Connecting a New, Advanced Coating Plant to Assembly Lines with a Futuristic Handling System. Comel’s Winning Choice

Maximum efficiency in using energy resources and coating products, premium coating quality in terms of parameters such as coverage, film distension, thickness uniformity, and finish, but also increased coating capacity and reduced assembly lead time. These were the objectives specified and achieved by Comel with its project for a new automatic powder coating plant integrated with its internal assembly logistics, which involved Futura, Imel, Wagner, Lesta, and Chemetall.

The development horizon of the contract coating industry is increasingly projected towards the vertical integration of processes and services to complement coating. Focussing on quality, implementing lean production practices to streamline production and shorten delivery times, and complying with international quality standards are all tools that the most professional contract coaters use to remain competitive and, at the same time, counter the trend that is seeing many manufacturing companies insource their coating operations.

By integrating surface treatments with new processes, the largest and most structured companies can become full-fledged external production departments for their customers, managing a number of production steps beyond finishing, including quality and conformity controls. At the same time, today, a coating contractor should provide measurable technical performance in line with the current requirements related to environmental, social, and economic sustainability. This is the path undertaken by Comel SpA (Arre, Padua, Italy), already the protagonist of an extensive report on ipcm® in 2015 after installing its first state-of-the-art automatic coating system to replace the two plants used until 2013. Thanks to a solid financial and industrial base and aiming to constantly increase process efficiency and profitability, Comel today offers a comprehensive, fast, flexible, and high-quality service to its loyal customers, of which it is often the exclusive contractor. Propensity to innovate, investment in advanced technology, and staff training also play a key role.

In October, we returned to Comel to visit what is one of the largest in-house handling and coating plants operating in Italy today, built in 2024 in collaboration with a pool of suppliers specially chosen to bring in their best technologies and meet the company’s primary objective: increasing its powder coating production capacity while optimising its process flow by linking its two main operating phases, i.e. finishing and assembly, thus reducing waste.

For this impressive project, Comel relied on the skills and experience of Futura (Robecco Pavese, Pavia, Italy), Imel (Codroipo, Udine, Italy), Wagner (Valmadrera, Lecco, Italy), Lesta (Dairago, Milan, Italy), and the Italian division of Chemetall (Giussano, Monza e Brianza, Italy), which collaborated for almost two years to realise the ambitious goals of this company.

Comel today

Founded by Luigino Giacometti in 1970 as a sheet metal, stainless steel, and aluminium treatment contractor exclusively for the air conditioning sector, Comel opened up to other industries in 2000. Since then, the composition of its turnover has diversified considerably. Its technical department provides constant support to customers not only for new projects or the industrialisation of existing ones but also in searching for alternative technical solutions to increase competitiveness. What sets Comel apart from its competitors is the comprehensiveness of its service, which ranges from cutting, bending, and welding to coating, assembly, and kitting.

“We have grown, improved, and transformed significantly over the past ten years. We constantly assess the best technologies on the market, and we rely heavily on our human resources when it comes to technical skills. In our coating department, some key roles have changed: since 2016, we have had a process optimisation manager, Nicola Cesarato, to support our management in the required investments and in the transition to a sustainable future. His role in the design of our new coating plant was crucial,” states Matteo Giacometti, technical sales engineer at Comel and one of the founder’s sons. “Like many other contractors, we saw a surge in volumes in 2021. Until then, the existing coating plant had been sufficient to meet our needs, although we had begun to rely increasingly on a subcontractor for work peaks and for handling special colours in small batches. That year, however, we realised that working on two shifts, we had saturated the plant’s capacity. As we did not intend to introduce a third shift and realised that an increasing number of parts to be coated also required assembly, we decided to improve our coating production capacity and create a more automatic and efficient workflow by linking surface treatment to assembly,” Giacometti explains.

“Our objectives were to be more independent, increase our finishing quality and response speed, and equip ourselves with a back-up coating system. Although, in ten years, the existing plant had never had any problem that kept it down for more than 24 hours, we felt it was our responsibility to eliminate any risk of downtime that would lead us to run out of stock and stop production, since volumes were increasing as were our customers’ expectations in terms of speed, flexibility, and quality of service. High-turnover workpieces requiring both coating and assembly now account for 35% of our activity. We knew that combining these two operational phases in a single workflow managed by one conveyor would have allowed us to streamline the handling of a very high quantity of parts, eliminating the risk of damage and reducing lead times, as well as to assign some operators to other tasks.”

