Sand casting and die casting are the two most widely used casting processes. Comparing the two according to information such as material, casting complexity, performance requirements, order size, etc., and choosing the right process can efficiently complete the order and save more costs. This article will make a detailed comparison of the two from the definition, history, molds used, castable materials, processes, costs, and the performance of the corresponding castings, whether heat treatment can be performed, and applications so that you can choose a more suitable process and find a supplier that suits you.

Compare from Meaning:

Sand casting is a process in which sand is bonded with a binder to make a mold with a cavity inside. Liquid metal flows into the cavity along the gate under the action of gravity, and parts are obtained after cooling and finishing.

Die casting is a process in which a special metal material is used to make a metal mold and liquid metal is injected into the cavity under the action of high pressure, and parts with higher precision are obtained after cooling.

Compare from Culture:

Sand casting has a history of thousands of years. In the earliest days, the binder was clay and the sand was silica sand, which is still in use today. Now, a variety of binders such as natural resin, synthetic resin, silica sol, water glass, quartz sand, corundum sand, limestone sand, zircon sand, chromite sand, etc. have been developed. Sand casting is still one of the most widely used casting processes in casting.

Die casting began in 1838. It was originally used to make molds for movable type printing. At that time, the main material was lead. In 1966, General Motors invented the precision die-casting process.

Compare from Types:

Both processes have different classification methods and names after classification. Below we will compare the two processes in terms of types.

Types of Sand Casting:

The classification method of sand casting is mainly based on the binder and the precision of the casting.

Green sand casting 

is a process in which clay containing a certain amount of water is mixed with sand as a binder to make a mold and complete the casting.

Resin sand casting 

is a process in which synthetic resin or natural resin is mixed with sand as a binder to make a mold. The precision of castings produced by this process is very high.

Water glass sand casting, 

water glass is an aqueous solution of polysilicate. It is used as a binder to make a mold. The precision of parts produced by water glass casting is also relatively high.

Types of Die Casting:

The classification of die casting is mainly based on the pressure during injection and the type of die casting machine.

Low-pressure die casting, 

the die casting pressure is about 20-100 kPa (2.9-14.5 psi), rather than gravity to fill the mold.

High-pressure die casting 

is a process of injecting liquid metal into the cavity at a speed of 30-80m/s at a pressure of 40-120MPa to complete the production of castings.

Cold chamber die casting 

is more suitable for producing low-melting-point non-ferrous alloy parts such as zinc and lead.

Hot chamber die casting 

is suitable for die casting aluminum, zinc, lead, and other low-melting-point metals.

Compare from Molds:

The two casting molds have huge differences due to the process. The following will compare them from the two aspects of material and production.

Mold Materials and Composition:

Die casting molds

are mostly produced with high-temperature and high-pressure resistant hot working die steel H13. The mold components include fixed mold and movable mold, guide parts, ejection structure, lateral core pulling mechanism, overflow system, and supporting parts.

Sand casting molds

are made of the above sand and a binder to make a sand mold and a sand core and assemble it into a casting mold. When making the sand mold, a model of the casting will be used. The material of this model can be wood, metal, plastic, etc. The mold consists of two parts: the sand mold and the sand core.

Mold Making and Cost

The manufacturing of die-casting molds is very complicated, but a set of molds can be used for a very long time under correct use and maintenance. It will be very cost-effective if the cost is calculated from a long-term perspective, but it will be very uneconomical if a mold is produced for a small batch of orders.

The manufacturing of sand casting molds will be much simpler, but each mold will be disassembled after the production is completed through the sand dropping process and then processed and reassembled.

There are two types of casting manufacturing processes: manual molding and mechanical molding:

Mechanical molding can be automated, which can greatly improve the production efficiency of castings. Its production efficiency is too high, so it is more suitable for the production of large batch orders.

Manual molding is more suitable for the production of small batch orders or large batch orders with long delivery cycles.

Compare from Process

Both processes cast liquid metal into metal castings with specific shapes and properties, but they are very different in details. Let's compare their processes below.

