Atas 8 Metode pengecoran paduan tembaga dan tembaga

1. Perkenalan

Copper and its alloys occupy a pivotal role in modern industry due to their outstanding electrical conductivity, resistensi korosi, Dan kinerja termal.

Secara historis, civilizations dating back to 5000 BC mastered copper casting in simple stone molds, laying the groundwork for today’s sophisticated techniques.

Dalam artikel ini, 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:

1. Pembuatan Cetakan – Technicians form a cavity in sand, logam, keramik, or plaster that mirrors the part geometry.
2. Penuangan – Furnaces melt copper (titik lebur 1 083 ° C.) or alloys up to 1 600 ° C., then pour the liquid into molds.
3. Solidifikasi – Controlled cooling—guided by thermal conductivity (~ 400 W/m·K for copper) and mold material—drives microstructure development.
4. 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.).

Selain itu, copper’s ekspansi termal (16.5 µm/m · k) requires exact pattern offsets to achieve final dimensions.

3. Major Copper Alloy Casting Methods

Tembaga and its alloys—brasses, perunggu, copper-nickels, and others—are cast using a range of methods that suit different production volumes, persyaratan mekanis, 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.

Casting pasir

Proses Tinjauan & Peralatan
Casting pasir 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 (pasir hijau) or hardened with chemicals (resin-bonded or CO₂-activated sands). After pattern removal, logam cair dituangkan ke dalam rongga.

 

Keuntungan

• Biaya perkakas rendah, cocok untuk rendah- untuk menjalankan volume sedang
• Flexible part sizes—from a few ounces to several tons
• Broad alloy compatibility

Batasan

• Coarse surface finishes (Ra 6,3-25 mikron)
• Loose tolerances (typically ±1.5–3 mm)
• Requires post-casting machining for most precision applications

Investasi (Lilin hilang) Pengecoran

Precision Shell Building
Casting investasi uses a wax model coated with ceramic slurry to build a thin, high-accuracy shell mold. Setelah kelelahan, molten metal is poured into the preheated ceramic mold.

Manfaat

• Bagus sekali ketepatan dimensi (±0,1–0,3mm)
• Ideal untuk rumit, thin-walled geometries
• Unggul permukaan akhir (Ra 1,6–3,2 mikron)

Tantangan

• 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 produksi

Shell Molded Casting

Detail Proses
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.

Keuntungan

• Improved surface quality and definition
• Toleransi yang lebih ketat than green sand molds
• Reduced machining allowance due to near-net shape casting

Batasan

• Higher material costs (specialized resins and silica sands)
• Expensive pattern tooling (metal patterns required)

Casting sentrifugal

Horisontal vs. Vertical Setups
Dalam pengecoran sentrifugal, logam cair dituangkan ke dalam cetakan yang berputar, either horizontally or vertically.

The centrifugal force distributes the metal against the mold wall, minimizing porosity and ensuring excellent material integrity.

Keuntungan Utama

• High density and reduced porosity—ideal for pressure-retaining components
• Solidifikasi terarah meningkatkan sifat mekanik
• Cocok untuk bushing, cincin, tabung, and hollow parts
• Vertical casting often used for small parts; horizontal for large cylinders

Batasan

• Terbatas pada bagian yang simetris secara rotasi
• Tooling setup is more complex and costly than static casting

Chill Casting

Kontrol Solidifikasi
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.

Kekuatan

• Produces lebih sulit, denser castings (hingga 50% increase in hardness vs. casting pasir)
• Excellent for phosphor bronze and gunmetal
• Cost-effective for repetitive casting of bars, batang, dan bagian-bagian kecil

Batasan

• Less suited for geometri kompleks
• Limited size range due to mold constraints

Casting mati (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.

Keuntungan

• 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 (MISALNYA., high zinc brasses can corrode dies)
• Die tooling is mahal (investment of $50,000 atau lebih)
• Terbaik untuk medium to high volumes

Pengecoran Berkelanjutan

Proses Tinjauan
Molten metal is poured into a water-cooled mold that continuously forms and pulls solidified metal through a withdrawal system.

Common outputs include rods, bar, and billets for downstream machining or rolling.

Keuntungan

• Produktivitas tinggi 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 (lebih 90% pemanfaatan material)

Paduan Khas

• Tin bronzes, leaded bronzes, phosphor bronzes, and copper-nickels

Plaster Mould Casting

Penggunaan Khusus
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.

Keuntungan

• Excellent for bentuk rumit Dan permukaan akhir yang halus
• Good for prototipe Dan volume rendah produksi

Kekurangan

• Permeabilitas rendah—limits to casting size
• Longer preparation time Dan limited mold life

Tabel Perbandingan Ringkasan

4. Common Copper Alloys Used in Casting

Foundries cast a wide array of copper‑based alloys, each engineered to balance mechanical strength, resistensi korosi, thermal and electrical performance, dan castability.

5. Kesimpulan

Copper and copper‑alloy foundries offer a rich toolbox of casting methods—each balancing biaya, presisi, kinerja mekanis, Dan volume produksi.

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 Dan real‑time simulation dewasa, copper casting will continue to evolve, sustaining its critical role in high‑performance manufacturing.

Pada INI, Kami senang mendiskusikan proyek Anda di awal proses desain untuk memastikan bahwa paduan apa pun yang dipilih atau perawatan pasca-casting yang diterapkan, Hasilnya akan memenuhi spesifikasi mekanik dan kinerja Anda.

Untuk mendiskusikan kebutuhan Anda, e-mail [email protected].

FAQ

Can all copper alloys be die-cast?

TIDAK. Only specific alloys like aluminum bronzes, high-tensile brasses, Dan silicon brasses are suitable for casting mati due to the high pressures and rapid cooling involved.

Paduan suka perunggu fosfor atau gunmetal are better suited to sand or chill casting.

What’s the difference between centrifugal and chill casting?

• Pengecoran sentrifugal uses rotational force to push molten metal into the mold, producing dense, defect-free components (ideal for pipes, bushing, dan lengan baju).
• 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?

Pengecoran terus menerus offers consistent quality, sifat mekanik yang sangat baik, and low scrap rates.

It’s optimal for perunggu fosfor, gunmetal, Dan perunggu bertimbal billet, 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