What Is Casting Process | Types of Casting Process | Classifications | Diagram | Applications | Advantages | Disadvantages

Casting Process Introduction

Casting Process Types

What is the casting process in manufacturing and mechanical engineering?

The casting process can be defined as a type of manufacturing process used to manufacture casting in a hollow cavity mould by pouring molten metal into it and allowing it to solidify until the final shape is formed in the mould made from sand, sand-resin, metal (permanent mould) or ceramic shell.

The casting process is a very unique manufacturing method for producing complex and intricate components in a factory called a foundry where the mould-production process, casting process, cleaning of casting, machining of casting, secondary operations on solidified casting, testing and inspection of casting and dispatching operation take place.

Casting parts manufactured from this process has a wide application in the automobile sector, machine sector, marine industry, mining industry, space industry, aerospace, military application, textile industry, tool industry, plumping, electrical industry, electronic industry and agriculture industry.

I have given a detailed explanation of the casting components produced using the casting process in the application of the casting process segment of this article below that engineers should refer to get an idea about wide examples and uses of this process.

Casting Process Type

What are the types and classifications of casting processes in manufacturing?

Sand casting process.
Green sand casting process.
Dry sand casting or Heavy casting process.
Skin-dry sand casting process.
Die casting process.
Vacuum dies casting process.
Investment casting process.
Slush casting process or Hollow casting process.
Shell casting or Shell moulding process.
Permanent mould casting process.
Centrifugal casting process.
Squeeze casting process.
Continuous casting process.
Lost-form casting process or Evoprated pattern casting process.
Bell casting process.
Jewellery casting process.
Full mould casting process.
Ceramic mould casting process.
Ingot casting process.
Strand casting process.
No bake casting process.
Resin casting process.

Sand Casting Process or Sand Moulding Process

Sand Casting Process

The sand casting is a type of casting process which is one of the oldest casting processes used to produce casting by pouring molten metal into the sand mould cavity using a ladle and allowing molten metal to solidify in the mould cavity made from sand.

Molten metal is poured into the cavity made from a tool called a pattern, the pattern is selected based on the shape, size and the application of the casting.

Sand casting process can produce casting from small size to large size depending upon the type of sand used in the process.

This process has the lowest initial investment and can produce casting at the lowest rate in the foundry as compared to any other casting process such as vacuum die casting, shell moulding or shell casting, die casting, investment casting, squeeze casting and centrifugal casting.

The green-sand-casting process is used to produce small to medium casting while the dry-sand-casting process is used to produce large-size casting. I have explained both these casting processes below in detail.

The sand-casting process consists of the following steps such as:

Step 1: Make a sand mould in the foundry using foundry tools, sands and patterns.
Step 2: Melting ingots in the furnace to produce liquid metal.
Step 3: Pour molten metal into the sand mould through the gating system.
Step 4: Allowing molten metal to solidify in the sand mould cavity.
Step 5: Breaking the expandable sand mould and cleaning solidified casting which was engaged in the sand.
Step 6: Fettling casting to remove gating system elements such as pouring basin, riser, sprue and runner.
Step 7: Casting inspection and testing of casting components.
Step 8: Processing casting for secondary manufacturing operations such as machining, drilling, milling, grinding, surface finishing and surface coating.

I have written a separate article explaining the sand moulding process or sand casting process in detail that includes working on sand casting, types, advantages, disadvantages and application with proper diagrams and animation that engineers must refer to.

Green sand moulding or Green Sand Casting Process

Green Sand Casting Process

The green sand casting process is a type of casting process which consists of pouring molten metal into the casting made from "green sand" which consists of a high amount of moisture content to produce casting at the lowest rate.

Casting components produced from the green sand casting process have limitations over the size of the casting as compared to the dry sand casting process and skin-dry casting process.

The process of making casting is similar to the sand casting process mentioned above except for the grain size, moisture and clay content in the green sand mould.

The final product produced from this casting process has a high amount of gas defects such as open-hole defects, shrinkage depression, pinhole defects, porosity, blowhole and air inclusions.

I have written a separate article explaining green sand moulding or green sand casting in detail with a diagram, of the difference between green sand moulding and dry sand moulding.

Dry Sand Moulding Process or Dry Sand Casting Process

Dry Sand Casting Process

The dry sand casting process is a type of casting process which consists of pouring molten metal into the mould which is made from dry sand to cast large size casting as compared to green sand casting or green sand moulding process.

The process to produce dry sand mould is similar to green sand mould except for the part where the mould is heated in the oven and moisture is released to make sand dry.

The advantages of dry sand mould are that this mould is stronger than green sand mould, has the least moisture and can produce casting with lower gas defects in casting such as porosity, blowholes, open-hole defects, porosity and pinhole defects.

I have explained the dry sand moulding process in detail in the dry sand casting process in the article with a diagram, advantages and disadvantages of the process.

Skin-Dry Moulding Process or Skin-Dry Casting Process

Skin-Dried Sand Casting Process

The skin dry casting process is a type of casting process which consists of pouring molten metal into a skin-dry mould to cast casting larger than the dry casting process and green casting process.

