Working with aluminum can be very frustrating due to heat and pressure. However, there are ways that can help you improve productivity, safety, and quality while minimizing labor costs and downtime. The following are some tips that can help you in choosing the appropriate disc or wheel when addressing the requirements of the post-weld and pre-weld processes.
For several decades now, aluminum has been used in the shipbuilding industry. But today, a large number of applications have used aluminum in metal fabrication due to its excellent corrosion resistance and extreme strength-to-weight ratio. The demand for aluminum has grown quickly compared to alloy or any other metal.
Essentially, this is due to its growing popularity in other industries. For instance, this has been used in platform construction, service decks, and ladders, manufacturing, the repair of trailers, as well as structural framing. The most notable instance was when Ford decided to use aluminum for the construction of its most popular truck, the F150.
Challenges When Working with Aluminum
While aluminum offers a lot of benefits to fabricators, it also brings its own set of challenges. Aluminum can be difficult to grind, cut, and finish. This is due to the fact that it has a lower melting point compared to other metals. During its processing, heat and friction can accumulate. As a result, the aluminum will melt faster and stick to the abrasive. It will even reach a point where it can become taller than the cutting grain.
Due to the clogging or loading of material, the abrasive will not be capable of cutting anymore, causing the wheel to stop functioning. Aside from this, there are also other challenges that you need to confront when working with aluminum. This includes the possibility of oxide inclusions, porosity, and contamination, as well as the difficulty in obtaining the desired finish.
Oxide Inclusions
It is very important that the aluminum oxide layer be properly removed in order to prevent oxide inclusions from appearing. Before you start welding, be sure to get rid of the transparent film from the surface. It usually comes from aluminum oxide. The purpose of this is to guarantee maximum weakness resistance and weld strength. In accomplishing this particular job, you will be needing a stainless-steel brush.
Porosity
Porosity can happen when the abrasive products release contaminants from the wheel, causing the weld surface to be contaminated. As a result, the structural integrity of the weld will be compromised. It is essential that these contaminants on the surface be removed before welding. This includes paint, dirt, oil, or grease. Be sure to only use high-quality abrasives that are free from contaminants when performing inter-pass grinding and surface preparation.
Finishing
Finishing can be very challenging when working with aluminum. The reason behind this is that the material can likely get damaged due to overly aggressive practices.
Abrasives for Aluminum Grinding Applications
Aluminum is considered one of the most common types of metallic elements in the whole world. Aluminum is lightweight and silvery-white. Although it is commonly used and readily available, the processing of aluminum can be very challenging, especially when it comes to grinding.
Furthermore, there are a few aluminum manufacturing applications wherein grinding is considered as an essential finishing process, particularly for cleanup and material deburring. If you want to make sure that your grinding process is efficient and gives you the result that you want, then you have to use the appropriate abrasive.
Essentially, there are three major abrasive products that are appropriate for aluminum grinding applications. These are flap discs, fiber discs, and depressed-center wheels. Each of these discs can provide you with the finishing results or aluminum deburring that you want when used for its particular purpose.
Flap Discs
The characteristics of flap discs are a combination of both fiber discs and depressed-center wheels. They are capable of doing cleanup finishing and aluminum deburring at the same time. This means that you can save a lot of time and money. Flap discs include three major components which are the adhesive, backing plate, and abrasive cloth. The abrasive cloth is layered, offering a cushioned substrate and resulting in extreme heavy stock removal rates and surface combination action.
Fiber Discs
With fiber discs, you can obtain cool cutting action both for repair applications and cleanup. Generally, fiber discs have a shorter lifespan compared to flap discs or depressed-center wheels. The most recommended type is the zirconia grain since it has the capability to microfracture, revealing sharp cutting points which is very helpful for the extension of its disc life.
Depressed-Center Wheels
Depressed-center wheels are strongly recommended for deburring applications. At the same time, it provides the best wheel life experience since it comes with a more resilient, much stronger backing compared to flap discs and fiber discs. The fact is this backing is durable enough to get rid of an aluminum weld completely. Typically, these wheels do not have any rubber fillers or wax which can obstruct loading, especially on hard-to-grind aluminum.
