The Difference between Cast Valves And Forged Valves

Casting vs. Forging

Before we compare casting and forging industrial valve, we should understand the two materials that are processed this way— steel and iron. Iron is a material that we often come across in our daily endeavors and is commonly used in making tools and other products. Steel alloys are composed mainly of iron. So, what is the difference between these two materials?

The first concept is that the iron referred to in our daily lives is mainly iron alloys, not iron elements. This is because the element of the pure iron has a higher melting point and, depending on the proportion of carbon and other elements through different manufacturing processes, gives way to various iron and steel alloys. It seems that everyone has some basic knowledge regarding iron and steel and can name some common goods made of them. Cast iron is used for traditional teapots as well as for manhole covers, while steel is used for kitchen knives plus common pipes. For example, industrial equipment makers have many options between using just wrought or cast iron with alloy steels or even specific stainless steels where necessary due to government agencies' regional standards, which also impact material selection in order to meet certain applications.

The difference between cast iron and cast steel

Steel and iron differ primarily in their carbon content. Typically, cast iron has more than a 2.0% mass ratio of carbon content. The carbon content during the production of steel is to be limited between 0.008% and 2.0%. Cast iron has a lower melting point (than pure iron), while steel has a higher melting point compared to cast iron. These differences have very important results in the way these metals are produced and used as well. It is mainly because of its relatively low melting point and good flow that cast iron can be poured into so many parts for products.

The name indicates itself that cast iron is entirely cast and cannot be forged. Also, even though it has good castability and can be more easily shaped through molds, it cannot be effectively welded because the high carbon content can readily lead to brittle welding. For this reason, it can not meet the strength and pipeline connectivity for use with high temperatures and high applications. In these circumstances, steel is a proper choice.

This means that steel can not only be cast but also forged into the desired shape. It can be welded and is stronger than cast iron; suited for high-temperature and high-pressure applications. The most common steel alloy is carbon steel. As the case may require and according to what the final product will be used for, the material might be made up of higher-grade steel alloys like stainless steel and molybdenum steel. By and large, these rather special alloy steels are designed to meet some special requirements: ultra-high corrosion resistance, for example, or wear resistance, or even high-temperature resistance.

Casting refers to completely melting the material into a liquid state, placing it in a mold and solidifying it. Once the mold has solidified, remove it from the mold. The steamer is a typical product formed by casting iron.

Forging is a process of forming metal (usually in the shape of an ingot or sheet) using high pressure, either by hammering with a hammer or by pressing with a metal mold. To make forging easier, the material needs to be preheated but remains solid during the process. Kitchen knives and their blades are classic examples of forging. Because steel can be cast or forged, manufacturers designate grades of materials such as "cast steel" and "forged steel" to indicate the process by which the material is formed.

What's the Difference between Cast Valves And Forged Valves

Why cast a valve?

Products with complex contours are best cast, as the material is relatively easy to shape. Placing materials into molds allows for more efficient production of products with complex internal structures, such as cavities or other hollow areas. We can uses a casting process to produce free-float steam traps to ensure that there are necessary passages and spaces in the trap to ensure the operation of the free-float ball.

Why forged valves?

Since the forging process uses pressure to form solid materials into the desired shape, it is not suitable for structural designs with hollow areas or more complex designs. If the forging process is used to produce the product, engraving or drilling will be required during later machining. Regardless, forging steel is a relatively fast process that allows for greater strength and uniformity. WKT uses a forging process to produce high-pressure disc steam traps because its design is relatively simple, does not have too many hollow areas and does not require much post-processing.

How production processes affect mass production?

As we mentioned before, steel can be cast or forged. Since casting can more flexibly produce products with complex shapes, why aren't all valves produced using the casting process? In fact, there is no superior or inferior distinction between the two production processes. The advantages and disadvantages of casting and forging depend on the specific application requirements of the product.

Steel's higher melting point makes it difficult to cast, and there may be a risk of air bubbles forming if the metal does not fill all the tiny crevices of the mold. On the other hand, the higher the output, the lower the cost of forging. Of course, it also has its own risks, such as misalignment. Misalignment can result in incorrect forging shape, cracking, or other damage to the product.

So in order to balance quality and cost during the production process, it is very important to consider all factors. For example, product size, shape complexity, quantity, the number of machining processes required after initial molding, etc. Balance these factors before making the final decision whether to cast or forge.

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