The Complete Starter’s Guide to Spray Metal Finishing

Before considering metal finishing for spray processes, it’s important to consider one thing: this is a “starter’s” guide. This doesn’t offer detailed engineering information. This also doesn’t offer safety or compliance standards nor does it offer a means to avoid health and safety risks or to improve an already existing complex process. There are an indefinite number of resources that are much better suited to that – we love the ones provided by PCI (the Powder Coating Institute). 

All that being said, if you’re producing any kind of metal product and looking to evaluate any kind of spray finishing process for metal – whether it’s liquid painting, powder coating or sandblasting – this article is a great place to start because we’re revolutionizing how manufacturers can approach these processes through robotics.

There are three primary spray processes applied in metal finishing: liquid paint, powder coating and sandblasting. Each has its own merit and goals — paint may be easier to repair or more forgiving where baking is not required, powder may function for higher volume and preferred materials, and sandblasting can provide the final finish that customers are looking for. Understanding how to maximize each process is critical to improving overall productivity. 

Liquid Paint Spray Metal Finishing

The primary goal of industrial paint is to provide both an aesthetic and materials-compliant finish that can be touched up or restored without significant challenge while also providing basic protection against surface damage and corrosion.

Paint is typically preferable for light-duty equipment or applications with defined maximum weights (often found in the aerospace industry). Generally, powder coating or other media (ecoat, thermal spray and more) are considered more useful, durable protective coatings for heavy-duty applications and equipment. However, these are also costly and difficult to touch up. 

For instance, why aren’t entire cars powder coated? Well, if a car gets into an accident and does have inevitable damage, the repair would entail re-coating the entire car and baking it to a finish. This may not be feasible or desirable given all the components that go into a finished car, where heavy equipment (like that for construction or snow removal) is usually practically-designed and has many replaceable parts, which means damage can justify rework, recoat or an entirely new part (not to mention that these types of goods don’t generally receive as much as “give” damage in a crash).

So, how do you know if liquid paint is your best spray metal finishing process? Here are a few tips:

  • The primary goal of your finish is aesthetic and you have multiple options
  • The material being coated is not resistant to high temperatures (e.g. 350 degrees Fahrenheit and up, as would apply to aluminium) that are required by alternatives like powder coating
  • High-gloss finish or easier touch-ups are more desired and preferred for the particular product being finished
  • You can’t afford the equipment that comes with powder recovery systems or you would prefer lower consumables costs overall

Powder Coat Spray Metal Finishing

Powder Coating is an electrostatic coating that is applied in a free-floating (but safely contained) environment to materials that can conduct electricity. This electromagnetic attraction allows the powder to “stick” to the surface of your metal products and then transit into a bake oven where the powder is essentially melted/”baked” on to produce a polymer-like finish after final cooling. 

Because of the nature of the coating, excess powder remains in the booth and as long as there is no cross-color contamination, it can be easily recovered and reused (with specialized equipment) to eliminate waste and reduce cleaning required in a booth.

Powder can also prove more durable in the long term, which is why it’s preferred for many applications from heavy equipment to fitness equipment to a variety of small tools and appliances that are deployed in rough circumstances. The total cost of powder can be much lower than paint in the long run, but equipment required may make start-up costs more expensive. 

At the same time, because powder sometimes requires a “spray and pray” approach, it can lead to excess coating beyond your actual thickness requirements. This is effectively the source of most “waste” in powder coating and even for small shops or lines can add up to hundreds of thousands in additional costs per year.

Overall, you should prefer powder for spray metal finishing if you need one of the following:

  • A strong, durable coating in a single color at a high volume
  • A matte-type finish with a fast, easy, forgiving and low-skilled application process
  • Highly automated coating with simple part shapes
  • Highly automated coating with complex part shapes (note: this is addressed through robotics rather than a fixed automated system, but the total price of each can actually be comparable)

Sandblasting Spray for Metal Finishing

Sandblasting or abrasive blasting is an important step that is sometimes the final one to spray metal finishing processes.

This can use a variety of different media to wear down, clean, smooth or flatten out a variety of surfaces in order to ensure that the final top-level coating applied can be sufficiently even to maximize results. 

As it happens, the way in which you want to achieve that best possible finish can vary depending on what media is best suited for the look. Everything from steel shot and grit to glass beads, different naturally occurring sands, walnut shells, corn cobs – all of these media and more enable you to achieve a refined look no matter what final finish you want to produce. 

Now, the challenge in sandblasting is more often how you want to apply this. A manual worker or generally automated systems can be helpful, but in situations where processes are predictable, robotics are generally preferred.

Processes must be very predictable for most robots, however. So, autonomous robots may actually be the best choice for highly varied sandblasting processes where parts or the shape of parts change frequently, but automation is still required. 

