1. Įvadas
Copper and its alloys occupy a pivotal role in modern industry due to their outstanding electrical conductivity, atsparumas korozijai, ir Šiluminis našumas.
Istoriškai, civilizations dating back to 5000 BC mastered copper casting in simple stone molds, laying the groundwork for today’s sophisticated techniques.
Šiame straipsnyje, we explore the full spectrum of copper‑based casting methods, examine their metallurgical principles, and guide engineers in selecting the optimal process for diverse applications.
2. Fundamental Principles of Metal Casting
Every casting method follows four core stages:
- Pelėsių kūrimas – Technicians form a cavity in sand, metalas, keramika, or plaster that mirrors the part geometry.
- Pilti – Furnaces melt copper (lydymosi temperatūra 1 083 ° C.) or alloys up to 1 600 ° C., then pour the liquid into molds.
- Kietėjimas – Controlled cooling—guided by thermal conductivity (~ 400 W/m·K for copper) and mold material—drives microstructure development.
- Shake‑Out – Once solid, castings exit the mold and undergo cleaning and post‐processing.
Copper’s high thermal conductivity demands higher mold preheat (200–400 °C) and precise pour control to maintain fluidity (viscosity ~ 6 mPa·s at 1 200 ° C.).
Be to, copper’s Šiluminis išplėtimas (16.5 µm/m·K) requires exact pattern offsets to achieve final dimensions.
3. Major Copper Alloy Casting Methods
Vario and its alloys—brasses, bronzos, copper-nickels, and others—are cast using a range of methods that suit different production volumes, mechaniniai reikalavimai, and dimensional tolerances.
Each technique carries distinct advantages and limitations based on alloy characteristics and desired component outcomes.
This section explores the most prominent copper alloy casting methods in modern manufacturing, along with technical insights to guide process selection.
Smėlio liejimas
Proceso apžvalga & Įranga
Smėlio liejimas remains one of the oldest and most widely used methods for casting copper alloys. It involves packing sand around a reusable pattern inside a mold box.
The sand is bonded with clay (Žalias smėlis) or hardened with chemicals (resin-bonded or CO₂-activated sands). After pattern removal, į ertmę pilamas išlydytas metalas.
Privalumai
- Maža įrankių kaina, tinka žemai- iki vidutinės apimties laidų
- Flexible part sizes—from a few ounces to several tons
- Broad alloy compatibility
Apribojimai
- Coarse surface finishes (Ra 6.3–25 µm)
- Loose tolerances (typically ±1.5–3 mm)
- Requires post-casting machining for most precision applications
Investicija (Prarastas vaškas) Liejimas
Precision Shell Building
Investicijų liejimas uses a wax model coated with ceramic slurry to build a thin, high-accuracy shell mold. Po perdegimo, molten metal is poured into the preheated ceramic mold.
Nauda
- Puiku matmenų tikslumas (±0,1–0,3 mm)
- Idealiai tinka sudėtingas, thin-walled geometries
- Viršininkas paviršiaus apdaila (Ra 1.6–3.2 µm)
Iššūkiai
- Higher tooling costs (due to the need for injection dies)
- Longer cycle times, especially for shell construction and burnout
- Typically economical only for medium-to-high volume gamyba
Shell Molded Casting
Process Details
Shell molding uses a heated metal pattern coated with resin-bonded sand. When exposed to heat, the resin sets to form a thin shell that acts as the mold.
The process produces more accurate and cleaner castings than traditional sand casting.
Privalumai
- Improved surface quality and definition
- Tighter tolerances than green sand molds
- Reduced machining allowance due to near-net shape casting
Apribojimai
- Higher material costs (specialized resins and silica sands)
- Expensive pattern tooling (metal patterns required)
Išcentrinis liejimas
Horizontal vs. Vertical Setups
Išcentrinio liejimo metu, išlydytas metalas pilamas į besisukančią formą, either horizontally or vertically.
The centrifugal force distributes the metal against the mold wall, minimizing porosity and ensuring excellent material integrity.
Pagrindiniai pranašumai
- High density and reduced porosity—ideal for pressure-retaining components
- Kryptinis kietėjimas enhances mechanical properties
- Tinka įvorės, Žiedai, vamzdžiai, and hollow parts
- Vertical casting often used for small parts; horizontal for large cylinders
Apribojimai
- Apribota rotacijos simetrinės dalys
- Tooling setup is more complex and costly than static casting
Chill Casting
Kietėjimo kontrolė
Chill casting uses metal molds (often iron or steel) to rapidly extract heat from the molten metal. This rapid solidification refines the grain structure and enhances mechanical properties.
