How are uPVC windows made

1. What is a UPVC Window

UPVC windows, also known as plastic-steel windows, are a combination of plastic and steel, originally developed in Germany. The main materials include modified PVC, calcium carbonate, titanium dioxide, and other additives. These materials are mixed in specific proportions and extruded into window profiles. 

2. Raw Materials & Profile Extrusion (Profile Manufacturing Stage)

UPVC windows are based on multi-chamber UPVC profiles, which determine thermal insulation, sound insulation, and mechanical strength.

2.1 Material Mixing

Base material: UPVC resin

Additives: stabilizers, impact modifiers, titanium dioxide (UV resistance), calcium carbonate, color masterbatch, etc. All materials are evenly mixed in a high-speed mixer.

2.2 Extrusion Process

The mixed material is fed into an extruder and heated to 170–275°C until it becomes molten. The material is then extruded through precision molds to form the cross-sectional shapes of window frames and sashes (multi-chamber structure).

2.3 Cooling & Shaping

Profiles are calibrated using vacuum shaping and rapidly cooled with water to ensure dimensional accuracy.

2.4 Cutting & Protection

Profiles are automatically cut into standard 6-meter lengths. To facilitate storage and transportation, a protective film must be applied.

2.5 Steel Reinforcement

For large-size windows or high wind load requirements, galvanized steel reinforcements are inserted into the profile chambers and fixed with screws. This significantly improves resistance to deformation and overall structural performance.

3. Equipment required for the production

4. Window Fabrication Process

4.1 Cutting

Profiles are cut according to drawings using a double-head cutting saw. A welding allowance of 3 mm on each end is reserved.

Angles:

Frame and sash corners: 45° miter joints

Mullions: 90° butt joints

4.2 Milling & Machining

Drainage holes, pressure equalization holes, hardware slots, and lock holes are milled to ensure proper drainage and precise hardware installation. Burrs at cutting edges are removed to ensure clean welding surfaces.

4.3 Welding (Core Process)

A four-head welding machine simultaneously welds four corners. Profile ends are heated to approximately 240°C until softened. The corners are then pressed together and cooled to form seamless, integral joints. After welding, corners are cleaned and polished to ensure a smooth and aesthetic finish.

4.4 Assembly & Sealing

Mullions, reinforcements, and steel inserts are installed and fixed with screws or connectors. EPDM rubber sealing strips are inserted (frame, sash, and glazing seals) to ensure excellent water tightness and air tightness.

4.5 Glazing

Typically uses double-glazed insulating glass units (IGU) filled with argon gas for improved thermal and acoustic performance. Glass is installed into the frame and secured with glazing beads. Neutral silicone weatherproof sealant is applied on both sides for sealing.

4.6 Hardware Installation

Install hinges, handles, locks, friction stays, and rollers (for sliding windows). Adjust to ensure smooth operation and tight locking performance.

4.7 Quality Inspection

Inspect dimensions, welding strength, sealing performance, hardware function, and surface quality. Qualified products are then packed and prepared for shipment.

5. Key Quality Control Points

5.1 Profiles

Wall thickness ≥ 1.8 mm with a multi-chamber structure.

It meets anti-aging and UV resistance standards for long-term durability.

5.2 Welding

Corner strength ≥ 30 MPa.

No false welding, cracks, or structural defects.

5.3 Sealing Performance

Triple sealing system (EPDM rubber gaskets + weatherproof sealant).

It ensures excellent water tightness, air tightness, and thermal insulation.

5.4 Hardware

Equipped with reliable branded hardware systems.

Tested for over 100,000 opening and closing cycles without failure.

6. Advantages of UPVC Windows

6.1 Excellent Thermal Insulation

UPVC has extremely low thermal conductivity, far lower than that of ordinary aluminum. This property effectively prevents condensation in winter, maintaining a warm indoor environment while reducing energy consumption.

6.2 Superior Sound Insulation & Sealing

The multi-cavity profile design, combined with a triple sealing system, provides superior sound insulation, dust-proofing, and waterproofing.

6.3 Cost-Effective

Compared to thermally broken aluminum windows, it has lower material and processing costs, while offering high-performance products at competitive prices.

6.4 Corrosion Resistance

It does not rust and is resistant to rain, humidity, acidic environments, and coastal environments. Maintenance requirements are extremely low, and no rust prevention treatment is necessary.

6.5 Electrical Insulation & Safety

A non-conductive material with excellent insulating properties. It can reduce the risks associated with lightning strikes and electrical leakage.

6.6 Comfortable Touch

The surface is smooth and warm to the touch, significantly improving user comfort.

7. Summary

The manufacturing of UPVC windows follows a clear process:

profile extrusion → cutting → welding & assembly → glazing & hardware installation.

Throughout the entire process, precision and sealing performance are the key factors that determine the final quality of the window.Therefore, good equipment is the key to ensuring processing accuracy.