The Core of The Matter – Foundry Cores – Types/Applications

Ever wonder how it is that an engine gets all of those pathways for pistons, exhaust gases, coolant, lubrication, fuel, and the like? There is no way it could be a one-piece iron casting. It isn’t just a bunch of individual parts bolted or even welded together (just try to imagine all the different potential leak paths that approach would cause!). Fortunately, the folks who design and work at foundries are pretty clever. Every iron foundry makes use of cores to create all those fancy hollow areas in an engine block and any other piece of metal that needs a fluid path through it. Even if the fluid (gas or liquid) winds up going through a pipe, that piece of iron casting had a core in it to make the initial hole. Sure you could drill it, but that doesn’t leave a nice smoothbore, which could mess up your flow characteristics. By using cores, in the foundry, it is possible to create perfectly smooth fluid paths or cavities of virtually any shape or size and to do it in an easy to reproduce manner that is quick and efficient.

Still, how does this work? What exactly is a core and how does it accomplish the task of creating empty spots in the middle of a block of iron casting? That is what we are going to learn in this article.

The most common type of core is a dry sand core. The basic process for making a dry sand core is by packing sand into a core box (essentially a mold) and then hardening it. The core is then supported in a mold by means of core prints or chaplets and the molten metal is poured into the mold, creating the desired iron casting.

There are a lot of different variations on the foundry process of making cores, however. The various methods differ in terms of cost, speed, and precision. Worry not, whatever your iron casting (or any other sort of casting) needs, Faircast Inc has you covered with some of the best core technology available.

The three main methods are Isocure (the latest and greatest version of the cold box method), Warm Box, and Shell Core. Let’s take a look at each of these.


This is the latest and greatest core technology being used by iron foundries the world over. It uses a core box the same as other methods. That box can be made of metal, some sort of urethane, or even wood. What sets it apart is how the core is hardened. The dry sand is mixed with resin before being blown into the core box. Then some Amine gas gets sent through the sand. The interaction between the gas and the resin causes the core to harden very quickly with a minimal amount of energy being expended. In some applications, the Isocure method can be as much as 50% more productive than earlier methods.

This method allows the foundry to use Isocure machines vertically or horizontally, can be used on a variety of scales, and be easily adapted to make many complicated cores.

Warm Box

Warm box is very similar to the Isocure method of creating cores for iron castings. Like Isocure, Warm Box uses a mixture of dry sand and resin that is blown into the core. The difference comes in the catalyst. While the cold box method uses Amine gas, the warm box relies on heat as a catalyst to solidify the core. After being heated to 450F, the core becomes extremely hard. This is great for smaller cores as the hardness of the core is very resistant to being broken down by the molten iron or other metal.

Shell Core

Like the Warm Box and Isocure methods, Shell Core makes use of a combination of resin and sand. Like the Warm Box, heat is also important. However, the heat is directly applied only to the core box which is heated prior to the resin-coated sand being poured (rather than blown) into the core box. With this method, the outer layer of the core is all that hardens (hence, the ‘shell’ name), making it easy to pour out and reuse that sand inside the shell. The Shell Core method is cheap, quick, and more than adequate for many applications.

There are a number of different ways to construct cores for a variety of applications that we did not cover. However, these are three of the most prominent and Faircast excels at all of them. Whether you need grey iron castings or ductile iron castings, we have the quality and capacity you need.