Casting is one of the core near-net-shape metal forming technologies in modern equipment manufacturing. By melting metal, filling molds, cooling and finishing, it enables the mass production of large-sized, complex-structured, and multi-material metal components. As industrial products impose increasingly strict requirements on precision, surface quality, mechanical properties and manufacturing costs, different casting processes present significant differences in applicable scenarios.
To help engineers, process technicians and R&D personnel select casting processes efficiently, this article systematically reviews 11 mainstream industrial casting technologies. Each process is analyzed in terms of working mechanism, core advantages and disadvantages, and typical applications. A full-dimensional quantitative comparison table is provided to eliminate ambiguity in process selection and parameter evaluation.
1. General Core Workflow of Casting Processes
All industrial casting processes follow a unified production sequence. The fundamental differences among various casting methods lie only in mold materials und metal filling driving force:
Pattern Making → Mold Preparation → Alloy Melting → Mold Filling → Cooling & Solidification → Shakeout & Finishing
2. Detailed Analysis of 11 Mainstream Casting Processes
2.1 Sand Casting
Sand casting uses silica-based sand mixed with binders to fabricate disposable sand molds. Molten metal fills the mold by gravity. It is the most versatile and widely adopted traditional casting method, compatible with all ferrous and non-ferrous metal alloys.
Core Features: Extremely low cost for small-batch production, no size limitation for castings, capable of forming high-melting-point metals such as steel and titanium. The main drawbacks are low dimensional accuracy, rough surface finish and large machining allowance.
Typical Applications: Engine blocks, cylinder heads, crankshafts, large machine tool bases, and heavy machinery structural castings.
2.2 Permanent Mold Gravity Die Casting
This process adopts reusable rigid molds made of steel or graphite. Molten metal fills the mold cavity purely by gravity. Classified as a semi-precision casting technology, the mold can be reused for cyclic production.
Core Features: Fast solidification leads to dense microstructure, better surface quality and higher dimensional accuracy than sand casting, suitable for thin-wall mass production. The main limitations are high mold cost and incapability of manufacturing complex or deep-cavity parts.
Typical Applications: Aluminum/magnesium alloy pistons, gearbox housings, pipe fittings, wheel blanks, and medium-small mechanical structural parts.
2.3 High & Low Pressure Die Casting
Pressure die casting is divided into two branches: high-pressure die casting (HPDC) injects molten non-ferrous metal at ultra-high speed and pressure for high-precision small complex parts; low-pressure die casting (LPDC) delivers metal steadily at low pressure for large and simple components. It is exclusively applicable to non-ferrous alloys.
Core Features: Ultra-high dimensional accuracy, outstanding production efficiency and minimal post-processing allowance. However, it requires high investment in equipment and molds, and internal porosity restricts its use in high-load structural components.
Typical Applications: Automotive electronic housings, precision hardware, and lightweight non-load-bearing automotive components.
2.4 Investment Casting (Lost Wax Casting)
Investment casting uses wax patterns coated with refractory slurry to form integrated ceramic shell molds. The wax is melted and drained at high temperature before metal pouring. It is a high-end disposable precision casting process.
Core Features: Capable of manufacturing ultra-thin-wall parts and complex structures with 90° right angles without draft angles. It delivers industry-leading surface finish and dimensional accuracy, and supports difficult-to-cast materials such as stainless steel and superalloys. The main disadvantages are long production cycle, high labor dependence and high manufacturing cost.
Typical Applications: Aerospace precision components, motorcycle brake discs, precision gears, and high-end mechanical spare parts.
2.5 Plaster Casting
Plaster casting utilizes plaster-of-Paris mixtures to make molds. Plaster exhibits extremely low thermal conductivity, which slows down metal solidification and enables full filling of thin-wall cavities, targeting high-precision small castings.
Core Features: Excellent surface smoothness and higher dimensional accuracy than sand casting, able to form ultra-thin sections as thin as 1mm. Limited by poor heat resistance, it only applies to aluminum and copper alloys with low production efficiency and relatively high cost.
Typical Applications: Precision instrument parts, thin-wall hydraulic components, and small high-end cast products.
2.6 Centrifugal Casting
Centrifugal casting relies on high-speed rotating molds to generate centrifugal force, pushing molten metal to adhere and solidify along the inner mold wall. It includes true centrifugal, semi-centrifugal and vertical centrifugal casting variants.
Core Features: Produces high-density castings with minimal porosity and shrinkage defects and high material utilization rate, supporting composite metal component manufacturing. The major limitation is that it only produces rotary symmetrical parts.
Typical Applications: Bearing bushes, cylinder liners, piston rings, clutch discs and other annular or cylindrical components.
2.7 Lost Foam Casting
Lost foam casting adopts EPS foam to create solid patterns coated with refractory coatings and buried in dry sand. High-temperature molten metal vaporizes the foam pattern and occupies the cavity for solidification, with no parting lines or flash burrs.
Core Features: High design freedom, eco-friendly clean production, and prominent cost advantages in mass production. It suffers from high pattern cost for small-batch production and easy deformation of foam patterns.
Typical Applications: Valve bodies, fire hydrants, pump housings, and special-shaped ductile iron/steel castings.
2.8 Vacuum Casting
Vacuum casting is performed in a negative-pressure chamber to extract trapped gas inside the mold cavity, fundamentally eliminating porosity and cavity defects for high-quality precision castings.
Core Features: Extremely low porosity, excellent weldability and heat treatability, suitable for ultra-thin-wall components and small-batch prototyping. The drawbacks are expensive molds and shorter mold service life under vacuum conditions.
Typical Applications: Automotive chassis structural parts, aerospace lightweight components, and precision electronic housings.