Stiprybės
- Produces sunkiau, denser castings (iki 50% increase in hardness vs. Smėlio liejimas)
- Excellent for phosphor bronze and gunmetal
- Cost-effective for repetitive casting of bars, strypai, ir smulkios dalys
Apribojimai
- Less suited for Sudėtingos geometrijos
- Limited size range due to mold constraints
Mirti liejimas (Hot-Chamber and Cold-Chamber)
Pressure Injection Process
Die casting involves injecting molten copper alloys into a high-strength steel mold under high pressure.
Cold-chamber machines are typically used due to the high melting points of copper alloys.
Privalumai
- Fast production rates—ideal for mass production
- Superior surface finish and precision (Ra 1–2 µm, tolerances ±0.05 mm)
- Reduces or eliminates machining
Constraints
- Not all copper alloys are suitable (Pvz., high zinc brasses can corrode dies)
- Die tooling is brangus (investment of $50,000 ar daugiau)
- Geriausia medium to high volumes
Nuolatinis liejimas
Proceso apžvalga
Molten metal is poured into a water-cooled mold that continuously forms and pulls solidified metal through a withdrawal system.
Common outputs include rods, barai, and billets for downstream machining or rolling.
Privalumai
- Didelis produktyvumas with minimal human intervention
- Excellent mechanical properties due to controlled solidification
- Smooth surfaces and straightness suitable for automatic feed machining
- Low scrap rate and better yield (virš 90% medžiagų panaudojimas)
Tipiniai lydiniai
- Tin bronzes, leaded bronzes, phosphor bronzes, and copper-nickels
Plaster Mould Casting
Specializuotas naudojimas
This process employs plaster or ceramic molds formed around a pattern to capture fine detail and tight tolerances.
The mold is removed after casting by breaking or dissolving the plaster.
Privalumai
- Excellent for įmantrios formos ir Lygus paviršiaus apdaila
- Good for prototipai ir Mažos tūrio gamyba
Trūkumai
- Low permeability—limits to casting size
- Longer preparation time ir limited mold life
Suvestinė palyginimo lentelė
| Liejimo metodas | Paviršiaus apdaila (Ra) | Matmenų tolerancija | Typical Volumes | Pagrindinės stiprybės |
|---|---|---|---|---|
| Smėlio liejimas | 6.3-25 µm | ±1.5–3 mm | Nuo žemo iki aukšto | Mažos išlaidos, alloy flexibility |
| Investicijų liejimas | 1.6–3,2 µm | ±0,1–0,3 mm | Nuo vidutinio iki aukšto | Aukštas tikslumas, Sudėtingos dalys |
| Shell Molded Casting | 1.6–3,2 µm | ±0,25–0,5 mm | Vidutinis | Griežtos nuokrypiai, automatizuoti |
| Išcentrinis liejimas | 3.2–6,3 µm | ±0.25–1.0 mm | Vidutinis | Didelis tankis, minimalūs defektai |
| Chill Casting | 3.2–6,3 µm | ±0,5–1,0 mm | Vidutinis | Enhanced mechanical properties |
| Mirti liejimas | 1–2 µm | ± 0,05–0,2 mm | Aukštas | Fast cycles, minimal machining |
| Nuolatinis liejimas | 3.2–6,3 µm | ±0.2–0.5 mm/m | Labai aukštas | Cost-efficient billet production |
| Plaster Mould Casting | 1.6–3,2 µm | ±0,1–0,3 mm | Žemas ar vidutinis | Detailed, įmantrios formos |
4. Common Copper Alloys Used in Casting
Foundries cast a wide array of copper‑based alloys, each engineered to balance mechanical strength, atsparumas korozijai, thermal and electrical performance, ir liejamumas.