The skin dry casting process has two layers of sand, the first layer of sand close to the molten metal is dry sand. The pattern is packed around the dry sand and a layer of green sand supports the dry sand enabling this casting process to produce large-size casting at the lowest cost.

The process of making gating elements, heating molten metal and pouring and solidification operations, fettling, cleaning and machining operations is the same as any other casting process.

The added advantage of this casting process is that fine sand has a smaller grain structure giving a better surface finish than green sand casting for larger-size casting.

Die Casting Process

The die casting process is a type of casting process which consists of injecting molten metal into the metal mould at high pressure with a plunger and piston mechanism and solidifying the casting in the die to produce more complex casting than the sand casting process, dry sand casting process and skin-dry casting process.

Die-casting process machines can produce high-quality casting at larger quantities, more accurately, with high precision, less sand mould defects and having better surface finish.

The die-casting process starts with melting the ingots in the oil-fired or induction furnace to the pouring temperature and injecting the liquid metal into the die from low to high pressure in the die cavity.

Another important point of the die-casting process is that the die mould does not need to be broken after the casting is solidified. In the sand casting process, the mould is expandable and needs to be broken to take the final casting out.

The die-casting process differs from the sand-casting process where metal moulds are used instead of sand moulds and the cavity is carved in metal blocks with advanced manufacturing processes such as AJM, EDM, ECM, WEDM and LBM.

The die-casting process consists of the following steps:

Step 1: Melting ingots in the furnace, in case of hot chamber casting the die is attached.
Step 2: Pouring the molten metal into the molten metal storage chamber keeping the molten metal ready to inject into the die for the hot chamber die casting process and for the cold chamber die casting process keeping the metal ready to be poured in the shot chamber.
Step 3: Clean the die and apply die coating to improve the surface finish of the casting.
Step 4: Closing the dies by ascending the moving die and locking it with the fixed die.
Step 5: Allowing the plunger to push the molten metal in the die at low to high pressure depending upon the casting application.
Step 6: Allowing molten metal to flow in all sections of the die cavity and allow molten metal to solidify in the die cavity sections of the casting.
Step 7: Opening the die remove the solidified casting out and send it for fettling operation removing all runners, sprue and riser.
Step 8: Send the casting to the inspection and testing department to check for any defects and repair the casting accordingly.
Step 9: Processing the casting with secondary manufacturing operation of lathe machine, milling machine, grinding machine etc.
Step 10: Dispatch the final die-casting product to the customer.

I have written a dedicated article on the casting process explaining the working, types, advantages of die casting, disadvantages of die casting and application of die casting process. that mechanical engineers should read to get a detailed explanation of the die casting process.

Vacuum Die Casting Process

The vacuum die-casting process is a type of die-casting process used to produce casting in a vacuum chamber with the objective of manufacturing casting without gas defects such as open-hole porosity, pinholes, blowholes, gas pockets and internal cracks.

The vacuum pump is used to suck all air from the mould cavity leaving a vacuum space for molten metal to solidify without any presence of air in the mould cavity.

The suction pump starts when both die (fixed and moving) close together and before the molten metal is injected into the casting with high pressure.

Moulds of vacuum die-casting machines are designed for a very optimized automated cooling mechanism of casting to provide directional solidification of casting components giving uniform refined grain structure high quality casting.

This process uses permanent moulds instead of expandable moulds that need to be broken to separate casting from mould. This allows this casting to produce porosity-free casting in higher volume in a production shift.

The vacuum die-casting process is shown below in diagram (), The presence of a vacuum pump to create a vacuum in the casting metal mould makes the casting process different from other casting processes such as sand casting process, high-pressure die casting without vacuum, investment casting process and shell casting process.

Investment Casting Process

The investment casting process is a type of casting process where molten metal is poured into the ceramic mould previously made from a wax pattern tree to produce highly accurate casting in complexity, surface finish, dimensions and accuracy that are difficult to produce by any other casting process such as shell casting process, sand casting process, die casting process, continuous casting process and centrifugal casting process.

The steps involved in producing investment casting are as follows:

Step 1: Make a mould to give shape to a wax tree. The shape of the metal mould should be made considering the shrinkage allowance of wax, metal and ceramic material that is to be used in the casting process.
Step 2: Heat wax and pour it into the metal mould to make the wax pattern. This is the only pattern that is made in the investment casting process. Wax pattern material is selected considering wax has low expansion and contraction rates and can be formed into different shapes, forms, counters and sizes.
Step 3: Assemble the wax patterns together into a common runner, sprue and other gating elements.
Step 4: Dip the wax pattern into the ceramic slurry and allow the slurry to solidify and form a ceramic mould.
Step 5: Heat the ceramic mould and allow the wax to drain or de-invest from the ceramic mould by heating the ceramic mould with a torch gun or in the oven. At this step, the wax is drained and what remains is the ceramic mould with the required cavity.
Step 6: Pour molten metal into this ceramic mould and allow molten metal to flow in every section of the ceramic mould letting the liquid metal cool down slowly to achieve directional soldification to produce thin sections of accurate castings.
Step 7: Break the expandable mould and separate solidified investment casting from the ceramic mould.

I have written a special article on the investment-casting process describing the type, working, function, advantages of the investment-casting process, disadvantages of the investment-casting process and application of the investment-casting process with an illustrative diagram.

