3 Powder Coating Issues You Should Avoid

There is constant debate about which is better: powder coating or painting. While the former can offer up a more durable and resilient coating, painting can still be the right option for a given process depending on the nature of the project. In this instance, let’s say powder coating is the ideal solution for your project. Maybe you need a thicker coat that’s consistent in both quality and time necessary to complete. Just because it can provide a better long-term solution doesn’t mean that the process of powder coating is as easy as just brushing it up and down a few times. There are a few problems and annoyances that can occur during the powder coating process. While tedious to fix, they are easily avoidable if you take the proper precautions before starting.

 

Pinhole

If there’s one thing the most common problems in powder coating have in common it’s their silly names. With a defect name like “pinhole,” you might think it’s some weirdly looking deformity. In all fairness, it most definitely is, but the defect itself is far less amusing than its name would let on.

Pinholes are generally defined as tiny circular voids found in a powder coating finish that is clearly visible to the human eye. Typically a single pinhole won’t cause that much of a problem, but when they show in bunches, then it’s a sign that you most likely need to recoat the metal. In an ideal finish, you want the metal to be smooth. Pinholes usually occur during the curing process. When the part heats up, the powder melts into a liquid which spreads into a film, causing the creation of holes or bubbles across the surface.

Pinholes don’t just happen without cause or reason. In most cases, they will appear due to a lack of proper preparation. The surface of the piece is always the game-changer. If it hasn’t been properly cleaned, then it opens up a plethora of opportunities for contamination. If the surface wasn’t properly wiped down prior to the powder coating, then dirt or other impurities such as oil, grease, or water can become trapped within the powder.

If you find pinholes on your piece, the only way to remove them is to recoat the entire surface. It’s much simpler to prepare yourself and minimize the odds of them even showing up. To avoid pinholes, clean the metal thoroughly. You can achieve this by blasting, washing appropriately, or even treating it chemically. As well, cleaning the booth and keeping the oven air clean are essential steps to avoiding these deformities. Avoid cross-contaminating the metal with other substances, like WD-40 for example. Finally, make sure that the curing temperature is set correctly before beginning the coating process.

Pinholes are easily visible to the human eye and can imply a lack of due dilligence from the coater themselves.

Orange Peel

Another common powder coating problem also shares a silly name: orange peel. Amusingly enough, the orange peel deformity got its name because, well, it looks like an orange peel. Powder coaters are notoriously humorous. Typically, a surface with an orange peel-like finish has an uneven texture on what should be a smooth finish. In that sense, it both looks and feels like the skin of an orange or any similar citrus fruit. Similar to the pinhole, fixing this imperfection will require a recoat, meaning you will have to restart from step one. The best way to avoid orange peel is by taking the necessary steps to ensure all parts of the surface are smooth.

The first step you’ll want to take to avoid the orange peel effect is to properly prepare the surface before the coating proceeds. There are several ways to do so. You can sandblast the surface or immerse it in zinc or phosphate. The former option is generally more approved due to the increase in durability that sandblasting can provide, but it also requires delicate attention from the person performing the sandblasting. If it isn’t done properly, the sandblasting can cause indentations in the surface that will also lead to orange peel. Be sure that during this preparation, you don’t cause the problem you sought to avoid. If you’re unsure, try using fine sandpaper to ensure proper protection.

Once you’re certain the surface is prepared, you can shift your attention to the powder coating itself. Powder coating revels in specifics and straying from the guidelines is begging for a deformity to appear. Adding too much or not enough powder can lead to orange peel. If the guideline suggests an amount, stick to it.

Finally, during the curing process, it’s important to maintain the proper temperatures and schedules throughout. If cured too long at too high a temperature, you can expect to see orange peel developing. The opposite is true as well. While the temperatures and curing times can vary, a happy medium can be found at around 200℃ for approximately 10 to 15 minutes. While this isn’t an explicit recommendation, most guidelines will have similar directions. Always be sure you’ve read the guidelines before attempting to cure the piece.

Orange peel certainly mimics the look of the skin from an orange. Its lack of smoothness is the clear indicator that the powder coating was imperfectly done. Image via Powder Coating Online.

Fish Eyes

Continuing the silliness of the names of recurring powder coating problems is the dreaded fish eye imperfection. Not unlike its imperfection siblings, fish eyes are a result of contamination in the piece’s surface that can also cause the powder to flake or peel. The fish eye deformities are apparent to the human eye and you can spot them as a depression in the surface that almost looks like a pitching mound, where the center is elevated. They do seem somewhat similar to the other imperfections mentioned earlier in the article, but there are distinct differences between typical craters and fish eye defects.

