Day3 Types of Casting Process
Overview & Classification
There are so many type of casting processes. The ones often encountered in industrial procurement include sand casting, die casting, investment casting, and lost foam casting. These casting processes can be further classified into different subcategories.
This class we will introduce the mainstream casting processes and subcategories, their production requirements and part characteristics.
As so many casting processes, content of this class is quite extensive. You can first learn the casting process you need now, save this webpage, and come back to learn other processes when needed in your future work.
Five Core Priority Indicators For Castings Procurement
For purchasers, just need to focus on five core indicators: quantity, accuracy, unit price, mold cost and lead time.
Quantity and dimensional accuracy are the most important factors in determining the casting process.
Quantity
The key to determining the casting process
★★★★★
01
Dimensional Accuracy
Directly relate to the subsequent machining costs
★★★★☆
02
Unit Price
Comprehensive cost control under bulk purchasing
★★★★☆
03
Mold Cost
Large initial investment that needs to be evenly distributed among batch production
★★★☆☆
04
Lead Time
Including molt making time, sample confirmation, and production
★★★☆☆
05
Green Sand Casting
Click here to learn What is Green Sand Casting
Advantages:
- Extremely low mold cost: can use wooden or resin material to make mold for small orders
- Short lead time: shorter production preparation time compared with investment casting or loast foam casting
- Wide range of casting sizes and weights are available
- Can cast various alloys
Liminations:
- Low accuracy: CT10-CT12
- High surface roughness: Ra25-Ra100μm
- Low efficiency: Relying entirely on manual labor for mold opening, shaping and box closing, makes it difficult to achieve automation
Key Procurement Data:
- Quantity: 1~50 pieces
- Mold Cost: 300~1200 USD
- Unit Price: Medium-high
- Material: Cast iron, cast steel, cast aluminium
- Typical Applications: Heavy structural components, agricultural machinery, first-piece verification
Note: green sand casting is a type of manual wet sand casting, there is another special automatic wet sand casting(automatic sand molding line), can produce large quantity orders with very limitted times.
Resin Sand Casting (Dry Sand)
Click here to learn What is Resin Sand Casting
Advantages:
- Higher accuracy: CT7-CT10
- Better surface: Ra6.3-25μm
- Can produce large & complex casting parts
- Can produce both small-batch trial production and large-batch production
Limitations：
- Higher cost of raw material
- Harmful gases during resin curing
Key Procurement Data:
- Quantity: 10~1000 pieces
- Mold cost: 300~3500USD
- Lead time: 10~20 days for raw castings
- Unit price: Medium, suitable for medium and high value castings
- Materials: cast iron, cast steel
- Typical applications: Machine tool beds, pump body valve bodies, engine cylinder blocks and various reducer housings
Click here to learn Applications of Resin Sand Casting
Shell Molding (Dry Sand)
Shell molding is one of the dry sand casting, it makes sand shell by injecting special sand into metal mold, heating the sand to create shell pattern, then pouring molten alloys into shell pattern to get the castings.
Advantages:
- High precision: CT6-CT8
- Good roughness: Ra3.2-12.5μm
- Few defects: less pores and shrinkage cavities
- Fast production
Limitations:
- Only for medium-small parts: Due to the strength limitation of the sand shell
Key Procurement Data:
- Quantity: 100~5000 pieces
- Mold cost: medium-high, 2000~5000 USD
- Lead time: 15-25 days
- Material: cast iron, cast steel, cast aluminium
- Key applicastions: auto parts, locomotive/rolling stock parts, truck parts, and other commercial vehicle suspension/braking/steering parts
High Pressure Die Casting / HPDC
Click here to learn What is High Pressure Die Casting
Advantages:
- Extremely high efficient: 5~20 pieces / minutes
- High accuracy: CT5-CT7
- Excellent roughness: Ra0.8-3.2 μm
Limitations:
- High mold cost
- Only for aluminium alloy, zinc alloy and magnesium alloy
- Only for medium-light load application
- Not friendly for small batches
Key Procurement Data:
- Quantity: 1000+
- Mold cost: Min 2500 USD
- Mold time: 30-45 days
- Unit price: medium
- Material: cast aluminium, cast zamak(zinc alloy), cast magnesium alloy
- Key applications: electrical products, automotive parts, home appliance parts
Gravity Die Casting (GDC)/Permanent Mold Casting (PMC)
Click here to learn What is Gravity Die Casting
Advantages:
- Higher accuracy: CT6-CT8
- Good surface: Ra3.2-12.5μm
- Can do heat treatment to improve strength
- Long lifetime of mold
Limitations:
- Lower efficient than HPDC
- Higher unit price than HPDC
Key Procurement Data:
- Quantity: 100-5000 pieces
- Mold cost: 1500-30000 USD
- Unit price: high, 7~9 USD/kg
- Lead time: 30-40 days / 500 castings
- Material: aluminium, brass
- Typical applications: aluminum alloy parts with requirements for structural strength and pressure bearing, such as motor casings, meter housing, pump bodies and valves...
Lost Foam Casting (LFC) / Expendable Pattern Casting (EPC)
Click here to learn What is Lost Foam Casting
Advantages:
- No draft angle, no need for parting
- Accuracy: CT8-CT10
- Roughness: Ra6.3~25μm
Limitations:
- Higher risk with internal defects: pores and carbon slag, etc
- Can not be used for thin wall-thickness parts less than 3mm
Key Procurement Data:
- Quantity: 1~5000 pieces
- Mold cost: lower for single or small quantitys(CNC machined foam pattern) / high for batch production with metal mold
- Lead time: 25-40 days
- Unit price: medium
- Materials: cast iron, cast steel
- Typical applications: complex-structured box-type parts, e.g. transmission cases, gerabox housing, reducer housing, etc.
Investment Casting
Click here to learn What is Investment Casting
Advantages
- Highest accuracy: CT4-CT6
- Best surface: Ra1.6-6.3μm
- Ultra complex structure castings available
Limitations
- Complicated processes, long production cycle
- High unit price
- Not available for large size parts (less than 100kgs)
Key Procurement Data
- Quantity: 100-10000 Pieces
- Mold cost: 200~500 USD for manual mold(small orders) / 1500~5000 USD for automatic mold (medium-large orders)
- Unit price: expensive
- Lead time: 40-60 days
- Material: cast steel, stainless steel, brass, bronze...
- Typical applications: Medical, turbine blades, precision hardware, high-end industrial components, stainless steel castings, valve parts...
No Best Casting Process, Only The Most Suitable One
Purchasers need to take into account the characteristics of various casting processes, combine product features, and comprehensively consider five major factors: batch size, precision, materials, cost, and delivery time. By collaborating with suppliers in advance to select casting processes and optimize product design, production costs can be effectively reduced.