Slush Casting Process or Hollow Casting Process

Slush Casting Process

The slush casting process is a type of casting process and one of the magnificent ways of casting hollow tin casting by pouring molten metal into the metal mould and only allowing the molten metal thin skin to solidify around the mould wall and draining the remaining molten metal out of the permanent mould.

Slush casting is done in permanent mould and allows the engineers to produce multiple hollow thin casting using the same die.

The step-by-step process and method are explained below in sequence to produce the casting.

Step 1: Melt metal ingots in the furnace, most preferred metal is the non-ferrous metal for the slush casting process.
Step 2: Pour molten metal into the permanent metal slush mould.
Step 3: Allow only the molten metal around the mould walls to be solidified.
Step 4: Once sufficient thickness is formed around the metal mould drain the remaining molten metal out of the casting.
Step 5: Remove any excess flash, burr, unevenness around the edges and internal cavity of the mould.
Step 6: Dispatch the shiny solidified high super finish decorative casting out of the customer.

I have written an entire article on the slush casting process explaining this casting process with animation, diagrams and work. Engineers can read the advantages and disadvantages of slush casting. Application of slush casting process.

The slush casting process is used for producing casting with a high surface finish from the outside giving a shiny, beautiful texture, smooth surface finish and exceptional aesthetic look that is difficult to produce using the sand casting process.

Shell Moulding Process or Shell Casting Process

Shell Casting Process

The shell casting process is a type of casting process used to produce accurate casting using a cured shell mould made from sand and resin mixture.

Sand and resin are mixed in a rotating dump box with a heated metal pattern allowing the sand-resin mixture to bind and stick together to form a hollow shell mould.

The steps involved in producing shell casting using the shell moulding process are as follows:

Step 1: Mix sand and resin together in an appropriate proportion using a muller before pouring it into the dump box.
Step 2: Heat the metal pattern to a temperature that melts the resin and fuses it with the sand particles.
Step 3: Allow the sand-resin mixture to rotate in the dump box and stick to the metal pattern layer by layer. All the mixture does not fuse at one time but in layers forming a strong shell mould but not as strong as sand casting.
Step 4: Once the shell mould of the required thickness is formed, the shell mould is removed from the dump box and cured in the oven to get the desirable hardness.
Step 5: The mould cavity of the shell formed in this casting process is not as strong as sand casting, which is why the shell is placed in the backing sand that supports the entire shell mould during the pouring operation.
Step 6: The pouring operation is carried out by melting the ingots to the required pouring temperature and pouring the molten metal into the shell mould.
Step 7: After pouring the liquid metal with the ladle, the molten metal is allowed to solidify in the expandable shell mould.
Step 8: After the casting has been solidified the casting is taken out of the shell mould by breaking the shell passing the casting through various inspection and testing methods and then processing it to various machining, surface finishing and surface coating processes.

The advantage of this process is that casting has higher accuracy than the sand casting process including the dry sand casting process, skin-dry casting process and dry sand casting process due to the use of fine sand.

Permanent Mould Casting Process or Gravity Die Casting Process

Permanent Mould Casting Process

The permanent mould casting process is a type of casting process which utilizes permanent metal mould to produce casting instead of sand mould but uses gravity as a force to allow molten metal to flow through all sections of the mould cavity and gating elements such as sprue, runner, riser and gates.

The permanent mould-casting process is different from the die-casting process where molten metal is injected into the die cavity at low to high pressure to make accurate complex castings at a faster production rate than the permanent mould-casting process.

No pattern is used in this process to make a mould cavity, instead, the cavity is carved into the metal casted block using electrical discharge machining, electrical chemical machining, wire electrical discharge machining, abrasive water jet machining and laserbeam machining.

Cores used in this process can be made from metal that will fuse in the final casting or sand cores made from core sand that are broken after the casting is taken out.

The steps involved in producing casting using the permanent mould casting process are as follows:

Step 1: Manufacture permanent mould die using the advanced machining process mentioned above such as EDM, ECM, LBM, WEDM and AJM.
Step 2: Produce the core in the core box using core sand according to the size of the hole or cavity.
Step 3: Clean the permanent mould removing any previous bits and pieces of metal remaining and apply die coating on the die. Place the cores in the permanent mould die before the pouring operation starts and close the metal dies with clamps.
Step 4: Heat the ingots in the induction furnace and pour molten metal into the die through a ladle.
Step 5: Allow the molten metal to pass through gating elements such as pouring basin, sprue, runner, in-gate, mould cavity and riser.
Step 6: Allow the solidification process to take place in all sections of the gating element and mould cavity taking the final shape of the casting.
Step 7: Declamp, open the mould remove the final solidified casting out and send it for fettling (removing gating elements), cleaning and secondary manufacturing operations such as drilling, grinding, milling and surface finishing.

I have written a detailed full article on the permanent mould casting process explaining the working casting process in step by step process, the advantages of the permanent mould casting process, disadvantages of the permanent mould casting process, application of the permanent mould casting process with illustrative diagram and images.

