Hardware System: A Dual Test of Mechanical Performance and Weather Resistance
Hardware components are the core parts that enable the opening, load-bearing, and locking functions of doors and windows, and their material selection directly determines safety and durability. Stainless steel, with its excellent all-round performance, is the mainstream choice. Type 304 stainless steel contains 18% chromium and 8% nickel, forming a passive film that resists corrosion from air and moisture—ideal for rainy or coastal regions. Type 316 stainless steel adds 2%–3% molybdenum, increasing salt spray resistance by more than five times, making it the preferred choice for tropical marine climates. However, stainless steel is costly; for dry inland areas, hot-dip galvanized steel can be used. Its sacrificial zinc layer protects the base metal, costs only about 60% of 304 stainless steel, and has a tensile strength of over 300 MPa, sufficient for standard load-bearing needs.
Transmission parts require a balance of wear resistance and lubrication. Zinc alloy die-cast parts are commonly used for handle and lock cylinder gearing due to their good fluidity, high precision, and ability to form complex tooth profiles. When paired with a chrome-plated surface, hardness can reach above HV500, withstanding over 100,000 cycles of wear. Hinge pins should use high-carbon steel (e.g., 45# steel) that has been quenched and tempered; after surface hardening, hardness can reach HRC50–55, ensuring resistance to deformation during frequent movement. Material pairing should also prevent galvanic corrosion—for example, when aluminum profiles contact steel hardware, nylon spacers should be added to prevent electrochemical rusting.
Sealing System: Balancing Elasticity and Aging Resistance
Seals are essential for thermal, acoustic, and waterproof performance, requiring long-term elasticity and weather resistance. EPDM (ethylene propylene diene monomer) rubber is currently the best all-round seal material. Its molecular structure contains no double bonds, making it over 10 times more resistant to ozone aging than natural rubber, and it retains elasticity between −40 °C and 120 °C. With a compression set of less than 20% (per GB/T 16584), it is especially suited for climates with large temperature differences, such as Australia and Northern Europe. For higher-grade sealing in system windows, foamed EPDM can be used. Its closed-cell structure improves resilience and reduces thermal conductivity to below 0.05 W/(m·K), combining insulation and sealing performance.
In high-end markets, silicone rubber is chosen for its extreme temperature resistance (−60 °C to 200 °C) in special scenarios such as kitchen windows near stoves or in high-heat climates. However, silicone rubber costs two to three times more than EPDM and has a lower tear strength (around 8 MPa), so it requires fabric reinforcement. For temporary or budget windows, neoprene (CR) can be a substitute—it has better weather resistance than natural rubber but tends to harden over time, with a service life of about 50% of EPDM. Seal profile design must match material properties: for example, European-style groove seals should use “lip-type” EPDM to achieve step-by-step waterproofing, while bottom seals for sliding doors should use a “brush + rubber composite” to balance dust prevention and smooth sliding.
Profile Connection and Auxiliary Materials: The Hidden Foundation of Structural Stability
Profile connectors, though not directly visible, are crucial to structural strength. Aluminum connectors are often used for corner joints in thermal-break aluminum profiles. 6063-T5 aluminum alloy has a tensile strength of 200 MPa, and after anodizing, the oxide layer thickness can reach ≥10 μm, effectively resisting internal moisture corrosion. For heavy-duty doors and windows (e.g., floor-to-ceiling windows over 3 m high), stainless steel corner brackets should be used with high-strength bolts (grade 8.8 or above). Bolts made from 201 stainless steel balance tensile strength with cost control.
Glass-to-profile fixing materials must balance adhesion and cushioning. Polysulfide sealant offers excellent oil resistance and sealing, making it suitable for secondary seals in insulated glass; it has an adhesion strength to glass of ≥0.4 MPa and can accommodate more than 10% displacement from thermal expansion and contraction. Silicone structural sealant, the key material for frameless curtain walls, must meet GB16776 certification and have a cured tensile modulus of ≥0.6 MPa to ensure long-term bonding between glass and profiles. Gaskets should be made from closed-cell polyethylene (PE) with a density of ≥0.3 g/cm³ to prevent moisture absorption and mold growth, and with a Shore hardness of 30–40A to avoid damaging glass edges.
Special-Function Parts: The Frontier of Material Innovation
With the rise of smart doors and windows, material selection for functional components has diversified. Sensor housings should be made from ABS engineering plastic, with an impact strength of 20 kJ/m² and an IP65 waterproof rating for reliable outdoor use. Drive motor gear sets should combine polyoxymethylene (POM) with powder metallurgy metal parts—POM’s self-lubrication reduces noise, while the metal parts increase torque for automated operation.
In fire-rated doors and windows, intumescent vermiculite is used for fire seals—it expands 3–5 times in volume when exposed to heat, forming a dense insulating layer with a fire resistance limit of over 1.5 hours. For hardware exposed to high heat, ductile cast iron is preferred, as it retains 70% of its strength at 600 °C, far outperforming standard cast iron.
In Summary
Material selection for door and window parts is a balance between performance matching and cost optimization: load-bearing components should prioritize mechanical strength and weather resistance; seals should balance elasticity and aging resistance; auxiliary materials should combine functionality with compatibility. Companies should tailor their material solutions according to target market climate conditions (humidity, temperature range, UV intensity), building codes (wind load ratings, fire safety requirements), and customer needs (budget, expected lifespan) to deliver long-term product value.