Casting processes: definition, mode of operation, types in detail, advantages, disadvantages, application [Notes and PDF] | MECHANICAL ENGINEERING.COM (2023)

In this article, I will go into detail about the casting process and its methods. At the beginning you will get to know the definition, methods and detailed work.

Next we will discuss the advantages, disadvantages and applications of the foundry process.

So let's start

What is the definition of the foundry process?

Casting process is the manufacturing process in which molten material such as metal is poured into the casting cavity or mold of desired shape and hardened or solidified within the mold, after solidification, the casting is removed from the mold by ejection or breaking.

This is one of the oldest and most widespread methods of the manufacturing process used to create many types of devices, tools and materials that would be quite difficult or expensive to produce using other methods.

Did you know? In the historical era, many of the weapons and defenses were made using the casting process. And India is considered to be the first civilization to use this process for mass coin production.

Main parts like a bedlathe,milling machineBed motor and IC gear are made using this method.

Working principle of the casting process in detail:

In this part we will learn the detailed working process and basic foundry terminology.

Basic terms of the foundry process:

• Bottle:A metal or wooden frame on which to form the shape.
• Lidar:The top half of the bottle is called the cup.
• Draw:The bottom half of the bottle is called the drag.
• Significant:The core is used to create an internal cavity in the end product.
• Openings:These are the spots created in the mold to transport the gases that are produced when molten metal comes into contact with sand.
• Formhohlraum:This is the cavity in the mold where the metal part is formed.
• Elevator:It is the molten metal reservoir that provides additional metal in the event of reduction.
• Hall:It is the passageway through which the molten metal can be regulated before it reaches the mold cavity.
• Pouring cup:It is the cup or bowl from which molten metal is poured onto metal.
• Muster:It is the duplicate of the form needed for molding.
• Angus:It is the cavity through which molten metal flows down.
• Parting line:This is the line that separates the cap and the drag.

Casting process steps:

There arefive steps of the casting process:

• pattern formation
• formation of the core
• mold making
• casting processe
• solidification process

pattern formation:

The first step in this process is to choose the shape that we need to sculpt. So we need to craft the dummy material of this gear that we chose to release. Dummy material is also known as pattern. The mannequin material can be wax, wood, metal, plastic, etc.

nucleation:

After making the pattern, the core is made. The core is made when casting requires some internal features such as a hole. The core consists of sand of the highest purity. Now, after making the core, comes the making of the mold.

mold making:

To make the mold, we take a wooden box and put the mold in the wooden box. Then we place the train over the wooden box and fill the train with sand. Let's fill the sand directly into the train.

Note: There are two types of sand used in casting: green sand and dry sand. Green sand is a mixture of silica sand, clay, other aggregates, and moisture. While dry clay is the mixture of sand and fast setting glue.

Once the sand has set we keep the drag with the pattern facing up. Now let's remove the pattern. If we remove the pattern we can see that the mold cavity has formed. Now we can create a corridor and gate that will regulate the flow of molten metal into the cavity.

Now we put the cover over the brake and secure it well with the help of locating pins. In the canopy we will use the sprue and riser.

Now comes the most important step, the casting.

Casting process:

The first step in this process is to select the type of metal to be used for the casting. Then the selected metal is melted to remove all impurities and gases. Metal treatment such as degassing, fluxing, etc. occurs during melting.

Then the molten metal is filtered and this step can be done directly in the mold or before pouring into the mold. This is done to remove impurities, slag, traces, etc.

And then this molten metal is poured into the mold in such a way that the release of gases resulting from the contact of the sand mold with the molten metal is minimal. In addition, the gases present in the mold are given sufficient time to escape through the vent openings.

Note: To avoid gas errors, all gases must escape. To avoid erosion and interactions with atmospheric gases, gases must escape with minimal turbulence.

solidification process:

This process depends on the gating system and the temperature gradients after pouring the molten metal. Efforts have always been made to increase the creator or use the coolers to obtain reasonable temperature gradients.

The casting must be designed so that directional solidification (end to end) occurs to avoid defects. Chills & Padding are useful for directional solidification.

The molten metal solidifies and is ejected from the mold by breaking the mold or using ejection tools.

After the casting is ejected, it is cleaned to remove any unwanted parts by cutting, blasting, tumbling, etc.

Now we have our last finished product.

