The Beginner’s Guide to Permanent Mold Casting
Like its name implies permanent mold casting is metal-casting that uses reusable molds. Conversely sand casting and other methods use molds that are disposable. Permanent molds can be beneficial in situations where you want to produce a significant number, sometimes thousands, of the same part.
To determine the ideal method for casting, it’s important to consider the project at hand. If it involves medium to high volume manufacturing with non-ferrous materials, permanent mold casting is absolutely advantageous.
How to Make a Permanent Mold
As a general rule, permanent molds are constructed from metal. The metals used should have a high melting point, and be able to resist thermal fatigue. These molds are frequently made of steel, cast iron, bronze, and other ductile metals.
Manufacturers use a variety of techniques to create these molds. The choice depends largely on the type of material. Investment casting, sand casting, and CNC machining are common methods used.
How Ductility Affects Thermal Fatigue
A ductile metal is better able to stretch without breaking. These are better able to resist damage caused by thermal fatigue. This means better structural integrity.
It’s also important to consider the type of metal that is being cast. Since it is poured into the mold in a molten state, the mold must have a higher melting point. This is one of the reasons that aluminum is so common in casting applications. It’s melting point is nearly half that of steel. When aluminum is poured into a steel mold, there isn’t concern of the mold becoming deformed.
Longevity of Permanent Molds
A quality mold can usually be used to manufacture hundreds of parts or more. Eventually, they do wear out. Companies must be able to make new molds quickly, or keep an assortment on hand. In many instances, a large aluminum casting firm will choose the latter method to prevent any delays.
Permanent Mold Casting: Cost of Price And Labor
There are costs involved in permanent mold casting, and its important to understand how these break down. Overall, permanent mold casting costs more up front. This is because of the cost of fabricating the mold itself. However, since the mold can be used repeatedly, the cost per part goes down quickly.
Permanent mold casting can lead to lowered labor costs as well. Once a part is taken out of the mold, the mold can be used again, almost immediately. This reduces preparation time.
Permanent Mold Casting Part Attributes
Permanent mold casting leads to final products that are very precise. They conform to tight tolerances, and have a smooth, unblemished finish. They are a good choice when there is little margin for error.
When to Avoid Permanent Mold Casting
There are times when it is better to choose a greensand casting or other method. For example, disposable molds are a good choice for small part runs, prototypes, and tooling permanent molds for other applications.
When it comes to producing a large run of parts, permanent mold casting is often the best choice. This is even more true when the standards of accuracy are high. However, it is also important to consider that the up front cost is going to be higher. Fortunately, it is possible to recoup some of that cost when you consider the cost per part when you are producing a large volume of them. Costs can also be controlled by producing a large number of replacement molds to ensure that manufacturing is not delayed.
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