Project genesis

“For this project, we turned to Futura for the design of the handling system, the logistical organisation, and the feeding of the assembly stations: we felt it was the only partner able to provide us with adequate and reliable solutions. We then chose to keep Chemetall as our pre-treatment chemical supplier: this way, we could use the same products in both our plants and achieve comparable quality results. Chemetall, in turn, collaborated with Imel, our selected partner to build the coating line and develop a pre-treatment cycle with the same number of stages as the previous one but with a higher degree of quality,” says Matteo Giacometti. “We chose Imel because, besides its know-how and the possibility of implementing its i4paintshop advanced management module, we trust it can provide us with a constant and reliable assistance service.

“Finally, Wagner’s IPS technology was a natural choice: we immediately asked the companies involved to enable us to paint parts with minimal human intervention, i.e. as much as possible with automatic reciprocators and without using systems to adjust the distance from the components via independent axes, and to achieve the best possible coverage. After several trials with test workpieces, the IPS technology was the only one to reach these results, minimising human intervention in all coating phases, from pre-finishing to colour change: the production rhythm is defined by recipes and programmes. This was exactly the same philosophy we demanded from the conveyor. Finally, we decided to install 2 articulated robots from Lesta with a 3D imaging scanning system to assist with pre-finishing operations. We have only equipped one of the 2 booths for now, but we intend to do the same on the other.”

Conveyor design: seamlessly joining two production stages

“We illustrated to Futura our requirements, the operating stations we considered necessary on the conveyor route, and the results of a preliminary study on workloads, assembly times, and positions,” says Nicola Cesarato. “We then adapted and modified their proposed solutions by conducting industrial simulations to ensure we could achieve the perfect balance between coating, assembly, and handling times, as well as between the necessary storage buffer’s size and assembly times. A highly productive coating line with bottlenecks during unloading or assembly would not have served our efficiency objective. I personally noted the assembly times of the main components that would be hung on the conveyor, and we reverse-engineered all the other processing times based on them.”

“This study led us to identify the number of parts to be handled per hour and, as a result, the characteristics of the line. In other words, cycle times were the starting point for developing this conveyor,” notes Paolo Chiesa, project manager at Futura Srl. “Compared to our ‘typical’ systems, Comel’s conveyor has the peculiarity of integrating a coating line with an assembly one. That is why it features storage buffers feeding several unloading lines near which other activities are carried out. “It is a power & free conveyor with a maximum capacity of 200 kg per load bar, each of which is 4 metres long, a throughput of 44 load bars per hour, and a chain length of just over 3 km. The line speed is 3.5 m/min, and the takt time is 82 seconds. The conveyor is built on two storeys to double its functions and features two types of storage buffers: on the lower storey, it takes the components along the coating line and has 1 storage buffer before the pre-treatment tunnel, 2 in front of the coating booths, and 1 after the curing oven; on the upper storey, it serves the warehouse for coated parts and empty load bars.”

“After the coating plant, the conveyor branches into two routes: one leads directly to an unloading station, the other takes the parts to the upper storey, where 8 storage buffers for coated parts are ready to feed 4 unloading and assembly stations below them. The conveyor’s PLC then recalls the load bars containing the workpieces to be assembled according to the daily production plan: each load bar thus leaves the warehouse and reaches the assembly area automatically. In total, the plant handles 370 load bars, 300 of which can be accommodated by the second-storey warehouse.”

“In the coating area, there are 2 continuous-flow loading bays, where the load bars initially move on a low height to enable the operators to hang the parts first at the top, which is at eye level; the conveyor then creates a vertical curve that allows the load bars to move up by 1.40 m so that the operators can load the parts at the bottom of the unit, ensuring excellent work ergonomics without the need for elevators,” explains Futura’s owner, Alessandro Longo. “In practice, the operator always finds the empty position for hanging the next workpiece at eye level. This was a specific request from Comel, which did not want to employ elevators during loading so that the plant itself could dictate the operating times: with this solution designed by Futura, the loading times are pre-set by the coating recipes matched to the individual load bars and are updated based on the operators’ recommendations, creating common working standards.”

