Laidos vs kalimas: Išsamus palyginimas

1. Įvadas

Liejimas vs kalimas are two fundamental metal-shaping routes.

Laidos puikiai tinka gaminti sudėtingas formas, internal cavities and large parts with relatively low material waste and low per-part tooling cost for moderate geometries.

Kalimas produces parts with superior mechanical properties, improved fatigue resistance and better grain flow, but typically requires heavier tooling and more machining for complex geometry.

The right choice depends on the application’s mechanical requirements, geometrijos sudėtingumas, apimtis, cost targets and regulatory constraints.

2. Kas yra liejimas?

Liejimas is a manufacturing process in which molten metal is poured into a mold cavity shaped like the desired component.

Kai metalas atvės ir sukietėja, the mold is removed to reveal the cast part.

This process is one of the oldest methods of metal shaping, dating back thousands of years, and is still widely used because of its versatility in producing both simple and highly complex parts.

Proceso apžvalga

1. Šablonų kūrimas – A replica of the part (modelis) is made from wax, mediena, plastikas, arba metalas.
2. Pelėsių paruošimas – A mold is created using sand, keramika, arba metalas, priklausomai nuo liejimo metodo.
3. Tirpimas & Pilti – Metal alloys are melted (typically at 600–1,600 °C depending on alloy) and poured into the mold.
4. Kietėjimas & Aušinimas – Controlled cooling allows the metal to take the shape of the mold cavity.
5. Shakeout & Valymas – The mold is broken or opened, and excess material (Vartai, RISERS) yra pašalintas.
6. Apdaila & Tikrinimas – Heat treatment, apdirbimas, and surface finishing are applied as required.

Variants of Casting

• Smėlio liejimas – Cost-effective, suitable for large and heavy parts; dimensional tolerance typically ±0.5–2.0 mm.
• Investicijų liejimas (Pamiršta vaškas) – Produces highly detailed, near-net-shape parts with excellent surface finish (Ra ≈ 1.6–3.2 µm).
• Mirti liejimas – High-pressure injection of molten non-ferrous alloys (Al, Zn, Mg) into permanent molds; excellent for high-volume production.
• Išcentrinis liejimas – Used for cylindrical parts like pipes, with high density and minimal defects.
• Nuolatinis liejimas – Industrial process for producing billets, plokštės, and rods directly from molten metal.

Pagrindiniai pranašumai

• Ability to produce Sudėtingos geometrijos, including internal cavities and thin-walled sections.
• Wide range of lydinio lankstumas (plienas, lygintuvai, aliuminis, Vario, Nikelis, titanas).
• Beveik tinklo forma capability reduces machining requirements.
• Ekonomiškai efektyvus Didelės dalys ir Mažos ir vidutinės apimtys.
• Scalability — from prototypes to high-volume production (especially with die casting).

Apribojimai

• Casting defects such as poringumas, susitraukiančios ertmės, intarpai, and hot tears.
• Mechaninės savybės (tempimo stiprumas, Nuovargio atsparumas) are often inferior to forged equivalents due to dendritic microstructures and porosity.
• Dimensional accuracy and surface finish vary significantly by process.
• Cooling rates can cause segregation and anisotropy in mechanical performance.

3. Kas kalimas?

Kalimas is a metalworking process in which metal is shaped into desired geometries through compressive force, typically using hammers, Presai, ar miršta.

Skirtingai nuo liejimo, where the material is melted and solidified, forging works the metal in a solid state, improving its grain structure and enhancing mechanical properties.

Forging is one of the oldest metal-shaping methods, historically performed by blacksmiths with simple hand tools.

Šiandien, it is a high-precision industrial process widely used in aerospace, automobilių, aliejus & dujos, energijos generavimas, and defense industries.

Proceso apžvalga

1. Šildymas (Neprivaloma) – Metal is heated to a plastic state (for hot forging) or left at room temperature (for cold forging).
2. Deformacija – The metal is compressed or hammered into shape between flat or shaped dies.
3. Apipjaustymas – Excess material (Blykstė) yra pašalintas.
4. Terminis apdorojimas (Jei reikia) – Normalizing, gesinimas, and tempering are applied to optimize strength, kietumas, ir lankstumas.
5. Apdaila – Machining, paviršiaus apdaila, and inspection complete the process.

