In today’s manufacturing environment, casting cost optimization often requires more than just a sharp eye on material prices or supplier quotes; it demands a deeper look at the entire process. From order quantity and tolerance reviews to finishing techniques and tooling configurations, small changes can drive significant cost savings. Let’s explore several real-world examples where collaboration and process re-evaluation led to measurable improvements in casting efficiency and cost.

Order quantity can have a large impact on casting cost, especially with castings that have lower annual volumes. For example, I was involved with the procurement of a casting that had an annual usage of approximately 30 pieces. The logistics plan, which focused on maximizing the number of inventory turns, called for the order quantity to be two pieces. Investigating this requirement revealed that the order quantity was determined only by a mathematical formula; no other considerations were included. 

Enlisting the assistance of the logistics team led to the discovery that these two pieces were stored in a standard sized container that had more than enough room in it for the entire annual quantity, so the logistics group was open to keeping more parts in inventory. Going back to the foundry, we were able to obtain a 40% cost reduction on each casting. 

Reconsider Tolerances 

It’s always a good idea to review the casting tolerances with the engineering and manufacturing teams. Castings that have been in production for a long time are a good place to begin your review. Let’s look at a casting that has been in production for over 10 years as an example. When the casting was first developed, the machining process required a relatively tight tolerance on the castings outside diameter (OD), which was the chucking location for the first operation. The foundry was required to verify the OD on each part. After several years, the technology used to machine the casting changed, and the chucking location was changed from the as-cast OD to a cored inside diameter. However, the foundry was not included in the machining update and continued to verify the OD after it was no longer required. Removing the gauging operation from the process improved processing time and throughput for the foundry, in addition to lowering their rework and scrap rates, which yielded a significant cost reduction.

Finishing Savings

The amount of finishing, such as grinding, also impacts the cost of a casting. Most OEMs that use castings want the parting line to be smooth or ground flush with the surrounding cast surface. So the question becomes: How can the casting be produced without the need for parting line grinding? 

Looking at the causes of parting line flash, the most common cause is that the sand mold at the interface of the mold joint and the casting are usually at a sharp angle. This condition causes the sand grains to not have difficulty compacting and holding together. An easy way to eliminate this is to incorporate a fillet or greater localized draft angle at the parting line. This can lead to much less parting line flash and a lower grinding requirement. 

One foundry I worked with performed significant development work on this concept and was able to almost eliminate the parting line grinding on their castings. The cost reduction generated by using this method resulted in a four-month payback on the tooling work that was required to add the parting line changes to the pattern. In addition to the cost savings per casting, the visual appearance of the casting also improved because the casting no longer exhibited grind marks. 

Traveling Tooling

An issue that most often happens when tooling is moved from one foundry to another is the number of castings that are produced in each mold. Since mold sizes often vary from foundry to foundry, tooling that has been moved several times may not be optimized to fit the production process. It’s an industry best practice to review older tooling and make sure the number of pieces per mold accurately reflects its production requirement. Simply retooling to add additional casting impressions to the pattern can result in improved quality and reduced cost.

Continuous improvement, such as the collaboration between procurement, engineering, and foundry teams, is key to identifying areas for improvement and driving sustainable savings. Ultimately, a proactive approach to process optimization not only lowers costs but also improves the overall quality and competitiveness of your product—with the added benefit of strengthening your relationship with your foundry.