Hot gas welding, solvent cement bonding, structural adhesive bonding, and cryogenic deburring — every joining and finishing method your plastic fabrication project requires, applied by an experienced team that knows which one to use and when.
Joining plastic parts correctly requires more than picking up the nearest tube of adhesive. The geometry of your part, the material it’s made from, the service environment it will operate in, and whether the joint needs to be invisible, pressure-tight, chemically resistant, or structurally load-bearing all determine which joining method is right. At Plastic-Craft, we offer the full range of plastic joining methods — welding, solvent bonding, and structural adhesive bonding — along with cryogenic deburring to deliver production-ready, finished assemblies from a single source.
| Plastic Welding | Solvent Bonding | Structural Adhesive | |
|---|---|---|---|
| Joint Type | Molecular fusion — parent material continuity | Molecular fusion — solvent dissolves & re-fuses | Adhesive interface — separate bonding agent |
| Optical Clarity | Not applicable | Excellent — best for transparent plastics | Good to excellent (UV-cure) |
| Joint Strength | Approaches parent material | Approaches parent material | Good — limited by adhesive |
| Chemical Resistance | Same as parent material | Same as parent material | Dependent on adhesive chemistry |
| Temp Resistance | Same as parent material | Same as parent material | Limited by adhesive rating |
| Dissimilar Materials? | No — same family required | No | Yes — plastic to metal, glass |
| Pressure Containment? | Yes | Application-dependent | Application-dependent |
| Polyolefins (PE, PP)? | Yes | No — not solvent-sensitive | Yes, with surface prep |
| Best For | Structural, fluid-handling, repair | Display-quality transparent assemblies | Thin sheet, dissimilar materials, gap-filling |
Not sure which approach fits? Send us your drawing and material specifications and our engineering team will recommend the right method before work begins.
Plastic welding joins two thermoplastic components by applying controlled heat and pressure to fuse the material at the joint interface — creating a bond that is molecularly integrated into the parent material. When performed correctly, a welded joint can approach or match the strength of the base material, making welding the preferred method for structural, pressure-containing, and fluid-handling fabrications.
Only thermoplastic materials can be welded. Thermoset plastics like phenolic cure permanently and do not re-melt, so they must be joined by mechanical fastening or adhesive bonding instead.
Hot Gas Welding uses heated air or inert gas directed at the joint alongside a compatible filler rod. The operator works the weld bead along the joint similar to manual TIG welding. Highly versatile and applicable to almost any joint geometry — the standard method for custom fabrication, tank construction, ductwork, and repair.
Extrusion Welding uses a handheld extruder that melts and continuously deposits filler material into the joint — similar to MIG welding. Faster filler deposition per pass makes it preferred for thick-section welds, tank fabrication, and structural joints.
Hot Plate Welding melts two mating surfaces against a heated platen, then presses them together under controlled force as the platen is removed. Produces clean, flash-free butt joints — commonly used for symmetrical parts and pipe or sheet edge joining.
Acrylic (PMMA), Polycarbonate (PC), Nylon (PA), UHMW Polyethylene, Polyethylene (PE), HDPE, PVC, Noryl (PPO), PETG, Polypropylene (PP), Polystyrene (PS), Polyurethane (PU), Ultem (PEI), Vinyl.
Acetal/Delrin, Teflon (PTFE), PEEK, Torlon, and Vespel require specialized parameters or inert gas shielding — contact us. Thermosets including Phenolic cannot be welded.
Solvent bonding uses a liquid solvent cement that temporarily dissolves the plastic surface at the joint interface. When the two surfaces are brought into contact under controlled pressure, the dissolved layers intermingle — and as the solvent evaporates, a true molecular fusion bond is formed. The joint is not a separate adhesive layer — it is a continuation of the parent material itself.
This produces the highest-quality, most optically clear joints achievable in transparent plastics — the standard for display cases, aquariums, and any application where joint visibility is unacceptable. Done correctly, a solvent-bonded acrylic joint is virtually invisible.
Compatible: Acrylic, Polycarbonate, PVC, PETG, Polystyrene, ABS, Noryl, Ultem, Vinyl. Not applicable to polyolefins (PE, PP, HDPE) or fluoropolymers (PTFE).
Structural adhesives — two-part epoxies, cyanoacrylates, UV-cure adhesives, methacrylates, and polyurethane adhesives — are used where solvent bonding is not applicable or where specific performance requirements call for an adhesive system. Applications include polyolefins and low-surface-energy plastics that cannot be solvent bonded; dissimilar material bonding (plastic to metal, plastic to glass); gap-filling joints; impact and vibration-resistant assemblies; and UV-cure optical bonding for crystal-clear optical elements.
| Solvent Bonding | Structural Adhesive | |
|---|---|---|
| Joint Type | Molecular fusion | Adhesive interface |
| Optical Clarity | Excellent — best available | Good to excellent (UV-cure) |
| Materials | Solvent-sensitive thermoplastics | Most materials incl. polyolefins |
| Dissimilar Materials? | No | Yes |
| Gap Filling? | No — requires tight fit | Yes |
| Best For | Display-quality transparent assemblies | Polyolefins, metal/plastic, complex geometries |
Burrs and flash are unavoidable byproducts of plastic and rubber manufacturing. Cryogenic deburring uses liquid nitrogen to rapidly chill parts to −100°F to −300°F, selectively embrittling thin flash and burrs while the main part body stays intact. A controlled blast of cryogenic media then fractures and removes only the embrittled material — delivering clean, consistent deburring across 100% of the part surface in a single cycle.
