PVC (uPVC) Plastic Window Welding Machine

📅 18.10.2025 • 👁️ 11 Views

PVC (uPVC) Plastic Window Welding Machine – The Heart of Modern Window Production

The Plastic Window Welding Machine: Core of Contemporary Window Manufacturing

The PVC (uPVC) plastic window welding machine is an indispensable component of modern window and door production. Without these highly specialized systems, the efficient, precise, and durable manufacturing of plastic windows as we know it today would be unthinkable. These machines are the technological centerpiece that joins precisely cut plastic profiles—typically rigid polyvinyl chloride (PVC)—into a rigid, airtight, and perfectly formed window frame. In a sector driven by efficiency, quality, and aesthetics, welding performance is a decisive driver of market success.

This article delves deeply into the world of plastic window welding machines, explaining the underlying technology, the various machine types, their historical development, the critical quality parameters, and the future trends shaping this fascinating field of engineering.

What Exactly Is a Plastic Window Welding Machine?

Before exploring the technical details, a clear definition: a plastic window welding machine is a stationary industrial system designed specifically to permanently join cut profiles made of thermoplastic materials (primarily PVC) using heat and pressure to form the corners of a window or door frame.

Basic Definition and Function

The machine’s core task is hot-plate welding, often referred to as mirror welding. The mitred profile ends (usually 45-degree cuts) are pressed against a heated plate (the “welding mirror”), plasticized (melted), and then joined under high pressure. Through intermolecular diffusion of polymer chains in the melt, a homogeneous, high-strength, and permanently airtight joint is created upon cooling—often stronger than the base material itself.

Why Is Welding Necessary for Plastic Windows?

Plastic window profiles are hollow and divided into multiple chambers (multi-chamber systems) to ensure thermal insulation and stability (often with steel reinforcement). To form a frame, these complex geometries must be joined at the corners.

Mechanical joining methods—common in timber or aluminium windows using corner cleats—are unsuitable for PVC and similar plastics. They cannot reliably seal the hollow chambers, leading to moisture ingress, reduced thermal performance, and instability. Welding, by contrast, creates a monolithic, material-bonded corner. The joint is:

Permanently sealed: No gaps through which water or air can penetrate.
Highly robust: The weld contributes substantially to the frame’s structural rigidity.
Efficient: The process is extremely fast and highly automatable.

Differentiation from Other Joining Methods

In industrial practice, several methods are used for joining plastics:

Adhesive bonding: While bonding is used in certain window applications (e.g., glazing), it is unsuitable for structural corner joints. It lacks the weathering resistance, long-term stability, and static strength of welding and is slower and messier.
Mechanical fastening (screws): For hollow-chamber plastic profiles, this cannot create a planar, sealed joint and thus is ineffective for corner connections.
Ultrasonic or laser welding: For the specific geometry, material (PVC), and volume of window profiles, these approaches are typically too complex, too slow, or not economically viable.

Hot-plate butt welding (mirror welding) has therefore established itself as the undisputed gold standard for plastic window profiles.

Historical Development of Plastic Window Manufacturing

Today’s high-tech plastic window welding machine is the result of decades of evolution closely linked to the rise of plastic windows themselves.

The Early Days of Plastic Windows

The story began in the 1950s, when the first patents for rigid PVC windows were granted. Early products often struggled with UV discoloration and poor dimensional stability. Corner joints were a particular challenge. Early experiments included solvent activation (solvent welding) and simple hot-air guns to join mitres.

From Manual Processes to Automation

In the 1960s and 1970s—driven by the oil crises and growing demand for insulating building materials—PVC windows achieved a breakthrough. Mass production increased the need for efficient, reliable joining methods.

The first “welding machines” were simple, manually operated single-head devices. An operator loaded the profiles, moved the hot plate manually or pneumatically between them, and pressed the parts together. Quality depended heavily on the operator; cycle times were long and dimensional accuracy inconsistent.

Milestones in Welding Technology

Key advancements included:

PLC control (programmable logic controllers): In the 1980s, electronics enabled precise, repeatable control of temperature, time, and pressure—kickstarting industrial quality assurance in window manufacturing.
Multi-head machines: To drastically reduce cycle times, two-head and ultimately four-head welders were developed. The latter can weld a complete frame (four corners) in a single cycle.
Integration of corner cleaning: In parallel, the corner cleaning machine (cleaner) evolved to automatically and contour-accurately remove the visually undesirable weld bead.
Zero-joint technology (from ~2010): A recent revolution enabling aesthetically perfect corners without visible weld seams, fundamentally transforming the market for colored/laminated profiles.

