Home > Products > Casting > Sand Casting

Sand Casting

Why Choose Us

Custom Solutions

Offers personalized services to meet unique client specifications and demands.

Quality Control

Strict adherence to quality management systems to ensure consistent product quality and reliability.

Experienced Professionals

A team of skilled engineers and technicians with extensive experience in the metal industry.

Competitive Pricing

Provides cost-effective solutions without sacrificing product quality or service.

First 12 3 4 5 6 7 Last 1/22

The 6-Step Process of Sand Casting

01/

Place Mold Pattern in Sand
The first step of sand casting involves the placement of the mold pattern in sand. The size and shape of the casting is directly influenced by the mold. Therefore, manufacturing companies must create new molds to create metal products and components in specific sizes and shape.

02/

Set Up the Gating System
Most casting processes involve the use of a gating system, and sand casting is no exception. Consisting of a pouring cup and tunnels or “gates” to the mold, it’s used to funnel the molten mold into the mold cavity. After placing the mold pattern in sand, manufacturing companies will set up a gating system such as this.

03/

Remove the Mold Pattern
With the gating system set up, manufacturing companies can then remove the mold pattern from the sand. The mold pattern is no longer relevant at this point. When the mold pattern is placed inside sand, the sand takes its shape. As a result, the mold pattern can be removed.

04/

Pour Molten Metal Into Mold Cavity
Now it’s time to pour the molten metal into the mold cavity. Sand casting supports a variety of different metals and alloys, some of which include iron, steel, aluminum, bronze, magnesium, zinc and tin. Depending on the specific metal or alloy used, manufacturing companies may need to heat it up to 3,000 degrees Fahrenheit. Once the metal or alloy has turned from a solid state to a liquid state, it’s poured into the mold cavity.

05/

Wait for Metal to Cool
After the molten metal has been poured into the mold cavity, manufacturing companies must wait for it to cool. Again, different types of metal take different lengths of time to cool. As the molten metal cools, it will revert from a liquid state back to a solid state.

06/

Break Open Mold to Remove the Metal Casting
The sixth and final step of sand casting involves breaking open the mold to remove the newly created metal casting. While molds patterns are typically reusable, the actual molds are not.

Advantages Of Prototype Casting

Design Flexibility - Sand casting is excellent for prototypes and jobs that might require flexibility in both size and weight. The only size and weight restrictions are the amounts of materials available and the size of the foundry.

Shape Complexity - Sand casting, while being flexible in both size and weight, is also flexible in the sense that it can be used to create prototypes of varying complexities. No other casting process allows for such a great number of complex shape components.

Large Material Choice - Another benefit of sand casting is the ability to use a number of different casting materials. As long as the alloy can be melted, it can be used to create products with sand casting.

Low-Cost Tooling - Tooling and equipment costs are generally much lower than the costs associated with other metal manufacturing processes. This makes sand casting one of the cheapest methods.

Short Lead Times - Sand casting allows for quick turnarounds in production — making it one of the fastest forms of casting.

Sand Casting Those Key Elements

Draft Angle - The draft angle is the angle that is applied to all vertical faces of the design to aid in removing the product from the sand mold cleanly and easily. This angle will be different from project to project, meaning that it is important to find an experienced foundry to sand cast your prototype.

Parting Line - A parting line is exactly what it sounds like — a line that separates the draft angles that change direction. The parting line is an important consideration in sand casting because it can drastically affect the price of the cast.

Undercuts and Cores - Undercuts are the part of the sand cast that prevents the design from being removed during the mold making stage. The use of loose core sand pieces can increase the cost and timeline of production — meaning that an early parting line should be used to prevent undercuts.

Cross Sections - Also known as uniform wall thickness, cross sections are support sections for the cast that are usually preferred to be thicker, but they can be infeasible, as larger masses of molten material will take longer to cool and harden.

Wall Thickness - Wall thickness is an important consideration in sand casting because an improper volume to surface area ratio can cause cavities and integral failures in the mold.

Corners and Angles - Corners and angles are cooling characteristics of the sand cast that have a major influence on the quality of the finished prototype. Sharp angles can cause localized heat spots that can degrade the overall quality of the casted prototype.

Junction Design - Junction design refers to the places where two different parts of the cast meet at an angle. There are five junction types (L, X, V, Y, & X-T) and they should be carefully placed to minimize the risk of shrinkage and tears in the cooling cast.

Casting Allowances - Casting allowances is the size that metal will shrink when it is solidifying. Each material will shrink differently, so it is important to consider what metal is being used in the casting process before engineering the sand mold.

How Does Sand Casting Work?