So that was the detailed process of pouring hope so you benefited a lot from these processes or steps.

Classification of the casting process:

The casting process was divided into three processes:

• disposable form
• Permanent molde
• Casting of composite molds

Disposable Molding:

This is the type of casting process where the molds are made of sand and cannot be reused. This process is used to make expensive parts or equipment at a lower cost. These are also called temporary mold. Because it is a temporary mold, the surface finish and precision is not so clean.

Permanent casting:

In this type, the mold is made of metal and can be reused many times. This process is used for mass production of the product. In this process, the manufactured product has a smooth and precise surface. The manufactured product has more strength. Tooling costs will be higher.

Composite molding:

This casting is the combination of permanent and stretch molding, where part of the mold is temporary sand and another part is permanent metal.

Now to the different types,

Types of foundry processes in detail:

Here I will explain everythingTypes of Casting Processes:

• Schalenguss
• Feinguss
• complete shaping
• CO2 injection molding
• Sandguss
• Real centrifugal casting
• Gravitationsguss
• diecast
• Hot Chamber Die Casting
• Die casting in cold chamber and
• mud cast

Shell casting process:

Shell molding is the casting process that uses a mold as a shell made of materials such as fine-grain silica, thermosetting resin, and alcohol. In this process, the pattern is heated up to 250 degrees Celsius.

This form has high strength and low weight. The mold is suitable for automatic pouring. This method can be used for both ferrous and non-ferrous metals.

Shell Casting Benefits:

• This operation can be performed by semi-skilled workers.
• The products have a smooth surface.
• Excellent dimensional accuracy is achieved.
• Simply automated

Disadvantages:

• Shell casting is more permeable, so the likelihood of gas failure increases.
• It is not suitable for small batch production.

Feingsverfahren:

This is the type of casting process where the cast is formed around a model made of wax or a similar material. In this cast, the model used is wax and the cast is formed around the model by dipping it in the paste of quartz flour, ethyl silicate and water.

This method of forming a cast around a pattern is called stuccoing. After the cast is formed, the pattern is melted, a process known as dewaxing. And this forms the cavity, and the molten metal is poured into the cavity for products.

Earnings:

• Fine surface finish
• Complex and intricate materials can be formed.
• Excellent dimensional accuracy is achieved.
• Low material waste.

Disadvantages:

• High costs.
• Core parts are difficult to cast.

Complete molding process:

This process is also known as cavity-less molding or evaporation patterning. In this process, the pattern used is made of plastic, PVC, styrofoam, foam, etc.

And when hot liquid metal is poured into the mold, the pattern placed in the mold starts to vaporize and turns into gases that form the cavity.

Then the molten metal is poured into the cavity to form a product. It is commonly used in the manufacture of an engine case.

Benefits of full molding:

• Can cast light parts
• Complex and intricate materials can be formed without a core or mold.
• Excellent dimensional accuracy is achieved.
• Provides high smoothness.

Disadvantages of full molding:

• High cost when the matrix to create the pattern is large.
• The cost of the pattern increases when the final product to be manufactured is large.

CO2 injection moulding:

This process is used to increase the strength and hardness of large molded parts. This technique increases the strength of the casting by forcing CO2 gas through the mold.

When preparing the mold, we add a special additive called sodium silicate. This will add about 2%-6%. And when the CO2 gas flows through the mold, this additive reacts with the CO2 and forms silica gel.

And this silica gel has better bonding properties, which further increases the strength and hardness of the mold. Therefore, CO2 molding is used to produce a larger format casting that requires good strength.

Advantages of CO2 molding:

• The raw material costs are lower.
• It can be performed by semi-specialized workers.
• It can be easily mechanized.
• Faster production rate.

Disadvantages of CO2 molding:

• Not suitable for non-ferrous materials.
• Minor imperfections can lead to gas defects and poor surface finish.

Sand casting process:

Sand casting is the most common casting process. This process is known as sand casting. In this technique, the pattern is placed on the train and filled with sand.

In addition to sand, certain binders are mixed with clay. More than 60% of metal casting is done using the sand casting process.

Earnings:

• Greater choice of materials as any type of metal alloy can be cast.
• The cost of the tools and equipment needed for the process is certainly lower than other metal casting processes.
• Because it has a short lead time, it's perfect for low-volume production.
• It can be used to create complex and intricate shapes.