| Lydinys | Paskyrimas | Kompozicija (masės %) | Pagrindinės savybės | Preferred Casting Methods | Tipiškos programos |
|---|---|---|---|---|---|
| Laisvai apdirbamas žalvaris | C36000 / CZ121 | 61 Cu–35 Zn–3 Pb | Tempimas: 345 MPa Pailgėjimas: 20 % Laidumas: 29 % IACS |
Smėlis, Investicija, Mirti, Korpuso formavimas | CNC‑machined fittings, pavaros, elektros gnybtai |
| Low‑Lead Brass | C46400 / CZ122 | 60 Cu–39 Zn–1 Pb | Tempimas: 330 MPa Pailgėjimas: 15 % NSF‑61 compliant |
Smėlis, Investicija, Mirti | Potable‑water valves, santechnikos įranga |
| Guolių bronza | C93200 | 90 Cu–10 Sn | Tempimas: 310 MPa Kietumas: HB 90 Puikus atsparumas dilimui |
Smėlis, Chill, Išcentrinis | Įvorės, atraminės poveržlės, heavy‑load bearings |
| Aliuminio bronza | C95400 | 88 Cu–9 Al–2 Fe–1 Ni | Tempimas: 450 MPa Kietumas: HB 120 Strong seawater corrosion resistance |
Mirti, Išcentrinis, Korpuso formavimas | Jūrų techninė įranga, siurblio sparnuotės, vožtuvo komponentai |
| Fosforo bronza | C51000 | 94.8 Cu–5 Sn–0.2 P | Tempimas: 270 MPa Pailgėjimas: 10 % Good fatigue & spring properties |
Investicija, Smėlis, Mirti | Spyruoklės, elektros kontaktai, diafragmos |
Copper‑Nickel (90–10) |
C70600 | 90 Cu–10 Ni | Tempimas: 250 MPa Pailgėjimas: 40 % Exceptional biofouling resistance |
Smėlis, Išcentrinis, Ištisinis | Seawater heat‑exchangers, marine piping |
| Copper‑Nickel (70–30) | C71500 | 70 Cu–30 Ni | Tempimas: 300 MPa Superior chloride and erosion resistance |
Smėlis, Ištisinis, Išcentrinis | Condenser tubes, offshore hardware |
| Berilis varis | C17200 | 98 Cu–2 Be | Tempimas: up to 1 400 MPa (amžiaus) Laidumas: 22 % IACS |
Investicija, Chill, Mirti | High‑reliability springs, non‑sparking tools, jungtys |
| Silicio bronza | C65500 | 95 Cu–5 Si | Tempimas: 310 MPa Corrosion resistant in marine/chemical |
Smėlis, Investicija, Korpuso formavimas | Decorative hardware, laivo armatūra |
5. Išvada
Copper and copper‑alloy foundries offer a rich toolbox of casting methods—each balancing Kaina, Tikslumas, Mechaninis atlikimas, ir gamybos apimtis.
By understanding process nuances—from mold materials and thermal management to alloy behavior—engineers can optimize part design, minimize scrap, and ensure reliable performance.
As technologies like additive mold fabrication ir real‑time simulation subrendęs, copper casting will continue to evolve, sustaining its critical role in high‑performance manufacturing.
At Tai, Džiaugiamės galėdami aptarti jūsų projektą projektavimo proceso pradžioje, kad užtikrintume, jog pasirinktas visas lydinys ar taikomas gydymas po kaupimo, Rezultatas atitiks jūsų mechanines ir našumo specifikacijas.
Aptarti jūsų reikalavimus, el. Paštas [email protected].
DUK
Can all copper alloys be die-cast?
Ne. Only specific alloys like aluminum bronzes, high-tensile brasses, ir silicon brasses are suitable for mirti liejimas due to the high pressures and rapid cooling involved.
Lydiniai kaip fosforinė bronza arba gunmetal are better suited to sand or chill casting.
What’s the difference between centrifugal and chill casting?
- Išcentrinis liejimas uses rotational force to push molten metal into the mold, producing dense, defect-free components (ideal for pipes, įvorės, ir rankoves).
- Chill casting uses static metal molds to rapidly solidify the surface, improving mechanical properties and reducing grain size—especially effective for tin bronzes.
Why is continuous casting preferred for high-volume copper alloy bars?
Nepertraukiamas liejimas offers consistent quality, puikios mechaninės savybės, and low scrap rates.
It’s optimal for fosforinė bronza, gunmetal, ir švinuota bronza ruošiniai, especially when integrated with rolling or extrusion processes.
What post-processing is required after casting copper alloys?
Depending on the casting method and alloy, post-processing may include:
- Heat treatment for stress relief or aging (especially for beryllium copper)
- Machining for critical surfaces or tight tolerances
- Surface finishing such as polishing or coating for corrosion protection or aesthetics
