Powder Coating or Liquid Painting? Choosing the Right Finish for Your Custom Metal Parts

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When you purchase custom metal parts, the biggest concern on your mind is likely function. You need your metal part to be the right shape, fit onto your machine correctly and perform its intended purpose. If it doesn’t satisfy these basic requirements, then there’s no point in having it.

Once your metal parts satisfy these requirements, however, it’s time to start thinking a little more outside the box. What finishing touches can you add to your metal parts to make them match the rest of your machine? How can you make them hold up better against strain and wear and tear? How can you make them look a little more finished and upscale?

As it turns out, there are two different ways you can do this — powder coating or liquid painting. Both options are good ones, and both have advantages and disadvantages that you’ll want to take into account. To help you decide which one is right for you and your facility, we’ve compiled this guide to explain what makes each type of finish distinct. With a brief overview of this information, you’ll be ready and equipped to choose which finish will be the right one for you.

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What Is Powder Coating?

Powder coating has the same job as a coat of paint. It covers a surface in a finishing layer and a protective coating. It gives the surface both a more finished and polished look that adds to the aesthetic while also protecting the bare surface from dust, dirt and corrosion. This type of coating can be used on metal brackets, sheet metal boxes, large panels and much more.

Despite having the same basic function as paint, however, powder coating is a little different in practice. Instead of going on in a liquid coat, powder coating is applied to a surface as a dry powder.

This powder is applied electrostatically and then subjected to high levels of heat. This heat causes the powder to dry and come together to form a protective covering or skin that neatly coats the surface in much the same way paint does. Unlike paint, however, a powder coating typically dries and hardens into a finished coating much tougher and more durable than ordinary paint.

What Metals Can Be Powder Coated?

The general rule of thumb is that anything that can hold an electrostatic charge and that can withstand the high levels of heat required for the curing process can be covered in a powder coating. Because this applies to most metals, this means that the majority of metal parts and objects can be powder coated. This applies to:

  • Aluminum

  • Stainless Steel

  • Galvanized Steel

  • Electroplated Steel

  • Mild Steel

  • Brass

  • Iron

  • Copper

This is not a complete list, but it begins to give you an idea of the vast number of materials this coating can be used on.

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What Are the Benefits of Choosing a Powder Coating Finish?

We’ve talked a bit about what a powder coating finish is, but now let’s talk about why you might want one. What makes it superior to an ordinary liquid paint coating? Let’s go over a few of the benefits of powder coatings.

1. It’s Durable

Powder coating metal parts results in a far more durable final product than painting them does. This is because a powder coating allows you to achieve a considerably thicker coating that gives the metal underneath more protection. On top of that, powder coating enables you to perform this thicker finish without any of the dripping or sagging you might get with paint if you try for a thicker coat.

In addition to a thicker coat, the powder coating itself is simply tougher and holds up better against outside forces. Whether you worried about scratching, chipping, weathering or fading, powder coatings are far better at withstanding these forces than a standard paint.

2. It’s Long-Lasting

A powder coating does more than hold up to outside forces like weather, chemical damage and human interactions. When you choose a powder coating, you also select an option that will stand the test of time regardless of the conditions it’s subjected to. Whether your powder-coated surfaces will be outdoors in all weather or locked in a climate-controlled glass case, you can rest assured the powder coating will hold up beautifully.

3. It’s Fast and Easy

Painting is sometimes a bit of a laborious process. A surface sometimes needs multiple coats of paint before it truly looks like it’s finished. This process isn’t just difficult, as you work to apply the multiple coats evenly and cover the surface properly. It’s also time-consuming, as you’ll need to wait for each coat of paint of paint to dry before you add the next one.

Powder coating isn’t like this. When you choose the powder coating process, your job will be much easier and will go much faster. This process only takes one coat, and while it does require time to cure, it will still be faster than applying multiple coats of paint.