Unfortunately, depressed-center wheels are not suitable for finishing applications since they can create a visible scratch pattern that requires you to perform additional finishing activities. These wheels can be availed in zirconia alumina, ceramic alumina, and aluminum oxide abrasives.
Tips for Grinding Aluminum
There are a lot of reasons why fabricators and welders perform grinding on aluminum. For instance, post-weld bead finishing or elimination as well as for the preparation of the pre-weld surface are just a couple of reasons. Keep in mind that aluminum has a very low melting temperature compared to other metals. I
Because of this low melting temperature, the aluminum will end up coating the abrasive disc during grinding. As a result, the grit will be covered while revealing only bits of aluminum. Furthermore, this can generate more heat at the point of contact. Continuous grinding can generate more heat, which generates more melting, and consequently, it encourages the grinding operator to push down harder. Aside from being more labor-intensive, it generates more heat that leads to loading. Once the abrasive has been coated with longer aluminum chips, it can prevent the grain from performing its job.
If you want to get great results when using flap discs, then light and even pressure should be used. This can help in optimizing the grinding process while reducing loading. With the use of a T29 (conical) disc set at a 15-degree angle, you will be able to obtain extreme surface contact as well as high stock removal rates. These are essential if you require speed and aggressive grinding. Using a T27 (flat) disc set at a flat work angle is ideal for surface cleaning as well as for applications that need a smooth finish.
Methods or Tools Used for Grinding, Cutting, and Finishing Aluminum
Today, most welding professionals use one or more of these tools or methods in grinding, cutting, and finishing aluminum. Take note that each of these has its own drawbacks when it comes to safety, productivity, quality, and cost.
Silicon Spray and Lubricants
These things can be flammable and could likely contaminate the work surface. This means that you have to be careful when cleaning up prior to welding.
Jig Saws, Shears, and Reciprocating Saws
The downside of these tools is that they can generate so much vibration and noise and form extensive burrs.
Excessive Pressure
One of the typical reactions when the wheel is not functioning well is to push at it harder. However, pushing it harder could agitate the problem since it can result in more heat and friction. As a result, the aluminum will melt down more quickly since the wheel loads faster and faster. The drawback of this method is that it can produce additional heat. This can likely damage your work and can cause the wheel to fail.
Wax and Grease
The disadvantage of these elements is that they can be dangerous, especially when they are used while discs are running. Welding professionals should be careful while using them for cleaning prior to welding.
A Better Option for Grinding, Cutting, and Finishing Aluminum
When choosing a product for finishing, grinding, and cutting aluminum, your objective should be to get the proper disc or wheel which can address the requirement of your post-weld and pre-weld processes. With the right choice, you can obtain better productivity, quality, and safety. It can also help in reducing downtime and labor costs.
When grinding and cutting aluminum, the best option would be a grinding wheel, particularly type 27, that does not load. These wheels come with a contaminant-free bond as well as grain blends specifically for consistent performance. High-quality products specifically designed for cutting aluminum smoothly while reducing burr formation. They can also minimize vibration and noise, which means it is easier to control. Some wheels are designed for grinding or cutting only, while others are used as a combination for both grinding and cutting.
RFDs (Resin Fiber Discs) are specifically designed for aluminum. They are the best option for blending, grinding, and finishing. RFDs should be used along with a sturdy rubber backing pad that provides consistent contact with the material, making it easier to handle and blend. The ideal discs are coated or pre-treated with a lubricant to minimize heat buildup while grinding. With this feature, the melting of the aluminum will be delayed. At the same time, it can prevent the disc from loading and providing higher cut rates. This means a longer product life.
Top-coated or treated flap discs are another alternative to a resin fiber disc. They are a great option for finishing, blending, and grinding aluminum. These discs include a wide variety of grain options. Nevertheless, they are not quite popular in the industry because they are pliable and need advanced skills to obtain the desired surface finish. Since grinding and finishing can be done simultaneously then you can save more time.
If you need discs and wheels, then you can check out Sparks and Arcs. If you have any questions, then you can always call us at 877-95-SPARK (877-957-7275) or send us a message at CS@sparksandarcs.com.
