Инвестициялық кастинг бойынша көбелек клапанының дискісі

1. Кіріспе

In butterfly valves, Диск бастапқы ағынды басқару элементі ретінде қызмет етеді, Қысымның төмендеуіне тікелей әсер етеді, Тұтыну, and actuation torque.

, Сорт, disc design and manufacturing determine valve performance far more than peripheral components.

Инвестициялық құю has emerged as the preferred method to produce complex, high-precision discs that meet stringent service requirements.

Бұл мақалада, we explore every stage—from design and material selection to casting, бастау, and validation—providing professional, data-driven insights and emphasizing best practices.

2. Инвестициялық құюға шолу

Инвестициялық құю, жоғалған-балауыз құю деп те аталады, is a time-tested method for creating intricate metal components.

The process begins with a wax pattern, which is coated with a ceramic shell to form a mold.

After dewaxing and high-temperature firing, molten metal is poured into the cavity, and the final part is finished through shot-blasting and machining.

Compared to sand casting or machining, investment casting offers near-net shape geometry with tight tolerances (± 0,1 мм) and surface finishes as smooth as Ra ≤ 1.6 мкм.

This precision is vital for butterfly valve discs, where even minor deviations can compromise sealing integrity.

Typical disc dimensions range from 50 мм дейін 1,500 mm in diameter, with weights spanning 0.5 кг дейін 50 кг, Қолдануға байланысты.

3. Materials Selection for Butterfly Valve Discs

Choosing the right alloy for an investment-cast Көбелек клапан disc demands balancing Коррозияға төзімділік, Механикалық беріктік, Температура мүмкіндігі, жіне құны.

Астында, we explore four material families—each with its advantages—and highlight quantitative property targets to guide specification.

Аұшпандар тот баспайтын болаттар (Cf8 / Cf8m / Cf3 / Cf3m)

Why Choose Them? Austenitic grades offer excellent general-service corrosion resistance in water, Жұмсақ қышқылдар, and steam up to 200 ° °.

Thanks to their face-centered cubic (ФСК) құрылым, they maintain toughness down to –50 °C.

Transitional Note:

For valves exposed to chlorides or weak acids, upgrading from CF8 to CF8M (316) doubles the Pitting Resistance Equivalent Number (Орман) from ~18 to ~25, markedly extending service life in seawater or brine.

Дуфлекс & Super-Duplex Stainless Steels (E.Г., Көмек 2205, 2507)

Why Choose Them? Duplex grades combine austenite and ferrite phases to deliver higher yield strength (~ 800 МПа) and superior chloride-stress-corrosion-cracking (Скр) қарсыласу.

Data Insight:

In full-strength seawater (3.5 % Торң у), 2205 discs resist pitting at up to 80 ° °, versus only ~ 60 ° C үшін 316L, making them the go-to for subsea valves.

Nickel-Base Alloys (Жұқпалы 625, Моник 400)

Why Choose Them? Nickel-based superalloys withstand temperatures above 550 °C and resist oxidation, сульфидация, and chlorination—ideal for Жоғары температуралы жіне sour-gas қолданбалар.

Application Example:

A steam-injection valve in a gas-turbine system specified an investment-cast Inconel 625 диск,

which operated leak-free at 575 ° C және 40 bar for over 18 айлар.

4. Butterfly Valve Disc Design Considerations

Designing a butterfly valve disc involves a delicate balance between hydraulic performance, Құрылымдық тұтастық, және Қасиеттілік.

, Сорт, engineers must evaluate geometry, pressure loading, ағын динамикасы, material distribution,

and gating strategy—each factor contributing to reliable operation over millions of cycles.

Disc Profile: Cambered vs. Пәтер

Бірінші және ең алдымен, та disc profile dictates flow resistance and torque.

А cambered or “waisted” disc—curved on both faces—reduces flow separation by up to 20% compared with a flat disc and lowers actuation torque by approximately 25% in typical 150 мм, PN16 valves.

Сонымен қатар, camber creates a self-centering hydrodynamic force, which enhances mid-stroke stability and extends seal life.

Керісінше, flat discs remain popular in low-pressure (≤ 10 төр) and simple on/off applications, as they simplify tooling and machining.

Қабырғалы қалыңдығы & Structural Rigidity

Moving on, Қабырғалы қалыңдығы determines both rigidity and cast quality.