Types of Forging

• Atviras mirimas kalimas – Large parts shaped between flat dies; used for shafts, diskai, and large blocks.
• Uždaras (Įspūdis-mirė) Kalimas – Metal pressed into shaped cavities for near-net shape parts; widely used in automotive and aerospace.
• Šaltas kalimas – Performed at room temperature; excellent dimensional accuracy and surface finish.
• Karštas kalimas – Performed above recrystallization temperature; allows shaping of large, tough alloys with reduced work hardening.
• Isothermal & Tikslumas – Advanced methods for titanium, Nikelis, and aerospace alloys, reducing machining and material waste.

Pagrindiniai pranašumai

• Aukščiausios mechaninės savybės due to refined grain structure and elimination of internal voids.
• Aukštas Nuovargio atsparumas and impact strength compared to castings.
• Consistent matmenų tikslumas in precision forging.
• Tinka Kritinės programos such as aircraft engine parts, automotive crankshafts, slėgio indai, and nuclear power components.
• Minimal porosity and excellent metallurgical integrity.

Apribojimai

• Didesnės išlaidos nei liejimas, ypač sudėtingoms formoms.
• Limited to parts that can be formed by deformation — less suitable for hollow, Plonos sienos, or highly intricate geometries.
• Reikalauja specialized tooling and high-tonnage presses for large parts.
• Longer lead times for custom dies.

4. Mikrostruktūra & Grain Flow of Casting vs. Kalimas

One of the most fundamental differences between casting and forging lies in the internal microstructure iš medžiagos.

How the grains are formed, aligned, and distributed during processing directly influences the mechanical strength, Tvirtumas, and fatigue resistance of the final component.

Casting Microstructure

• Solidification Process – In casting, molten metal cools and solidifies inside the mold.
  Grains nucleate randomly and grow outward, formuojantis Equiaxed arba columnar grains depending on cooling conditions.
• Grain Orientation – No preferred orientation (isotropic structure), but often heterogeneous. Grain boundaries may be weak points under stress.
• Defektai – Possible poringumas, susitraukiančios ertmės, intarpai, and segregation of alloying elements due to uneven cooling. These reduce fatigue resistance and fracture toughness.
• Savybės – Adequate for static loads and complex shapes but generally lower tensile strength and fatigue resistance compared to forged parts.

Forging Microstructure

• Plastic Deformation Process – Forging plastically deforms metal in its solid state, breaking up cast dendritic structures and eliminating porosity.
• Grain Flow Alignment – Forging aligns grains in the direction of applied forces, Gamina a continuous grain flow that follows the shape of the part.
  This improves impact strength and fatigue resistance, especially in components like crankshafts and turbine blades.
• Defect Reduction – Forging compacts voids and inclusions, reducing defect size and improving metallurgical integrity.
• Savybės – Forged parts show superior mechanical properties, especially in dynamic or cyclic load conditions.

5. Typical Mechanical Property of Casting vs. Kalimas

6. Dizaino laisvė, Tolerancijos, and Surface Finish

Lyginant casting vs forging, one of the most decisive factors is the balance between dizaino lankstumas, matmenų valdymas, ir paviršiaus kokybė.

Kiekvienas procesas turi unikalių stipriųjų ir apribojimų, which determine suitability for different applications.

Dizaino laisvė

• Liejimas offers unmatched design flexibility. Complex geometries such as internal cavities, Plonos sienos, Grando struktūros, and undercuts can be produced directly in a single pour.
  Investment casting in particular enables near-net-shape parts, reducing machining by up to 70%.
  Components like pump impellers, Turbinos ašmenys, or intricate brackets are almost exclusively made by casting because forging such shapes would be impossible or economically prohibitive.
• Kalimas, priešingai, is constrained to relatively simpler geometries.
  Although closed-die forging allows near-net-shape parts, intricate internal passages, fine lattice structures, or sharp undercuts are not achievable.
  Forging excels when the part requires solid, continuous geometry without hollow sections, such as shafts, pavaros, ir jungiamieji strypai.