2.9 Squeeze Casting (Liquid Forging)
Squeeze casting is a hybrid process combining casting and forging. After quantitative molten metal is injected into the mold, high pressure is applied during solidification, integrating the forming flexibility of casting and the densification performance of forging.
Core Features: Completely eliminates internal defects such as porosity, shrinkage and cracks, delivering high-strength components with superior surface quality and zero material waste. It is limited by low structural flexibility, low productivity and ultra-high precision process control requirements.
Typical Applications: Automotive safety structural parts, steering knuckles, chassis frames, and high-strength aluminum alloy load-bearing components.
2.10 Continuous Casting
Continuous casting injects molten metal into water-cooled crystallizers for outward-inward continuous solidification, producing constant cross-section metal profiles uninterruptedly, serving as the core process for steel billet mass production.
Core Features: Continuous operation, minimal material waste and ultra-low mass production cost. It can only fabricate regular constant-cross-section profiles instead of irregular complex parts.
Typical Applications: Steel billets, bars, rebars, steel plates and other standard metal profiles.
2.11 Shell Mold Casting
Shell mold casting uses resin-coated fine sand heated and hardened to form thin shell molds, serving as an upgraded refined alternative to conventional sand casting.
Core Features: Better surface finish and dimensional accuracy than ordinary sand casting with reduced secondary machining. Restricted by mold specifications, it is unsuitable for large-size and heavy castings and uneconomical for small-batch production.
Typical Applications: Gearbox housings, connecting rods, camshafts, and medium-small valve bodies.
3. Full-Dimensional Quantitative Comparison of 11 Casting Processes
The table below quantifies the core parameters of all processes, available for direct reference in process selection, scheme evaluation and cost accounting:
|
Casting Process
|
Unit Cost
|
Dimensional Accuracy
|
Applicable Metals
|
Minimum Wall Thickness
|
Production Batch Suitability
|
Surface Quality
|
Core Limitations
|
|
Sand Casting
|
Very Low
|
Niedrig
|
All ferrous & non-ferrous metals
|
≥5mm
|
Optimal for small batches
|
Schlecht
|
Low precision, rough surface, large machining allowance
|
|
Gravity Permanent Mold Casting
|
Medium
|
Medium-High
|
Aluminum, magnesium, bronze alloys
|
≥2mm
|
Optimal for mass production
|
Good
|
Unable to form complex cavity structures
|
|
Pressure Die Casting
|
Hoch
|
Extremely High
|
Aluminum, zinc, copper & other non-ferrous alloys
|
≥0.5mm
|
Optimal for mass production
|
Excellent
|
Internal porosity, not applicable for load-bearing structural parts
|
|
Investment Casting
|
Very High
|
Ultra-High
|
Stainless steel, superalloys, special steels
|
≥0.3mm
|
Suitable for medium & large batches
|
Prämie
|
Long production cycle, high manufacturing cost
|
|
Plaster Casting
|
Relatively High
|
Hoch
|
Aluminum & copper alloys
|
≥1mm
|
Suitable for small & medium batches
|
Very Good
|
Poor heat resistance, material limitation, low efficiency
|
|
Centrifugal Casting
|
Medium-High
|
Medium
|
Cast iron, copper, aluminum alloys
|
≥3mm
|
Suitable for mass production
|
Good
|
Only for rotary symmetrical parts
|
|
Lost Foam Casting
|
Medium (mass) / High (small batch)
|
Medium-High
|
Cast steel, cast iron, aluminum alloys
|
≥3mm
|
Optimal for mass production
|
Good
|
High pattern cost for small batches, easy pattern deformation
|
|
Vakuumgießen
|
Hoch
|
Hoch
|
Various non-ferrous alloys
|
≥0.8mm
|
Suitable for small & medium batches
|
Very Good
|
High mold investment, short mold service life
|
|
Squeeze Casting
|
Very High
|
Hoch
|
Mainly aluminum alloys
|
≥2mm
|
Suitable for small & medium batches
|
Very Good
|
Low structural flexibility, limited productivity
|
|
Continuous Casting
|
Very Low
|
Medium
|
Carbon steel & various structural steels
|
≥8mm
|
Optimal for continuous production
|
Medium
|
Only for constant cross-section regular profiles
|
|
Shell Mold Casting
|
Medium
|
Medium-High
|
Cast iron & medium-small carbon steel parts
|
≥2.5mm
|
Suitable for medium & large batches
|
Good
|
Limited part size and weight, not for large castings
|
4. Quick Selection Guide for Engineering Scenarios
For efficient practical application, precise selection rules are summarized based on parameter comparison:
✅ Large castings, multi-material adaptation, small-batch prototyping → Sand Casting
✅ Medium-small aluminum/magnesium parts, mass production of regular components → Gravity Permanent Mold / Pressure Die Casting
✅ Complex special-shaped, thin-wall, high-temperature resistant precision components → Investment Casting
✅ Shaft sleeves, bearings and annular rotary parts → Centrifugal Casting
✅ Mass production of special-shaped iron castings such as valves and pump housings → Lost Foam Casting
✅ Automotive load-bearing parts, high-strength precision aluminum structural components → Squeeze Casting
✅ Standard profiles such as steel billets and rebars → Continuous Casting
✅ Medium-small high-precision box and shaft parts → Shell Mold Casting
5. Conclusion
The core differences among various casting processes lie in five key dimensions: precision, cost, material adaptability, structural limitations and mass production capacity. In practical engineering selection, high-precision processes are not always necessary. The optimal solution requires comprehensive consideration of product structure, material requirements, production volume and budget. Sand casting is preferred for cost-effective small-batch production; die casting for mass-produced precision parts; investment casting for high-end complex components; and squeeze casting for high-strength structural parts. This matching strategy maximizes product quality and production economy simultaneously.