4. It’s Customizable

Powder coating offers you a whole world of choices when it comes to both finishes and color options. Choose from hundreds of different color options, all of which are long-lasting and resistant to the chipping or fading you might find in an ordinary paint. Differently textured finishes are available, too, and you can choose from smooth, wrinkled, matte, shiny or rough to achieve the look or function you’re going for.

5. It’s Good for the Environment

Powder coatings benefit the environment in scores of different ways, making them good for you, good for your business and good for the earth itself. First, powder coatings don’t emit harmful toxins or organic compounds that might pollute the air, as opposed to certain types of paints that may give off harmful odors and chemicals.

Additionally, the leftover powder can be recycled. This means that even if you overspray, or if you simply have some powder left over at the end of the job, you don’t have to worry about wasting it or about contributing to pollution. The recyclable nature of these coatings means you can use nearly 100 percent of them without adding toxic waste to the planet.

Finally, the production of powder coatings is a much safer and less wasteful process than the process that creates standard liquid paints. These powder coating production lines are more efficient and produce less hazardous waste that will need to be disposed of.

6. It’s Uniform

Because powder coating is applied in one large coat all at once and then dried together, it dries in an extremely uniform way. There are no remaining traces of brushstrokes or visible paint layers, as you might find in liquid paint. This results in a final polished surface that’s one uniform color and texture with no blemishes that are obvious traces of the production process.

What Are the Disadvantages of Choosing a Powder Coating Finish?

No matter how many positive sides there are to something, there will always be a few downsides. Powder coatings are no exception to this. With this in mind, here are a few of the potential snags you may run into if you decide to opt for the powder coating finish.

1. It Has a Hard Time Producing a Thin Finish

In most cases, a thick finishing coat is ideal. This is more durable, more long-lasting and leaves fewer traces of application. However, some objects require a thinner finish to fit onto machines or perform their intended functions. This is one area where powder coatings have a difficult time delivering. By trying to thin the coating, you’ll often be left with a surface that’s hard, bumpy and far from the desired final texture.

2. It’s More Complicated

The process of applying and drying a powder coating is not a simple one. It requires an electrostatic application, which involves a variety of complex equipment, spraying materials and an oven to dry the coating out. Of course, this complexity helps make the powder coating into such a beautiful and reliable finish.

However, because the process is complicated and a little pricier than liquid painting, it’s impractical for small-scale operations. If you only have one small piece that you want to coat, you may be better off with a simple liquid paint, as it’s not worth the investment in all the equipment you would need for the powder coating. For smaller jobs, it’s much more practical and cost efficient to stick to the simpler method. Even if you end up needing to re-do your paint coating every so often, it will still likely win out as the more cost-effective method for small projects.

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What Are the Benefits of Choosing Liquid Painting?

Traditional liquid painting is something we’re all familiar with. Ordinary paint is brushed on over the metal surface, often in multiple coats until the entire object is well covered. Like powder coating, it can be used on most types of metal and is commonly used on surfaces like brackets, shelves, panels and more. Of course, a method like this wouldn’t become as popular as it is if it didn’t have a few major benefits. Here are a few of them.

1. It’s Simple and Easy

With an ordinary painting job, there’s no complicated equipment or in-depth procedure. Painting metal parts is simple and involves painting on one coat of paint at a time. The paint will need to dry, but this happens naturally and doesn’t require any additional equipment to do so.

2. It’s Cost-Effective

Paint and paint brushes are cheap tools. Because these are the only things you will need to complete this task, costs will stay at relatively low. This makes simple paint coverage a choice great for your budget.

What Are the Disadvantages of Choosing Liquid Painting?

On the flip side of things, liquid painting comes with quite a few disadvantages that are difficult to avoid and make many consider powder coating to be the superior option. A few of these disadvantages include:

1. It’s Less Durable

The paint is thinner and less likely to hold up against things like weather, corrosion, scratching or peeling than the powder option. This means if your metal parts are going to undergo lots of strain, it might be best to stick with a powder coating.