“Each load bar has an ‘identity card’ that defines its route along the line, loading speed, pre-treatment cycle, blow-off power before drying, and powder application recipe,” confirms Matteo Giacometti. “Another optional value attributable to the load bars is quality control,” adds Nicola Cesarato. “If it is set, after coating and on leaving the oven, the load bar will stop to undergo an operator check. For example, we do this for the first load bar coated with a new colour or carrying a critical component, as well as with a certain frequency for specific production batches.”

“From the mechanical point of view, Futura has fitted the conveyor with another technology that is very useful in the pre-treatment phase,” indicates Alessandro Longo. “The load bars can tilt while in motion without stopping to be repositioned horizontally. This mechanical movement eliminates any liquid build-up formed within the parts during the pre-treatment cycle, thus facilitating the subsequent blow-off and drying phases and minimising the drag effect from one tank to the next.”

The powder coating plant. Efficient and aesthetically appealing

“The coating line supplied to Comel includes a stainless steel spray pre-treatment tunnel that performs a 7-stage multi-metal cycle, including double alkaline degreasing, double rinsing with distilled water, rinsing with demineralised water, nanotechnology conversion with Chemetall’s Oxsilan, and further rinsing with demineralised water,” says Marco D’Angela, the owner of Imel. “The pre-treatment tunnel is U-shaped, with 4 tanks on the left side and 3 tanks on the right side: this design solution allowed it to fit within the dimensional limits of the building that was to house the line. It is followed by a continuous-flow blowoff station that avoids any liquid build-up in undercuts before the drying phase in a hot-air oven. After drying, the parts follow a cooling path and then stop at 2 storage buffers, each feeding one of the 2 Wagner application booths. Both booths are housed in air-conditioned, temperature-controlled, dust-free, and humidity-controlled boxes. They work simultaneously: one applies light colours and the other dark ones.”

“The biggest design problem Imel faced was avoiding mutual contamination between parts coated in different colours within the humpback curing oven,” says D’Angela. “That is why we created a hot-air gelling pre-chamber. The special feature of the drying and curing ovens, both with a combustion chamber and a gas burner, is that they are superimposed: the lower part is for drying, the upper part for curing. This results in considerable energy savings. Finally, we also paid great attention to the aesthetics of this plant and the colour of its metal parts – yet another high-quality choice for Comel.”

After curing, the load bars with the coated parts reach the area where the conveyor branches off: one route leads to a direct unloading station, the other the upper storey’s warehouse from where the load bars are then recalled according to the production schedule, descending to the 4 unloading stations dedicated to assembly operations. All 5 unloading stations are equipped with lowerators. “The surface treatment process also includes the possibility of retaking the load bars in the coating booths for the application of a second layer of powder, which is increasingly required by our customers”, Matteo Giacometti points out.

“Imel’s i4paintshop module for plant management and predictive maintenance is another plus in this project. This module and the conveyor and booth management software programs are highly integrated with each other and with our company’s management system, where all treatment recipes are recorded. Every load bar sends back information at the end of each cycle, so we know exactly the process times, all operating parameters, and any alarms caused by problems during processing.”

“There are three reading points for the barcodes on the load bars, located in three strategic areas within the plant: the entrance to the pre-treatment tunnel, the quality control area, and the entrance to the assembly area,” explains Paolo Chiesa from Futura. “Thanks to them, the conveyor’s management system knows which load bar is passing through any given point and at any given moment: this information is essential, also for recalling the bars to the assembly stations. The conveyor’s PLC collects and distributes all this data to Comel’s company management system, Wagner’s PLC, and Imel’s i4paintshop module.”

Wagner’s IPS technology

“At Comel, Wagner has installed 2 Supercube booths with 2 IPS powder feeding systems,” says Marco Spada, the Area Manager-Powder Coating of Wagner SpA. “When a load bar arrives, the booth recognises the application recipe matched with it and performs the programme automatically. The IPS system – which has no wearing parts except for one component of the electrostatic feeder – guarantees powder delivery with consistent parameters for each coating recipe over time, for at least 2,500 working hours.

“One of its advantages is that it ensures remarkable penetration and uniformity even in the absence of 3D part recognition devices because it has the Dual Zone system, which enables it to change the flow rates of the nozzles simultaneously in a fraction of a second, thus increasing the amount of powder dispensed and the air speed used when covering the deepest surfaces and decreasing the powder output kinetics on flat surfaces, to obtain uniform thicknesses on both flat and concave areas. Comel, in particular, can exploit 90% of the IPS system’s potential, as it coats parts with sometimes very complex geometries, controls coating thicknesses, and has high quality requirements. On box-type profiles with a depth of 600 mm, for example, it only needs to pre-finish a few inner edges, while covering the outside, inside, and bottom with minimal pre-finishing requirements.”