Squeeze Casting Process

The squeeze casting process is a type of casting process which consists of squeezing molten metal in the permanent mould die with a punch resulting in final casting having excellent mechanical, forging and casting properties.

Squeeze casting process starts with pouring molten metal into the metal die and squeezing (forcing) the molten metal between the punch and the die cavity allowing solidifying molten metal to take the complex shape of the mould cavity.

This process is the only casting process which results in casting having mechanical properties better than any other casting process as products formed in this process are cast using both casting and hot working operations such as forging and refining grain structure.

The steps involved in the squeeze casting process are as follows:

Step 1: Clean the die surface from any remaining metal pieces and fins and apply die coating on the surface for a better surface finish and smooth flow of the metal while solidifying when the punch forces metal in all sections of the cavity.
Step 2: Pour molten metal into the die cavity with a ladle and allow the molten metal to solidify while ascending the punch towards the die.
Step 3: Squeeze the solidifying metal by force between the punch and the die shaping the casting in the negative mould and forming the final shape of the casting in the mould.
Step 4: Descending the casting to its original position and removing the casting out of the mould cavity and sending it for secondary manufacturing operations such as machining, drilling, milling, reaming, boring and surface finishing.

The squeeze casting process is an interesting and unique non-expendable casting process which is a combination of the casting process and forging process that production engineers must read.

That is why I have written a separate article on the squeeze casting process explaining working with a diagram and animation, the Advantages of the squeeze casting process, the disadvantages squeeze casting process and the application of the squeeze casting process.

Continuous Casting Process or Direct Strip Casting Process

Continuous Casting

The continuous casting process is a type of casting process which enables engineers to manufacture casting with infinite length by continuously passing casting out of the copper mould and fully solidifying it until it is cut into required pieces according to the customer's demand.

Molten metal is poured in the tundish which allows the proper flow and feed of molten metal in the mould without any turbulence. Once the molten metal flows in the copper mould from tundish the molten metal is allowed to solidify around the starter bar and the mould is opened allowing the semi-solidified casting to pass around the supporting rollers.

The outlet of the copper mould is the same shape as the final casting to be expected such as I, L, C and T. This process is a continuous casting process without the need for an interepted casting cycle as we see in the die casting process and squeeze casting process where for every casting operation there is need for pouring operation.

Here once the initial molten metal is solidified and the starter bar starts descending the process is continuous as metal is solidified according to the feed of the molten metal with tundish, starter bar feed rate and feed rate of solidified casting out of the copper mould.

Step by step process of continuous casting process consists of the following steps:

Step 1: Melt ingots in the furnace and pour molten metal into the tundish for proper flow and feed of molten metal in the copper mould.
Step 2: Allow the molten metal to fill the copper mould which consists of the starter bar, let the starter bar and molten metal fuse and semi-solidify into the same casting.
Step 3: Once the metal freezes around the mould wall to form a solid casting in the mould allow the casting to pass continuously along the mould.
Step 4: Allow continuous cooling of the casting supported by the rollers through water jets and blowing air.
Step 5: Cut the continuous casting into sections specified by the customers with the saw, welding and other cutting tools.

This is the only casting process that can produce casting continuously without interruption as there is no concept of cooling molten metal, then opening the die and taking the metal out of the die after solidification as we see in the permanent mould casting process, die casting process and squeeze casting process.

Here the solidification process happens as the metal cools along the casting process in series along the supporting rollers with an automated cooling mechanism.

The solidification process starts from the other edge of the casting first in the mould and then slowly casting starts solidifying towards the inner centre of the casting. Once the casting section is solidified fully the casting is ready to be cut and processed before it is dispatched to the customer.

Centrifugal Casting Process

The centrifugal casting process is a type of casting process used to manufacture casting by centrifugal force by pouring liquid molten metal into a closed permanent metal mould that rotates around its own axis to produce the dense casting.

The centrifugal casting process is of three types, centrifuging casting, semi-centrifugal casting and true centrifugal casting.

The true centrifuging casting process is used to manufacture casting by pouring molten metal into a horizontal or vertical mould making longer hollow casting dense components that are difficult to produce by sand casting process, die casting process, investment casting process and continuous casting process.

The semi-centrifugal casting process can produce more complex shapes casting than the true centrifugal casting process because of the use of the sand and metal cores but this process has limitations over the length of the casting to be produced.

The centrifuging casting process consists of manufacturing casting in a multiple permanent metal cavity mould to mass produce casting in large quantities by spinning the molten metal in a metal die having sand or metal core to produce hollow casting in large volume.

This casting process is important from the point that it can produce hollow casting applications with dense properties for the military, robotics, aerospace and marine engineering sectors.

The step-by-step process for producing centrifugal casting is as follows:

Step 1: Melt metal ingots and pour molten metal into the rotating spinning mould. Clean spinning dies and remove all burr and metal pieces from the previous centrifugal casting cycle and apply die coating on the centrifugal dies.
Step 2: Allow the mould to spin about its own axis controlling the rpm of the mould operator can control the thickness of the final casting.
Step 3: While the mould rotates allow casting to solidify in the mould itself keeping in mind the thickness of the casting.
Step 4: Stop the rotating centrifugal mould and open the split metal mould to remove the centrifugal casting from the true centrifugal die, semi-centrifugal die and centrifuging casting.
Step 5: Send the final casting to the machining department to machine and turn the internal castings sections to remove unwanted foreign material that accumulates in the inner diameter of the hollow casting sections.

