Everyone has annual goals and objectives. As a buyer, I’m sure you have been challenged to reduce the purchased price of the components you procure, improve their quality, or reduce the amount of inventory on hand. 

These can be challenging to accomplish, especially when you find yourself in a sellers’ market. With this in mind, let me give you an idea that can positively impact all three of these goals––get together with your engineering team and the foundry team to contemplate redesigning your fabricated parts into castings. To help you understand why you should consider doing this, let’s review a few of the benefits you can receive through the redesign process.

Cost reduction. Properly designed castings give the designer the ability to add material where it is needed and remove material where it isn’t required. Since fabrications are welded assemblies of plate and bar stock components, placing material only where it is needed can be complex and expensive. But because of the very nature of castings, you have the ability to purchase shape at a lower cost regardless of the overall part complexity. Depending on your casting design and the foundry process that would be used to produce your part, you may also have the opportunity to reduce or eliminate machining. As an example, cores can be designed to eliminate the need for spot-facing of bolt holes. 

The material from which the casting will be made very often offers a viable option to reduce cost. For example, a fabrication may be made from steel simply because of its weldability, but keep in mind that other materials, such as iron, are about 10% lighter than steel. The optimization of the casting design can lead to a lighter part overall, which often results in a lower part cost. 
If you are making the fabricated parts in house, castings also offer potential cost savings through the reduction of on-hand inventory by combining a multipiece welded assembly into a single part. If you are currently bolting several fabrications together in your assembly process, have your design team review the potential of combining the smaller fabrications into one main cast component.

Quality Improvement. From the design aspect, many fabrications often have weld joints at corners and section thickness changes that can negatively impact the load-bearing strength of the finished part. Failures tend to occur at these areas and result in an increase in warranty costs to the OEM. Castings can reduce warranty costs by eliminating welds in the finished part. In support of this concept, many times you will see castings used in the high-stressed areas of larger structural fabrications. This is done to move the weld joints out of the higher-stressed or load-bearing areas to reduce potential failures.

In comparison with a welded fabrication, a casting offers you a smoother surface and blended sections to improve the look of the part when cosmetic appearance is an important design feature. Your company logo and part identification markings can be easily cast onto the surface of the part, eliminating the cost of secondary operations and additional handling.

One issue associated with fabrications is their tendency to warp during the manufacturing process. Heating of the part is the culprit in this case, setting up stresses that can distort the final component due to uneven or rapid heating. Excessive heating can also have the effect of impacting some of the physical characteristics of the base metal, making the part weaker in that area. 

The overall result of warping of the fabrication is the need for a straightening operation. While straightening is common in the industry, it can actually weaken the fabrication because the part will move in the high-stressed area, which is usually in the weld joint. Castings are not as prone to warpage, which gives them the added benefits of better repeatability during the machining process along with the ability to hold tighter tolerances.

What to do next? By now, you have seen the power of casting conversion based on the potential for cost reduction and quality improvement. If you are using fabrications in your products, there may be a good chance that several of these would be great as castings. 

To summarize, you should look for parts that have complex shapes with more than three or four parts in the fabricated assembly. Look at the number of inches of weld required, and remember: The more welding, the more attractive the use of a casting becomes. Consider fabrications that have high internal scrap rates or high warranty costs as potential candidates. Let your foundry team look at these parts and explore the improvements that can be realized with conversion to castings.