2. It Can Look Messy

Because paint is usually thinner and requires additional coats to adequately cover the surface in question, the final result appears messier. Oftentimes, brushstrokes may be visible in the surface as well as different layers in the paint or even certain areas that are covered more completely than others.

3. It’s Less Environmentally Friendly

Liquid paint production is known for creating unhealthy amounts of hazardous waste on the production line. Not only this, but also the final product can sometimes give off harmful toxins and vapors, leading to a greater footprint on the earth and a less environmentally conscious method of coating your metal parts.

Can You Paint Over Powder Coating?

What happens if you’ve applied a powder coating only to decide a year or two later that you’re looking for a different color or finish? You don’t feel you need to put the metal through the entire powder-coating process again so soon. Is painting over a powder coating something that’s even possible?

The short answer is yes, it is possible. The longer answer is that you’ll want to take the precaution of following these steps before you do:

  • Clean: Make sure your coated surface is clean, so you aren’t just painting over old dirt.

  • Sand: Rough up the coated surface to help your new coat of paint adhere better.

  • Prime: To get the best coverage, you’ll need to provide the proper base coat for your paint.

  • Paint: Choosing the right paint for the job is critical. Stick to an enamel- or epoxy-based paint for the best results.

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Choosing the Right Finish for Your Metal Parts

To decide whether powder coating or liquid painting is better for you, you need to think about what your goal is as well as what your limitations are. For example, is durability the highest concern for you? Maybe you’re most worried about achieving a smooth, blemish-free finish. Or perhaps you’re concerned about your environmental impact. If any of these concerns are your highest priority, you may want to consider the benefits that powder coating can offer you. If, however, you’re only looking to finish one small item, your best bet may be to stick with painting.

Neither option is always right or wrong. As you weigh the choices, take the time to really consider your situation and think about what will be best for you. This way, you can feel confident in your decision and know that you have made the right choice for you and your custom metal parts.

Contact APX York Sheet Metal for Powder Coating Services

Have you decided to move forward with powder coating your metal parts? Then we want to help. We’re a family-owned business with over 70 years in the business, meaning that we’ve got the know-how and experience you’re looking for. Here at APX York Sheet Metal, we take pride in our quick turnaround time as well as our quality customer service, and when you work with us, you’ll experience both. To get started, contact us for your quote today.

Types of Welding

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Custom sheet metal working requires impressive skills that professional craftspersons acquire after years of trade training and practical experience. Metal working might be intimidating for the novice, but few people look at a custom-built piece without noticing the smooth joinery and precise seams you’ll see in a finished product. Most impressive of all are flawless welds that seem almost magical.

In theory, welding sounds simple. The welding process joins metal parts through fusion. That involves extremely high temperatures that melt metal and fuse the joints together. In practice, welding can be complicated. There are so many different metal types as well as differing welding techniques. No doubt you’ve heard terms like arc welding, mig welding, tig welding and gas welding.

If you’re planning to have a sheet metal project custom-built, it’s very important to understand what welding techniques your fabricator might use. That way, you’ll be in the best-educated position to approve a welding process that your fabricating company recommends. Custom metal work is a serious investment, and you need assurance you’re doing it right.

It’s easy to be confused about welding terminology. There are so many acronyms and abbreviations used in the sheet metal fabrication and welding business, and each term has its meaning and application. To help educate you on welding forms employed in custom metal work, here is a detailed explanation of welding types, terms and techniques.

Shielded Metal Arc Welding (SMAW)

Shielded metal arc welding, or SMAW, is the oldest metal bonding form next to the ancient heating and pounding method used by blacksmiths. For countless centuries, metal workers fused their pieces together by heating them to a cherry-red temperature in a forge and then hammering seams on an anvil. That ancient technique still exists in small craft and hobby shops, but electric welding replaced blacksmith skills in the late 1800s.

By the early 20th century, electric welding reached a technological sophistication where it became mainstream in metal joinery. According to the Fabricators & Manufacturers Association, shielded metal arc welding is still the most popular form of electric welding despite many high-tech advancements made in the welding field. SMAW is easy to learn and highly versatile for a variety of metals. It’s also a very portable process, so it can be used everywhere from shops to the field.