That is why I have written a separate article on centrifugal casting that includes working, function, diagram, advantages of the centrifugal casting process, disadvantages of the centrifugal casting process and application of the centrifugal casting process.

Jewellery Casting Process

The jewellery casting process is a type of casting process used to produce jewellery using a continuous casting process, centrifugal casting process, sand casting process, shell casting process and die casting process.

Step 1: The process of making jewellery starts with melting gold, silver, platinum, copper, brass and bronze in a small induction furnace.
Step 2: This step consists of the pouring operation. In the pouring operation, metal is poured into the different kinds of mould depending upon the respective type of casting process. Pouring precious metal in die, centrifugal mould, shell mould made from ceramic, sand mould made from sand, die mould for die casting and slush casting mould.
Step 3: Allow the molten metal to solidify in the respective moulds depending on the casting method used.
For sand casting process allows the metal to solidify in the sand mould to produce gold spheres, masks, religious idols and statues.
The continuous casting process let it be vertical or horizontal allows the metal to solidify at the copper mould and allows the starter bar to carry forward the produce strands for producing gold and silver bangles.
In centrifugal casting process allows the metal to solidify around the mould wall to manufacture jewellery such as rings.
In slush casting process allows the metal to solidify around the slush casting walls to produce hollow casting with beautiful gold bowls, silver pewters and exterior high-quality surface texture.
Step 4: Shake out operation- Remove casting from respective sand mould, die mould, centrifugal mould, continuous casting mould, shell mould and slush mould.
Step 5: Send solidified unfurnished casting for secondary manufacturing operations such as coating, polishing, grinding and machining. After finishing operations Dispatch the respective finished casting to customers. Leftover gating systems such as sprue, runner, riser and pouring basin are reused again as they consist of valuable precious metal.

Jewellery making casting process is a very interesting casting process which utilizes all the casting processes mentioned above to produce casting products such as ornaments, idols, statues, sculptures, bangles, men's rings, women's rings, women's neckless, women's pendants, decorative bowls, pewters, men's gold chains, women's gold chain, antique style ornaments.

Bell Casting Process

The bell casting process is a type of casting process that uses a sweep pattern for making cavities in the loam sand for producing bells made from brass, stainless steel, aluminium, cast iron and bronze material.

This process starts with pouring desirable metal into the loam sand and allowing the molten metal to solidify in the mould cavity made from a sweep pattern. The sweep pattern has a pivot, vertical stand and a sweeping side used to produce a cavity in the loam sand.

After the cavity is formed the pattern is taken out and molten metal is poured into the loam sand mould cavity. Bells shape cavity is allowed to solidify, shake-out operation is carried out and casting is taken to send for surface finish processing.

Lost Form Casting Process

Lost-Form Or Evaporated Pattern Casting Process

The lost form casting process is called the evaporated pattern casting process, full mould casting process, disposal pattern casting process, lost form, evaporated form or patternless casting process.

Normally when using sand mould the pattern is used to create the cavity in the sand mould in both the cope and drag section of the mould using specific pattern materials such as wood, plastic and metal.

This pattern is taken out once the desired mould cavity of a specific requirement is formed in the casting process.

But in the lost form casting process disposable pattern (form) is used in the sand mould and the foam pattern is kept there until it comes in contact with the molten metal and evaporates.

In this casting process, the pattern holds the mould cavity intact until it evaporates and can produce complex shape casting.

For complex shapes, the need for loose piece patterns reduces making this process very demanding for casting projections and areas having extruded overhanging sections.

The time of removing the pattern is eliminated in this process saving time in the foundry. Form pattern material is light in weight and easy to work with, simple tools are used for producing this pattern.

Form patterns with any shape, size, geometry, section, segment, counter and offset from the part line can be produced giving high flexibility for this casting process to produce accurate, complex and versatile casting parts.

The step-by-step process of producing casting is the same as the sand casting process. Pouring basin sprue, riser, runner and gates are produced using the foundry tool, except for the fact that the pattern once placed to make the mould cavity in the mould is not taken out and left there to get burned or evaporated by the hot liquid metal.

The pouring operation, solidification process, shake-out operation, fettling operation, removal of the gating system and finishing process are the same as the sand casting process.

The foam pattern material used in this process is made from polystyrene and can be easily cut. The accuracy of the casting produced is high in this process as casting can be customized to the smallest sections with skilled operators.

Machining of casting components is low, the surface finish is high, the pattern is cost-effective and there is no storage of the pattern required.

Casting Process Advantages

What are the advantages of the casting process?

