Robotics in the Paint Shop, by Pierre Bachand
- Published: October 22, 2001
Before writing this article I contacted an industry colleague, Patrick Lagrandeur of Groupe Maninge Groupe Conseil, who provided some advice for finishers considering adding robotics to their paint shops. I first met him many years ago when he worked at Bombardier and was involved in that company's robotic projects for its liquid and powder finishing shops at the Valcourt plant.
Robotics won't solve all your problems. One of the dangers with robotics is the perception that the technology can do everything. Many years ago, while still a junior in industrial sales, I experienced a situation when representing a large paint equipment manufacturer and accompanying a group of technical people on a visit to our facilities. The people took absolutely no heed to the warnings of the three or four specialists present, all having more than 20 years of automotive experience when they red flagged certain elements of the project. The robot could do the job but not the applicators. The project went through. It was later scrapped because no one took the time to better understand how the technology would work in the paint shop.
Here are a few good reasons to invest in painting robotics:
- A large volume of standard parts not subject to continuous or frequent changes to be painted. The 80/20 Pareto principle.
- Large volume of large (big) parts requiring a large envelope for application. Parts really difficult for manual operators.
- Discomfort and injuries to painters due to repeated non ergonomic movements.
- Special dangers associated with painting certain parts.
- Lack of personnel (not reliable, untrained , high turn-over, etc.).
Tip 1: Consult a Robotics Specialist
Once you've outlined the main components of your project based on your knowledge, your expectations and your capacities, consult a specialist at the beginning of the project. It is much easier to scrap a project at the initial stages then once a large volume of effort and money has been invested. The worst situation is to have to abandon the project and liquidate the equipment at a fraction of the cost, something that happened to a large Quebec company a few years ago. The problem? The robots could do the job but the application equipment required would be available a couple of years down the road. It was not only a financial fiasco but it caused lay-offs and the destruction of more than one career. If you have no experience or if it's above your level of expertise, the expert will ask the right questions and will find the correct answers.
Tip 2: Keep it Simple
What's a robot ?
Here is a simple Wikipedia definition:
"A robot is a mechanical intelligent agent which can perform tasks on its own, or with guidance. In practice a robot is usually an electro-mechanical machine which is guided by computer and electronic programming.”
If you're considering ABB, Motoman or Fanuc multi-axes robots and they address your robotic needs, then you're set. But there is more to robotics than this. You need to consider a reciprocator with applicator(s) that track ¨lead and lag ¨triggering¨, with zone control and possibly ¨in-out¨ positioning. The old KISS rule applies: the simpler the solution the more the probability of success. It is easier to install a simple to run, less expensive system that solves 90 per cent your needs than it is to bring in higher technical equipment requiring specialized personnel, important equipment modifications (e.g. part positioning) that will only solve 10 per cent of the problem. The simpler system is generally flexible and can improve productivity on a large volume of parts. One more warning: even if it is now possible to go from 5 ft / min to 12 ft / minute you have to ensure the rest of the system is also able to run at these speeds.
Tip 3: Run Multiple Tests
If the initial study looks favouable make sure that you run tests at one or many of the possible suppliers or in a company that has the type of equipment you are looking for and that is open to renting production time. This option is more probable with simple robot automation because there is virtually no programming. It can almost be done on the fly for powder painting to get a good idea of how robotics will work on your finishing line.
I remember one day I visited a client's company, Les Clotûres Oasis, in Lachute, QC, a manufacturer of fences who was eager to show me the new manual powder coating equipment he had purchased. I could see from the operation that it was a good candidate for automation so I asked him why didn't he go with an automatic system in his powder finishing shop? His answer surprised me. He said that the equipment supplier told him his parts weren't suitable for automation because of the difficulty in powder finishing the Faraday Cage area. After running tests at another client's plant, Les Clotures Oasis purchased a complete entry level automatic system that fit the company's needs. The result was optimization of his paint line, maximization of the line speed and elimination of two painters who became welders (better salaries and increase in manufacturing). The company's bottleneck had been the finishing process but the automation made it so efficient that the manufacturing department could barely keep up with the paint shop. And the company achieved the added benefit of better quality control and lower production costs.
Never forget to run the tests with your most difficult coatings. Do not hesitate to run the yellows, oranges and reds, especially if their opacity is low and you have difficult to coat areas with electrostatic applicators (powder and liquid). One company that ran a test with a robot-mounted liquid electrostatic bell system realized once the system was in place that coverage of deep recesses was impossible without over painting other areas. I was told that all the test had been run with dark color paint.
Tip 4: The Importance of Racking
It is critical to plan racking of parts. The part holder is one of the most important elements in determining line density and line speed. What is the benefit of installing a robot if there is a reduction in actual paint volume? It is also useful to remember that with powder coatings, the overspray may complete the coverage of other parts. The conveyor is an important consideration in racking. Sometimes, a finisher may realize too late how imprecise conveyor movements can be. As the robotic precision increases, this problem gains in importance. Variance in movement such as conveyor lag, or jolting, may change the sprayed area on the part or target zone. Precise tracking of the parts is critical.
Tip 5 :Supplier Selection
Most if not all the paint / robotic suppliers should be able to deliver and install equipment that will fulfill your needs. They will also have the means to train your personnel. Robots all share one limitation: pay-load capacity of the robot arm. This limitation is becoming less important as the applicator technology becomes more refined. Units today are lighter, modular in construction and easily maintained for liquid and powder use.
Ideally the supplier you select will have a local presence. Distance always increases costs, delays and loss of production. Make sure you and your supplier have a goo relationship because it will impact on the success of your robotic installation.
Tip 5: Have a Back-Up strategy
We must never forget Murphy's law. Even when the purchase and installation of a robot goes well and the operational results are satisfactory, plan for exceptions and problems. When designing the system anticipate the use of manual painters in the event of a catastrophic failure, a change of targets, or recurring random problems that prevents use of the robot.
Pierre Bachand is president of finishing consulting and training firm ChromaTech Inc, based in St. Eustace, QC.