For investment-cast discs, a nominal thickness of 4-8 мм supports pressure ratings up to 40 төр while avoiding shrinkage porosity.

Сонымен қатар, transitional fillet radii of 3-5 мм at the hub–disc junction prevent stress concentration and promote uniform solidification.

Finite-element analysis (Ақиа) routinely confirms that such sections deflect less than 0.2 мм under a 16 bar differential, thereby maintaining seal integrity.

Pressure Balancing & Reinforcement

Үстіне, designers often incorporate pressure-balancing holes немесе relief grooves in larger butterfly valve discs (≥ 300 мм) to equalize inlet and outlet pressures.

By reducing net unbalanced force by up to 60%, these features shrink actuator sizing by one class.

Сонымен қатар, localized ribbing on the downstream face—typically 4–6 ribs -ден 5 mm thickness—further stiffens the disc without appreciable weight gain.

Hydrodynamics & Torque Reduction

Equally important, hydrodynamic contours ensure smooth flow transitions.

Есептеу сұйықтығын динамика (Ауыртпалық) analyses highlight that rounded leading edges with a curvature radius of 0.1× disc diameter delay flow separation,

improving the discharge coefficient (Cd) from ~0.65 to ~0.75 at 50% ашу.

Болғандықтан, actuation torque drops by 15-20%, directly translating into lower operational energy costs.

Сүйинг, Riser Placement & Басшылық

Соңында, gating and riser design adapt the disc geometry for defect-free casting.

Engineers place the main gate at the disc hub, where metal pools promote directional solidification toward a single peripheral riser.

This layout ensures feeding into the last solidifying zones, reducing shrinkage defects to under 0.5% of castings.

In tandem, a shell thickness of 6 мм and controlled cooling rates (≤ 5 ° C / мин) avoid thermal shock and microcracking.

5. Butterfly Valve Disc by Investment Casting Process Details

Investment casting—often called жоғалған балауыз—transforms a precision wax pattern into a metal butterfly valve disc via a ceramic mold.

Among various shell systems, silica‐sol binders have emerged as the industry standard for high‐integrity, dimensionally accurate castings.

Wax Tooling & Pattern Production

• High‐Precision Dies: CNC-machined die cavities produce wax patterns within ± 0.05 % of nominal dimensions.
• Үлгіні жинау: Engineers attach sprues and gating systems—designed for hub‐first metal flow—to each pattern, assembling them on wax trees that hold 20–50 discs per pour.

Керамикалық қабық ғимараты (Silica Sol Coating):

The wax assembly is dipped into a silica sol slurry (a colloidal solution of colloidal silica and fine refractory particles) және stucco-мен қапталған (zircon or fused silica sand).

This process is repeated 8–12 times, with each layer dried at 70–100°C to build a shell thickness of 5–7 mm.

Silica sol shells offer superior thermal stability and surface finish compared to water glass or ethyl silicate systems.

Аяқтау және өртеу:

The shell is heated to 850–950°C in a controlled furnace to melt out the wax (Дезавакс) and sinter the ceramic shell.

This step eliminates residual hydrocarbons and strengthens the shell to withstand molten metal.

The firing temperature is carefully calibrated to avoid cracking while ensuring the shell’s refractoriness matches the alloy being cast (E.Г., 1,500–1,600°C for stainless steels).

Металл балқыту & Pouring Practices

• Еңбегі & Оттық: Пайдалану vacuum induction furnaces (Фим) to melt alloys—stainless, дуфлекс, or nickel‐base—maintaining O₂ < 50 ppm and H₂ < 5 ppm for clean castings.
• Температура: Maintain 1 480-1 520 ° ° for CF8/CF8M; 1 550-1 600 ° ° for Inconel 625.
• Inert Shrouding & Pressure Pour: Employ argon or nitrogen shrouds over the mold and apply slight positive pressure (0.1–0.3 bar) to drive metal into thin sections, reducing gas porosity to < 0.2 %.

Қабықты алып тастау және әрлеу:

Елеуленгеннен кейін, the ceramic shell is removed via shot-blasting (using aluminum oxide grit) to reveal the near-net shape disc.

Final finishing includes trimming gates/risers and polishing to achieve surface roughness (RA) ≤ 1.6 мкм,

critical for minimizing flow turbulence in the valve.

