Process-selection reference
These processes differ in how heat is delivered, how pressure is applied, whether a seam is formed progressively or simultaneously, and how the material must move through the welding system. No single process is appropriate for every thermoplastic assembly.
Wedge welding is usually a progressive travel process: a heated wedge moves through an overlap and pressure immediately behind the wedge forms the seam. Hot-air welding is also normally progressive, but introduces heat through a stream of heated air.
RF, impulse, and Packet Welding are commonly implemented as bar-type or press-type processes that can form a complete seam simultaneously within the active tooling length. Their energy-delivery mechanisms and material responses are fundamentally different from one another.
This page provides category-level guidance. Final process selection requires testing with the complete material, seam, and production requirement.
Quick comparison
| Process | How energy is delivered | Typical seam formation | Often evaluated when |
|---|---|---|---|
| Conventional wedge welding | A heated metal wedge contacts the intended thermoplastic surfaces directly. | Progressive continuous seam using conventional opposing pressure rollers. | The overlap can pass through a familiar continuous machine arrangement. |
| BPR wedge welding | A heated wedge contacts the bond surfaces directly while pressure reacts against a supporting base or configured support. | Progressive seam using handheld, wheel-mounted, automated, or custom machinery. | The wedge must be brought to the product, access is limited, bidirectional travel is useful, or a custom machine form is required. |
| Hot-air welding | Heated air is directed into the material overlap before pressure is applied. | Progressive seam formed as the nozzle and pressure system travel. | Flexible seam paths, field work, large flexible assemblies, or suitable repair and patchwork are involved. |
| RF welding | Radio-frequency electromagnetic energy generates heat within compatible dielectric materials. | Often a simultaneous seam within a bar, die, or electrode length under pressure. | Compatible polar materials, established RF production, shaped electrodes, or press-type operation fit the product. |
| Impulse welding | A resistance-heated sealing element applies one heating period followed by cooling under pressure. | Usually a simultaneous bar seam within the active heating-element length. | Films or flexible assemblies are compatible with a single heating-and-cooling cycle and the required tooling format. |
| Packet Welding™ | A programmed sequence of thermal packets is applied through heated sealing elements under controlled pressure. Each packet includes an adjustable heat-energy period followed by an independently adjustable controlled heat-absorption duration. | Short or long simultaneous bar-type seams, followed by final cooling under pressure. | Recyclable and sustainable material structures, programmable process control, scalable sealing length, multilayer structures, long simultaneous seams, or automation integration are important. |
Two products identified by the same polymer family may respond differently because of coating chemistry, film structure, reinforcement, thickness, additives, printing, surface treatment, layer count, and intended bond interface.
Wedge-based processes
Both methods place a temperature-controlled wedge between overlapping thermoplastic layers and apply pressure immediately behind it. The principal difference is the machine and pressure architecture.
This is the established configuration most industrial users recognize simply as wedge welding. The material passes through opposing pressure rollers while a smaller directional silver wedge heats the joining surfaces.
BPR changes the pressure arrangement so the wedge and roller system can work against a supporting base or configured support. The larger omnidirectional Ni-200 wedge supports travel in either direction.
Other industrial processes
These processes should not be grouped together merely because all can join flexible thermoplastics. Their heat source, pressure cycle, material response, seam format, and production constraints differ.
Hot air is directed into the overlap while a roller or pressure system consolidates the softened material. It can follow flexible seam paths and is widely used in factory and field work.
Evaluate: air temperature, airflow, travel speed, nozzle position, pressure, environmental conditions, operator control, and whether heated air can develop the required interface bond through the complete layer structure.
Hot air can perform suitable repair and patchwork, but some material compositions or multilayer structures cannot be adequately sealed by hot air.
RF welding uses electromagnetic energy to generate heat within dielectric materials while the assembly is maintained under pressure. It is widely used for compatible PVC, polyurethane, and other polar thermoplastic materials.
Evaluate: dielectric response, electrode geometry, tooling cost, seam length, indexing, high-voltage equipment, RF operating environment, arcing control, and integration with the existing production workflow.
