Pros and Cons of 5 Casting Processes: Sand, Permanent Mold, Die, Investment, and Lost Foam

With so many casting processes, it can be hard to decide which one to use. Therefore, it is important to understand each option and how it relates to production costs, production volume, casting size, tolerance, surface finish, complexity and more.

If you are looking for more details, kindly visit our website.

Compare and contrast with us the 5 main casting processes (sand casting, permanent mold, die casting, investment casting, and lost foam casting), so you can make your decision based on the facts.

Casting Methods Cheat Sheet

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#1 Sand Casting

Sand casting is one of the most common casting processes. In this process, molten metal is poured into a mold made of compacted sand.

Advantages

• Design flexibility (complexity and size)
• Low cost tooling
• Short lead time

Disadvantages

• Single-use mold
• Poor surface finish and accuracy
• Prone to shrinkage and porosity, leading to low material strength

There are 4 specific  types of sand-casting processes, each with their own advantages and disadvantages: green sand, nobake, coldbox, and shell.

1. Green Sand

Green sand is the most common sand-casting process. Its components include sand, clay, water, and other additives.

A benefit of green sand casting is that it can be used for high volume or short/prototype runs. It is cost effective for many metal applications.

However, green sand casting cannot hold as tight of dimensional tolerances and surface finishes as other processes. Therefore, it typically requires more machining to reach the final dimensions and surface finish than other processes.

2. Nobake

This process involves a simple sand and resin mixture that cures at room temperature through a chemical reaction.

Benefits of the nobake process include good dimensional control, uniform strength, and size flexibility.

Unfortunately, the nobake sand mixture has a limited shelf life and you must be conscious of the sand temperature during the process. Overall, this process can be very costly.

3. Coldbox

This resin process cures at room temperature, using a gas or vapor catalyst.

Coldbox sand casting can achieve complex parts with low labor and energy costs.

However, this process is limited to small and medium sizes. The core box design is an important factor. It is also only cost efficient in high volumes.

4. Shell

This resin coated sand process requires heat to cure.

Benefits of shell sand casting include high dimensional tolerances and surface finish, opportunity for complexity, and a long shelf life.

Yet, shell sand casting is only available for small to medium sized parts. It requires metal tooling, making it only cost efficient in high volumes.

#2 Permanent Mold

The permanent mold process is our specialty. It involves pouring nonferrous alloys into a preheated, reusable steel mold. The steel mold is prepared with a coating that prevents sticking and lengthens mold life.

Permanent mold foundries are typically cleaner than sand casting facilities because they do not involve loose sand.

Different pouring methods can be used in permanent mold that impact the success of your part: static standard/gravity pour, tilt pour, and reverse tilt pour. To learn more about permanent mold pouring methods, watch this short video:

Advantages

• Stronger and less porous than sand casting or die casting
• Good surface finish/texture control
• Long reusable mold life
• Good dimensional accuracy &#; high precision
• Good for moderate to high volume production
• Relatively quick cycle time
• Can use sand cores, making it semi-permanent mold
• Fine grain structure

Disadvantages

• Higher tooling costs
• Not cost effective for low volume production
• Size limitations
• Parting lines (can be removed by machining/polishing)

#3 Die Casting

Die casting is similar to permanent mold casting. Die casting also involves a steel mold but uses pressure to inject molten nonferrous metals.

Advantages

• High accuracy and complexity
• Design flexibility
• Good surface finish
• Quick production rate
• Good for high volume production

Disadvantages

• Highest tooling costs
• Size limitations
• Can only use low melting point alloys
• Parting lines

If you&#;re annually running tens or hundreds of thousands of parts, like an automotive company, you&#;re going to want to go with die casting.

#4 Investment Casting

Investment casting uses a wax (or thermoplastic) pattern that is layered in slurry and stucco to form a shell. The wax is melted out of the shell, the now hallow shell is cured, and the metal is poured while the ceramic shell is still hot.

Advantages

• Achieve complex shapes and details
• High surface finish and accuracy &#; No flash or parting lines
• Near net shape &#; Little to no machining required
• Can be the most expensive casting method
• Limitless in terms of alloy choices

Disadvantage

• Lengthy process
• High manual labor
• High piece price
• Size and handling limitations

#5 Lost Foam Casting

In the lost foam casting process, the part or clusters of parts are coated in a slurry and sand. They are vibrated to create a compact mold. When the molten metal is poured, the pattern evaporates, eliminating the need for cores.