Taking Steps Towards a Robotic Process

While spray metal finishing requirements can vary both across and within industries, all industries are facing challenges in terms of both labor and skills shortages, as well as quality of output.

For both of these challenges, robotics is usually a compelling problem solver given its ability to predictably and reliably follow the same instructions over and over again.

Autonomous robots are able to provide this reliability and automation but actually adapt to different parts and circumstances without the need for manual programming or jigging – an opportunity to improve spray metal finishing processes far into the long term. 

With AutonomyOS™ and AutonomyStudio™, it’s never been easier to deploy an autonomous robotic system. Using 3D Perception with AI-based Task Planning and Motion Planning, manufacturing engineers and integrators can configure autonomous robotic systems for value-added processes that allow manufacturers to achieve more consistency and flexibility in production than ever before. Contact us for more info!

How Spraying Robots Improve Consistency

Robots are already well understood as productivity multipliers. Whether it’s on an assembly line or in a simple machine tending scenario, a robot can provide the ease of use and utility needed to do a simple task “on repeat” thousands of times, or even thousands of days on end.

When it comes to more complex value-adds like welding, actual machining or spray processes, the complexity of programming a robot becomes more challenging. When the parts change frequently, it becomes nearly impossible to use a robot – just storing all the jigs to position parts correctly can be an all-consuming task.

So, using a spray robot can help improve consistency, but using an autonomous spray robot can function even better. How is this possible? Autonomous robots can generate complete plans for themselves, which ultimately takes away the programming challenges and allows for the same level of consistency as parts vary. This ultimately gives your workforce more capability while improving your overall productivity and reducing rework. 

Generating a Complete Plan

An autonomous spray robot can SEE, PLAN and EXECUTE processes all on its own. All that’s required from operators is simple process instructions – the robot behavior – and potentially some oversight for high process compliance.

The SEE aspect relies on 3D Perception – depth vision cameras in multiple positions that enable the robot to identify parts in space and make evaluations about which faces to target, at what angles, and what position parts are in. This is all similar to how a human being visually assesses parts when they work in a paint shop, but the way in which decisions are actually made can be a lot more complicated.

The PLAN component of this process relies on the 3D Perception data a robot has, along with process constraints, requirements, targets or goals, behaviors (like standoff from a part or a spray gun cone) and a mix of AI and conventional algorithmic techniques to deduce the most efficient possible robot motion and generate a program for it.

Once all that computing takes place, autonomous robotics technology can EXECUTE a process by taking control of existing industrial robots, including those from brands like FANUC, ABB and more. By taking all of this into account, any type of part or part order can take on the same robotic consistency without the traditional limitations of robotics. 

Simplifying Existing Quality Challenges

By allowing robots to process parts the same way humans do, they can finally compensate for a lot of the limitations human painters face. What are some of the examples here? 

These include fatigue, inaccuracy, inconsistency, incorrect muscle memory and – everyone’s favorite – natural human error. These kinds of issues don’t happen with robots because they are entirely predictable machine systems. Their ability to adapt to different circumstances has been limited in the past because of the extensive programming requirements present in most, but with autonomy, that’s no longer a problem.

So, what happens when you combine the adaptability of humans with the consistency and reliability of a robot? Essentially, the best of both worlds, but you can actually overcome the quality limitations found in many high-mix productions while further reducing the constraints of skills shortages, general labor shortages, supply or consumable limitations and most of the inflexibility that is found in today’s higher volume manufacturing processes.

Giving Your Teams a More Relevant Role

By overcoming these dual limitations — machines that aren’t adaptable, humans that are unreliable — autonomous robots don’t just execute processes in a better way. They actually make it easier for humans to get better jobs and do more thanks to the productivity benefits of working with robots.

When you reduce the burden of highly physically demanding jobs that are ill-suited to human capabilities, you actually make your people more capable of managing new forms of automation, coming up with new approaches to your production and empowering your other team members with more insight on what can be done better.

Improving your Output and Reducing Rework

By reducing rework and improving the continuity of your production, you ultimately make it easier to meet demand, shorten lead times, manage labor challenges, and accelerate your growth. At the same time, the same technology can improve the performance of new processes over time, while also simplifying the ramp-up to new SKUs and productions. All of this makes for an autonomous manufacturing future that has never looked brighter!

With AutonomyOS™ and AutonomyStudio™, it’s never been easier to deploy an autonomous robotic system. Using 3D Perception with AI-based Task Planning and Motion Planning, manufacturing engineers and integrators can configure autonomous robotic systems for value-added processes that allow manufacturers to achieve more consistency and flexibility in production than ever before.