Matmenų nuokrypiai (ISO 8062 Nuoroda)

Paviršiaus apdaila (Roughness Ra, μm)

7. Secondary Operations and Heat Treatment Impact

Secondary operations and heat treatment play a critical role in optimizing the performance of components produced by casting or forging.

These post-process steps directly influence mechanical properties, matmenų tikslumas, paviršiaus apdaila, ir ilgalaikis patvarumas.

Antrinės operacijos

Apdirbimas:

• Liejimas: Cast components often require significant machining to achieve tight tolerances and critical surfaces, especially for holes, Siūlai, and mating faces.
  Investment casting reduces machining requirements due to near-net shape capabilities, whereas sand casting usually requires more extensive post-machining.
• Kalimas: Forged parts generally require minimal machining, mostly for finishing surfaces and precision holes, due to the uniformity and near-final dimensions of closed-die forging.

Paviršiaus apdaila:

• Poliravimas ir šlifavimas: Enhance surface quality, reduce roughness, and remove minor surface defects. Investment castings can reach Ra < 1.5 μm after mechanical or electropolishing.
• Šūvys sprogdinimas / Karoliukų sprogimas: Used to remove scale, Blykstė, and improve surface uniformity.
• Dangos ir dengimas: Secondary coatings (Pvz., Nerūdijančio plieno pasyvavimas, zinc or nickel plating for corrosion protection) are often applied post-machining.

Susirinkimas & Fitting:

• Critical for components with multiple parts, such as bushings, Smeigtukai, or hinge assemblies. Proper secondary operations ensure proper clearance, interference, and functional alignment.

Terminis apdorojimas

Tikslas:
Terminis apdorojimas is employed to enhance mechanical properties such as strength, kietumas, ausmingumas, ir atsparumas dėvėjimams. Its effects vary between cast and forged components.

• Liejimas:

• • Cast stainless steel and low-alloy steels often undergo Sprendimo atkaitinimas, Stresas palengvina, arba Amžius sukietėjimas to reduce residual stresses, homogenizuoti mikrostruktūrą, and improve machinability.
  • Care must be taken to avoid partial melting or grain coarsening in thin sections, particularly in investment castings.

• Kalimas:

• • Forged components benefit from normalizavimas arba quenching and tempering to refine grain structure and maximize mechanical performance.
  • Forging inherently produces a denser, Vienodesnė mikrostruktūra, so heat treatment mainly optimizes hardness and stress relief rather than compensating for defects.

Advanced post-processing

• Hip can close internal porosity in castings, bringing properties closer to wrought/forged material at high cost.
• Paviršiaus procedūros (Nušauti peening, nitridavimas, Carburizacija) improve fatigue life and wear resistance.

8. Pramonės programos: Matching Method to Need

Casting and forging dominate distinct industrial sectors based on their inherent strengths—geometry complexity, Mechaninis atlikimas, tūrio reikalavimai, ir išlaidų apribojimai.

Casting Applications

Automobiliai:

• Variklio blokai: Sand casting is widely used for iron engine blocks, accommodating complex water jackets and internal cavities.
• Cilindro galvutės: Investment casting enables precision cooling channels and intricate geometries in high-performance engines.
• Aluminum Wheels: Die casting allows high-volume production with excellent surface finish and dimensional consistency.

Aviacijos ir kosmoso:

• Turbinos ašmenys: Investment casting of superalloys like Inconel 718 achieves complex airfoil geometries essential for efficiency and high-temperature resistance.
• Engine Housings: Sand casting of aluminum alloys supports lightweight structures with moderate complexity.

Aliejus & Dujos:

• Siurblių korpusai: Sand casting of cast iron or steel provides robust, cost-effective solutions for fluid handling.
• Vožtuvo kūnai: Investment casting in 316L stainless steel achieves tight tolerances and corrosion resistance for critical valves.

Statyba & Infrastruktūra:

• Šulinio dangteliai: Sand casting in ductile iron offers high strength and durability.
• Pipe Fittings & Komponentai: Die casting aluminum or brass provides lightweight, corrosion-resistant solutions for water and gas networks.

