Question Mark
Straightforward, experience‑based answers to common shop and process challenges.
I am trying to repair an aluminum casting with TIG. What filler should I use?
There are several ways to answer this question. Repair welds on aluminum castings are challenging for a couple reasons. It can be difficult to know the best filler to use because there’s often no way to determine exactly what the casting is made of. In addition, the casting material is often dirty, especially if the casting is used to hold oil or other fluids, so repairs can be challenging to the inexperienced welder.
It helps to understand the basic function of the part you’re repairing. Is it a structural part, or does it just need to be sealed up because it’s made to hold oil, for example? A filler like 4043 has silicon in it and this filler has a good flow, good strength and is suitable for many applications. 5356, which contains magnesium, might also be a good choice. However, there are many different aluminum fillers that are more specific and could be the better choice. Some research up front will help you make an educated guess.
Cleaning the casting material can be a challenge. Once the joint is properly prepped, the part can be preheated with a torch to help burn any fluids or impurities out of the pores of the aluminum. The AC current of the TIG welder can also be very helpful. When you start welding on a casting, the impurities will usually surface in a black soot that makes it difficult to establish a puddle. Before you even make a puddle, run the AC back and forth across the weld joint to allow the current to boil out impurities from the material. Use a stainless-steel wire brush to clean the joint, then repeat the process until you’ve brushed away as much of the dirt and impurities as possible.
Once the joint is sufficiently clean, increase the amperage and start making the weld. Most aluminum castings are weldable and can be repaired successfully, but they can be tricky for the reasons mentioned above. The more you know about the type of material you’re welding, and the cleaner you can make the joint, the better luck you’ll have.
What is the difference between 6011 and 6013 stick welding electrodes?
We often hear about 6010 and 7018 stick electrodes because they are probably the most commonly used electrodes for many different applications. Keep in mind that all stick electrodes have different characteristics for different deposition rates, different materials, different thicknesses and even for welding in different positions. 6010 and 7018 are the most common combination, but 6011 and 6013 are also a good choice for certain applications.
6011 is an all-position, deep-penetrating electrode that can run on DC, but runs best on AC. 6011 is the alternative to 6010 if an AC welder is your only option, but both have similar characteristics and abilities. 6011 handles surface impurities well, has a thin cellulose/potassium-based flaky slag, and is commonly used for repair and maintenance welding.
6013 is quite different because of the thick high-potassium type of slag. 6013 is also an all-position electrode that can run on AC or DC. This electrode has a smooth arc which many welders prefer in comparison to 6010 or 6011. 6013 creates a wide, shallow penetration with a heavy flux, but it does not handle surface impurities very well. The 6013 is commonly used on thin materials with little or no surface impurities.
These are the basic differences between 6011 and 6013. Both electrodes have desirable characteristics, but as always, it’s best to do as much research as possible and understand the differences well enough to make educated choices about what to use.
Why does my MIG wire sometimes push against the metal without arcing?
For the purposes of this conversation, we’ll assume the machine is set up correctly. Incorrect machine settings can certainly cause the wire to push too hard into the materials. But there can be several other reasons why this is happening, and they’re usually simple. MIG welders are, after all, fairly simple machines, but the components within them need to work together to feed the electrode consistently.
First, let’s start with the work clamp. We string our welding leads across the room everyday and wrap them up in different configurations all the time, so it’s very easy for a cable to become loose, particularly at the connection where the cable attaches to the work clamp. Remember that welding is one big electrical circuit, and circuits need good connections to work, so make sure to check all the cable connections. You should also place the work clamp as close to the work area as possible. A slight bad connection can cause the wire to stub into the metal before arcing.
Second, check the contact tip. This is very often overlooked, but can be a very simple fix. The contact tip is where the electrical connection is made with the wire in the MIG welding process. If the contact tip is loose or worn, it can cause problems. Contact tips are consumables that need to be replaced when they wear out.
Another possible issue is the silicon ball that forms on the end of the wire when you stop welding. This can make arc starts more difficult. Clipping the end of the wire off will help with arc ignition.
Wire pushing into the metal with bad arc starts can be very frustrating but these issues are usually pretty easy to identify and fix with a little effort. Always start with the basics, such as machine settings and connections – the areas that are the most commonly overlooked.