The sand cast molding process includes several steps. The sand casting process starts with the creation of a mold pattern and a gate system. Each pattern requires a new mold designed to the exact size and shape of the intended part. The setup also requires a two-part casting flask, referred to as cope and drag.

The mold pattern is placed in sand and the gate system is set up with a series of tunnels, a pouring cup, and a sprue. After packing sand around the pattern, the pattern is removed, leaving a mold cavity.

Metal is then heated to a high temperature, turning the metal into a liquid state also known as molten metal. The temperature needed to melt the metal depends on the alloy. Some metal takes longer to heat.

The molten metal is poured into the mold cavity. After the metal is poured into the mold, the metal starts to cool and solidify. To remove the part, the sand mold is separated along a parting line. During this process, the mold cavities are destroyed. However, the mold pattern is typically reusable.

Types Of Sand In The Sand Casting Process

Green sand
Green sand contains sand (75% to 85%), clay (5% to 11%), water (2% to 4%) and other additives. Clay and water act as a binding agent. Sand itself is not green, its water content is the reason for its "green" label.
Green sand for casting is suitable for mass production and can be reused after casting. However, green sand casting is not suitable for designs with tight tolerances, and sand cast parts require secondary finishing.

Dry sand
The dry sand contains clay or other binding agents, is shaped into molds and baked. This sand is suitable for ferrous and non-ferrous metal parts with complex designs and tight tolerances. Therefore, it is widely used in several sand casting foundries that manufacture parts such as engine blocks and gearboxes. Dry sand, while popular, is not reusable.

Resin sand
Resin sand or furan sand is a mixture of silica sand or other aggregate material and a synthetic resin binder that creates stable and strong molds for sand casting metal parts. Resin sand is stronger and has better dimensional stability, making it better suited for making parts that require precise consistency. In addition, it has a shorter curing time, does not require secondary finishing due to fewer surface defects, and the mold is less susceptible to deformation when pouring molten material.

Water glass
This type of casting sand uses a sodium silicate binder to integrate the sand to form the mold. Therefore, it is preferred for parts with complex and delicate patterns. Molds made from water glass are less flexible in use and handling, but are dimensionally stable, inexpensive, and require shorter curing times.

Core sand
This is a mixture of silica sand, a core oil like mineral oil or linseed oil, and a binder like dextrin and sodium silicate. Due to its compressive strength, it is suitable for the manufacture of core materials.

Loam sand
This molding sand contains water and equal parts sand and clay. Suitable for manufacturing large and heavy metal parts. Examples include hoppers and turbine components.

Eight Steps of the Traditional Sand Casting

Drawing Design Sand Casting Aluminum Parts

Sand Casting Grey Iron Automotive Spare Parts

Sand Casting Pump Stainless Steel Spare Parts

Sand Mixing: To begin with, you should prepare several kinds of sand needed. And then a sand mixer comes to show its value or role. With a sand mixer, you could fully mingle the appropriate amounts of clay with the several kinds of sand.

Mold Making: In accordance with the drawing design, the production of the mold and core box can be available. In the current market, the majority of mold can be manufactured with the engraving machines. That greatly lessens the period of production to 2 to 10 days.

Modeling or Core Making: The modeling is a crucial link in the process of casting. Detailly dividing, this step has small three links, namely Modeling ( making a cavity of the casting from molding sand ); Core-Making ( doing the interior shape of the casting ); Mold Matching ( placing the core into the cavity, simultaneously closing the upper and lower sandboxes).

Melting: To begin with, you should calculate the reasonable mixing proportion of the required materials. Next, you could choose a suitable melting furnace to process the material. Finally, the desired metal liquid can be available. It must be noted that mixing proportion and temperature must be under accurate control. Considering the eco-friendly factor, It is only the cupola or electric furnace that serves as the optimum container to deal with the materials. Nowadays, the electric furnaces take up the market, with the cupolas gradually banned.

Pouring: To pour the metal liquid of the electric furnace into the mold by resorting to using a ladle. There is a kind warning that such deed is of risk, so pay attention to safety!

Cleaning: After pouring, there needs a span of time to wait for the molten metal to congeal. Next, removing the gate with a hammer and shaking off the sand on the casting. And then using the sandblaster to carefully processing the sand in the narrow split. In this way, the casting surface will be very clean.

Casting Processing: After the cleaning process, it is inevitable that there are some casting can’t reach the standard. In such a case, simple processing may be required. Commonly, the technician will seek to apply a grinding wheel or a polishing machine to remove burrs, making the casting surface smoother.

Casting Inspection: Generally speaking, some unqualified castings have already been found in the stage of cleaning. However, there are some castings needed to be tested in the practical application. For example, according to the standard, one casting must capable to let a 5 cm shaft pass through its center hole. In this case, you should fetch a 5 cm shaft to have a try.