Shielded metal arc welding is commonly called "stick welding." That’s due to the simple welding electrode, or stick component, that distinguishes it from other welding types. The term "shielded" comes from the part of this welding process where particular gasses from the melting electrode shield the fresh weld from common atmospheric gasses like oxygen and nitrogen that threaten a new weld’s integrity.

SMAW welding works on a simple principle. Positive high-voltage electric current electricity from a power grid or generator flows through heavy welding cables and into a welding electrode, or stick, mounted in a hand-held grip. The metal work surface has a grounded negative charge. Once the positive charge in the electrode makes close contact with the work surface, a blindingly bright electric arc flashes.

This energy arcing creates enormous heat in the 7,000-degree-Fahrenheit range. That causes both the welding rod and the work surface to melt and bond together. As the electrode stick dissolves into a liquid, its flux coating changes to a gas state protecting or shielding the weld pool from atmospheric forces. A slag coating forms over the cooling weld joint as it turns back to solid form. Usually, the slag gets chipped or brushed away to expose a shiny new weld.

Welders and custom sheet metal fabricators normally use stick or SMAW welding on routine jobs involving carbon steel and stainless steel. SMAW welding allows joining reasonably thick metal components due to the immense heat generation. High-quality stick welding equipment lets the welder adjust temperatures depending on the size of their work and the metal composition. Many welders claim their welded joints have stronger tensile strength than the parent or native material.

Gas Metal Arc Welding (GMAW)

Gas metal arc welding, or GMAW, is the second most popular welding form used in custom sheet metal fabrication. You’ll usually hear GMAW welding called "MIG welding," which comes from "metal inert gas" (MIG). In fact, the term "MIG" is so familiar in the welding world that using the acronym GMAW might puzzle even the most experienced welder. They’d probably recognize the term “heliarc” welding in place of GMAW due to the helium gas once used when the MIG process started.

The big difference between SMAW and GMAW welding is the electrode composition. Both welding forms rely on high-voltage current to create an electrically charged arc that melts both the electrode and the work surface to form a bond. However, with the GMAW or MIG welding process, the atmospheric shielding gas is artificially introduced by a separate feed rather than gassing-off from the melting electrode.

GMAW/MIG welding also employs a different electrode type. Instead of the consumable stick that melts and fumes, the MIG electrode is a continuous feed of wire from a pre-stocked spool. This metal filler is automatically fed to the weld joint and runs at a steady rate. Where the SMAW welding electrode melts down and needs constant replacement, the GMAW process allows continuous joint and seam welding.

There are no breaks or gaps in the MIG welding process. The weld is smooth and uniform, which presents far better on the finished product that the stop-and-go stick arc welding process. You get a faster and more dependable product with the gas metal arc welding technique than with the shielded metal arc welding process.

GMAW systems operate on a steady shielding flow of argon, carbon dioxide or helium gas. Some use a blended mixture of two or all three. These safe and common gasses effectively shield the new weld from oxygen and nitrogen, which immediately compromise a fresh weld and cause it to oxidize or prematurely rust as it sets up. Because argon, carbon dioxide and helium are common, they’re also inexpensive, which lowers overall welding costs.

Larger MIG welding equipment utilizes multiple electrode wire spools. You’ll find the multi-spool approach in big shops that mass-produce products. However, you’ll also find compact MIG or GMAW outfits in small fabrication facilities. Besides being economical equipment to buy, the MIG welding technique is easy to learn and highly dependable for producing cleanly welded joints.

Gas Tungsten Arc Welding (GTAW)

Gas tungsten arc welding is also called "tungsten inert gas arc welding" or "TIG arc welding." Like the SMAW and GMAW welding techniques, GTAW uses high-voltage electricity to heat the work and a metal filler rod to extremely high temperatures, causing both the work and filler to melt, pool and fuse once cooling. The primary difference with TIG welding is that it utilizes inert tungsten gas to shield the weld as it forms.