How Does a Plastic Window Welding Machine Work?

Even though a four-head machine completes a cycle in just a few minutes, the welding process is a finely calibrated physical operation typically divided into three phases.

The Welding Process Step by Step

Regardless of whether a single-head or four-head machine is used, every corner follows the same hot-plate butt-welding cycle.

Phase 1: Profile Loading and Clamping

Mitred plastic profiles (e.g., 45°) are placed in the machine’s clamping fixtures—manually by an operator or automatically via a transfer system in a production line.

Once positioned, pneumatic or hydraulic cylinders clamp the profiles immovably. This fixation is essential; any movement during welding will compromise the joint. Clamping fixtures (often called “jaws” or “tools”) are precisely matched to the profile system geometry to prevent deformation of the hollow chambers.

Phase 2: The Hot Plate (Mirror Welding)

A central component—the welding mirror (one or more heated metal plates, typically with a non-stick coating such as PTFE/Teflon)—is brought to welding temperature. For rigid PVC, this is typically 240–260 °C.

Heating (plasticizing): The mirror moves between the clamped profile ends. The profiles are pressed against it at a defined preheat pressure. Heat penetrates the material and plasticizes the cut surfaces to a depth of a few millimeters (approx. 2–3 mm). The duration (preheat time) is critical: too short produces a “cold weld” (insufficient fusion); too long burns the material, releases corrosive gases (HCl), or deforms the profile.
Changeover time: After reaching the target plasticization depth, the profiles retract slightly, the mirror withdraws rapidly. This interval must be extremely short (often under 2–3 seconds) to prevent cooling or oxidation of the melt, which would drastically reduce joint quality.

Phase 3: Forge Pressure and Cooling

Immediately after mirror removal, the plasticized profile ends are pressed together at a precisely defined forge pressure.

Joining: The pressure ensures complete intermixing of the melt zones. Long PVC polymer chains entangle (diffusion) to form an inseparable, homogeneous joint on cooling.
Material displacement (weld bead): Excess melt is expelled from the joint, forming the characteristic weld bead on the inside and outside corner.
Cooling: Profiles must remain clamped under forge or hold pressure until the melt cools below the glass transition temperature (for PVC approx. 80 °C) and solidifies sufficiently. Premature unloading causes the joint to “tear” (shrinkage stress) or the frame to warp.

After cooling, the clamps release and the finished frame (or corner) is removed and transferred to the next process (corner cleaning).

The Significance of the Weld Bead

While aesthetically undesirable, the weld bead is an important quality indicator. A uniform bead indicates sufficient plasticization and correct forge pressure.

Traditionally, the bead is removed mechanically in the subsequent corner cleaning step. Modern technologies aim to minimize or precisely control the bead on visible surfaces.

Types of Plastic Window Welding Machines

The market offers different machine types, varying by automation level, capacity, and application. The choice depends directly on plant size and desired output.

Single-Head Welding Machines (For Specials and Small Batches)

Function: One corner is welded at a time. To produce a complete frame, the operator loads and runs the process four times.
Advantages: Low investment, small footprint, high flexibility (ideal for arches, triangles, sharp angles, or repair work).
Disadvantages: Very low productivity; high labor cost per unit; dimensional accuracy depends heavily on operator care and cut quality.
Use: Small shops, prototyping, special work in larger plants.

Two-Head Welding Machines (Parallel and Corner Welding)

Function: Two welding units. They can weld two corners in parallel (often mullions) or prepare two frame halves (U-shapes) for a second pass to close the frame.
Advantages: Significantly faster than single-head; more flexible than four-head machines.
Disadvantages: Still requires two to three passes to complete a frame; dimensional stability is better than single-head but below four-head.
Use: SMEs requiring higher throughput without fully utilizing a four-head line.

Four-Head Welding Machines (The Industrial Standard)

Function: Four welding units, typically arranged at 90°. The operator (or an automation system) loads all four cut profiles (two rails, two stiles) simultaneously. The machine clamps, inserts the hot plates, and welds all four corners in one cycle.
Advantages: Extremely high productivity (one complete frame per cycle, often under 2–3 minutes); highest precision and dimensional stability (the frame is clamped and welded as a whole).
Disadvantages: Higher investment; reduced flexibility for special shapes (though modern systems can weld variable angles).
Use: Industrial window manufacturers with medium to high volumes.