The 2 coating booths are identical. However, one is equipped with 2 Lesta articulated robots for pre-finishing, installed on the same side; the other has 2 manual pre-finishing stations, although already prepared for the future integration of robots. As 98% of pre-finishing operations are required on the concave surfaces of parts, the robots or operators work on the same side, although the stations allow for both right- and left-handed use.

“We installed industrial-grade, ATEX-certified Kuka robots with Image Match 3D, a scanning system we developed in recent months that recreates various points on the part to be coated by identifying the actual position of the object as it passes through the coating line. That allows adapting the pre-set pre-finishing path very precisely to the component’s actual position and its multidirectional movement in space, due to the use of different hooks than expected, for example,” explains Lesta’s owner, Emanuele Mazza. “In addition, we have recently released an update of our self-learning programming mode that allows importing the generated programme into the offline programming software package, optimising details or correcting errors, and then regenerating the file to be sent to the robot.”

“This project was a significant experience for Wagner in two respects,” Marco Spada emphasises. “The first was the high finishing quality specified by Comel, higher than that required in the household appliance industry. With some powders, we are using 140-μm sieves despite coating huge surfaces with high line speeds. Indeed, Comel’s requirements included the total absence of paint pitting, maximum penetration, uniform distribution, and thickness consistency on all surface areas. “The second aspect of this project that has allowed Wagner to grow a lot was the booths’ suction requirements. Having 2 prefinishing stations on the same inlet side – controlled by 2 robots or 2 operators, respectively – spraying next to each other, it was challenging to properly position the suction point where the overspray produced by this operation should be conveyed. We had initially thought of placing a suction point directly on the platform, but we would have lost the possibility of recovering the overspray generated during colour changes. Working in close cooperation with Imel, we opted for a system ensuring that overspray is sucked out of the booth and sent to the cyclone for recovery, even in the absence of a down-draft suction device at the pre-finishing stations. On the part of both Imel and Wagner, a great deal of effort was put into optimising the airflow and fluid dynamic balance within the clean rooms and booths. The design work we did with Imel has led to extraordinary results: a suction system with perfect fluid dynamics and, therefore, unrivalled coating quality and high colour-change efficiency.”

“Over the past year, we have counted 130 active colours on both plants. 5 of these account for 40% of our total production volume. This new system handles between 70 and 80 tints, with an average of 3 colour changes per day on each booth,” illustrates Nicola Cesarato. “Our goal is to apply all colours with both plants.” “The finishing quality that our customers have appreciated over time is the one we have to stick to: while it is true that we use many textured colours that are easier to apply, we also use numerous wrinkled, matte, or metallic colours that are much more critical. I realise that achieving these quality standards was a challenge for the suppliers that worked on this line, particularly Wagner,” says Matteo Giacometti. “Precisely intending to maintain consistent quality, we have relied on two main suppliers of powders for many years now, AkzoNobel and Sherwin-Williams, also trying to steer any customers specifying powders of different brands towards these two providers, which specifically fine-tuned their formulations when we implemented this new plant. Indeed, for the same colour, Wagner’s IPS application technology requires powders meeting certain standards, with formulations adapted to it.”

A high degree of satisfaction and praise for the team

“The plant has been in operation since January 2024. There were some initial problems, but once solved, I can say we are fully satisfied with the investment and the group of companies we chose as our partners,” states Matteo Giacometti. “By the end of the year, we should also have data on savings rates. After eight months of use, however, we are already seeing several improvements in terms of efficiency that justify the investment made and that we appreciate. Reducing waste as much as possible and making paint and energy consumption – the two main cost items of a coating line – more efficient were among our main goals with this project.”

“I would also like to applaud Comel’s operators and technicians, who have worked hard to understand this change in technology and learn to use both the booths and all other equipment to their full potential. Such a positive and collaborative attitude was not to be taken for granted: there was a risk of bringing in operating methods that could be incorrect if applied to these new technologies.” “We are already thinking about the future,” Giacometti concludes. “A short-term project is the further expansion of the coating plant’s direct unloading area with the addition of a second station, again in cooperation with Futura. The contract coating market evolves rapidly, and our mission is to stay ahead of the curve to always meet our customers’ needs.”