Common materials for sand casting

Sand casting is compatible with a wide range of materials; however, this is more common with metals. Choosing the right material depends on casting performance, output, etc. The most commonly used materials for sand casting include:

Aluminum material
Aluminum material is one of the most common sand casting materials due to its mechanical properties. It has a high strength-to-weight ratio, low density, corrosion resistance, and good castability. Common aluminum sand casting alloys include ADC12, AL6061 and A356. Sand casting aluminum involves the use of base sands such as silicochromite and clinker.

Bronze
Bronze is an alloy of copper and tin, commonly used as a sand casting material. Sand cast bronze depends on its different alloys, depending on the percentages of copper and tin or the presence of other elements such as aluminum, zinc, nickel and iron.

Brass
Brass is an alloy of copper and zinc, known for its resistance to rust and corrosion due to its elemental content. Additionally, it does not contain any iron or iron oxide. Brass has good electrical conductivity and tensile strength. Therefore, it is a very popular sand casting material for parts requiring such properties.

Zinc
Zinc is a strong material with high stiffness, corrosion resistance and castability. Additionally, its strength and hardness make it easy to create thinner-walled parts when alloyed. Sand casting zinc is easier than aluminum.

Lead
Lead was one of the most popular sand casting materials among the Romans. It is heavy and corrosion resistant. However, it poses some health risks, so they need to be used under strict conditions. However, it is suitable for manufacturing small to medium-sized parts such as pipe fittings.

Copper
Copper is an expensive, tensile-strength, and heavy material known for its electrical and thermal conductivity. Since it does not rust and is highly castable, it is suitable for making sand castings such as pipe fittings.

Iron
Iron is common in sand casting due to its fluidity and low volume/linear shrinkage. However, its mechanical properties are poor, that is, high compressive strength and low tensile strength, so it is suitable for parts with complex shapes or asymmetric structures. For example, gray iron castings have excellent castability and machinability, ductile iron castings have good fluidity and large shrinkage, and malleable iron castings have excellent ductility, machinability, toughness and corrosion resistance.

Low-carbon steel
Mild steel has a low carbon content (0.15% to 0.30%) and therefore is highly ductile and malleable. Common due to its low cost and ease of casting. However, pores, shrinkage and cracks make processing the material difficult.

Stainless steel
Stainless steel's corrosion resistance, durability, and strength make it popular for sand casting. In addition, it has a low coefficient of thermal expansion, improving its accuracy, high tolerances and dimensional stability. However, it is an expensive metal and its high strength and stiffness make demoulding parts from sand casting molds difficult.

Typical applications of sand casting

Sand casting is an ancient manufacturing method that is still relevant in today's manufacturing industry. Typical applications of this technology include:

Automobile industry
Sand casting is a common method used by the automotive industry to manufacture complex designed automotive parts. Sand cast products for the automotive industry include engine blocks and transmission housings.

Aerospace industry
Sand casting is also popular in the aerospace sector, often used to manufacture aircraft engine components and structural parts that require strength and precision, such as turbine blades, casings, brackets and fittings.

construction

Common sand casting products in the construction industry include pipe fittings, manhole covers, etc. Sand casting ensures the production of a durable and strong product, ensuring a long life in construction applications.

Hardware

Sand casting is suitable for manufacturing parts for pipeline applications. These include valve bodies, pipe connectors and fittings.

metal work

The sand casting process is commonly used in metal product manufacturing around the world. This includes swords, pots, tripods, etc. While other manufacturing methods have replaced sand casting, its cost-effectiveness and high-volume production continue to make it more suitable.

Our Factory

We have more than 20 years of experience in manufacturing and trading services, providing the parts of auto, power equipment, feed processing equipment, shipbuilding pumps and valves, agricultural machinery, construction machinery, general equipment and other industries. Main customers include Siemens/CPM/Hitachi Zosen/John Deere/Robert Bosch/TVH/Danfoss/YAMAHA, etc.

FAQ

Q: What Is Sand Casting?

A: Sand casting is a commonly employed and very ancient metal casting technique. It involves forming cavities within packed and bonded sand that is then charged with molten metal. The chosen metal solidifies to reproduce the cavity shape in fine detail. The most common technique uses a pair of boxes into which is packed the sand, to form two sides of a cavity. It is also common to cast into an open depression in sand, for a flat-backed result.

Q: Why should you choose sand casting?

A: While sand casting is one of the oldest production processes, modern sand casting uses technology to optimise the entire process; from initial enquiry stage through to production and inspection. Data-driven science has evolved sand casting massively in just the last 20 years, delivering a process that can achieve the complex castings needed to meet global 21st century challenges.