Final Heat Treatment

• Шешім: Heat discs to 1 050 ° ° (CF8/CF3M) немесе 1 100 ° ° (Никель қорытпалары) -ге 30 мин,
  then water‐quench to dissolve segregated phases and optimize corrosion resistance.
• Стрессті жеңілдету (Ерікті): А 650 ° °, 1-hour hold can mitigate residual stresses from finishing operations.

Advantages of Silica Sol for Butterfly Valve Discs

• Бетті аяқтау: Silica sol shells produce smoother surfaces than traditional methods, reducing the need for post-casting machining.
  This is vital for discs operating in high-purity environments like pharmaceutical or potable water systems.
• Өлшемді дәлдік: The rigid shell structure maintains tight tolerances (± 0,1 мм), ensuring concentricity and flatness critical for disc-seat alignment.
• Жылу тұрақтылығы: Silica sol’s high refractoriness (up to 1,600°C) prevents shell distortion during pouring, preserving intricate pressure-balancing features on the disc.
• Материалдық үйлесімділік: Ideal for casting austenitic steels, дуплексті қорытпалар, және никельге негізделген суперқорс, which are common in butterfly valve applications.

6. Беттік тұтастық & Коррозияға төзімділік

As‐Cast Surface Finish and Post‐Cast Polishing

Even with high‐precision silica‐sol shells, as‐cast discs typically emerge with Ra 2.5–3.5 µm.

Дегенмен, investment casting’s fine ceramic grains limit surface peaks to under 10 мкм in height. To meet valve‐industry standards—which often require Ra ≤ 1.6 мкм—manufacturers apply:

• Vibratory Tumbling: Ceramic media and light abrasives reduce Ra by 30–40% in 2–4 hours.
• Precision Polishing: CNC‐guided polishing with diamond paste (3 µm grit) achieves Ra ≤ 0.8 µm on sealing faces, ensuring leak-free performance.

These steps eliminate surface micro‐notches that could initiate corrosion pits or damage elastomeric seats.

Жинау & Passivation Cycles

To build a uniform passive film and remove embedded inclusions, butterfly valve discs undergo:

• Жинау: Immersion in a 10 % HNO₃–2 % HF solution at 50 °C for 20–30 min dissolves surface oxides and scale.
• Rinse & Neutralization: Subsequent rinsing in deionized water and a sodium bicarbonate bath neutralizes residual acids.
• Ауысу: A second dip in 20 % HNO₃ -та 60 ° C үшін 30 min promotes formation of a 2–5 nm Cr₂O₃ film,
  verified via ASTM A967 citrate testing.

Surface analytical studies show a 30 % арттыру in Cr content at the outermost 50 nm,

translating into a passive‐film breakdown potential rise of +50 м.В. in potentiodynamic tests.

Corrosion Performance in Representative Media

Қоршаған орта	Disc Material	Corrosion Rate	Тест стандарты
Теңіз суы (3.5% Nacl at 25 ° °)	Cf8m / 316	0.05 ММ / жыл	ASTM B117 salt spray
Ferric Chloride (pitting test)	Cf8m / 316	No pitting < 24 н	ASTM G48 Method A
10% H₂SO₄ at room temperature	Cf3m / 316Өшпін	0.10 ММ / жыл	ASTM G31 immersion
Superheated Steam @ 550 ° °	Жұқпалы 625	0.02 ММ / жыл	Ni‐alloy oxidation test

High‐Temperature Oxidation and Stress‐Corrosion Cracking

For applications above ambient:

• Тотығу кедергісі: Жұқпалы 625 discs exhibit < 0.02 mm/year oxide scale growth in air at 550 ° °.
• SCC кедергісі: Duplex‐cast SAF 2205 discs show no chloride SCC when tested per ASTM G36 -та 80 ° C және 1000 psi for 720 н, outperforming 316L by 40 %.

7. Butterfly Valve Disc Casting Tolerance

Maintaining tight dimensional tolerances on the cast disc ensures proper fit, reliable sealing, and minimal post-cast machining.

Investment casting delivers finer tolerances than sand casting, but designers must still specify realistic expectations to balance cost and performance.