Cost of Production: The production cost of casting components is lower than other manufacturing processes such as machining as machining for higher volume production cycles.
Automation: Advanced automation is possible in casting processes such as die casting, from pouring molten metal into the die, die opening and closing, die lubrication, solidification process and to the removal of solidified casting out of the split die, all process is done automatically without the interference of the operator.
Near Net Shape: Casting produced from casting processes such as slush casting, shell casting process and investment casting process have the near net shape with the lowest waste of metal and reduce the machining cost of the final casing.
Better Surface Finish: Products and components produced from the casting process such as the investment casting process, slush casting process and die casting process have better surface finish than any other manufacturing process at rolling, extrusion and welding process.
Tooling Cost: Tooling cost can be lowest by using the sand casting process for producing casting in high volume with the lowest machining cost as mould is made from cost-effective material such as sand, moisture, binding agents such as clay and additives.
Environmental Impact: Processes such as sand casting have reduced environmental impact as sand can be reused again for making moulds and gating elements (pouring basin, sprue, runner, riser and ingates) from all casting processes can be reused again by re-melting them.
Complex Geometry and Shape: Casting produced from casting processes such as shell casting, investment casting, jewellery casting and ceramic casting process have the highest capability of producing complex shapes and geometry due to special moulding and pattern material.
Versatility: There is high flexibility in the casting process to choose pattern material, pattern design, mould material and mould type making this process very versatile.
Mass Production And Uniformity: The casting process such as the die casting process and investment casting process has uniformity in manufacturing even when it comes to producing casting in large volume.
Low Operator Cost: Dependency on labour skill reduces as casting processes such as die casting have become fully automized reducing the need to hire fully skilled operators.
Improved Safety: Pouring operation, casting ejection and casting removal operations have been made automated with advanced mechanical mechanisms, robotics and the use of sensors in casting machines improving the safety of the operator and promoting a safety culture in the foundry.
Casting Quality: Engineers can achieve excellent casting quality of components by providing better microstructure, uniform grain growth, reduced stress concentration, casting parts that are suitable for heat treatment, and have excellent metallurgical structure, and isotropic properties.
Casting Design: Thin sections, hollow sections, intricate design, complex casting, circular casting, large size casting, highly accurate casting, high surface finish texture casting and low weight high strength components. Customization of casting components can be easily done from geometry to the surface texture of the casting.
Casting Coating: Coating casting sections are possible by paint, corrosion resistance material, antique look coating and polishing.
Accuracy And Tolerance of Casting Parts: Tolerance and dimensional accuracy are achieved by casting processes such as the investment casting process, die casting process and shell moulding process is very superior. Consistency of geometrical tolerance is high in the casting process.
Production Cycle And Lead Time: Casting produced by this process has a lower lead time and the production rate for this process is better than machining the same components. As the production cycle and lead time are lower mass production of casting components is possible.
Casting Yield: Yield achieved by casting processes such as investment casting, die casting and shell casting process is better than any machining process for producing the same casting components.
Casting Size: Large-size castings can be easily reduced using the dry sand casting process and skin-dry sand casting process. Small-size casting can be produced using the green sand casting process. The uniformity of casting parts produced with consistency in this process is high.
Secondary Manufacturing Process: Casting produced from casting processes such as investment casting and shell casting requires fewer secondary manufacturing operations and machining reducing the overall cost, time and resources of manufacturing casting. Scrap produced from these casting processes is the lowest. The material efficiency of these casting processes is high as the wastage of metal is minimal.

Casting Process Disadvantages

What are the disadvantages of the casting process?

Secondary Manufacturing Process: All casting products produced by the casting process need secondary machining operation to active tight tolerance which cannot be achieved by the casting process alone.
Metal And Alloy Application Limitation: There is a limitation in using some metals such as ferrous metal which are high-temperature metals which do not give good casting when used with metal dies in the slush casting process, die casting process, gravity die casting process and permanent mould casting process.
Process Parameters: High control over process parameters such as solidification rate, solidification time, pouring temperature, pouring time and casting pressure is required to produce casting with high quality. Any disturbance in the casting process parameters results in defective casting.
Production Cost: Based on the volume of the casting the casting orders are taken keeping in mind the profit of the foundry as the order should justify the resources put in the casting process. For example for small-volume casting sand casting is preferred as compared to die casting where high-volume casting orders are preferred as the cost of manufacturing die is higher than sand mould.
Environmental Impact: For producing casting ingots need to be melted in a furnace to produce molten metal for pouring operation. Many furnaces still used are fired through coal and oil producing pollution and negative impact on the environment. Few casting processes such as the resin-sand casting process the sand cannot be reused easily as sand is used in the sand casting process.
Difficulty In Dimensional Tolerance And Accuracy: Not all casting can produce complex castings, A few selected casting processes such as investment casting, die casting process and shell casting process can produce casting with topmost accuracy and dimensional tolerance. For small batches, it becomes important to produce casting in sand casting and bear heavy machining costs if there is a limit on the production order from the manufacturer side.
Composite Casting: Very few casting processes such as the true centrifugal casting process, centrifuging casting process and sem-centrifugal casting process provide a facility to manufacture casting with composite casting sections which are not possible to produce using other casting processes.
Scap Rate And Remelting: Even if many casting processes have high yields still it becomes necessary to remelt the riser, pouring basin, sprue, runner and gate sections of the casting. Few casting processes such as slush casting, centrifugal casting and squeeze casting do not have complex casting sections but casting methods such as sand casting produce higher scrap that requires re-melting.
The durability of Mould And Pattern: The durability of sand mould is extremely low as compared to mould made from sand mould. Wood patterns and plastic patterns are subjected to changes in dimensions and wear over time due to environmental factors and continuous use.
Casting Design And Sections: It becomes difficult to produce casting with thin sections in a few casting processes without casting defects such as distortion, hot tears, coldshut and misrun casting defects.
Larger Floor Space: Few casting processes such as sand casting require more space for casting production as sand mould needs to be produced first then the casting process needs to be carried out in steps.
Resources Consumption: The casting process resources consumption process requires huge consumption of electricity, oil, coal, sand, additives, floor space, manpower, machines, dies, mould material, mould coating, highly trained engineers, safety equipment, inspection and testing equipment and other energy sources for producing.
Casting Defects: The inspection and casting testing department is responsible for inspecting the casting sections with defects. This process is prone to a few defects that cannot be completely eliminated such as porosity, pinhole, air inclusions and other gas defects. Continuous monitoring and control over the process parameters is required to manufacture defect-free casting.
Mechanical Properties: Casting sections once taken out from the sand/die/ceramic mould are not suitable to directly be used as an application. These casting process needs to go through heat treatment processes such as normalizing, hardening, annealing, carbonizing, nitriding, surface hardening and tempering.
Inspection, Maintenance, Repair, Service And Replacement: Casting moulds need to be continuously inspected, repaired, serviced, maintained and replaced to produce high-quality casting without defects. Die moulds need constant inspection to check for any change in the internal cavity surface due to thermal and shock impact induced during the casting process. Sand moulds need to be repaired and sure cavity is intact during the moulding process. This also adds to the running cost of the foundry.
High Initial Investment And Setup Cost: The casting process has a high initial investment cost for casting processes such as continuous casting, die casting and investment casting processes as die manufacturing requires high costs along with automated cooling and solidification processes system.