Six- and Eight-Head Machines (High-Volume Production)

Function: For absolute mass production (e.g., large projects or standardized markets). A six-head machine can weld a frame with an integrated mullion in one cycle; eight-head machines can weld two smaller frames simultaneously or complex door frames (e.g., with two mullions).
Advantages: Maximum output per unit time.
Disadvantages: Extremely high investment; very low flexibility; economical only for very large uniform series.
Use: Large-scale industry and specialized project manufacturers.

Horizontal vs. Vertical Welding Systems

Horizontal (standard): Profiles are loaded and welded lying down. This is the most common type because it is easy to load and integrates well into a horizontal production line (saw → machining center → welding → cleaning).
Vertical: Profiles are processed standing. This design is gaining ground because it is often more space-efficient and better suited to automated logistics (buffer stores, transfer carts). Gravity can assist precise positioning.

The Technology Behind the Perfect Weld

Weld quality depends not only on the machine but on the precise interaction of parameters tailored to the specific profile.

Mirror Welding (Hot-Plate Welding) – The Gold Standard

As described, hot-plate welding dominates. The key is optimal temperature control of the mirror. High-quality machines use precise PID controllers to maintain mirror temperature within ±1–2 °C. The PTFE (Teflon) coating is a wear part; if damaged, PVC adheres to the mirror, burns, and contaminates the next weld, causing visual defects and reduced strength.

Parameter Control: Temperature, Time, and Pressure

For each profile system (each series from a profile supplier), welding parameters must be determined precisely and stored in the PLC. These “recipes” are the heart of the know-how.

Temperature: Too high burns PVC (HCl release, discoloration); too low leads to insufficient fusion (cold weld).
Time (preheat and cooling): Strongly dependent on profile mass and ambient temperature. A massive door section needs longer preheat than a slender glazing bead; color also matters (dark profiles absorb heat differently).
Pressure (preheat and forge): Preheat pressure ensures contact with the mirror; forge pressure ensures diffusion. Excessive forge pressure displaces too much material (“starved” joint); too little prevents adequate diffusion.

The Role of Profile Geometry

Modern plastic profiles are complex (e.g., 5-, 6-, or 7-chamber systems). The welding machine must ensure uniform heat input and prevent collapse of internal webs. Depth stops or bead limiters are often used to prevent profiles from being pressed too deeply into the melt.

Welding Laminated and Colored Profiles (Special Challenges)

Laminated (decor foils such as woodgrain) and colored (through-colored or coextruded) profiles pose particular challenges:

Heat sensitivity: The foil is heat-sensitive; the hot plate must not damage or burn the exterior surface.
Aesthetics: Traditional welding forms a bead. During cleaning, the bead (and thus the foil) is milled off, exposing bare PVC at the corner (usually white or brown), interrupting the woodgrain or color.

Solutions:

Touch-up pens: Manual recoloring (time-consuming, variable durability).
Weld bead limiters (e.g., 0.2 mm): Special PTFE forms or blades at the mirror shape the melt to create a minimal, defined bead that is barely visible.
Zero-joint technology: The most advanced solution, avoiding the problem entirely.

Innovative Welding Technologies: Zero-Joint and V-Perfect

The pursuit of the “perfect corner” has revolutionized the industry. Especially for laminated profiles, traditionally cleaned welds were a visual compromise. Technologies known as zero-joint, V-Perfect, seamless welding, or contour-following welding address this.

The Problem with Traditional Welds

With classic welding and cleaning, the bead is planed or milled off. A shallow groove—or at least a visible interruption—remains at the visible edge, which can also accumulate dirt.

Technology to Avoid the Weld Bead

The innovation is to modify the welding process so that displaced material does not extrude uncontrollably outward but is intentionally formed or directed inward.

Mechanical pinching/forming: Some systems use blades or slides that pinch or actively shape the melt at the visible edge during forging, channeling it into cavities or to the non-visible interior of the corner.
Contour-following forming (e.g., V-Perfect): Other systems use specially shaped, often heated tools that effectively “iron” the corner during cooling and bring the foil edges together perfectly. This requires extremely precise mitre cuts.

