placing on assembly table.
- IRB4600: Robot 7 – Picking assembled door from assembly table, place into curing oven. Pick cured door from curing oven and place onto overhead conveyor.
All product conveyors, robot grippers, curing oven, regrip tables and assembly tables were designed and manufactured by Leviathan Design. Gluing systems are German-made SCA Schucker supplied by Australian distributor H Technologies.
Transfer system
To transfer the doors 45m down the factory to a storage buffer cell, a conveyor was designed and manufactured using tabs to align the doors on a plastic top steel chain. Westonsmith says this conveyor is 4.5m off the ground to provide access underneath for forklifts and cranes as well as pedestrian access.
"The longer reach IRB4600 can pick the doors from 900mm high in the bonding cell and place them onto the conveyor at 4.5m high. The robot sits on a 2m high stand to enable this reach.
"At the end of this conveyor, a transfer unit lifts and transfers the doors into the buffer cell and rotates them through 90 degrees so that they are oriented for storage. The doors are then lifted by another IRB4600 and loaded into the buffer storage cell.
"At the same time, as doors are required for production, they are picked out of the storage cell by the same robot and loaded onto the out-feed conveyors. The doors are picked on a 'first in, first out' basis."
The automated production cell designed for Electrolux is extremely compact with seven ABB robots all working together in the one cell.
According to Peter Bradbury, channel manager robotics at ABB Australia, the IRB4600 enables more compact manufacturing cells with increased production output due to its small footprint, slim swing base radius around axis 1, the fine elbow behind axis 3, small lower and upper arms, and the compact wrist.
"The IRB2600 robots are part of an ABB Multi-Move System which offers a number of cost cutting benefits including the ability to keep investment costs low by controlling up to four robots with the one controller. Savings flow on to reduced wiring costs because overall wiring of system controls is greatly simplified," Bradbury said.
Custom design
Senior manufacturing engineer at Electrolux, Chris Henkens, says the strongly integrated one cell system developed by Leviathan Design is ideal for operation in the limited floor space available.
"We were presented with a major challenge to meet the target cycle time of 14 seconds, but achieving that cycle time and combined with the new construction methods for the door outer assembly, our cost reduction targets have been realised," Henkens said.
"A unique element in the design of the system is the inclusion of the IRB4600 buffer cell robot. This robot utilises all of its working envelope and physical range to enable maximum storage for the doors.
"We are now in a much better position to compete with imports from low cost countries, which has been a significant issue due largely to the high Australian dollar."