I. Metal Materials (Commonly Used)

　　The main structural components of pressure control valves—such as valve bodies, spools, spring seats, and more—are typically made from metal materials to ensure strength, corrosion resistance, and sealing performance. Common metal materials and their recommended forming temperatures are listed below:

　　1. Cast iron (such as gray cast iron, ductile iron)

　　Material properties: low cost and excellent casting performance, but relatively poor toughness—commonly used in low- or medium-pressure valves.

　　Melting temperature:

　　Gray cast iron: 1300–1450°C (ensure proper molten metal flow to prevent insufficient filling).

　　Ductile iron: 1400–1500°C (higher temperatures may be required to ensure complete reaction of the spheroidizing agent).

　　Key to forming:

　　Temperatures that are too low can easily lead to cold shuts and insufficient filling defects; while temperatures that are too high increase the shrinkage rate, resulting in shrinkage cavities and looseness.

　　The difference between the tapping temperature and the pouring temperature must be controlled (typically, the pouring temperature is 50–100°C higher than the melting point).

　　2. Cast steel (such as carbon steel, stainless steel)

　　Material properties: High strength and excellent toughness make the two-way logic valve suitable for high-pressure, high-temperature, or corrosive environments—such as those involving stainless steel 304/316.

　　Melting temperature:

　　Carbon steel (such as Q235, 45 steel): 1500–1580°C (melting point around 1450°C; overheating is required to ensure proper fluidity).

　　Stainless steel (e.g., 304): 1550–1650°C (melting point is around 1400°C; alloying elements increase melting difficulty, requiring higher temperatures to prevent compositional segregation).

　　Key to forming:

　　Easily oxidized at high temperatures, requiring controlled deoxidation processes during melting (such as adding ferrosilicon or ferromanganese for deoxidation).

　　The pouring temperature must be strictly controlled to prevent overheating, which could lead to coarse grains and negatively impact mechanical properties.

　　3. Aluminum alloys (such as aluminum-silicon alloys, aluminum-magnesium alloys)

　　Material properties: Lightweight and highly corrosion-resistant, ideal for lightweight valves or non-pressure-bearing components.

　　Melting temperature:

　　Aluminum-silicon alloys (such as ZL102): 700–750°C (melting point around 577°C; avoid overheating to prevent gas absorption).

　　Aluminum-magnesium alloys (such as ZL301): 680–730°C (magnesium is prone to oxidation, so a covering agent is required for protection).

　　Key to forming:

　　Excessive temperature can lead to gas absorption (hydrogen), causing porosity in castings due to the holding valve; meanwhile, too-low temperatures may result in cold shuts.

　　The refining temperature needs to be controlled (e.g., around 720°C when argon gas is introduced for degassing).

　　4. Copper alloys (such as brass, bronze)

　　Material properties: Excellent wear resistance and high thermal conductivity, used in valve cores, seals, and more.

　　Melting temperature:

　　Brass (copper-zinc alloy): 1000–1100°C (zinc evaporates easily, so melting time must be carefully controlled).

　　Tin bronze (copper-tin alloy): 1100–1200°C (avoid tin oxidation by adding phosphorus-deoxidized copper).

　　Key to forming:

　　Zinc volatilization can lead to compositional deviations, so a low-temperature, rapid-melting process is required. Tin oxidation results in slag formation, necessitating the use of fluxes, such as charcoal, for coverage.

　　II. Non-Metallic Materials (Auxiliary Components)

　　Sealing elements, springs, plastic components, and other parts of the pressure control valve may be made from non-metallic materials, with the following molding temperature requirements:

　　1. Rubber (such as nitrile rubber NBR, fluoroelastomer FKM)

　　Application scenarios: Sealing elements such as O-rings and diaphragms.

　　Molding temperature:

　　Vulcanization temperature: 150–200°C (requires matching vulcanization pressure, e.g., 10–20 MPa).

　　Nitrile rubber: Typically vulcanized at 160–180°C for 10–30 minutes.

　　Fluororubber: Requires higher temperatures (180–200°C) and longer vulcanization times (over 30 minutes).

　　Key requirements:

　　Insufficient temperature leads to incomplete vulcanization and poor sealing performance; excessive temperature, on the other hand, can cause aging and cracking.

　　Temperature control must be strictly maintained with high precision (±2°C) to prevent localized overheating.

　　2. Engineering plastics (such as nylon PA, polytetrafluoroethylene PTFE)

　　Application scenarios: lightweight valve cores, wear-resistant bushings, and more.

　　Molding temperature:

　　Nylon PA66: 250–280°C (melt extrusion or injection molding—raw material must be dried to prevent hydrolysis).

　　Polytetrafluoroethylene (PTFE): 350–380°C (requires high-temperature sintering to prevent insufficient crystallinity due to inadequate temperature).

　　Key requirements:

　　PTFE decomposes above 400°C, releasing toxic gases, so the diversion and flow control valve requires strict temperature limits.

　　Nylon must be rapidly molded after melting to prevent prolonged residence time, which could lead to degradation.

　　3. Spring steels (such as 65Mn, 50CrVA)

　　Application scenario: Pressure control springs (e.g., overflow valve springs).

　　Molding Temperature (Heat Treatment):

　　Quenching temperature: 830–860°C (65Mn), 850–880°C (50CrVA).

　　Tempering temperature: 400–500°C (adjust according to hardness requirements; for example, medium-temperature tempering produces troostite, ensuring elasticity).

　　Key requirements:

　　Temperature control affects the strength and toughness of the spring, so it’s essential to avoid insufficient austenitization or overheating that leads to excessively coarse grains.

　　III. Key Points for Controlling Molding Temperature

　　Temperature sensors for injection molding machines and die-casting machines must be monitored in real time to prevent thermocouple failures that could result in uncontrolled temperatures.

　　Melting equipment (such as electric furnaces and induction furnaces) must be equipped with a high-precision temperature control system (accuracy ±5°C) and undergo regular calibration.

　　Temperature sensors for injection molding machines and die-casting machines must be monitored in real time to prevent thermocouple failures that could lead to temperature失控.

　　Material Preprocessing:

　　Metal furnace charge materials must be dried (e.g., cast iron chunks should have a moisture content of less than 0.5%) to prevent reactions with water at high temperatures, which could lead to porosity.

　　Plastic raw materials must be dried (e.g., nylon PA needs to be dried at 80–100°C for 4–6 hours) to prevent bubble formation during molding.

　　Cooling rate:

　　The cooling rate of metal castings influences grain size—rapid cooling, for instance, results in fine grains and higher strength—and must be carefully controlled through mold design, such as using metal or sand molds.

　　The cooling temperature of plastic parts must match the molding temperature (e.g., injection mold temperatures typically range from 50 to 100°C) to prevent internal stress-induced cracking.

　　Process Records and Traceability:

　　Each batch of material must have its real-time temperature curve recorded during molding, enabling quality traceability—for example, allowing analysis of temperature fluctuations if defects occur.