More than metal and other material costs go into the price of your cast component and tooling.

MCDP Staff Report

(Click here to see the story as it appears in March/April 2014's Metal Casting Design & Purchasing.)

Estimating the cost of a casting requires knowing all the variables of the metalcasting process. Depending on your casting supplier and component, these can change due to the type of metal required and specific process to be used. To help build your knowledge of these variables, the following is a list of 14 factors commonly used when estimating the cost of a casting. It is not intended to be a complete list, but a foundation to build upon in further discussions with your suppliers.

1. Metal

The cost of the metal required for your casting depends heavily on the material desired. While iron typically accounts for about 10-25% of total cost, aluminum can escalate to 40-60%. Several online databases provide up-to-date metals pricing.

2. Melting

The electricity required to melt the metal for your casting is based on the pour weight, which can be significantly higher than the casting weight, depending on gating and risering. Energy accounts for about 5-7% of operationg cost and more than 50% of that cost is melting.

3 Molding

A relatively small percentage of the total casting cost, molding can be performed in a variety of ways. With permanent molds, molding costs will be nil, though tooling will have to be factored in. Expendable molds, sand molds for example, should comprise a maximum of 5-10% of the total casting cost (while also having a tooling cost). 

4. Pouring

This operation can be performed either manually or automatically. Pouring and melting, accounted together, make up roughly 15-20% of your casting costs. 

5. Cleaning

This portion of the cost accounts for the time and resources used to shotblast the casting free of sand after shakeout. 

6. Coremaking

Unlike molding, coremaking can make up a significant portion of your casting costs, depending on the number of cores required for your casting. Expect 10-20% of your casting cost to come from this operation, depending on the number of cores. Consider the number and intricacy of hollow passages in your component to estimate the number of cores that will be required.

7. Core finishing and/or dipping

Some cores will require some filing and grinding to obtain the desired final shape. Others must be dipped in a coating to prevent adverse reactions in the casting process.

8. Core assembly

Depending on the number of cores used in a casting, a package or individual cores will have to be put together and set into the mold.

9 Finishing

Finishing is a significant financial burden that can account for more than 25% of the total casting cost when sourcing a ferrous component. Nonferrous pieces that are more conducive to trim pressing can have far lower finishing costs. Finishing times often depend on the size and number of gates and risers used in the mold.

10 Inspection

Nondestructive testing and any other processes you require to ensure your casting meets standards should be accounted for here.11 Painting and heat treating—Value-added services like painting and heat treating may not be necessary, but if they are, they must be included to develop an accurate cost estimate.

12. Container

This will be based on the number and size of the castings to be shipped. Specialized containers that have more strength than the typical cardboard box, for example, will incur an additional cost.

13. Shipping

Shipping costs are based on the weight of the total castings delivered to the customer.

14. Setup charge

Based on the minimum order quantity, setup charges may or may not apply.As an example, above is a cost estimating form a group of metalcasters developed for a 2.5-lb. aluminum valve body an automotive company sourced. (This estimating form provides one example only. All castings are unique, and costs can fluctuate significantly according to part type.) The final cost assumes the metalcaster can make 12 castings in each mold produced on a green sand matchplate molding machine. The casting requires three separate cores, none of which need finishing, dipping or assembly. Finishing costs are kept to a minimum with the use of a trim press, but they could escalate depending on the capabilities of the metalcaster. Other costs are accounted for, as well.