A: Not all of us have the luxury of having a contiguous run of a product from a single base metal. The ability to be flexible with a production line or cell is a vital part of the productivity goal through optimizing capital resources. If you have a product that is being produced both in aluminum and steel, or coated steel, or equipment that has quick-change tooling to convert from one product to another, and one is aluminum and the other is steel, there is a simple approach to being able to produce both on common equipment with optimal results without the need to carry a wide variety of tools and consumables. First, let’s take a look at the general scope of equipment that gives you a wide range of ability to carry out this task: 1. An inverter weld control and transformer. The inverter can weld most of what an AC/SCR weld control and transformer can, but the reverse is not a claim that typically can be made by a standard AC/SCR weld control system. 2. Consumables produced from CDA1815, CuCrZr, as there are myriad alloys it can weld well. With both middle of the road hardness, conductivity, and sticking reduction, it is a good do-all alloy. 3. A highly responsive proportional valve, an integrated control valve pneumatic cylinder, or an electric servo system with constant force control. If you choose an external proportional valve, make sure the plumbing distance to the cylinder is minimal and that it definitely has no elbows. We will save the numbers behind these as being valuable assets in a flexible system for a future RWMA Q&A. Now let’s look at what you have currently performing the welding on the aluminum and steel products. We are going to use your current weld schedule as a baseline, or boggy, to work from for each product and apply some simple rules to easily switch between the two. 1. If your welding machine is an AC/SCR weld control and transformer, you can continue applying the rules but more than likely we will have to fine tune your baseline weld schedule for the aluminum when we are done. 2. As long as your current consumable is made from RWMA Class II or RWMA Class I material, we can use the weld schedules for them as the baseline schedule. If not, you need to procure consumables with the same geometry you are using now but made from CDA1815 and develop a baseline schedule with this material. 3. If you do not have a system to actively control force, you first need to procure a proportional valve for a RWMA Q&A 20 WELDING JOURNAL / MARCH 2016 BY MICHAEL S. SIMMONS AND HAMILTON TERRELL Q: Can you provide some simple solutions for resistance welding short runs between aluminum and steel? For info, go to www.aws.org/adindex
Welding Journal | March 2016
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