Advantages

• Design freedom
• Near net shape
• Low tool wear

Disadvantages

• Not cost effective for low volume production
• Large initial die cost
• Porosity
• Pattern weakness
• Pattern are not reusable, so require a pattern for each part
• Metal tooling required for pattern making
• Few suppliers

BONUS: #6 Stamping

Metal stamping is a common alternative to casting. It is best for simple parts, as it involves using high pressure to shape a sheet of metal into your desired part.

Advantages

• Cost effective
• Quick production time
• Great tolerance and surface finish
• High volume capacity

Disadvantages

• Lack of design flexibility in terms of shape and thickness
• Not for highly complex parts
• Produces lots of waste
• High tool cost

Choose the Best Method for Your Next Casting

To kick start your next project, we have many allies in the casting business. We are happy to look at your next project and help decide what casting process is right for you.

Give us a call at (812) 537- or you can us at

Posted on: 04-10-

DETAILED COMPARISON of SHELL MOULDING vs SAND CASTING 

Two of the most common casting techniques are shell moulding and sand casting. Both methods have their own unique advantages and applications. In this article, we&#;ll take a closer look at the key differences between shell moulding and sand casting. We&#;ll explore the manufacturing process, material compatibility, surface finish, and other important factors to help you determine which approach is best suited for your metal casting needs.  

Shell Moulding: A Modern Technique

 

Shell moulding is a relatively new casting technique developed in Germany in the mid-20th century. It involves creating a mould from a thin shell of sand and resin, which is then heated to form a hard, durable mould. This method is known for its precision and ability to produce complex shapes with fine details. 

The Shell Moulding Process

 

1. Tooling production

   : the process begins with creating a cast iron tool, machined to precise dimensions.

    

2. Mounting and heating

   : the tool is mounted in a machine and heated.

    

3. Filling with resin sand

   : the heated tool is filled with resin-coated sand, which hardens upon heating.

    

4. Shell removal

   : the hardened shell is removed from the tool.

    

5. Assembly

   : two shell halves are glued together to form a complete mould.

    

6. Support and casting

   : the assembled shells are placed in a steel box and supported with fine sand before molten metal is poured in.

    

7. Finishing

   : after cooling, the shell is removed, and the casting is cleaned and finished.

    

Sand Casting: A Traditional Approach

 

Sand casting, on the other hand, is a more traditional method that has been used for centuries. It involves creating a mould from sand, which is then filled with molten metal. This method is versatile and can be used for both small and large-scale production. 

The Sand Casting Process

 

1. Tooling production

   : similar to shell moulding, the process starts with creating a tool, often from aluminium or wood.

    

2. Mould creation

   : half of the tool is placed in a steel box and filled with sand, which is then compacted. 

   Link to Yitai

    

3. Cavity formation

   : the tool is removed, leaving a cavity in the sand. 

    

4. This is repeated for the second half of the tool.

    

5. Core placement

   : if needed, a core is placed in the cavity to create more complex sections.

    

6. Assembly

   : The two boxes are assembled.

    

7. Casting

   : molten metal is poured into the mould.

    

8. Finishing

   : after cooling, the sand mould is removed, and the casting is cleaned and finished.

    

Comparing Shell Moulding and Sand Casting

 

• Environmental impact

  : shell moulding is more environmentally friendly due to less use of moulding and binding materials therefor less pollution.

   

• Complexity

  : sand casting allows for more complex designs due to its flexibility in mould creation.

   

• Precision

  : shell moulding offers tighter tolerances and smoother surfaces.

   

• Material suitability

  : sand casting is better suited for high melting point materials like steel and stainless steel.

   

• Production speed

  : shell moulding is faster, taking about 10 minutes per shell compared to 20-30 minutes for sand casting.

   

Applications

 

• Offshore industry

  : prefers sand casting for large, single-off parts.

   

• Equipment manufacturing:

  often uses shell moulding for its precision and ability to handle thin walls.

   

• Agricultural and machine building

  : utilise both methods depending on the specific requirements of the parts.

   

Conclusion

 

Both shell moulding and sand casting have their unique advantages and applications. The choice between the two depends on factors such as part complexity, material, production volume, and cost considerations. As technology advances, these casting methods continue to evolve, offering even greater precision and efficiency. 

For more detailed information or to discuss which method would be best for your casting needs, please reach out to your ELCEE contact person. We&#;re here to assist you in navigating the complexities of casting and ensure you achieve the best results for your projects. 

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