Below are typical шыдам guidelines for investment-cast butterfly valve discs, based on ISO 8062-3 (CT8) and industry practice:

Белгі	Nominal Size Range	Шыдам	ЕСталдар
Overall Diameter	Дейін 200 мм	± 0.10 мм	Ensures concentricity with valve body; critical for full-bore applications
	200–400 mm	± 0.15 мм
	> 400 мм	± 0.20 мм
Қабырғалы қалыңдығы	3-8 мм	± 10 % of nominal	Designers maintain 4–8 mm sections to avoid shrink porosity
Hub Bore Diameter	Дейін 50 мм	- 0 / + 0.05 мм	Slip fit onto shaft; may require reaming to H7 for precision actuators
	50–100 mm	- 0 / + 0.10 мм
Болт шеңбері & Holes	PCD Ø up to 300 мм	± 0.10 мм	Matches pipe flange standards (E.Г., Ansi, -Ден)
	PCD Ø > 300 мм	± 0.15 мм
Out-of-Roundness	Any circular feature	≤ 0.05 % of diameter	Ensures seal compression uniformity
Тегіс (Seating Face)	Across disc face	≤ 0.05 мм	Critical for valve shut-off; often ground to final dimension
Edge Profile Radii	Филе / түймелер	± 0.5 мм	Designers specify 3–5 mm radii to balance flow and stress concentration

Практикалық салдар

1. Seal Engagement: Tolerances on seating faces and out-of-roundness directly impact packing and O-ring compression, affecting leak tightness.
2. Actuation Alignment: Hub-bore accuracy ensures concentric disc rotation, reducing eccentric loading on bearings and actuators.
3. Модерлік жәрдемақы: While many butterfly valve discs meet finish tolerances as-cast, critical sealing surfaces often receive a light grind (0.2–0.5 mm stock) to guarantee flatness and surface finish.
4. Inspection Strategy: Coordinate-measuring machine (См) audits of 100 % of discs validate compliance; statistical process control (Зат) flags trends before they exceed CT8 limits.

8. Осы Supply Value-Added Services

Beyond production of the investment-cast disc itself, Осы now bundles a suite of value-added services that accelerate time-to-market, reduce in-house workload:

Дәлдік техника

• CNC бұру & Араластыру: Suppliers often deliver discs with finished hub bores, Кірме жолдар,
  and bolt-hole patterns to H7/H8 tolerances (± 0,02 мм), eliminating secondary machining.
• Balancing & Бұрғылау: Static or dynamic balancing to G6.3 grade limits (< 2.5 µm unbalance per mm) for discs ≥ 300 mm diameter, plus optional bleed or balance-hole drilling.

Термиялық өңдеу

• Шешім Ақша салу: Vacuum or salt-bath anneals at 1 050-1 100 °C followed
  by rapid quenching restore duplex and austenitic microstructures, ensuring full corrosion resistance.
• Стрессті жеңілдету: Sub-critical holds at 600–650 °C for 1–2 hours reduce residual stresses
  from machining or welding by up to 60%, preventing distortion in final assembly.

Беттік емдеу

• Жылтырату & Сырып тастау: Final finishes down to Ra ≤ 0.4 µm on sealing faces ensure leak-free performance; typical turnaround: 1–3 days per batch of 20–50 discs.
• Жабындар & Таллеттер: Эпоксий, Ptfe, or ceramic coatings add chemical resistance in aggressive media; thickness control to ±10 µm meets OEM specifications.

Custom Packaging & Logistics

• Protective Crating: ISO-compliant wooden crates with anti-corrosion VCI inserts, shock-monitoring sensors, and humidity indicators safeguard discs during transit.
• Fast-Track Shipping: Expedited air-freight or “milk-run” consolidation cuts lead times to 2–3 weeks from order to door, compared with standard sea-freight of 6–8 weeks.

9. Тұжырымдар

Investment casting provides a one-step route to high-performance butterfly valve discs, delivering complex geometries, Қатаң төзімділіктер (± 0,1 мм), және жоғары беті әрлеу (Ra ≤ 1.6 мкм).

By selecting appropriate alloys—ranging from CF8M stainless to Inconel 625—and applying rigorous process controls and inspections,

manufacturers achieve discs that meet mechanical targets (tensile ≥ 550 МПа; созылу ≥ 25 %), exhibit outstanding corrosion resistance,

and sustain demanding service conditions across water treatment, майлау & газ, және электр қуатын өндіру секторлары.