How to realize tooling for painting processes with PEEK 3D printing

Industrial painting to prevent the breakdown of materials

Painting is an extremely common process that is done in a huge variety of industries, from user electronics to commercial vehicles to spacecraft. It is typically done in paint shops, dedicated facilities that have the instruments to apply and cure the paint. These paint shops can be used to coat customized one-off parts, low volume parts (such as aircraft), or high-volume parts (such as cars). Paint shops are often integrated into a production line and can be largely automated, especially in the case of high-volume manufacturing processes.

Why are painting processes so important?

All materials break down over time as they interact with their surrounding environment, compromising their effectiveness over time. This can be very slow, like the breakdown of plastic in the environment, or relatively fast, such as the rusting of iron. One of the easiest methods to prevent this is by coating them with paint, a process that creates a thin layer of solid material on top of the part, shielding it from the environment.

Painting is not only used for protection, but it also acts as decoration for the parts. Decoration can be purely aesthetic, or it can serve a specific purpose such as camouflage or reducing the reflection of radar waves.

The issue of maintenance and storage of spare parts in painting processes

The painting process comes with its share of criticalities. Like any other manufacturing process, paint shops have several types of equipment that need maintenance and spare parts. These need to be ordered and have a lead time associated, and once the spares arrive, they are stored until needed. Spare parts often must be ordered in bulk to reduce the price per item, which means they occupy more space than is needed.

There is sometimes a need for specialized tooling for the painting process that will either need to be ordered or manufactured on-site. If ordered, the usual problems of lead time, storage, and cost per item present themselves. A slow-down in the delivery by the supplier can wreak havoc on a production line and cause severe delays. If the tooling can be manufactured in-house, there is the issue of ordering and storing the raw materials until they are needed.

These are issues that are common to all paint shops to varying degrees. In the article, we will look at the painting process of the automotive industry since its criticalities are fairly universal.

The industrial painting in car production

Car bodies need protection from atmospheric agents, and at the same time, they must look good. Although not all parts of car bodies are made of metal, it is important that non-metallic parts also have an aesthetic consistency with the rest of the car. Over the decades, owners have become more demanding and will continue to do so as achieving a high-quality finish is extremely important - both because of its aesthetic qualities and because of the protection it offers.

An automotive assembly line consists of stamping, welding, painting, and assembly shops, with painting being done towards the end of the process and before assembly. Figure 1 shows a typical automotive painting process. As can be seen, it involves both automated and manual painting and several passes inside ovens, where temperatures can rise to above 140°C for several hours. Several steps in the process are automated.

Which tooling is used for car painting processes?

As previously mentioned, specialized tooling is often used in the painting process. When painting car parts, sections must often be masked off to prevent them from being coated, examples can be seen in Figure 2. Doing this by hand can be a laborious and long process that slows down the entire production. For one-off custom jobs it is manageable but when the volumes increase, it becomes unfeasible.

During the painting process of cars, many different tools and equipment are used, ranging from fixtures to robotic manipulators. All these need spare parts, which can be difficult and slow to acquire and create problems, especially when there is an unexpected breakdown. Having stocks of spare parts or being able to manufacture them on-site is preferable but, as discussed, has its own set of criticalities in the form of warehouse space management and lead times.

Following assembly, as well as masks it is also sometimes important to keep parts separated while being painted and cured, for example doors that have been mounted on bodies. Metallic masks and fixtures are heavy, expensive, and made of a material that industrial car paint is designed to stick to: so the difficulty lies in finding a material to which the paint won’t stick and one that can survive the curing process. On top of that, it would need to be easily processable to manufacture masks for different car bodies.