Casting Process Application

What are the applications of the casting process?

Automobile: Crankcase, piston, cylinder, clutch and brake components, gearbox, crankcase, housing and casing, mirror housing, radiator components, tesla body panels, alternator housing, battery housing, headlight brackets, muffler, exhaust pipes, exhaust manifolds, suspension parts, bearings, fuel pump and water pump casing, brake fluid reservoir, off-road and heavy-duty vehicle parts, door frames, car chassis, taillight brackets, disc and dump brake, brake and clutch pedal, fender and bumper brackets, and cylinder heads.
Medical Industry: The investment casting process is used to make tooth prosthetics, medical devices, surgical instruments, knee replacement parts, joints, x-ray machine housing and orthographic implants.
Construction Industry: Manhole covers made from sand casting, casting sections (I, L, T and C sections) made from continuous casting and interior decorative structures made from the slush casting process. Sewage and drainage parts are made from a true centrifugal casting process.
Railway Industry: Rail tracks are made from continuous casting, brake drums, ail engine blocks and engine blocks are made from die casting. Other components made from the casting process are seat frames, train brakes and couplings.
Hydraulic and Pneumatics Industry: Flow control valves, actuators, pipe fittings, supporting brackets, pistons, pneumatic brakes, throttle valves, hydraulic brake callipers, oil rig parts, piston covers, wind and gas turbine blades, fuel injectors, fuel tank connectors, impellers, pumps and compressor parts, cylinders and housings.
Statues, Figurative, Home Decor, Artefacts And Jewellery: Casting processes such as slush casting, jewellery casting and investment castings are used to produce antique-looking objects, artefacts, statues, jewellery, models, toys (cars, trains and spacecraft ), ornaments, pewters, decor, decorative bowls, ampulla, symbols and collectables.
Electrical And Electronic Components: Electrical brackets, transformer, ignition system and battery housing, electronic connects, switchgear, HVAC components, alternators, generators and electrical motor parts.
Foundry Pattern: Die blocks for die-casting processes are made from the sand-casting process. Parts of the furnace, crucible, complete ladles, pouring equipment, outer cover and casing of robot and material handling types of equipment.
Machine Manufacturing Industry: Bed, legs and supporting structure of the lathe machine, shaper machine, milling machine, surface finishing machine, grinding machine, drilling machine, planner machine, jigs and fixtures, hammers, punches, die and tools. Machines parts of food machine, muller machine blades, blender parts, knitting machine parts, agricultural parts, textile machine parts, spinning machine, skillet conveyor parts and heat exchanger components.
Marine And Ship Industry: Ship components, casting anchors, pumps, large ship propellers, submarine parts and ship engines.

Expandable And Non-Expandable Moulds In Casting Process

What are expandable and non-expandable (permanent) moulds?

Expandable moulds are moulds that are not made from metal but from other materials such as sand, sand-resin, ceramic and cement that can be broken easily to take the final casting out to produce solidified casting. Eg sand casting, investment casting and shell casting.

Whereas the permanent mould (non-expandable mould) is used to produce casting by not breaking the mould but by splitting the die metal mould and taking the solidified casting out of the metal mould. Eg. Continuous casting, die casting, slush casting and centrifugal casting.

I have explained both expandable and non-expandable permanent moulds below in detail.

Expandable Mould

What are expandable casting processes and which casting process uses expandable mould?