Seamless Aesthetics: Appearance Meets Strength

The result is an almost seamless corner. The mitre may remain as a fine line (hence “V-cut”/“V-Perfect”), but there is no wide, cleaned groove. The foil visually continues “around the corner.” This is not only an aesthetic leap but also improves cleanability (no groove to trap dirt). When correctly parameterized, corner strength remains at the highest level.

Practical Advantages of Zero-Joint Technology

Machines capable of this (often specialized four-head welders) offer significant benefits:

Superior aesthetics—particularly for woodgrain and dark trend colors (e.g., anthracite grey).
Elimination of rework—manual touch-up with pens is unnecessary.
Higher process security—fewer manual steps mean fewer error sources.

These systems demand even more precise control and often profile-specific tooling. Companies like Evomatec have played a key role in developing precise, process-reliable machines to enable this step-change in quality.

Downstream Process: The Corner Cleaning Machine

A plastic window welder rarely operates alone. In industrialized production, a corner cleaning machine (also called cleaner or corner processor) follows immediately.

Why Must Weld Seams Be Cleaned?

With traditional welding (without zero-joint), the bead must be removed for two reasons:

Functional: The inner bead (in glazing and hardware rebates) would hinder installation of glass and fittings.
Aesthetic: The outer bead on visible faces is visually undesirable.

Integration of Welding and Cleaning

In modern weld-clean lines, the four-head welder transfers the finished frame automatically (e.g., via a cooling table) to the cleaner. The cleaner clamps the frame and processes the freshly welded corners with knives, cutters, and drills.

A typical cycle includes:

Top/bottom planing: Knives remove the bead from flat visible faces (leg surfaces).
Inner-corner cleaning: Special knives/cutters clean complex contours in glazing and hardware rebates as well as gasket grooves.
Outer-corner contour milling: A cutter follows the outer profile to remove the bead and round or chamfer the corner.
(Optional) Drilling drainage slots or hardware holes directly in the corner.

The Path to a Finished Window Corner

Only the interaction of precise welding and clean finishing yields the final corner. With zero-joint machines, the aesthetic exterior milling is largely unnecessary; functional cleaning of the inner corners (rebates) is usually still required.

Applications and Industries

The plastic window welding machine naturally belongs to a clearly defined industrial sector.

Core Window and Door Manufacturing

This is the primary application. Companies producing windows, patio doors, balcony doors, and entrance doors made of plastic (PVC) for residential and commercial construction—as well as renovation—are the main users.

Special Constructions and Façades

Although aluminium often dominates façade construction, welded plastic elements are used in specific applications (e.g., combined with post-and-beam systems). Conservatory and specialty skylight manufacturers also employ adapted welding techniques.

From Small Shops to Industrial Lines

Small fabricators: Often use single-head machines for flexible small orders or repairs.
SMEs: The backbone of the industry. They typically rely on flexible two-head or highly efficient four-head machines, often combined with cleaners into compact lines.
Large-scale industry: Fully automated weld-clean lines with four- or six-head machines, automatic loading (gantry loaders), and integration with central production control (ERP/PPC).

Advantages of Modern Plastic Window Welding Machines

Precision and Repeatability

Modern CNC/PLC-controlled machines ensure identical welds every time. Adherence to parameters (temperature, time, pressure) guarantees consistently high quality unattainable manually, resulting in dimensionally accurate frames that greatly simplify downstream glazing and installation.

Structural Strength and Corner Tightness

The weld is the frame’s structural backbone. Properly executed welds (especially with steel reinforcement) provide exceptional torsional stiffness. At the same time, the monolithic corner is absolutely air- and watertight—crucial for thermal performance (U-value) and durability.

Efficiency and Production Speed

A four-head welder produces a complete, dimensionally stable frame in under three minutes. This cycle time forms the basis of profitable series production. Integration into lines with saws and cleaners minimizes manual handling, reduces labor cost per unit, and shortens throughput times.

Cost Efficiency and Material Savings

Precise welding reduces scrap. “Cold welds” or burnt profiles—common with manual or outdated machines—are costly. Modern machines also optimize material displacement (the portion forming the bead), so only the necessary amount of profile is consumed.

Challenges and Considerations

High Capital Expenditure

The most obvious drawback: industrial plastic window welding machines—especially four-head models or those with zero-joint technology—require substantial investment, reaching six figures depending on automation and features.

Energy Consumption and Maintenance

Heating large hot plates (four on a four-head machine) above 240 °C is energy-intensive. Although modern machines are better insulated, use smarter heating cycles, and employ energy-saving components (e.g., servomotors instead of pneumatics), energy demand remains a relevant cost factor.