Sand Casting Process

1. Manufacture casting models according to drawings or samples.

2. Split the model into a part for making sand molds and a part for making sand cores.

3. Manufacture sand molds and sand cores separately.

4. Assemble the sand mold and sand core to obtain a casting with a gate.

5. Heat the metal to a molten state.

6. Pour the molten metal into the casting along the gate.

7. After cooling, drop the sand and clean it.

8. Perform finishing on the casting such as machining, heat treatment, surface treatment, etc.

9. Get the final casting

Die Casting Process

1. Manufacture die casting molds according to drawings or samples.

2. Install the die casting mold on the die casting machine.

3. Overall debugging of the die casting machine.

4. Preheat the die casting machine.

5. Heat the metal to a molten state.

6. Close the mold.

7. Press the metal into the cavity under high pressure.

8. Cooling post-processing.

9. Perform finishing on the casting, such as machining and surface treatment.

10. Get the final casting.

The differences are:

Die casting requires a die casting machine for production. Sand casting does not need it, but if sand casting is equipped with an automatic pouring machine, it will have higher production efficiency.

Die casting requires high pressure to complete the cavity filling, while sand casting only needs gravity.

The die casting process is more complicated, while sand casting is simpler.

Compare from Casting Parts Materials:

The two castings have their own suitable materials.

Sand Casting Parts Materials

Sand casting can be used to produce castings made of metals such as iron, steel, copper, aluminum, and zinc.

Die Casting Parts Materials

Die casting can be used to produce die castings made of die casting aluminum ADC10, ADC12, ADC3, A380, A383, A360 and other die casting aluminum alloys and zinc alloys such as low melting point metals.

Compare from Products

The process is for the final product. The purpose of our comparison is to select which one is more suitable for your product. To this end, we can choose from four aspects: product tolerance, structure, surface quality, and when heat treatment is needed.

Die Casting Parts

Tolerance

The dimensions of die castings are more accurate, and even some castings with strict requirements can be used directly. Of course, if it is a die casting that requires a tolerance of less than 1μm, it still needs to be processed. When designing the mold for the casting that needs to be processed, the machining allowance needs to be calculated.

Structure

Die casting can complete very complex castings in one go.

Surface

The relative surface of the die casting is smooth. Basically, no surface processing is required. If the surface requirements are strict, polishing is required.

Die castings can be subjected to surface treatments such as powder spraying, electrophoresis, and electroplating, but cannot be anodized.

Heat Treatment

Die castings cannot be heat treated. This is because there are high-pressure pores inside. After heating, the casting becomes soft and the pores expand, which will cause the casting to deform or damage.

Sand Casting Parts

Tolerance

The dimensions of castings are not as precise as die castings, so for castings with strict tolerance requirements, it is necessary to directly reserve machining allowances when designing the mold to facilitate CNC machining.

Structure

Some sand casting processes can only complete castings with relatively simple structures. Water glass sand casting, resin sand casting and coated sand casting can produce more complex castings.

Surface

The surface of sand castings is not as smooth as that of die castings. Compared with the classification of sand casting itself, the surface roughness of castings is coated sand casting ≈ resin sand casting > water glass sand casting > clay sand casting. Sand castings are often used for castings with less stringent surface requirements.

Heat Treatment

Sand castings can be heat treated to increase their performance. Common methods are:

Annealing:

Normalizing:

Quenching:

Homogenization treatment:

Tempering:

Solution treatment:

Precipitation hardening:

Stress relief:

Dehydrogenation treatment:

If you want to learn more about heat treatment, you can click to view our other article on heat treatment.

Compare from Application

Die casting is mainly used to produce metal castings with low melting points, such as aluminum, magnesium, zinc, lead, etc. Sand casting can be used to produce metal castings of most materials, such as aluminum, iron, copper, steel, etc. The following is a comparison of their applications in various industries:

Die casting:

Automotive industry:

Automobile manufacturing is one of the largest application areas of die casting. Since automotive parts require high strength, durability and light weight, die-cast aluminum alloy and magnesium alloy parts are widely used in key components such as engines, gearbox housings, radiators, and wheels.

Electronic and electrical industry

The die casting process is used to produce the housings and internal parts of products such as mobile phones, laptops, and household appliances. Magnesium alloys are widely used in the housings of electronic devices for their light weight, heat dissipation and strength. Die casting is also used for small motor housings and connectors in electrical appliances to ensure the accuracy and performance of these parts.