| Cryogenic Deburring | Manual Deburring | |
|---|---|---|
| Consistency | 100% consistent across all parts | Operator-dependent |
| Speed | High — full batch per cycle | Slow — per-part manual labor |
| Internal Features | Yes — reaches all surfaces | Difficult |
| Damage Risk | Very low — controlled process | Higher — tool marks possible |
| Volume Suitability | Excellent | Poor |
| Cost at Volume | Lower | Higher |
Compatible materials: Nylon, Acetal/Delrin, PP, PE, HDPE, PVC, PETG, PS, PU, Noryl, Ultem, Hydlar Z, Vinyl, and rubber/elastomeric molded parts. Very thin-walled or delicate features should be reviewed before processing.
APPLICATIONS
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We review part drawings, material specs, joint geometry, and application requirements to confirm the right method. For multi-method assemblies, the full sequence is planned before work begins.
Filler rods matched to parent material for welding. Solvent cements selected for specific plastic grade. Adhesive systems chosen based on substrate chemistry and service environment. Surface preparation completed before joining begins.
Welding, bonding, or cryogenic deburring performed using parameters appropriate to material and application. Joint fit-up, mating surface quality, and cycle parameters verified before processing.
Welded joints cooled fully before handling. Bonded assemblies fixtured and cured under appropriate conditions. Cryogenically deburred parts returned to ambient temperature before inspection.
Finished assemblies inspected for joint quality, dimensional integrity, and surface condition. Leak testing available for fluid-handling assemblies where required.
Plastic welding fuses the parent material itself — heat brings the thermoplastic to melt temperature, the surfaces intermingle, and the joint solidifies as a continuation of the base material with no separate bonding agent. Adhesive bonding uses a separate adhesive at the interface — joint strength and chemical resistance are determined by the adhesive, not the parent plastic. Welded joints generally offer superior performance for demanding environments; adhesive bonding is right for dissimilar materials and those that cannot be welded.
All thermoplastics can be welded — plastics that soften when heated and resolidify when cooled. Common weldable plastics include polyethylene (PE, HDPE, UHMW), polypropylene (PP), PVC, acrylic (PMMA), polycarbonate (PC), nylon, and many others. Thermoset plastics such as phenolic cannot be welded because they do not re-melt once cured.
A properly executed plastic weld can achieve 80–90% of the tensile strength of the parent material, and in some cases approaches 100%. Weld strength depends on correct temperature control, filler rod compatibility, joint preparation, and operator skill.
Solvent bonding uses a liquid solvent cement to temporarily dissolve the plastic surfaces at the joint interface, allowing them to fuse together as the solvent evaporates. The result is a molecular fusion bond that approaches the strength and clarity of the parent material. It is the preferred method for display-quality acrylic and polycarbonate fabrications where joint visibility must be minimized.
No. Polyolefins are not solvent-sensitive — solvents do not dissolve their surfaces. These materials are joined by structural adhesive bonding with appropriate surface preparation, mechanical fastening, or plastic welding.
Invisible solvent bonds in acrylic require perfectly flat, cleanly cut, and polished mating surfaces with intimate contact across the full joint area; the correct solvent cement for the specific acrylic grade; careful, even application to avoid air entrapment and flow lines; and appropriate fixturing and cure time under controlled conditions.
Cryogenic deburring uses extreme cold to selectively embrittle thin flash and burrs on plastic and rubber parts, then removes them with a controlled blast of cryogenic media — without damaging part geometry. It produces consistent, complete deburring across 100% of the part surface in a single cycle, far more consistently and economically than manual deburring at volume.
No. The process removes only flash and burrs that project beyond intended part geometry. Media blast energy is calibrated to fracture embrittled thin material while leaving dimensioned surfaces intact. Parts are inspected after processing to confirm dimensional integrity.
Hot gas welding uses a stream of hot gas to heat the parent material and filler rod simultaneously, with the operator manually working the weld bead — similar to TIG welding. Extrusion welding uses a motorized extruder to continuously deposit molten filler into the joint for faster deposition — similar to MIG welding. Extrusion welding is typically faster for heavy fabrication; hot gas welding offers more flexibility for complex geometries.
Mechanical deburring uses abrasive or cutting tools through direct contact — it can cause tool marks, dimensional changes, and inconsistent results on complex geometries. Cryogenic deburring uses thermal mass differential: flash embrittles faster than the part body when chilled, allowing selective removal without mechanical contact on dimensioned surfaces.
Guides and articles on plastic welding, bonding, and deburring.
When to weld, when to bond, and how to decide for your application.
Surface prep, solvent selection, and technique for display-quality acrylic bonds.
How cryogenic deburring works and when it outperforms manual methods.
Whether you need a structural fabrication welded, a display-quality assembly bonded, or production flash removed from a molded part run, Plastic-Craft has the methods, the materials, and the experience to deliver. Share your requirements and we’ll recommend the right approach and provide a quote.