The expandable casting process is where moulds are always broken to take out the final casting after solidifying the final casting.

These moulds are made from sand, ceramic, cement and sand-resin combination.

The advantage of expandable moulds is that these moulding sand can be reused for making sand moulds again reducing the overall cost of manufacturing casting products.

Few processes use resin material with the combination of sand eg. shell casting, it becomes difficult to separate and reuse the sand material immediately. In this case, the resin is burned at a higher temperature to burn the resin so that the remaining sand can be reused.

Material such as ceramic and cement are difficult to reuse in the same manner as sand in the shell casting process and sand casting process.

Sand casting process- Sand moulds are used which are made from silica sand, clay and moisture.
Shell moulding or casting process- Shell moulds are made from ceramic moulds and broken to take out solidified casting.
Investment casting process- Moulds are made from ceramic material by dipping a pattern into the ceramic slurry and curing it further to make an accurate mould cavity.
Green sand casting process- This mould uses a combination of green sand, moisture and clay to produce green sand casting. Breaking green sand mould is easier than dry sand and skin-dried moulding process.
Dry sand casting process- The dry sand moulding process makes dry sand casting using fine dry sand that is free from moisture as the mould is dried in the oven and broken after the casting has solidified.
Skin-dried casting process- This process is used for producing skin-dried casting, mould is broken once the casting is solidified. Shake-out operation is easier than the dry-skin moulding process.
Lost form casting process- Sand moulds here are broken after the casting has solidified after the form has evaporated as it comes in contact with the molten metal.
Ceramic mould casting process- Ceramic moulds here are made from ceramic and broken after the casting has solidified in the mould cavity.

Permanent Mould or Non-Expandable Mould

Which is the expandable casting process and what casting process uses non-expandable mould or permanent mould?

The casting process uses permanent mould or non-expandable mould moulds that are made from metal dies such as cast iron, tool steel etc to produce high-quality surface finish casting.

Die casting process. (Split moulds are made of metal as molten metal is injected at high pressure)
Vacuum die casting process. (Vaccum moulds are made from metal and have a vacuum in them to reduce gas-related defects)
Squeeze casting process. (Both punch and die (mould) are made from metal to squeeze the casting between them)
Permanent mould casting process. (Metal moulds are clamped together rest of the process is similar to the sand casting process)
Strand casting process.
Continuous casting process. (Open-end moulds are used for continuously producing infinite casting)
Centrifugal casting process. (Rotating permanent metal moulds are used for producing solid circular hollow casting)

True centrifugal casting.
Semi-centrifugal casting process.
Centrifuging casting process.

Casting Process Conclusion

The casting process is a manufacturing process used to produce casting components for sectors such as automobile, marine, military, aerospace, mining, agriculture, petroleum, machinery production, medical and space industries in a factory called foundry.

The foundry consists of various departments such as the ingot melting section, casting production department, maintenance department, machining department, casting inspection department and testing department.

The selection of the casting process depends upon various factors such as size, shape, dimensional accuracy, tolerance, surface finish, counter, cost of production, final price of casting, quality of casting, defects tolerance in casting, volume of casting and final application of casting products.

The casting processes used for producing casting are sand casting process, slush casting process, permanent mould casting process, die casting process, shell casting process, investment casting process, vacuum die casting process, gravity die casting process, green, skin-dry and dry sand casting process, continuous casting process, centrifugal casting process and squeeze casting process.

Almost all casting processes have a few operations in common such as pouring operation, solidification operation, shakeout or ejection operation and finishing operations.

Early there was only one process, the sand casting process, but as the need for mass production with high tolerance increased, the die casting process was invented.

In the die-casting process, metal is injected from low to high pressure into a metal die allowing the metal to solidify uniformly in the die cavity and ejecting the solidified casting out of the die mould.

The squeeze casting process is used to produce casting with higher mechanical properties having both casting process and forging properties. In the squeezing operation the molten/liquid metal is poured into the die and pressure is applied using a punch allowing the metal to solidify uniformly between the die and punch.

The sand casting process produces casting from small size (green sand casting) to large size (skin-dry casting) in smaller volumes in a mould made from sand and cavity produced in sand using various patterns.

The centrifugal casting process produces hollow sections in closed die mould with uniform dense material characteristics having longer casting (true centrifugal casting) and complex sections (semi-centrifugal and centrifuging casting process).

The slush casting process produces casting in permanent die moulds that are lightweight, hollow, aesthetically appealing, shiny and decorative in nature but the products do not have sufficient engineering strength and mechanical properties.

The vacuum die casting process can produce casting without any gas defects such as porosity, blowholes, pinhole defects, gas inclusions gas pockets as these products manufactured in vacuum casting are solidified in the closed die mould.

The shell casting process produces casting with high tolerance and complex dimensional accuracy as compared to the sand casting process using ceramic shell mould and metal pattern.

The investment casting process used the wax pattern to produce ceramic mould to manufacture high dimensional accurate casting with better surface finish than the sand casting process.

The production order for manufacturing casting components depends upon the volume of casting that is to be produced as order should justify the profit of the plant.

What Is Casting Process | Types of Casting Process | Classifications | Diagram | Applications | Advantages | Disadvantages | Mechgrace |