Aerospace

The aerospace industry requires high-strength, low-weight materials to ensure the performance and safety of aircraft. Die-cast aluminum and magnesium alloys are used to manufacture aircraft structural components and engine components. The application of die casting technology in aerospace can help reduce material waste while ensuring the accuracy and consistency of complex components.

Medical Devices

Die casting is widely used in the medical device industry to manufacture precision instrument housings and structural components inside medical devices. The corrosion resistance, strength and surface quality of the material make it indispensable in medical devices.

Consumer Products

Die casting is also widely used in the manufacture of daily consumer products such as door locks, kitchenware, lamps, furniture accessories, etc. Die casting metal products are beautiful in appearance, good in feel and durable, making them competitive in the consumer goods market.

Power Tools

Die castings are also widely used in the housings and internal transmission structures of power tools due to their precision and robustness. High pressure casting can meet the requirements of power tools for precision, strength and impact resistance.

Lighting Industry

The lighting industry also uses die casting to produce lamp housings and related components. Die casting aluminum alloys play an important role in such applications because lamps require good heat dissipation and durability.

Sand Casting 

can produce large-sized, complex-shaped and multi-material castings, and is widely used in many industries. The following are the main application areas of sand casting:

Automobile Manufacturing

In the automotive industry, sand casting is used to produce large and complex metal parts such as engine blocks, cylinder heads, intake manifolds, exhaust manifolds, etc. These parts need to withstand high temperatures and pressures, so cast iron or cast aluminum materials are usually used.

Heavy Machinery

Sand casting is widely used to manufacture parts for heavy machinery, such as construction equipment, mining equipment, and agricultural machinery. These parts are usually large in size, complex in shape, and need to withstand high-load working conditions, so the sand casting process is very suitable.

Pumps and Valves

Sand casting is widely used in the pump and valve industry, especially large industrial pump housings and complex valve bodies. Sand casting can accurately cast the complex internal channels required by pumps and valves to ensure that fluids can pass smoothly.

Aerospace

Sand casting is also used in the aerospace field, mainly for the manufacture of aircraft engine housings, turbine components and other complex structural parts. Sand casting can handle high-temperature resistant alloys and other special materials to meet the high material performance requirements of the aerospace industry.

Shipbuilding

The shipbuilding industry uses sand casting technology extensively to produce large parts such as hull parts, propellers, bearing seats and valves. Sand casting can produce corrosion-resistant and wear-resistant metal parts, ensuring that ships can operate for a long time in harsh marine environments.

Power Generation Equipment

Sand casting is widely used in the manufacture of power generation equipment, especially large components in thermal power generation and nuclear power plants. These components require high heat resistance, pressure resistance and complex internal structures, and the sand casting process can provide a reliable solution.

Construction Industry

Sand casting is used in the construction industry to produce various structural components and decorative parts. Common applications include stair supports, railings, bridge structural components, etc. The strength and durability of sand-cast cast iron and cast steel products are very suitable for the needs of the construction industry.

Artworks and Sculptures

Sand casting is widely used in the field of artistic casting to make large sculptures, monuments and artistic decorative pieces. The sand casting process can capture fine details and allow artists to create complex and durable metal works.

Compare from Cost

Cost is one of the main factors we consider when choosing a process. And the calculation of cost is very complicated. Below we mainly compare the costs of the two castings from the two aspects of mold making and production.

Molds Cost

The number of castings is the X-axis and the mold is the Y-axis. As the value of X increases, the average cost of die casting molds to die castings will become lower and lower until it reaches a stable value. Because in production, there is also a part of the cost of mold maintenance.

Sand casting molds have always been in a stable state of low cost.

Production Cost

Die casting production has a long start-up period. If a small batch order is produced, this part of the cost will be abnormally high. Therefore, die casting technology will only be more suitable for large-scale production.

Sand casting is more flexible because its casting can be done by hand. Regardless of the size of the order, the production cost is controllable.

Choose the Right Process For Your Parts

Die casting is suitable for completing the following orders.

Low melting point materials: die casting aluminum, magnesium alloy, zinc alloy, lead alloy, etc.