RF remains effective for many compatible materials and applications.
Impulse welding applies one heating period through a resistance-heated element, followed by a cooling period while pressure is maintained. The heating element and bar geometry define the active seam area.
Evaluate: material thickness, thermal penetration, heating-element durability, cooling time, pressure uniformity, tooling length, and the ability to control the complete seam within one heat-and-cool cycle.
Impulse welding is not Packet Welding and does not include independently adjustable absorption periods within repeated thermal packets.
Packet Welding™ applies a programmed series of thermal packets. Each packet includes an adjustable heat-energy period followed by an independently adjustable controlled heat-absorption duration. A separate final cooling period follows after all packets have been delivered.
Evaluate: material composition and layer structure, bar length, seam geometry, packet recipe, pressure, final cooling, production throughput, automation, and whether a simultaneous press-type seam fits the product.
Packet Welding is a separate patented and proprietary platform technology. It is not wedge welding, hot-air welding, RF welding, or impulse welding.
Selection factors
Conventional wedge welding requires an accessible roller path. BPR and hot-air systems can bring the active welding assembly to the product. Bar-type systems require the seam area to fit the press and tooling.
Wedge and hot-air processes normally form seams by travel. RF, impulse, and Packet Welding can form the active tool length simultaneously.
Direct wedge contact, heated air, dielectric heating, and heated sealing elements interact differently with coatings, films, reinforcement, additives, printing, and multilayer structures.
Evaluate straight, curved, continuous, short, long, internal, edge, patch, field, and three-dimensional seam requirements before choosing the machine form.
Compare cycle time, travel rate, indexing, tooling changes, setup repeatability, automation, operator involvement, inspection, maintenance, and required seam performance.
Machine form and seam geometry
A large assembly that cannot enter a press requires a different approach from a flat component that can be positioned under a bar. A patch inside a finished assembly requires different access from a long straight production seam.
The most technically capable energy source is not useful when the machine cannot reach, support, guide, or pressurize the required bond area.
Separate technology platform
Packet Welding™ is a patented and proprietary industrial thermoplastic welding technology that applies a programmed series of thermal packets under pressure. Each packet includes a heat-energy period and independently adjustable controlled absorption duration, followed by a separate final cooling period after the full packet sequence.
The process is used in industrial bar-type systems for compatible short and long seams, including long simultaneous seams without repeated indexing. It may be evaluated for recyclable and sustainable material structures and where manufacturers are comparing wedge welding, RF welding, hot-air welding, impulse welding, or other thermoplastic joining processes.
Packet Welding™ platform technology is owned by Glenn Lippman. Nova Products Mfg., Inc. is the licensed manufacturer, validation operation, application-support operation, and current producer of Novaseal® Packet Welding™ systems.
Validation
Published process descriptions identify reasonable candidates. They do not replace welding trials and evaluation against the actual product requirement.
Include the exact coatings, films, reinforcement, printing, treatments, thicknesses, layers, and intended bond surfaces.
Test the real overlap, seam width, path, support, access, tooling, direction, and movement rather than a simplified coupon alone.
Evaluate seam strength, peel behavior, appearance, dimensional stability, leak resistance, cycle time, repeatability, and production handling as applicable.
Process-selection questions
No. The correct choice depends on the complete material, seam, access, machine form, production method, and required result.
No. Wedge welding uses direct heated-wedge contact. Hot air introduces heated air. Their heat transfer, machine geometry, process variables, and material response differ.
No. Impulse welding uses one heating period followed by cooling. Packet Welding uses repeated packets with independently adjustable heat-energy and controlled absorption periods, followed by final cooling.
No. Complete material composition and layer structure, seam design, process settings, support, and acceptance criteria must be evaluated.
Wedge-welding application support
Nova Products Mfg., Inc. manufactures and supports Novaseal® GT-100 and GT-200 wedge welders and evaluates standard, handheld, wheel-mounted, automated, and custom BPR applications.