It’s true that all these problems are caused by a form of contamination, the contamination leading to fish eye can sometimes occur before the pre-treatment which occurs before the coating itself. While the contamination can occur on the surface, other times it happens in the powder itself. This is largely dependent on the quality of powder selected. Some powders can handle contamination decently, while others, like high-flow resins, will more easily develop fish eyes. Unlike the other defects, fish eyes are nearly impossible to fix once they’ve occurred. You will need to recoat the entire piece and ensure that the surface is now cleaned and that contaminants are kept to an absolute minimum.

To prevent fish eyes from arising, it’s essential to clean the surface to perfection. Perform a white rag test afterward to ensure no contaminants, dirt, or dust make their way to the surface. As well, keep the equipment as clean as you would the surface. Any chance a contaminant gets to ruin the coating will likely occur, but mitigating this potential deformity is easy if enough attention is paid to the process.

Fish eyes are easily spotted and a pain to remove. Taking extra precautions could ensure they never appear.

Powder Coating: A Cleaner Dream

There’s a pattern with all these deformities and imperfections. Most of them are caused by contaminants left on the surfaces due to a lack of preparation and cleaning. Fixing these mistakes after they happen is a pain and time-consuming. Naturally, preventing these problems is a much more sustainable method than attempting to fix them. Following guidelines, cleaning thoroughly, and paying proper attention to the coating process as it happens are key elements to ensuring your coats don’t become unusable or delayed.

To avoid errors caused by tired humans, powder coaters can look to AutonomyOS. Using 3D Perception with AI-based Task Planning and Motion Planning, manufacturing engineers and integrators can configure autonomous robotic systems to analyze and coat various pieces of metal regardless of their shape, complexities, and sizes. Contact us to learn more.

5 Common Welding Problems and How To Solve Them

To the untrained eye, welding can come across as a more pleasurable form of labor. The action of welding just seems that much more interesting than other processes. But just because it looks fascinating doesn’t mean it’s all glitz and glamor. It’s a physically and mentally demanding job that, if done without the proper care, could lead to many problems and hiccups along the way.

Some of the recurring issues in welding can be attributed to faulty equipment but most come from improper actions, blink-and-you’ll-miss-it errors, and sometimes just some bad luck. Fixing problems in welding can be difficult as it’s not always possible to walk back on the process and just patch over a mistake, given the transformation through which the metals go. Instead of fixing, it’s often easier to prevent these problems. In order to prevent them, we need to understand why certain problems happen and what practices will help mitigate them.

 

Spatter

Weld spatter is about as annoying as it sounds. Spatter usually forms from droplets of molten material produced during the welding process, namely near the welding arc. These droplets often look like molten balls of metal that attach themselves to the surrounding surfaces such as the metal piece the welder might be working on, or, well the welder themselves. While they aren’t physically devastating to the piece being worked on, it does look wonky and might give the impression that the welding process was done with little to no care. While it might be annoying to remove the spatter afterward, preventing them altogether will save precious time.

The causes of spatter can vary. Sometimes the metal composition is at fault; not every type of metal is meant for welding. Some components don’t have the strength to withstand the heat that welding brings. Other times, the metal coating could be erroneous, the metal could simply be dirty, or improper welding techniques and settings could be at play. These problems aren’t necessarily rare, however, a little further research and attention to the setup could be the difference between spatter flying around ruining the metal and finishing the task with no hiccups or hurdles.

Quick ways to prevent spatter could be to reduce the current and the arc length, increase the torch-to-plate angle, and clean the gas nozzle. By taking a few precautions, you may be clear in avoiding spatter on various welding processes.

 
Spatter marks are easily visible and are a sign of poor quality assurance from the welders themsevles.

Porosity

Porosity is another common welding defect that’s easier to prevent than it is to solve after the fact. This defect happens when there’s the absorption of nitrogen, oxygen, and/or hydrogen in the weld pool. This generally occurs inside the weld during the cooling process. There are several types of porosity such as surface, subsurface, wormholing, and cratering each with its own causes and deformities.

The most common one is surface porosity which shows deformities to even the most untrained eye. The other forms can be slightly more difficult to see as you take a gander, but their subtle imperfections can affect the welded metals negatively. 

Porosity can be caused by the contamination of the metal at hand, including by paint, oil, moisture, mill scale, etc. As the heat from the welding increases, these contaminants will transform into gasses that then become trapped within the weld pool, essentially weakening the weld itself.