Castings with high precision requirements and no need for heat treatment.

Orders with a large number of single castings.

Sand casting is suitable for producing almost all casting orders.

Choose a Suitable Casting Service Supplier

Choosing a suitable casting service supplier is crucial to ensure project quality, efficiency and cost control. HULK Metal, a long-established service provider that has provided services to customers around the world for more than 20 years, recommends that you consider the following 8 aspects when choosing a casting service provider.

Choose a More Suitable Process

They can help you choose a more suitable process to complete the order

First, clarify the type of casting service you need. You need to consider the process to complete the order based on the material, surface accuracy, structural complexity, performance requirements, order quantity and other factors of the casting. A professional casting service provider can help you complete these tasks to save you more energy.

Huge Production Capacity

Their production capacity is sufficient to complete the order within the required delivery cycle.

The production capacity of the supplier mainly needs to understand the following points:

Equipment and facilities: 

can meet the production requirements of the order and produce products that meet the quality standards.

Material support: 

have a wealth of raw material procurement channels to meet the material requirements of the casting or find alternative materials to meet the performance requirements of the casting.

Certification: 

If the foundry has ISO 9001, ISO16949, it can be more trustworthy. This is a plus point for a company, but it is not a must. An excellent factory or company can provide high-quality services even without these certifications, but for some special castings, the factory must have the corresponding qualifications. .

Rich Experience in Your Industries

They have experience in producing this type of casting or similar castings.

If a casting service provider has produced your product or similar products, then they have raw material procurement channels, production equipment, and experienced workers who can efficiently complete high-quality orders:

Industry experience: When a casting service provider has experience in casting production in your industry, he will provide you with more comprehensive casting services. As long as the price is right, the production capacity can meet your requirements, and the product quality is acceptable, then he will be your best choice.

Comprehensive Supply Chain

They have a complete supply chain:

This will help you save more time and energy. You don’t need to spend time managing a complex factory, and your location is very far away from the factory and you can’t often go to the factory to check the progress of order production. A supplier with a complete supply chain is often closer to the factory. They will give you more effective reports when you want to know the progress of the order. And suppliers with a complete supply chain can often help you control costs from the entire order process. You can complete the order with less money.

Cost Control Capacity

The degree of control they have over price and cost control

Although price is an important consideration, it cannot be at the expense of quality. Cost factors to consider include:

Material costs: 

Different suppliers may have different pricing for the same material, especially in terms of material procurement channels. Excellent suppliers will have multiple closely cooperating material factories to deal with some emergencies.

Production costs: 

The complexity of the casting process, the degree of automation, etc. will affect the cost. We will optimize the production process and use more advanced equipment and experienced workers to complete the order, which can greatly save production costs.

Transportation costs: 

Especially when purchasing overseas, transportation and import costs are also part of the budget. With our own logistics team, we can help you save a lot of money from the factory to the destination port. Our freight consulting team can also help you save time and money looking for a freight forwarder.

Of course, you can compare prices from multiple parties to ensure that the price is reasonable and transparent.

Communication Capacities and Service Attitude

Their communication timeliness, effectiveness and cooperative attitude:

Timely and effective communication can ensure that orders are completed more smoothly and effectively. The service time we provide can be said to be the longest in the industry. It starts at 6 am and ends at 11 pm China time. This can cover the working hours of most countries as much as possible and deal with customer problems.

Super high cooperation is a must-have advantage for an excellent supplier. They will actively respond to customer requirements and meet customer requirements as much as possible.

QA & After Service

They must provide quality assurance and after-sales service

Quality assurance is a must-have service that a good supplier will provide you. Our quality control center will attach a complete test report to each order and provide return, exchange and replenishment services for every product with quality problems.

After-sales service is our attitude towards quality issues.

Introducing Their Factory to You

They will definitely take you to visit the factory.

Whether they have their own factory or have a close cooperation with a factory. A good casting service provider will definitely take you to visit the factory.

Conclusion:

The comparison and selection of sand casting and die casting requires comprehensive consideration from multiple aspects. It is recommended that you choose an excellent casting service provider and tell them the drawings and requirements. They will help you develop a perfect solution and a more suitable price.