UNDERSTANDING CUSTOM CASTINGS
 Nov/Dec 1992

While many variables come into play in determining costs, ultimately the project is a success if end user needs are met at an acceptable price.

Custom designed aluminum castings can be produced in a wide range of sizes, weights, and shapes for any type of ornamental application.  The front end cost of creating the master pattern and the production tooling is an important consideration for the project's total cost and can range from three percent to 90 percent of that total.  These costs are typically overcome by the customer's desire for a product that is unique and aesthetically pleasing.
This article will outline some of the extremes that we have encountered in custom designed castings.  We have completed jobs that range in size from one inch by one inch by two inches to 48 inches by 48 inches by two inches, from weights of .2 pounds to 250 pounds, and from quantities of four to 10,000 pieces.
These jobs have had tooling charges of three percent to 90 percent of the total project cost.  In all cases, the casting was original and achieved the cost/beauty relationship the fabricator needed to please the customer.
Custom casting projects arrive at the foundry in many forms, including sketches, engineered drawings, and miniature and full-scale models.  In each case, the foundry was able to use wood carvers, pattern makers, and shop personnel to create the master patterns and production tooling.
Figure 1 shows some of the smaller items that we have custom produced.  Typically, these small aluminum castings range from .2 to .5 pounds.  The length of the production run heavily influences the cost of the individual item because the tooling cost must be amortized over the entire run.  In these small items tooling costs have ranged from a low of 10 percent for a 10,000-unit run to a high of 90 percent for a 200-unit run.  Figure 2 shows some of the unique, long baluster castings.  The lengths go up to 49 inches and weights range from three to five pounds.  Tooling charges have varied from three percent to 50 percent of the total project cost.  The three percent tooling charge was a result of the fabricator providing a dimensionally correct master pattern for a large, 3,100-unit production run.
The items in figure 3 and figure 4 are mid-size castings with weights from five to 20 pounds.  The tooling charges were five to eight percent of the total project.  The low tooling charges are again related to the high production run of the Hawaiian hotel pineapple plaque (figure 4) and the simplicity of the contemporary plaque (figure 3).  In both of these cases, the foundry was provided with an engineered drawing.  The wood carver used the drawings to provide an oversized, dimensionally correct master pattern before the matchplate maker created the production tooling.
The picture frame in figure 5 is 44 inches by 54 inches and weighs 42 pounds.  The tooling charges were only ten percent on this total project cost because the customer provided a master pattern that was single faced and had the correct dimensions, drafts, smoothness, and tolerance.
 The sea shell shown in figure 6 and figure 7 first came to the foundry as a 4 inch plaster miniature to extrapolate the size to a two foot by two foot pattern and a four foot by four foot pattern.  The final two foot casting weighed 50 pounds (figure 6) and the four foot casting weighed 250 pounds.  The unit is shown here on location at a Florida bay front development (figure 7).
Another option in the quest for uniqueness and originality is to modify existing patterns.  Figure 8 shows a common ornamental aluminum bench end customized to accept varying logos and symbols.  Typically, adjustments can be made by adding to (epoxy) or taking away (machining) existing patterns.  Tooling charges for this approach are commonly on the low side because the starting master pattern is already available as a sample of the full size original casting.  The concept of adding symbols or letters to existing patterns can give a fabricator a chance to sell a common theme to developers of malls, townhomes, or parks.  In this way, trash containers, park benches, tables, tree grates, and entry areas can easily have a common logo or symbol.
Table I is a summary of the technical data for the items pictured in this article.  Each of these aluminum castings started as an original idea and was the creation of a homeowner, architect, or fabricator.  In all cases, the foundry's job was to help the fabricator implement each custom project to the cost-aesthetic satisfaction of the end user.