Programų kalimas

Automobiliai:

• Alkūniniai velenai: Closed-die forging in AISI 4140 steel ensures high fatigue resistance and superior grain flow for performance engines.
• Connecting Rods: Forged from 4340 steel for strength and toughness under repeated dynamic loading.

Aviacijos ir kosmoso:

• Landing Gear Components: Closed-die forging in titanium alloys combines high strength-to-weight ratio with excellent fatigue life.
• Engine Shafts: Atviras „Inconel“ kalimas 625 Gamina komponentus, atsparius aukštai temperatūrai ir įtempiams.

Aliejus & Dujos:

• Gręžimo apykaklės: „Open-Die“ kalimas AISI 4145H Plienas užtikrina aukšto slėgio ištvermę atšiaurioje downhole aplinkoje.
• Vožtuvo stiebai: Uždarytas 316L nerūdijančio plieno kalimas garantuoja matmenų tikslumą ir atsparumą korozijai.

Sunkiosios mašinos & Pramoninė įranga:

• Pavarų ruošiniai: Closed-die forging in AISI 8620 Plienas pasiekia didelį kietumą ir atsparumą dilimui, kad būtų galima perduoti galią.
• Hidrauliniai cilindrai & Velenai: „Open-Die“ kalimas A36 pliene užtikrina atsparumą stiprumui ir smūgiams sunkiasvorių operacijų metu.

9. Comprehensive Comparison of Casting vs. Kalimas

Laidos vs kalimas yra pagrindiniai gamybos metodai, kiekvienas turi skirtingus pranašumus, apribojimai, ir idealaus naudojimo atvejai.

Žemiau esančioje lentelėje apibendrinti pagrindiniai skirtumai tarp kelių matmenų, Pateikti inžinieriams AT-a-Glance vadovą, Dizaineriai, ir gamybos vadovai:

10. Išvada

Casting vs forging are not competitors but complementary tools—each optimized for specific manufacturing needs:

• Choose Casting If: You need complex geometries, low upfront cost for low volume, or parts made from brittle metals (ketaus).
  Investment casting excels at precision, sand casting at cost, and die casting at high-volume non-ferrous parts.
• Choose Forging If: You need high strength, Nuovargio atsparumas, or tight tolerances for simple-to-moderate shapes. Closed-die forging is ideal for high-volume, didelio streso dalys; open-die forging for large, low-volume components.

The most successful manufacturing strategies leverage both methods—e.g., a car engine uses cast blocks (Sudėtingumas) and forged crankshafts (stiprybė).

By aligning process selection with part function, apimtis, ir kaina, engineers can optimize performance, reduce TCO, ir užtikrinti ilgalaikį patikimumą.

 

DUK

Can forging produce parts with internal cavities?

No—forging shapes solid metal, so internal cavities require secondary machining (gręžimas, nuobodus), which adds cost and reduces strength.

Liejimas (especially sand or investment) is the only practical method for parts with internal features (Pvz., engine water jackets).

Which process is more sustainable for steel parts?

Forging is more sustainable for high-volume, didelio streso dalys: it uses 30–40% less energy than sand casting, produces less waste (10–15% vs. 15–20%), and forged parts have longer service life (reducing replacement cycles).

Sand casting is more sustainable for low-volume, Sudėtingos dalys (lower tooling energy).

What is the maximum size for casting vs. kalimas dalys?

• Liejimas: Sand casting can produce parts up to 100 tonos (Pvz., ship propellers); investment casting is limited to ~50 kg (Tikslios dalys).
• Kalimas: Open-die forging can produce parts up to 200 tonos (Pvz., power plant shafts); closed-die forging is limited to ~100 kg (didelės apimties dalys).

Why are aerospace turbine blades cast instead of forged?

Turbine blades have intricate airfoil geometries and internal cooling channels—impossible to forge.

Investicijų liejimas (using single-crystal superalloys like Inconel 718) produces these features with the required precision, while heat treatment optimizes strength for high-temperature service.