These machines also require maintenance. PTFE films on mirrors must be replaced regularly; clamping fixtures need cleaning; pneumatics/hydraulics and guides must be inspected.

Calibration and Setup Complexity

A welding machine is not plug-and-play. It must be calibrated precisely to the profile systems used. Switching, for example, from a 5-chamber to a 7-chamber profile often requires different clamping tools (contour jaws) and always parameter adjustments in the control system—tasks for trained personnel.

Quality Assurance and Maintenance: Critical Factors

A plastic window welding machine delivers consistently high results only if perfectly maintained and calibrated. Quality assurance in the welding process is therefore central.

The Importance of Regular Calibration

The three pillars—temperature, time, pressure—must be checked regularly. Temperature sensors can drift; pneumatic pressures can fluctuate. Even small deviations can impair joint strength. Quality assurance also includes corner strength testing (destructive testing) to validate attained strength.

Maintaining Hot Plates and Clamping Fixtures

Deposits of burnt PVC dust on clamping jaws or damaged PTFE films on the mirror are among the most common causes of defective welds. Daily cleaning and preventive maintenance are essential to minimize downtime.

Our Expertise in Ensuring Quality and CE Compliance

Commissioning and maintaining such complex systems requires deep expertise. Based on many customer projects, we ensure that inspections are carried out with the utmost diligence with respect to quality and CE-compliant safety. A machine that does not meet CE requirements (e.g., protective devices, emergency circuits, electrical safety) presents a significant risk to operators and staff.

Troubleshooting: Common Welding Issues

Cold weld (insufficient strength): Temperature too low, preheat time too short, or changeover too long; the joint fails easily, and the fracture surface appears crystalline rather than ductile.
Burnt weld (visual defect): Temperature too high or preheat time too long; PVC discolors (yellow/brown) and becomes brittle.
Angular or dimensional errors (distortion): Profiles not clamped correctly (e.g., dirty stops), machine not mechanically square, cooling time too short (frame warps on removal).
Poor aesthetics (with zero-joint): Incorrect tooling, wrong parameters, or inaccurate mitre cuts (saw and welding machine must be perfectly coordinated).

Integration into Production 4.0

Modern welding machines are no longer isolated “islands.” They are integral components of the digitized and networked factory (Industry 4.0).

Networking Welding Machines with Production Planning (PPC/ERP)

Production data (frame type, dimensions, profile) no longer arrives on paper but digitally from the office (ERP/PPC) directly to the machine. The machine often sets itself to the correct dimensions (on four-head machines) and loads the correct welding program (recipe) for the detected profile.

Data Capture and Process Optimization

Conversely, the welding machine sends data back: frames welded, alarms/faults, energy consumption. This big data enables end-to-end traceability for each window and helps identify bottlenecks or quality fluctuations.

Remote Diagnostics and Predictive Maintenance

Modern controls allow service technicians (e.g., from Evomatec) to access machines remotely, diagnose faults, and adjust parameters without being on-site. Sensors monitoring the condition of wear parts (e.g., hot plates, PTFE films) can predict when maintenance will be required (predictive maintenance) before a failure occurs.

Economics: Costs and ROI

Capital Costs by Machine Type

Used single-head machines: a few thousand euros.
New single-head machines: approx. €10,000–20,000.
New two-head machines: approx. €30,000–60,000.
New four-head machines (standard, traditional welding): approx. €80,000–150,000.
New four-head zero-joint lines with integrated corner cleaner: often €250,000 and significantly more, depending on automation.

Operating Costs (Energy, Labor, Maintenance)

In addition to acquisition, operating costs apply. While a four-head line has higher energy consumption, it requires significantly less labor per frame than four single-head machines. Maintenance costs (PTFE, knives) rise with throughput, but on a per-unit basis are typically lower.

Payback (ROI) for Window Manufacturers

ROI is usually calculated through labor savings and output increases.

Example (simplified): A plant produces 50 window units per day.

Single-head: 1 operator, 4 welds per frame, ~10 min/frame (incl. handling) → ~8.3 hours pure welding.
Four-head: 1 operator, 1 weld cycle per frame, ~2.5 min/frame (incl. handling) → ~2.1 hours pure welding.