Disadvantages:

• It cannot make large castings due to its low strength.
• Bad surface finish.
• It increases the effort as it requires post-production finishing.
• The probability of defects in tools and equipment is low.

centrifugal casting process:

Centrifugal or rotational molding works on the principle of centrifugal force to produce hollow cylindrical parts or products. During this casting process, a cylindrical mold rotates around its central axis at high speed while molten metal is poured into it.

This rotation of the cylindrical mold creates a centrifugal force that pushes the molten metal toward the perimeter of the mold. This creates hollow cylindrical parts and products.

Earnings:

• The high-density object is created.
• No chance for the gas defect.
• Due to the rapid rotation, the object obtained has a fine-grained structure.
• No riser or gating system required

Disadvantages:

• Skilled workers are in demand.
• This procedure is expensive.
• Few shapes can be formed by this method.
• The imprecise diameter of the inner surface of the product.

Gravity Casting Process:

Gravity casting is a type of permanent casting where molten metal is poured into the mold using the ladle. When filling the mold with molten metal, no other force acts than gravity. The material with high fluidity is made by gravity die casting.

Earnings:

• The surface finish of the material produced is high.
• Excellent accuracy of the manufactured product.
• The mechanical and physical properties are superior to other types of casting.
• Parts can be made from inner inserts and core.

Disadvantages:

• Certain alloys have a lower production rate.
• Tools and equipment required are more expensive.

Die casting process:

Die casting is the type of permanent casting where molten metal is poured into the mold under high pressure. Technical force is applied to molten metal with a piston. There are basically two types of die casting:

Hot Chamber Die Casting:

This method is only applicable to metals such as zinc and other low melting point alloys. The oven is attached to the gooseneck.

Cold Chamber Die Casting:

The difference between a hot runner and a cold runner is that the gooseneck of the cold runner is not attached to the furnace. And the molten metal is poured through the hole in the gooseneck with the help of a ladle. In general, the melting of steel, along with copper and aluminum, occurs through a cold chamber.

Merits of the cold room:

• Produce high-volume devices with greater precision.
• Excellent accuracy of the manufactured product.
• Molten metal freezes in a second, even milliseconds.
• Suitable for large long-term productions.

Disadvantages of the cold chamber:

• Used complex equipment.
• Tools and equipment required are more expensive.
• It is not suitable for short-term individual products.

Mud Casting Process:

Mud casting is the type of permanent casting used to create thin-walled, hollow objects. This technique is widely used to craft decorative items, components, and ornaments.

With this method, the molten metal cannot completely solidify. When the desired thickness is reached, the rest of the molten metal is poured.

Earnings:

• A wide range of ornaments and decorative products can be made.
• The preferred thickness can easily be achieved by pouring off excess molten metal.
• Good surface finish.
• Faster cooling rates.

Disadvantages:

• Requires manual work.
• The material thickness can vary.
• Late.

Advantages of the casting process:

consequencesAdvantages of the casting processIt is:

• Complex and intricate shapes can be formed.
• We can fuse any type of material.
• The tools and equipment used in the casting process are inexpensive.
• Casting of any shape and size is possible.
• Castings of any size up to 200 tons can be carried out
• It is the cheapest way to make shapes and sizes with different mechanical properties.

Disadvantages of the casting process:

consequencesDisadvantages of the casting processIt is:

• High probability of error.
• The dimensional accuracy of the casting is not so good.
• In general, sand casting, the popular casting technique, is labor intensive.
• In some cases it is not possible to fix the defects.

Application of the casting process:

Casting process is used to manufacture various products in industry such as: B. Cylindrical hollow cylinders, pistons used in automobiles, pulleys, engine manifolds, valves, nuts, defense equipment, etc.

The casting process is used in various industries such as aerospace, defense, automotive, railway, construction, agriculture, mining, chemical, etc. It is also used in the manufacture of home decor and ornaments.

Internal resources:

• injection molding process
• Drill
• modeling machine
• slot machine
• lathe
• NC machine
• Hot working process
• cold working process

Conclusion:

Casting is an important manufacturing process that helps manufacturing industries produce a different variety of products. There are various casting processes such as sand casting, die casting, solid casting, investment casting, etc.

I hope then this article helped you get a clearer view of the casting process and its pros and cons. Be sure to comment any doubts you may have on the topic.