Robot Use in Painting Processes

With the increasing adoption of robotic applications, manual processes in many areas of industry are being replaced by robots. This transition must be undertaken consciously, as it is of great importance for the efficiency of the new system. The degree to which the robot is properly integrated for its intended purpose will affect the return on investment timeline. For this reason, understanding the work the robot will perform is just as important as understanding the robot itself during its integration. Painting is a precise operation that must be mastered and involves many parameters. As expectations for surface quality of painted products increase, this precision becomes even more critical. Painting facilities designed for manual or robotic painting must be designed appropriately for their intended use and method. Otherwise, operating costs increase unnecessarily and unit production costs rise. Simply placing a robot in a paint booth designed for manual application and programming it to mimic the operator's movements does not result in a robotic paint shop. The benefits of the robot emerge when the paint booth is designed specifically for robotic painting. For this reason, to obtain maximum benefit from the application, both the robot and the painting process, as well as the paint facility parameters, must be well understood. Let us substantiate these general statements in several points. These points will also demonstrate what benefits can be obtained for those planning robot investments in their paint shops.

Paint Consumption

In manual spray application of wet paint, painting efficiency varies depending on part geometry and operator skill, but typically ranges from 30 to 40 percent. In other words, only about one-third of the purchased paint ends up on the material being sent to the customer; the remainder (over-spray) requires filtration and treatment activities—additional costs. With robot application, efficiency can reach up to 85 percent. In other words, 85 percent of the purchased paint reaches the material. By reducing paint expenditure to this degree, some companies can recover their robot investment in just a few months.

Treatment and Filtration Costs

In wet paint booths, waste paint is filtered through wet or dry filtration. Mud-separation chemicals are used in wet filtration systems, and paint-capturing filters in dry filtration systems are consumables for paint shops and depend on the amount of waste paint generated. With robotic application, as waste paint volume is reduced, these consumables decrease proportionally. Additionally, whether filtered dry or wet, paint waste is harmful to the environment and must be treated. As volume decreases, treatment costs also decline.

Energy Costs

For waste paint to reach dry or wet filters, air flow must exist in the painting environment. The air providing this flow must also be maintained within a specific temperature and humidity range for paint quality. In most processes, this means heating, cooling, and humidifying the air supplied to the paint booth. These operations translate into energy costs. In manual applications, 100 percent fresh air is used for operator health reasons. That is, we draw air from the atmosphere, condition it, filter it, and then return it to the atmosphere. In robotic applications, we can recycle 90 percent of the conditioned air. This reduces energy costs by approximately 70 percent. In other words, while conditioning air costs 100 units in manual application, it costs 30 units in robotic application.

Rework Costs

The robot's talent is repeatability. When you set up the system correctly and program it well, it can repeat painting at the same quality level. Manual application quality depends on the operator's initiative. Painting defects require reworking and repainting the product, or at minimum touch-up work. In any case, it means labor and material costs. Repeatable quality reduces these costs.

Color Change Costs

Changing colors in a paint facility requires consumption of some paint and some solvent. Especially with two-component paints, the farther the mixing point of paint and hardener is from the spray point, the greater the waste generated during color changes. Since a robot can carry significantly more weight than an operator, mixing equipment can be positioned on the robot arm, immediately before the spray point. This reduces the waste generated during color changes. All these benefits, in a properly designed paint shop, can dramatically reduce operating costs. On the other hand, there are several disadvantages of robotic application that should also be mentioned.

Less Flexibility

In manual application, an operator can paint whatever material comes before them. However, robotic painting requires programming for each different material type. Additionally, errors in hanging the material do not create problems in manual application, but in robotic application, proper positioning of the material is important. For this reason, the conveyor system of a paint shop designed for robotic painting must also accommodate this.

Need for More Qualified Personnel

While the need for paint operators is eliminated with robot investment, there is a need for more qualified personnel for robot operation and programming.

Need for More Precise Climate Control

Changes in paint fluidity due to seasonal variations can be corrected by the operator during manual painting. In robotic painting, however, environmental conditions inside the booth must be maintained at the same level throughout the year. This necessitates conditioning of the supply air and the paint kitchen. In conclusion, when choosing robotic application in paint facility investment, feasibility studies should be conducted taking into account part geometry, part variety, number of colors, and quality expectations. While robotic application provides significant cost advantages in many facilities, in some facilities it may be an investment that is not necessarily required. What is important is to conduct feasibility studies during the investment phase and to consciously evaluate the robot, paint, paint booth parameters, and the integration of all these elements.     Semih Şenocak Mechanical Engineer Sales Manager Boysis A.Ş.