Production of tooling and spare parts for paint shops with Roboze 3D printing

The criticalities highlighted above for the automotive industry are representative of the issues facing painting processes in all sectors. Using a combination of 3D printing and PEEK, Roboze offers the ideal solution for making spare parts and tooling for paint shops that are durable, light, cheap, and can be customized to fit any production line. PEEK (Polyether ether ketone) is a high-performance thermo-polymer that has excellent mechanical and thermal properties, as well as a wide chemical resistance. This means that paint and other chemicals will not stick to it and that it can be easily cleaned off. The thermal properties of PEEK produce parts that can easily survive the curing processes thanks to its high melting temperature of 338°C. The low coefficient of thermal expansion ( 52x10^-6 K ^-1 ) means that PEEK parts will undergo minimal deformation during heating and cooling cycles.

But a great material is useless if not paired with a 3D printing technology that allows the production of high-quality parts, which is where Roboze printers come in.

Roboze ARGO: optimize your supply chain in the industrial painting process!

Roboze’s ARGO solutions are advanced additive manufacturing systems developed to streamline and make production processes flexible with a reduction of time and costs compared to traditional methods - allowing to optimize the supply chain with 3D printing of parts and large scale finished components with the most performing high-temperature composite materials and super polymers.

The Roboze ARGO series is the result of years of research and collaboration with the best players in the aerospace, motorsport, energy sectors and represents the combination of product innovations offered by Roboze. Learn more about its advanced 3D printing technology:

• heated chamber system up to 180 ° C (356 ° F);
• patent-pending high temperature extrusion system; 
• automation and process control thanks to a set of smart sensors for the acceleration of printing operations;
• thermal process control system of the filaments during all production phases; 
• the patented Beltless system that makes it the most precise in the world, with a mechatronic precision of the X and Y axes equal to 10 µm (0.4 mil).

The result translates into high-quality levels of the parts produced with high precision, process repeatability, and the availability of many super polymers and composite materials such as PEEK, Carbon PA PRO, Carbon PEEK.

 Application of PEEK and 3D printing in car painting

An example application of PEEK to automotive paint shops was completed in collaboration with a major automotive manufacturer. A fixture was needed to keep the doors of a van away from the body that they had been mounted on during painting and curing. This fixture was made of steel, but it was heavy, and the paint would stick to it, meaning it could only realistically be used for 3 or 4 paint cycles before needing to be replaced or the paint removed. The fixture also ran the risk of scratching the surface and ruining the paint job, which would have severely slowed the manufacturing process. Finally, the fixture had to be ordered externally, which has an associate lead time and would mean that several needed to be ordered in a batch to revoice a bulk discount.

The Roboze solution was to print the door-holding fixture with PEEK, resulting in a lighter, cheaper part that could easily be washed and did not run the risk of scratching the paint, shown in Figure 3. Table 1 shows how the production with 3D printing compares that of traditional materials and manufacturing. As can be seen, the printed part costs 40% less, and on top of that, it only weighs 18% of the original, thus making it is much safer to handle and transport. The part also only needs a couple of hours to print, versus a couple of weeks of lead time when ordered externally.

Get all the advantages of Roboze 3D ecosystem in only 1 solution

The true strength in Roboze’s 3D printing solutions is in flexibility by being able to print many different types of parts that might be needed in paint shops, including:

• holders;
• rollers;
• centering pins;
• nozzles;
• electrical / thermal isolators;
• seals;
• protectors against surface contact;
• tools;
• gears.

All of these can be made simply, quickly, with a single machine and in-house thanks to the huge variety of materials printable on Roboze machines: from simple ABS and PLA to specialized materials like Flex-TPU (to produce gaskets) and high-performance thermoplastics such as the aforementioned PEEK and Carbon PA PRO (ideal for metal replacement applications).

Roboze’s 3D printing ecosystem provides a complete solution that dramatically lowers costs no matter the production line. Ordinary maintenance parts and tooling can be printed in record time and with little hassle, freeing other equipment to be used on essential components. The added design freedom afforded by 3D printing means that the part count of components can be reduced while at the same time customised to reduce the weight, material usage, and improve the functionality.