Optimizing Transfer Efficiency With a Robotic Cell

Industrial-scale operations require industrial-scale solutions. One of these comes with powder and other forms of coating where transfer efficiency is key.

Transfer efficiency is usually defined as a ratio between coating material that sticks to an object vs the total weight of coating used in a process interval. This is generally expressed as a percentage. For example, if only half the coating makes it onto the part being processed, that could be considered a transfer efficiency of 50%. The more that makes it onto the part, the higher that percentage.

Where Transfer Efficiency Is Important

For a few reasons, powder coating transfer efficiency may not need to be particularly high. Some powder coating booths allow for the recovery of material, although color changes can lead to contamination that ultimately compromises the whole endeavor of material recovery.

This is where the challenge becomes impactful. For even an average powder coating shop, spending $1 million or more per year on powder is not uncommon. If within this expense, 50% or more of the material is wasted, this can be incredibly burdensome for a small or medium-sized business. 

When we consider larger shops which may be running 2 or 3 shifts on multiple lines, 6 or even 7 days per week throughout the year — these enterprise-grade production environments can be spending tens of millions or more coating complex part shapes where faraday caging and unique targeting challenges make powder waste a huge cost. Often the biggest cost in powder is simply in finding enough skilled labor to get enough material on the part. 

What Is a Good Transfer Efficiency

Good transfer efficiency is generally considered to be 65% and up. This is because of a few things, including the need to overspray faraday caging areas in order to ensure that sufficient coating can adhere to the part. Generally, powder as a material can be a little cheaper than paint — particularly specialized industrial paints — so those using powder coating in manufacturing are able to spray more liberally and less accurately than they might for conventional paint.

That being said, high transfer efficiency is always more desirable in the sense that more powder on target is better. The challenge again becomes that if too much powder is deposited on the target parts, then money is wasted for every pound of powder that is in excess of what is required by the customer or the overall production process. 

Transfer efficiency overall can be improved by increasing voltage or improving the grounding of your operation as well as overall design or “batch run” improvements that optimize how your coating process works according to the shape of your parts, but these specific improvements can vary according to the specifics of a certain production. For more on how to improve the fundamentals of your powder coating booth, the Powder Coating Institute can be one of the best resources out there!

How Is Powder Coating Done Today

Powder coating is done today through two primary means: handheld, pressure pot-driven systems and automated booths utilizing overhead conveyors, reciprocating arms and quick color change or rapid recovery additions.

For manual coating, the process can be challenging in that workers must wear protective equipment since inhaling powder coating is essentially toxic, while said equipment can also reduce the desirability or accuracy in doing a manual powder coating job. Secondly, the equipment used has to be safe within the bounds of human presence and then essentially relies on lower pressure and volume of coating with a higher need to rest over trouble spots or faraday cages.

When it comes to automated systems, higher volume and broader distribution of coatings are achievable through automated arms that have a consistent 24/7 output. Maintenance on these systems is minimal, but accuracy according to uniquely-shaped parts or parts with varied cavities can be a challenge. In this context, many vendors still provide systems with light screens or other vision components that can overcome the limitations of some part nuances, and while these can work within specific scopes or for most manufacturers’ needs, many may still find themselves returning to manual coating or touch up for trouble parts. 

How a Robotic System Can Help

A robotic system can help improve powder coating in both transfer efficiency and in reducing unnecessary overcoat by better targeting coating according to the shape of a part. If, for instance, 35% of coating is lost due to mixing and another 15 or 20% to overcoat, the savings of reducing these losses by even 50% respectively can amount to hundreds of thousands of dollars per year for even the smallest powder coating production. 

The challenge in incorporating robotics, however, is that each robot needs specific programming and jigging in order to be effective for individual parts. For mass manufacturers or those working with highly specialized, expensive coatings with very low part mix, this could allow some to benefit from robotics. However, the real challenge here is that most coaters who use A LOT of coating have a lot of different parts to process, meaning traditional robotics may not really have the answer they’re looking for. 