GTAW/TIG welding can also perform without fillers. Some GTAW equipment has wire reels similar to those you’d see in a heliarc or MIG system. Instead of utilizing low-cost helium, carbon dioxide or argon gasses, the TIG welding system relies on tungsten gas, which is considerably more expensive for a fabrication shop to source.

Tungsten gas has a superior advantage over its competitors. Although more expensive, tungsten gas is stable at all heat levels. GTAW welding can achieve temperatures far greater when shielded with tungsten. This makes a GTAW welding system versatile for operating outside a welding electrode or wire reel filler.

Some TIG welding processes eliminate any consumable wire, filler or electrode. They employ a non-consumable electrode that creates an immensely hot arc that causes the metal surfaces to bond or blend without an additive. Tungsten gas injection around the electrode’s tip shields the fusing metal from oxygen and nitrogen contamination.

With no filler or auxiliary material introduced to the meld, all that’s left is the original metal, now seamlessly fused together. The weld retains the same tensile strength of its native metals and is practically invincible to breakage. Because TIG welds are so precise and use original metal if operated without a filler, the welded joint is practically invisible.

The TIG or GTAW welding technique is ideal for thin and specialized metals. You’ll find TIG welders often working with aluminum projects, as aluminum is a notoriously difficult metal to weld. GTAW welding also suits brass, copper, magnesium, titanium and high-strength alloys. As a rule of thumb, TIG, or tungsten inert gas welding, suits more expensive materials and more complex metal joinery requirements.

Oxygen-Acetylene Welding (Oxy-Acetylene)

Most welding students cut their teeth on oxy-acetylene welding equipment. The oxy-acetylene process works on combustible gas heat rather than harnessed electricity. Here, a welder lights an open flame using a blended ratio of compressed oxygen and acetylene emitted from a torch head mounted on hoses connecting the gas cylinders. The torch flame heats the work surface to temperatures slightly lower than those found in SMAW and GMAW processes.

All oxygen-acetylene welding processes require fillers. With oxy-acetylene operations, that’s usually a welding rod made of metal like brass or steel. There’s no gas shielding with oxy-acetylene welding. This technique isn’t designed for the same oxygen and nitrogen protection you find in regular arc, MIG and TIG welding.

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"Brazing" and "soldering" are two terms you’ll often hear used to refer to oxy-acetylene welding. Brazing is a moderate heat application where the metal work surfaces get heated at the same time a brazing rod melts and pours into the joint gap. Because of lower temperatures and a more gradual heating time, the weld strength is nowhere near what you’ll get with fast-acting SMAW, GMAW and GTAW welds. Brazing strength is mostly in the filler rather than the native material. It’s often employed in quick repairs rather than in custom sheet metal work.

Soldering requires even less heat. Solder is a soft metal product containing an interior liquid flux. As solder melts, the flux drips into the work joint and cleans it from dirt, oil and oxidation. Rather than repair work like brazing, you’ll find solder often used on metal joins in electrical and plumbing work. It’s almost unheard of to find solder in sheet metal fabrication.

Although oxygen-acetylene welding is suited more for light construction and metal work where the finished appearance isn’t important, there is one clear advantage to an oxy-acetylene outfit. This equipment excels at cutting metal where arc welding processes don’t. All oxy-acetylene sets have two torch heads. One is a low-heat configuration for welding, brazing and soldering. The second head is a cutting nozzle.

Types of Welding Joints and Positions

Just as there are different welding forms and equipment types, there are various welding joint types and application positions to be aware of. You’ll find these joints and positions spread across most welding facilities and applications. That ranges from custom sheet metal fabrication shops to large industrial and manufacturing facilities.

Not every piece of welding equipment works with all joints and positions. SMAC, or stick welding, is the most versatile form. But it doesn’t produce the perfection that MIG or TIG welding does. Generally, there are four welding positions where you can have any number of joint types:

 

  1. Flat Welding: These work surfaces lay like a bench or table top. The welder approaches them from a top-down position and lets gravity help with molten flow. Flat surfaces really suit MIG and TIG welding equipment, where wire feed and gas flow works best on a straight and level surface.