Q: What are the advantages of sand casting?

A: Sand casting is a reliable, relatively quick and cost effective casting process, allowing highly complex parts to be created in almost any size, weight or alloy, and at low cost compared to other methods. It's a powerful process for prototyping. Sand casting is also a sustainably manufacturing process – it’s almost 100% circular.

Q: How can sand casting optimise part properties and function?

A: Sand castings allows for flexibility and optimisation across the entire production process. This includes:
Optimising materials used (both in the sand for moulds and the ability to create bespoke alloys)
The casting process method chosen
Finishing methods
Validation methods chosen

Q: What shapes can be made with sand casting?

A: Sand casting is suitable for complex and simple net shape forms, limited only by the pattern produced. The ability to cast large parts in a single piece provides opportunities for future automotive applications, allowing drastic part reduction and lightweighting.

Q: How fast is the casting process?

A: Additional finishing with machining is usually required after casting, but the lead times are short compared to other methods (any company supplying Formula 1 with just two weeks between races must be able to turn round design changes very quickly!).

Q: What applications use the sand casting process?

A: The flexibility of a manual assembly process and the fact that tooling board can be machined quickly mean that sand casting has a fast turnaround. This makes it suitable for low quantities- particularly prototyping and low volume series production.

Q: What process considerations are needed in sand casting?

A: Old fashioned casting techniques used to cause porosity and mis-runs, but these are much reduced with today's simulation technology. The process is tremendously versatile. Consideration needs to be given to dimensional tolerancing and the ability to generate fine detail. Good method and process design is required to put the right material properties in the right places.

Q: How many times can a sand cast be used?

A: A sand mold can only be used once, because the mold must be broken apart to remove the casting. However, the sand itself may be used many times over before being discarded.

Q: What are the basic requirements of sand casting?

A: There are four main components for making a sand casting mold: base sand, a binder, additives, and a parting compound.

Q: What are the 4 stages of sand casting?

A: Sand casting involves four basic steps: assemble the sand mold, pour liquid metal into the mold, allow the metal to cool, then break away the sand and remove the casting.

Q: Does sand casting use a permanent mold?

A: As we previously said, sand casting needs a new mold for each part that is produced – increasing your costs and cycle time. Permanent mold counters this by employing molds that have a lifespan of 100,000+ parts. Reusing the same mold shortens cycle time and reduces cost.

Q: Do sand castings need draft?

A: Draft, and Why It's Needed
In sand casting a draft angle reduces the tendency of sand particles to come free as the pattern is lifted out. Typical draft angles are 1.5°. Die casting also uses draft angles, albeit smaller than those used in sand casting, to help eject the cast part.

Q: Does sand casting require machining?

A: In order to get a casting into its final state it will almost certainly need to be machined. Machining offers a much finer degree of control over part dimensions and surface finish. This can include areas of the casting which join with other components, or have specific performance requirements.

Q: What is the minimum wall thickness for sand casting?

A: The sand casting process involves pouring molten zinc, aluminium or copper into a sand mould. The designer should take into account the limitations of the sand casting process such as low casting rates, a 3-5mm minimum wall thickness, poor linear tolerance (e.g. 4mm/m.)

Q: How accurate is sand casting?

A: The level of accuracy produced with sand casting is generally lower than with other methods. The products yielded from this process, including aluminum casting with the sand casting method, also tend to have a comparatively rougher surface finish.

Q: How do you harden casting sand?

A: Self-hardening: when adding sand, add binder and hardener. In this way, the sand mold or core will harden by itself after it is made. 2）Gas mist hardening: no hardener is added during sand mixing. After modeling or core making, gaseous hardener or atomized liquid hardener is blown in.

Q: How big can a sand casting be?

A: Versatile – Size, Weight, Shape:
Sand castings can be produced in weights from ounces to 200+ tons. Through the use of cores, internal structures can be cast in place. Shaped parts rely mainly on the imagination of the designer.

Q: What is better than sand casting?

A: For producing complex, small-to-medium-sized parts with high dimensional accuracy and a smooth surface finish, die casting is a clear winner. If a fast turnaround, a restrictive budget, or very large-sized parts define your project, then sand casting could be more suitable.

Q: How many types of sand casting are there?

A: Sand casting is a popular method of producing non-ferrous alloy casts. This process was invented over 6,000 years ago and continues to undergo modernization. There are three types of sand used in casting, green sand, water glass or sodium silicate, and resin sand.

We're professional sand casting manufacturers and suppliers in China, specialized in producing customized products made in China. We warmly welcome you to buy or wholesale quality sand casting with ISO9001, TS16949, ISO14001 certificates from our factory.