Why Autonomous Robotics Is the Next Step

Autonomous robotics is different because it’s based on the concept that a robot can be programmed automatically, in real-time, based on simple instructions or parameters driven by the manufacturer. In these circumstances, autonomous robots are able to adapt to the variations in part shapes that most need without compromising the consistency, reliability, or precise output that robots are generally known for.

With this in mind, it’s important for coaters to consider what the real scale of their needs is. If it’s simply one or two robots on a single production line, the autonomy to power them and save those hundreds of thousands (or more) per year may actually be cheaper than you think. 

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.

Which Industrial Paint Robots Work Best?

While many can often think of robots as far off, futuristic, unrealistic or attainable technology, robots have in fact existed as an industry for more than 50 years. And yes, while autonomous robots that fight crime and solve mysteries may be far off, we’re actually approaching an age where these robots we’ve conventionally ignored can conduct tasks autonomously as well.

In all the time that the robotics market has taken to develop, they have evolved from general to many specific and purpose-built uses and designs. Specific robot models are designed to lift many thousands of pounds, conduct precise operations in very low tolerance ranges, transfer materials at high speed, execute welding or other complex and caustic processes, and do it all within standardization and compliance ranges that ensure they can safely function for decades on end. 

What Makes a Paint Robot Different

Paint robots have to have the appropriate performance, but also the right equipment. Range, reach, speed and degrees of freedom all make a difference – this means that a paint robot won’t support a large payload, just enough for the right tooling, paint or powder gun – but it will need to be fast and reliable in terms of position. 

This is critical for two reasons: accuracy (or complete coverage) and avoiding dry spray. Dry spray can happen in many contexts where, if a paint or coating system is not fast and efficient enough, it will leave parts of the surface to dry while others are still wet. This is difficult when coatings are particularly thin, which is often the case in industrial manufacturing (no worse waste than excess). 

While this is most common in humid environments, the reliability of paint robots to achieve an accurate spray with aggressive settings is essential because – in order to realize significant quality and efficiency improvements over human operators – being able to function at a high level in adverse conditions is essential.

Finally, whether there is a paint pump, a powder mixer or another mix and feed system, paint robots work best when they have a hollow wrist to allow for easy tube management and feeding through the end-effector position of the robot. These robots further require explosion proofing for caustic, flammable or highly volatile coatings (which includes most industrial paints in liquid form). 

What is explosion-proofing?

Explosion-proofing works by effectively forming a pressurized jacket within the casing of the robot. A safety mechanism manages this pressure to ensure that it is constant. If there is a collision or other instance of depressurization, the power source to the entire robot is cut off. 

This may seem drastic, but why is this the case? Robots have active motors that can, in certain conditions, produce a short circuit which could ignite atomized coatings in the air. If said coatings would infiltrate a non-explosion-proofed robot, this would cause an explosion that would destroy the robot and most materials in the paint booth while also posing risks to the health and safety of everyone in the facility. 

Finally, software that can allow you to program (or even automate robot programming in real-time) is essential to driving the output of your paint robot. Depending on the number of parts and variations in your process, traditional programming approaches may not be cost-effective. This is where AutonomyOS™ and AutonomyStudio™ can help. 

What Brands have a Paint Robot

Almost every major industrial brand has its own paint robots, but ABB and FANUC have more than 90% of the market in North America. These robots have unparalleled reach and nimble designs which make them flexible and versatile for a variety of spraying applications, including the ability to flip over and use balanced-arm applications that provide more work volume and more versatility for skilled workers. 

Kawasaki, Yaskawa, Staubli and others of course have their own fine models of paint robots, but in order to best select your paint robot, considering whether your existing robot vendor meets your needs is the best approach as the complexity of going through multiple vendors, drivers, or programming methodologies is more trouble than its worth.

How to Get Started

In order to get started, the best choices are as follows:

  • Speak to your integrator
  • Speak to your OEM provider
  • Speak to a distributor or other expert who can ensure that the mechanical function of a particular robot model will meet your needs

Give and excess envelopes are always essential, even if a slightly higher price is called for. If your application is high-mix (e.g. more than 100 parts per year or batches under 1000) then traditional programming methods will likely create significant inefficiencies. In this context, self-programming or autonomous robotics technology is the most effective way to meet your spray needs – no matter what you want to throw at it!

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.