Nissan South Africa employs innovative robots for primer painting application for all body structures manufactured locally.
There are now around 1.1 million working robots around the world, according to the International Federation of Robotics. They’re building cars, phones and other everyday products – and in some cases they’re doing it as well as, if not better than, their human counterparts.
While they might not share our critical faculties or emotional intelligence (yet), they’re particularly adept at performing repetitive tasks with perfect accuracy. Oh, and they never get tired. Or sick. Or bored.
Robots can be used for primer, base coat, finish coat, clear coat and spray dispensing, using water-based, solvent-based, powder, glaze and glue/adhesive materials
Machines now perform around 80% of the work involved in manufacturing a car. As robots become more advanced, they’re also moving into areas such as smartphone manufacturing. Smartphones, as many of you are no doubt aware, are assembled using numerous small, fiddly pieces. Unless you have the dexterity of a concert pianist, taking one apart is a nightmare – so just imagine how difficult it is to put one together. It’s a task beyond the ability of most humans, but not, it seems, our robot brethren.
Painting-specific robots
“Robots can be used for primer, base coat, finish coat, clear coat and spray dispensing, using water-based, solvent-based, powder, glaze and glue/adhesive materials. Today’s flexible, high-performance paint robots can efficiently coat intricate parts with recesses, curved and contoured surfaces, and even picture-frame-like shapes. A robot can be programmed to use a complex spray path to apply coating materials to different areas of the part to various film thicknesses — without runs or sags,” explains Yaskawa Motoman South Africa MD Terry Rosenberg.
“In addition to traditional paint robots that use external hoses and cabling to feed the paint gun, robot manufacturers now offer application-specific robots designed to optimise finishing operations. These hollow arm models feature integrated cabling and paint hoses through the upper arm to make programming easier and also improve access into tight spaces that otherwise could not be painted robotically,” continued Rosenberg.
“Various types of robot wrists are available – each designed to facilitate painting of specific types of parts.”
“The Three-roll wrist – provides three axes of motion (RBT axes – roll/bend/twist), all in a compact wrist assembly. A three-roll wrist is well-suited for painting complex contours, such as car body interiors and the insides of box-shaped objects and other enclosures.”
Today’s flexible, high-performance paint robots can efficiently coat intricate parts with recesses, curved and contoured surfaces, and even picture-frame-like shapes
“The Lemma wrist – also provides three axes of motion, but has slightly less flexibility to maneuver in tight spots. A Lemma wrist is well suited for high-speed painting or coating of less complex part shapes in horizontal and vertical planes, such as a frame or the outside of a cabinet.”
“The Hollow wrist – has the same type of movement as a three-roll wrist, but includes a large opening through the robot base, arm and wrist for hoses, cables and direct connection of various spray application devices to the robot wrist. With a hollow wrist, interference between the hoses and parts/fixtures is avoided, ensuring optimum cycle time and robot reach/access. Programming is also simplified without hose interference worries. However, hollow wrists cost approximately 10-15 percent more than non-hollow models.”
“Some robot manufacturers offer a variety of fully integrated spray gun options for these different wrist types, including traditional air spray guns, electrostatic guns and high-speed bell applicators, as well as powder coating applicators.”
New approaches in automotive exterior paint lines
“New robot designs are starting to change paint lines in automotive exterior paint applications. Manipulator arms are narrower, and feature hollow wrists, providing better part access. Previously, paint robots were nearly always floor-mounted, which created a limited working area due to interference between the robot, applicator, and car body coming down the line. Newer design paint robots can be shelf / (wall) or overhead mounted, which offers significant advantages by expanding the effective work envelope and decreasing potential interference.
“One automotive company has been able to reduce the width of their paint booth by 25 percent (from approximately six metres to 4,5 metres). Overhead robot layouts reduce floorspace requirements, resulting in additional cost savings. Overhead-mounting configurations also provide less contamination from paint overspray onto the robots and base risers, which decreases maintenance requirements.”
Growth markets – coating and finishing applications
“Automotive companies and suppliers were early users of paint robots, and they continue to take advantage of today’s more flexible robots to minimise floorspace on paint lines. Use of robotic painting has expanded into Tier 1 automotive suppliers, as well as to general industry. Aircraft manufacturers are also turning to paint robots to provide the kind of high-quality finishes needed on large components. Paint robots are easy to cost-justify for virtually any application where coating or finishing is needed.”
“These include white goods manufacturers, rim (wheel) manufacturers, shock absorber manufacturers and many others where production runs are applicable. They are also very popular for applications in the wood and plastics industries and where release agents are required to be applied, for example.”
Nissan South Africa installs four EPX 2700 Yaskawa Motoman painting robots
For an innovative Parent company that has become the first car manufacturer to apply UV absorbing paint on a production car that allows the car to glow-in-the-dark (The ‘ultraviolet-energised paint’ on the Nissan Leaf electric car is a demonstration of a secret paint formula made up of organic materials, which was launched mid-February 2015), demands on equipment suppliers are high.
Nissan South Africa reached a point where their mechanical articulators, which had been in operation for 20 years, needed to be replaced. In line with Nissan Motor Co. Ltd of Japan policy, the South African operation employed four EPX 2700 Yaskawa Motoman painting robots, which began operating in mid-January 2015.
A robot can be programmed to use a complex spray path to apply coating materials to different areas of the part to various film thicknesses — without runs or sags
“The installation took place over the annual shutdown period in December/January. The existing booth was adapted to incorporate the four new robots of the hollow wrist type, each equipped with an electrostatic bell applicator,” explained Rosenberg.
“The vehicle painting process now follows the traditional solvent-based paint process”. In the case of Nissan South Africa the robots are being used for the primer application on the exterior of the body structure before it is sent for a 30 minute baking cycle through natural gas operated ovens. The paint robots are programmed to follow the profile of the vehicle bodies that reduces the waste of paint and solvents, thereby reducing the emission of volatile organic compounds (VOCs) and making the operation more environmentally friendly. Shortly thereafter the base and varnish (clear coat) applications are done. All vehicles manufactured at the Nissan South Africa plant, located in Rosslyn north of Pretoria, will pass through this process.”
“Besides the advantages already mentioned using the Yaskawa Motoman painting robots will realise a consistent painting quality, thus eliminating reworking, as well as a reduction in the time needed to coat each body structure which can be substantial in real terms,” concluded Rosenberg.
Yaskawa Motoman provides automation products and solutions for virtually every industry and robotic application including arc welding, assembly, coating, dispensing, material handling, material cutting, material removal, packaging, palletizing and spot welding.
For further details contact Yaskawa South Africa on TEL: 011 608 3182 or visit www.yaskawa.za.com
