Infrared vs. Hot Plate Welding



Highly accurate part temperature control based on utilization of Phase Angle Control type logic and Power Control (line/load regulation) Transformers Accurate part temperature control based on feedback from thermocouples into temperature controllers.
Temperature control requires constant incoming voltage as system does not allow for readily available feedback from output/tooling.  Correction for varying incoming voltage (5% or more) requires costly Power Control Transformer. Temperature control not easily affected by voltage.  Feedback from the thermocouples built into the heat platen allow the system to correct for variable incoming voltage.  Power Control Transformer not required even when incoming voltage varies.
Instant on/off design requires no warm-up time (pre-heating) and allows faster tooling changeover (no cool-down required). Warm-up time (Preheating) required for roughly 20-40 minutes prior to start of production. Tool changes often require cooling of the heat platen to tolerable temperatures prior to changing tooling.
Lower power requirement.  Higher power drawn only when IR turned on. Higher power requirement.  Heaters constantly pulsing on/off throughout day to constantly maintain temperature.
Cost increase up to 60% or more dependant on emitter design (custom vs. standard) and whether or not Power Control Transformers are needed.  Incoming voltage variances can create IR output density changes which are not readily apparent to the equipment via feedback. Much lower cost system overall.  Constant voltage transformers not required as heat platen incorporates temperature controllers which provide feedback of actual platen temperature.
Very cost effective when designing a common emitter platen and change of masks only. Typically, heat platens are designed for optimal temperature distribution for each application, often requiring an optimized heat platen with each tool.
Emitters last only a few years and are very expensive to replace. Cartridge heaters also require replacement although the replacement cost is very inexpensive by comparison with Infrared emitters.
Due to limited displaced material, flash traps are often not required. Flash traps may be required for cosmetic applications when welding with contact.
Parts must be molded very precisely as there is no contact based melt step to flatten/parallel joint surfaces. Parts can be molded without absolute precision as joint surfaces will be made parallel to one another during melt phase when polymer is making contact with heat platen.
No need for replacement inserts/coating materials. If required to run at low temperature, Teflon coating on heat platen must be moved (sheet) or replaced (coatings)
Greater design flexibility in materials (all non-contact). Materials such as polyethylene, acetal, nylon and polycarbonate will require release coatings between polymer and heat platen.
Not ideal for clear materials (particularly polycarbonate). Clear materials and polycarbonate are easily weldable without complexity although some may require release coatings between polymer and heat platen.
Convection currents not a factor unlike HP welding. Heat platen temperature distribution is affected by convection currents.
High amount of smoke created during the process. Smoke produced at temperatures above 500ºF only.
If Custom emitters are used, customer MUST purchase spares immediately as leadtimes for replacements are up to 6 weeks. Typically standard “off the shelf” parts are used with no leadtime issues on wear-item parts.

Infrared vs. Vibration Welding



Slower cycle times:  20 to 60 seconds typical. Faster cycle times:  8 to 15 seconds typical.
Can weld tall, thin, non-supported inside and outside walls. Cannot weld tall, thin, non-supported either:  a) inside walls or b) outside walls perpendicular to the direction of vibration.
Process works well for a variety of materials (few limitations). Process works well for a variety of applications (some limitations).
Almost no part size limitations. Can be difficult to weld VERY large parts.
Higher joint strength with Polypropylene and Polyethylene as the process heats the interface without friction. Lower joint strength with Polypropylene and Polyethylene due to absorption of vibration within the material instead of transfer to the joint area.
Process can join certain dissimilar materials (limited number). Process can join certain dissimilar materials (limited number).
Can weld parts with contours in both directions. Can weld parts with contours in one direction only.
Weld plane limited to 45° maximum from flat plane. Weld plane limited to 10° maximum from flat in the axis parallel to vibration.
Higher tooling costs (requires infrared platen). Lower tooling costs (no infrared platen required).
Process requires an infrared platen assembly. Less complex tooling.
Infrared platen maintenance; periodic replacement of infrared emitters required. Lower tooling maintenance.
Slower tooling change-over times; may have to change infrared platen. Faster tooling change-over times. No platen to change.
Process creates solid, smooth flash bead with virtually no particulate. Process can create flash that can break off causing loose particles (application and material dependant).
Process most often will create smoke and fumes. Virtually no smoke or fumes during welding process.