  2. Horizontal Welding: This position refers to welding on a line of sight position like across an upright wall. SMAW welding using a stick electrode works well in horizontal positions where it’s more challenging to get a MIG or TIG welder balanced. Oxy-acetylene welding is also tougher on horizontal surfaces than on flat ones.

  3. Vertical Welding: Like horizontal welds, running beads on a vertical or up-and-down surface has its problems. It’s simple for a SMAW welder to strike vertical beads but not so simple for the TIG and MIG people. When possible, metal fabricators adjust their horizontal and vertical work to a flat position.

  4. Overhead Welding: By far, overhead welding is the toughest task for any welder. Fortunately, you’ll rarely have this need in a custom sheet metal fabrication facility. Overhead welds show up in factories and industrial sites that have suspended equipment. Conventional SMAW welding equipment is the only practical solution for overhead problems.

 

Regardless of what welding position you might have, you’ll have some basic welding joint types or styles that regularly appear. Each joint has its procedures that metal welders learn proficiency at. These are the most common joints in welding:

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  • Butt joints have their work surfaces facing each other from end to end.

  • Lap joints have overlapping surfaces with mating faces on each work side.

  • T-joints intersect each other on 90-degree angles in a T-shape.intersect each other on 90-degree angles in a T-shape.

  • Corner joints touch at inside and outside corners, usually forming a right angle.

  • Edge joints are similar to butt joints but have more metal face connecting the work.

 

Custom Sheet Metal Fabrication Welding

APX York Sheet Metal is your premium metal fabrication company serving central Pennsylvania and northern Maryland. Since 1946, we’ve built a reputation for dependability and excellence in welding and fabricating outstanding custom sheet metal work as well as customer service. We’ve accomplished this by using the highest-quality materials, the best cutting-edge technologies and the most efficient welding processes.

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For a request for quote (RFQ) on your custom fabricated metal projects and parts, call APX York Sheet Metal today at 717-767-2704. You can also reach us for a quote through our online contact form.

APX York Sheet Metal Wins the Manufacturers’ Association’s Manufacturer of the Year 2016 Award

While APX York Sheet Metal’s focus remains squarely on delivering superior value to our customers and investing in continuous improvement efforts, it’s important to take time to celebrate successes along the way. APX York Sheet Metal is very proud to have been awarded Manufacturer of the Year 2016 and would like to express our appreciation to The Manufacturers’ Association for this prestigious honor. 

At APX York Sheet Metal we know that to be successful, we have to work together as a team. Therefore, we’d like to thank all the members of the team who wake up early and stay up late working hard to make sure we get the job done right and exceed our customers’ expectations. Awards like this are evidence that consistency and hard work pay off – congratulations team!  

The 7 Things You Should Look for in Your Sheet Metal Fabricator

Satisfying your customers’ needs is at the top of your list, but if your sheet metal fabricator doesn’t have the same priorities as you, it could be time to re-evaluate who’s supplying your custom metal parts. When seeking out a sheet metal fabricator that will exceed your performance expectations, there are several factors that you need to take into consideration. Keep reading to decide if your sheet metal fabricator is right for you.

1.      Quality – It almost goes without saying, but in fact it should at the top your list. If you can’t count on quality parts coming in from your sheet metal fabricator, it’s time to find a new one that will surpass your quality test. Your customers don’t tolerate poor quality and you can’t either from your sheet metal fabricator. Period.

2.      Delivery – While speed is important, the real key is to look for fabricators that hit the dates they commit to. This means that at times you want your fabricator to push back on your due dates when they cannot meet the due date. Having that openness and trust is at the heart of any good customer relationship. The question you need to be asking isn’t ‘how quickly can you get it to me?’ but rather, ‘how confident are you that I will receive my parts when you say I will?’  The certainty that a stronger parts fabricator provides to your supply chain beats aggressive promises and missed deliveries. It also helps if your sheet metal fabricator has their own delivery trucks. This means you avoid costly, time-consuming product damages as well as shipping costs by avoiding 3rd party freight companies.

