Metal Casting: Expendable or Permanent Mold?

In truth, there are countless factors that will determine a good metal manufacturing provider versus a poor one. Something that can separate the best from the rest is the type of molds that are being used. While there is room for both expendable and permanent molds in this industry – for some uses, one is definitely more suitable than the other.

The expendable option

As the name of the expendable mold suggests, this is designed only for one metal casting before it is discarded. As such, there are obvious production issues here although if you know you are only in the business for a one-off order, it goes without saying that this expendable option will be much more cost efficient.

When we mention these one-off orders we do so in a completely literal sense though. A company won’t be able to use the mold for umpteen different products – it can be used once, and once only. The mold has to be destroyed for the casting to be removed, meaning that it is completely unsuitable if you are looking to create a large quantity of models. If on the other hand you need the casting for just one part, most of the time the expendable mold will be used.

One of the reasons behind its cost-efficiency is because of how the mold itself is manufactured. Generally, materials like sand and plaster are used to construct it, and unsurprisingly, these are inexpensive and cost very little to put together. Again, we’ll reiterate the fact that the mold is destroyed, so it makes sense that the materials to form it are so cheap.

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One benefit that makes the decision for a lot of companies is the flexibility that expendable molds offer. It’s possible to be a little more specific in regards to the shape and geometries, which is absolutely crucial in the design of some metal parts. In fact, even in bulk orders, this could be one reason why a company opts for the expendable mold – even though it has to be destroyed each and every time.

Permanent molds

As you may have gathered, permanent molds are just the complete opposite. They are completely permanent for a start, which means they don’t have to be destroyed for every order.

There are a couple of reasons why the casting can be removed without destroying the entire mold. Firstly, permanent molds are designed with removable sections – with these slotting in and out whenever a cast needs to be taken out. Additionally, the fact they are made from metal or ceramic means they are much sturdier and the chances of the mold breaking away are slim to start with.

However, the benefits of permanent molds also prompt drawbacks. The inclusion of the removable segments means that the shape can be limited, and certain parts won’t be manufactured. Again, this sometimes means that companies turn to an expendable mold – even though it might have to be destroyed for every component that is manufactured.

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