Savings: Over 6 hours of labor per day, allowing the operator to handle loading, logistics, and quality checks. The investment in a four-head machine often pays back within 2–4 years through labor savings and the ability to increase output.

Used vs. New

The used market for welding machines is substantial and can be attractive for limited budgets or as an entry point. Caution is required: the mechanical condition (guides, pneumatics) and control system (spare-part availability) are crucial. With comprehensive technical acceptance—including CE safety—older machines can be viable; outdated systems that fail today’s energy or safety standards can quickly become cost traps.

Evomatec and the Evolution of Window Welding Technology

As a provider of high-quality machinery solutions for plastic window production, Evomatec operates at the intersection of innovation and practical manufacturing. We understand that a welding machine is not just a product but a central value-creation asset for our customers.

Our Approach to Optimizing Welding Processes

We focus on machines that weld precisely while being robust, user-friendly, and energy-efficient. We analyze each plant’s specific requirements—from profile systems to target throughput—and configure the appropriate technology, whether a flexible two-head solution for mid-sized manufacturers or a fully automated zero-joint line for industrial producers.

The Importance of Service and Support in Mechanical Engineering

A machine is only as good as the service behind it. Fast response times for faults, reliable spare-part supply, and competent operator training are a given for us. Drawing on experience from numerous customer installations, Evomatec ensures that all inspections and maintenance comprehensively cover CE safety and manufacturing quality.

Outlook and Trends

Robotics and Full Automation of Frame Production

The step beyond the automatic weld-clean line is the “lights-out” factory, where robots handle logistics end-to-end: removing profiles from the saw, inserting steel reinforcement, loading the welder, and stacking finished frames.

Energy Efficiency and Sustainability in Welding

With rising energy costs, hot-plate efficiency is increasingly important. Faster heat-up times, improved insulation, and smarter standby modes will reduce energy consumption. Minimizing “waste” (i.e., bead mass) also contributes to sustainability.

New Materials and Composites

The window industry is experimenting with new materials, such as PVC composites (glass-fiber reinforced) or profiles with recycled core material. These materials require adjusted welding parameters (temperatures, pressures; fiber behavior in the melt) that future machines must address.

AI-Assisted Quality Control

Rather than merely controlling parameters, future machines may monitor welding in real time. Vision systems (optical inspection) or sensors measuring melt viscosity could, with AI, detect deviations (e.g., contamination on the profile) and immediately adjust parameters to guarantee a perfect seam.

Selecting the Right Plastic Window Welding Machine

Needs Analysis: How Many Units Do You Produce?

The most important question is output. A four-head machine running only two hours a day is not economical; a single-head machine in three-shift operation becomes a bottleneck. Capacity must match demand.

Flexibility Requirements (Specials vs. Series)

If a plant primarily produces rectangular standard windows, a four-head line is ideal. If many triangles, arches, or custom dimensions are made, a flexible single-head or two-head machine (or a special angle-adjustable four-head) is preferable.

Space and Infrastructure

A complete weld-clean line can exceed 20 meters in length. Space is a critical factor. Utilities (power, compressed air) must also be available. For complex planning and technology selection, an experienced partner is essential. With Evomatec consulting and commissioning, customers benefit from deep experience ensuring every inspection meets the highest standards of quality and CE safety.

FAQ – Frequently Asked Questions About Plastic Window Welding Machines

What Is the Difference Between Mirror Welding and Other Methods?

Mirror (hot-plate) welding is a butt-welding process that melts the two faces to be joined and fuses them under pressure. Other methods, such as hot-air welding (more common for roofing membranes) or friction welding, are unsuitable for window-profile geometries. Hot-plate welding offers the best balance of stability, sealing, and process speed for PVC hollow-chamber profiles.

How Long Does a Welding Cycle Take?

Duration depends strongly on the profile (material mass, color) and the machine. A complete cycle (clamp, heat, join, cool, release) on a modern four-head machine for a standard plastic window frame typically takes 1.5–3 minutes. Single-head machines require a similar time per corner, quadrupling the per-frame time (plus handling).

Can Colored (Laminated) Plastic Profiles Be Welded Reliably?

Yes—this is standard today—but requires special technologies. Because traditional cleaning would damage the foil (exposing bare PVC), the visible-side bead must be limited. This is achieved either with bead limiters (typically 0.2 mm blades) or—for the best appearance—with zero-joint technologies (e.g., V-Perfect) that form the corner without a visible bead and bring the foil edges together cleanly.

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