3.      Track Record/Longevity – How long has your sheet metal fabricator been in business? While the two are not necessarily related, there is a solid correlation between longevity and capacity. There is truth in the axiom that ‘we’ve been around this long so we must be doing something right’, but that only goes so far. Is your sheet metal fabricator modernizing their systems and equipment? Are they keeping up with the latest technology and investing in their team? These are all signs of health you want to look for in your sheet metal fabricator.

4.      Price/Value – Are you getting competitive pricing? Make sure that your metal parts fabricator is providing you with solid pricing. If they’re not, push to understand what the underlying cause is. Maybe there is a design-for-manufacturing conversation that needs to take place, or there needs to be a clearer picture of the purchasing forecast anticipated over the next few quarters. The number at the bottom of the quote is not the whole story, but you need to see pricing that will work for your business and allow you to provide excellent value to your customers.

5.      Responsiveness – When you call or email your sheet metal fabricator, how long does it take for them to get back to you? What is the quality of that communication? Working with global customers and compressed lead-times, being able to manage changing customer demands is an important part of your business. Make sure you partner with a sheet metal fabricator that is able to keep up with the dynamic nature of your needs and work alongside you to help you satisfy your customers.

6.      Willingness to Take on Tough Challenges – A true partnership requires both trust and the ability to take risks. Does your sheet metal fabricator shy away from a challenge? Growing your business means incorporating new materials or technologies that allow you to out-compete.

7.      Accountability – Accountability is the foundation of trust and trust underpins every strong fabricator/customer relationship. When things don’t go as planned, does your sheet metal fabricator take responsibility and work to improve for the future? If not, you need to find a new sheet metal fabricator.  

About the Author:

Andy Mulkerin (General Manager of APX York Sheet Metal) has 20 years of experience leading advanced technology development programs and overseeing global manufacturing operations. He has managed production/operations within the chemical processing, electronics, and commercial nuclear industries. He has worked on multi-billion-dollar investment and infrastructure deals, as well as spent more than a decade advising US companies on how to successfully navigate the Chinese energy market. Andy led initiatives setting up fabrication operations in China to produce equipment to the ASME NQA-1 and NNSA’s HAF604 specifications.

Andy has successfully driven technology transfer initiatives for dozens of Western energy companies including Babcock & Wilcox, Bechtel, Thermo Fisher Scientific, Energy Solutions and TerraPower.  Andy is a recognized global leader in the field of US-China nuclear energy strategy and has been cited by the Wall Street Journal and the New York Times. Andy has collaborated on numerous initiatives with the US Department of Commerce and Department of Energy related to maximizing commercial opportunities for US companies in China. Additionally, Andy also was part of the core Blu-ray strategy team for Sony in Tokyo, Japan.

Andy has a BS in Chemical Engineering from Columbia University and an MBA from Harvard Business School.

Galvanizing & Galvannealing for Beginners

When deciding on which steel to spec for your next project, you may want to look at either galvanized or galvannealed steel. While not appropriate for many applications, if you’re considering an external application where rust is a factor, galvanized and/or galvannealed merit consideration.  It’s important to understand the uses of each as well as the differences. Both provide significant rust and corrosion protection, but there are material differences between the two types of zinc coated steel that should be understood.  

Galvanizing…

The process of galvanization involves steel sheet being immersed in molten zinc at 850 °F, through which a zinc layer is bonded to the steel substrate at a molecular level. Zinc protects the steel from oxidation when it is exposed to a corrosive environment, creating a protective layer at the base. While there are many applications wherein galvanized steel is the proper material, common uses include HVAC ducts, wrought iron gates, roofing, body parts of vehicles, safety barriers, balconies, and building framework. Galvanized steel has a spangled appearance, but is very durable and can withstand salt and the elements, which is useful in outdoor applications.