As is the case with spatter, removing porosity after the fact is time-consuming and arduous. Your time is better spent taking the necessary precautions to avoid porosity. Some of them include keeping the workspace clean, using fresh welding consumables, having dry and clean plate edges, and regularly checking the equipment. The last thing you need is a leaky welding torch because you didn’t check it before using it!

Cracks

Of all the recurring problems in welding, cracks may just be the most annoying of them all. Cracks happen when the internal stresses of a weld exceed the strength of the filler metal and/or base metal. Unlike the other problems, which could be solved after the fact, cracks are much more of a nuisance. To fix them, the weld would need to be ground out, and then a new weld would need to be performed. Essentially, you would need to eliminate the problem and restart from scratch. If that sounds like lost time, that’s because it very much is.

While the cracks often happen because of external and internal stresses, they aren’t all the same. The physical loads may be too heavy for the welding process; residual welding stresses, the more frequent cause, can weaken the joints, leading to cracks in the metal. Cracks also occur in two extremes: very hot and very cold temperatures.

Hot cracks occur at higher temperatures when the liquid metal can’t sufficiently fill the spaces between the weld metal that’s in the midst of solidification. As the metal shrinkage begins, so does the cracking as there’s an excessive amount of stress that occurs simultaneously. Hot cracks can be attributed to a strain on the weld pool, a blockage of weld liquid, impurities in the metals, and above-average temperatures. To avoid these cracks, it’s best to keep the causes in mind and keep the strain and temperature to the lowest possible without sacrificing the quality of the weld.

Cold cracks, while on the opposite side of the temperature spectrum, are still just as annoying. Cold cracks cause sharp-edged crevices to form throughout the weld. Like its warmer brother, it can absolutely ruin the weld. It can occur after the weld has solidified and can be caused by a combination of welding stress, a brittle hard structure, the presence of hydrogen, and temperatures below 150°C. To prevent cold cracks, ensure you have a proper width to depth ratio on weld beads, select your base material properly, and validate your technique to mitigate any improper moves or processes you may not be sure of.

 
Cracks in sanding can be minimized using cover sheets. Statistics via Research Gate by Zhanxiang Ling.

Undercut

Undercutting in welding is when grooves begin to appear on the base metal near the root of the weld. While this is sometimes the result of a weak welding process if undercuts do appear they can drastically reduce the strength of the weld and workpieces. Some of the causes for undercuts include maintaining too long an arc length and maintaining excessive current which causes edges of the joint to melt and drain into the weld. The latter will leave a drain-like impression across the weld. As well, selecting the wrong gas shield, poorly depositing the filler metal along the edges of the weld, using incorrect filler metal, and using an improper electrode angle can all cause undercuts in the weld. 

Simply put, undercutting in welding isn’t uncommon. Correcting the undercuts is doable, but, like clockwork, prevention is key. To ensure proper welds and to avoid undercuts, double-check the heat input, work at a decent speed (one you can properly supervise), correct the electrode angle and size, and perfect your weaving technique as much as possible before starting your weld. 

Distortion

One of the more visible defects, distortion of the metal occurs when the heating and cooling is uneven. Usually caused by compressive stress that occurs on the area around the edges, the metal can begin to deform and turn into an unwanted shape. Different forms of distortion include longitudinal shrinkage, transverse shrinkage, angular distortion, bowing and dishing, buckling, and twisting. While these all may sound a bit odd, it’s important to take the proper steps to avoid distorting the shape of the metal you are working on.

Preventing distortion in metal isn’t always a one-size-fits-all solution, but it can mitigate any unwanted disasters. Avoid welding from both sides of the joint. Weld from the center all the way, also going in opposite directions. Use large electrodes and clamp firmly. As well, alternate sequences of welds and locations if you begin to notice the beginning of the distortion.

Different forms of distortion could properly imbalance the way the metal is welded. Prevention is the key to avoiding these annoying problems. Figure via TWI Global.

Much Ado About Welding

 

Welding is a nifty but complicated process. Errors are easy to come by but they are also easy to prevent. Considering that a good portion of welding is done by real welders, problems may sometimes arise as a lapse of judgment, which could be caused by fatigue, stress, and other human factors. Humans are imperfect and sometimes that leads to imperfect welds. Other times, it can just be bad luck. In any case, these problems are common and easy to identify, giving you the most information possible to complete your welds in the most efficient manner possible.

When human welders are no longer an option, autonomous robots can answer the call. Using 3D Perception with AI-based Task Planning and Motion Planning, manufacturing engineers and integrators can configure autonomous robotic systems to analyze and weld various pieces of metal regardless of their shape, complexities, and sizes. Contact us to learn more.

