Any serious welder comes across pot metal at some point in their welding assignments. But not every welder knows what pot metal is or how to weld it.
Failure to have the facts can seriously compromise the quality of the welding that you do. You might easily, but wrongfully, weld this metal the same way you weld traditional metal.
What is Pot Metal?
The mention of pot brings the kitchen to mind. You might not be very far-fetched to think in those terms, although this has nothing to do with welding any kitchen utensils. Instead, it has more to do with the origins of pot metal.
In days gone by, automotive repair shops would gather scrap metal and melt it in a pot for use on small jobs such as patch jobs. This scrap metal was a super-mix of different metals. Since it was melted in a pot, it was informally referred to as pot metal.
In a nutshell, pot metal is a colloquial term referring to alloys consisting of inexpensive, low-melting-point metals. For starters, an alloy is any metal made by combining two or more metallic elements to have a stronger or corrosion-resistant metal.
Some of the common metals in pot metal include:
Although pot metal can consist of a broad spectrum of metals, the primary ingredient in most cases is zinc. When making pot metal, all the metals are melted together. This action alters the properties of each of the metals included in the mix, which gives the outcome (pot metal) a low melting point.
It’s for the same reason that this type of zinc-rich hybrid metal is weak and has a low melting point.
Identifying Pot Metal
It might be a bit difficult to identify this metal. Remember, pot metal is a mixture of metals. We earlier said it’s an alloy. That is why you can easily confuse it with one of the primary metals used to make it. For instance, if the pot metal you are looking at has a higher amount of iron, it might pass for iron.
The problem here is that though it will look like that metal, it will not have the exact attributes of that metal. This lack of clarity can easily mess your work if you treat the pot metal the same way you would handle the primary metal used in its ingredients.
It is, therefore, crucial for you as a welder to accurately identify pot metal so that you know how to work with it without compromising the quality of your work. There are several methods you can use to identify pot metal.
Heating a sample of the metal will show you the melting point of the metal you are using. Pot metal has a relatively low melting point. So if the sample melts at low temperatures, the chances are high that what you have is pot metal.
On the same note, if the metal you are heating contains a high level of zinc, it will produce white smoke.
If you are not sure whether the metal is aluminum or pot metal, weighing your sample will tell you the difference. Pot metal is much heavier compared to pure aluminum. Besides, although pot metal looks a lot like aluminum, the finish of pot metal leaves some pattern that is not present in aluminum.
In any case, you’ll also see some darker areas in the finish, which are excellent indicators that the metal you are using is pot metal.
Importance of Pot Metal
There are times when you need might need to make items finished in a mold. In such cases, pot metal comes in handy. It does cast very well, and the process of casting is easy and fast. Pot Metal is quite inexpensive compared to other metals.
It is for these reasons that welders find this metal quite beneficial when it comes to some projects that require a metal that has these characteristics.
Uses of pot metal
Pot metal doesn’t age well. That’s why the metal is generally used to make items that are not exposed to the elements or rough use. Some of the purposes of this metal include:
1.1 House Hold Use
If you are keen, you must have noticed that this metal has a wide range of applications in the kitchen. For instance, many of the cookie cutters you find in the kitchen are made using pot metal. The good thing about these cookie cutters is that they are easy to bend. This ease is a big plus for any cookie-cutting device.
You’ll also find pot metal in toy boxes. Toy cars and other similar toys are usually made from this metal. The primary reason for this is that using this cheap metal helps lower the cost of these inexpensive toys.
Still in the household, pot metal is found in the fittings used in inexpensive furniture. Don’t be surprised to see this metal in low-end guitar and other musical equipment.
1.2 Electronics and Accessories
In years gone by, this metal was used to make automotive window cranks. This usage was before the modern-day electronic windows became popular. Due to its low cost, the use of pot metal ensured the manufacturing costs remained low.
Also, the use of pot metal remains popular in the making of jewelry. Many artists and makers of jewelry find it easy to shape and is a quick way to make this jewelry.
The next most important thing is to identify this pot metal. Yes, you might want to use pot metal, but you can’t tell it from other types of metal. Consider the following:
Challenges of Using Pot Metal
We’ve highlighted the benefits and uses of this metal and how to identify it. But this doesn’t mean working with this metal will be easy for you as a welder. Working with this metal presents its fair share of challenges when you are welding.
Most of the problems you’ll encounter with this metal come from the fact that this is an alloy, so it’s a mixture of metals. The first thing you always consider before you start welding is the type of metal you are going to work to use. Now, this is where the mixed metals pose a challenge.
For instance, there are some metals that you just should not weld. Zinc, for example, produces toxic fumes that can make you sick. So if you determine that the pot metal you intend to use has a high level of zinc, don’t weld it at all.
Similarly, if the pot metal contains quite some high amount of aluminum, the welding is going to be rather tough.
Pot metal melts at low temperatures. This can easily pose a challenge since the high temperatures from the welding machine can quickly melt this metal and leave you with a lump of metal instead of your desired product. In such cases, it might be better to fuse port metal parts rather than work the entire project as one.
How to Weld Pot Metal
Most likely, you will get assignments that require you to weld with pot metal. But as noted earlier, this metal has its fair share of problems when it comes to welding. Due to its mixed nature, pot metal will not behave like the usual metals you are accustomed to in your everyday welding life.
A wrong move with pot metal can be disastrous to your project.
Although this metal has a low melting point and might contain zinc – which emits toxic fumes when welded, you can still use some tricks to accomplish your welding project.
The first thing you need to do is to TIG-weld the pot metal. For starters, in this process, you use the heat generated by an electric arc. The high temperature is applied between the metals you want to join. This process requires some skills and the right equipment.
However, if you have adequate experience in welding aluminum, then TIG welding will not be such a big challenge to you. The reason is simple: pot metal is quite similar to aluminum, and thus the approach you use to weld aluminum is the same you’ll use to TIG-weld pot metal.
When you start the actual welding, ensure you work slowly using low-temperature settings. Remember, pot metal has a low melting point, so use the same approach you’d use if you were welding aluminum. Always keep the temperatures low otherwise; you might quickly melt the piece you are trying to work on.
Don’t weld non-stop. Doing this can still melt your piece. Instead, work in short intervals of around five to ten seconds. This practice gives your parts and the pot metal sufficient time to cool down. Most importantly, don’t allow the pot metal to heat too much; as soon as it starts to flow, you have to stop welding and let the metal cool down.
With these facts, you now know what pot metal is and how you can weld it. You don’t have to shy away from this metal. In fact, with practice and patience, you can become a pro in welding pot metal.