Galvannealing…

The Galvannealing process is very similar to that of galvanizing, but with galvannealing, the steel substrate is heated to 1050 °F. At this temperature, more iron is drawn out of the steel where it bonds with the zinc to form an alloy coating that is lower in zinc and higher in iron, than that of galvanized. This creates a stronger surface that allows for better weld (and paint) adhesion. Additionally, galvannealed steel has a scratch resistant surface and a low-luster, dull, matte finish which does not require a primer for paint, unlike galvanized steel. Galvannealed steel is often found in industries where long, reliable service life is required, such as the automotive, architectural, electric equipment, and signage industries.

So how do you know when to use each of these two materials in your application? When choosing between galvanized or galvannealed, consider these issues:

1.) Is significant welding involved? Due to the additional iron in the coating layer, galvannealed steel offers more weldability as compared to a galvanize coating.

2.) Is your product going to remain unpainted? If the answer is ‘yes’ then galvanized steel is almost certainly a better choice. Unpainted galvannealed steel will exhibit a reddish-orange appearance (the increased concentration of iron at the source leads to accelerated oxidation) when exposed to moisture. In almost all cases, this discoloration is something procurement professionals would look to avoid.

Now that you know when to use either of the coatings, let’s better understand how galvanized and galvannealed steel is spec’ed.

As discussed above, galvanize and galvanneal differ in the zinc coating/bonding process primarily due to difference in contact and exposure temperature. But for both galvanized and galvannealed materials, steel suppliers are able to adjust the thickness of the zinc coating to provide higher or lower density zinc penetration. For galvannealed steel, Type A40 is the minimum thickness of zinc coating in common use. Where the “A” indicates “Anneal” and the ‘40’ indicates that there is a nominal weight of .40 ounces of zinc/iron coating per square foot. Therefore, A60 galvannealed steel has a relatively thicker zinc/iron coating with .60 ounces of zinc/iron coating per square foot. As the thickness of the coating layer increases, it becomes relatively easier to weld and paint, but this thickness tends to correlate with cost from the mill so it is wise to not over spec your galvannealed requirements.

As with galvanized steel, the materials are denoted with a letter/number combination, but this time a “G” is used to signify ‘Galvanized’ while the number represents the same nominal weight (in ounces) per square foot. So G40 and G60 are both galvanized steel with .40 and .60 ounces of zinc per square foot respectively.

Based on the environment your product will be exposed to, it’s important to make sure you specify both the steel type as well as the coated zinc thickness to ensure the best performance of the material over the life time of your application.

Experienced fabricators can work with you and your engineering team to make sure that you’re using the best material for your application. Contact your supplier to discuss how you can optimize the best lifetime value of your purchasing decisions. 

About the Author:

Andy Mulkerin (General Manager of APX York Sheet Metal) has 20 years of experience leading advanced technology development programs and overseeing global manufacturing operations. He has managed production/operations within the chemical processing, electronics, and commercial nuclear industries. He has worked on multi-billion-dollar investment and infrastructure deals, as well as spent more than a decade advising US companies on how to successfully navigate the Chinese energy market. Andy led initiatives setting up fabrication operations in China to produce equipment to the ASME NQA-1 and NNSA’s HAF604 specifications.

Andy has successfully driven technology transfer initiatives for dozens of Western energy companies including Babcock & Wilcox, Bechtel, Thermo Fisher Scientific, Energy Solutions and TerraPower.  Andy is a recognized global leader in the field of US-China nuclear energy strategy and has been cited by the Wall Street Journal and the New York Times. Andy has collaborated on numerous initiatives with the US Department of Commerce and Department of Energy related to maximizing commercial opportunities for US companies in China. Additionally, Andy also was part of the core Blu-ray strategy team for Sony in Tokyo, Japan.

Andy has a BS in Chemical Engineering from Columbia University and an MBA from Harvard Business School.


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