 

Understanding The Division of Labor In Robotics

It may seem like an eternity ago that collaborative robots, or cobots for short, were introduced to the labor force in an effort to help ease a burdening workload for employees who may have needed a hand. Their first use dates all the way back to the late 1990s when Northwestern University professors J. Edward Colgate and Michael Peshkin helped invent them. As time has passed, their use has only increased. Advancements in robotics have allowed robots to alleviate the stress of demanding and tiring jobs. With fewer workers entering the manufacturing workforce as the years pass, more robots are being tasked with performing jobs that people simply do not want or have the energy to do on a long-term basis. With the saturation of robots in manufacturing, a clear division of labor is present, showing the ever-growing distance between human and robotic labor. 

Traditionally, robots would execute tasks that never changed in nature; they repeated the same movements since the job itself wouldn’t change from part to part. The automotive industry has long used robots to help build different pieces of each car. However, that industry only represents 20% of manufacturing. In the time since the mass installation of robots in the automotive industry, more manufacturers are looking to automate their factories. It’s clear that they want to add robots to improve productivity after the largest shift in labor hit manufacturing harder than most other industries.

 
Cobots have assisted humans in various tasks for over two decades. Expanding robots to become fully autonomous can allow manufacturers to compensate for lost time and labor.

High-Mix Environments and Process Use-Cases

For high-mix environments, the pieces that need work often change in size and form. The processes aren’t always identical either as they can vary from powder coating, to sanding, to deburring. Each process has its own share of wrinkles too. For powder coating, there could be weak penetration of powder into the faraday cage areas. For sanding, it can be chatter marks. And for deburring, it can simply be the lack of precision by human hands. Regardless of the process, problems will inevitably arise and cause a backlog in production as humans can only work so fast under tiring conditions. 

The backlog only becomes more prevalent when you take into consideration the fact that fewer people work in manufacturing than ever before. In the 1950s and 60s, 36% of employed males worked in manufacturing; today that number hovers around 11%. Those that remain have to make up for the lost work.

 

Freeing Up Time & Labor

In an effort to compensate for the loss of manufacturing employees, High-Mix manufacturers have opted to invest heavily in robots. Through a myriad of options to help program the robots such as ROS, manufacturers can ensure that autonomous robots not only are capable of handling tasks that require a certain skill set, but that they can do so in a timely manner. 

By transitioning these tasks toward autonomous robots, manufacturers will also see several byproducts of this maturing technology. Autonomous robots can and will perform the necessary tasks but they won’t push the remaining human workers out of the factories. In fact, they will be as necessary as ever and their jobs, while less physically demanding, will allow them to achieve more by solving tasks that a robot can’t necessarily do.

Humans are intrinsically creative. Their best work can generally be achieved by allowing them to create and solve problems in different ways. If a manufacturer needs consistent sanding for different wooden parts, then it removes the physical strain from the employee who can instead focus on whether the machine is in good condition, if the pieces of wood can go to the robot without any game-breaking imperfections, or simply taking the extra time saved to devise a plan that could allow for faster production or fewer problems within the working environment.

Short-Term Planning For Labor Losses

Naturally, robots aren’t replacing every human in manufacturing. On the opposite side, humans aren’t exactly returning to manufacturing in droves now that the pandemic has eased. The goal isn’t to directly replace their labor either. Getting them back is another task on its own. In the interim, setting up an autonomous robotics system is an easy stopgap solution that can alleviate manufacturing employees in the short term, while alleviating costs for owners who need to continue to produce at the rates they’re used to.

Autonomous robots can compensate anywhere between 80-90% of a given manufacturer’s labor utilization, thus opening the gates for their employees to work on other tasks that have been paused due to production backlogs. Autonomous robots are still relatively new, but the industry is burgeoning. 

ROS allows for the programming of autonomous robots, but even that requires programmers to constantly update what the robots can do. Omnirobotic’s AutonomyStudio™ allows manufacturers to remove coding from the equation, instead opting for behaviors that will allow autonomous robots to see, plan, and act accordingly for every new part placed in their line of sight.

The labor shortage may begin easing up, but not all ex-manufacturing employees will return. To replace human labor for arduous tasks like sanding, autonomous robots can provide a stopgap solution to continue producing at high rates.

 

While autonomous robots at the moment may be short-term solutions for a long-term problem, in the future they will be even more powerful and capable, furthering the amount of time is freed up for employees looking to help their respective companies grow in a fruitful way.

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 to sand various pieces of wood regardless of their sizes. Contact us to learn more