1. Square & Rectangular Cartridge Heater for Milled Slots
Hongtai Square Cartridge Heaters and Rectangular Heating Elements are engineered for applications where a drilled round hole is not feasible or where maximum surface contact is required. Unlike round heaters that only touch a slot at the tangent point (line contact), our square heaters provide three-sided surface contact when installed in a milled groove.
This geometric advantage makes them the ideal tool and die heater for long sealing bars, hot cutting knives, and manifold plates. By eliminating the air gaps found in round-heater-in-square-slot installations, heat transfer efficiency is improved by over 20%, resulting in faster startup times and longer element life.
2. Key Technical Features
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Maximum Surface Contact: Flat sides transfer heat directly to the tooling, reducing the internal temperature of the resistance wire.
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Slot Installation: Perfect for milled slots which are often easier to machine than deep drilled holes.
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Swaged Construction: Just like our round high-density heaters, these are compacted (swaged) for ruggedness and vibration resistance.
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High Watt Density: Capable of watt densities up to 15-20 W/cm² due to superior heat dissipation.
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Versatile Sizing: Available in metric and imperial cross-sections (e.g., 6x6mm, 10x10mm, 1/4″ x 1/4″).
3. Technical Specifications
| Parameter | Standard Specification | Customizable Options |
| Cross-Section Shape | Square, Rectangular | Flat (Thin) |
| Standard Sizes | 6x6mm, 8x8mm, 9.5×9.5mm (3/8″) | 15x15mm, Custom Rectangular |
| Sheath Material | Stainless Steel 304 / 316L | Incoloy 800 |
| Length | 40mm to 1000mm | – |
| Voltage | 120V / 240V / 480V | – |
| Watt Density | up to 20 W/cm² | Distributed Wattage Available |
| Tolerance | ±0.05mm | – |
| Termination | Swaged-in Leads / Crimped | Right Angle Block |
4. Why Choose Square over Round?
In “Platen” or “Manifold” heating, machining a long milled slot is often cheaper and easier than drilling a deep, straight gun-drilled hole.
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The Problem: Putting a round heater in a square slot leaves insulating air gaps.
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The Solution: A Rectangular heating element fills the slot completely. The vastly increased contact area allows the heater to run cooler while delivering more energy to the tool.
5. Applications
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Packaging: Long sealing bars and hot knives (VFFS machines).
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Tooling: Heating large platens or molds with surface grooves.
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Extrusion: Die heating where space prevents round holes.
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Medical: Sterilization chambers requiring uniform surface heating.
6. FAQ
Q: Do I need to use heat transfer cement?
A: While our square heaters fit tightly, we highly recommend using a thin layer of high-temp transfer paste to fill microscopic voids in the milled slot, ensuring 100% thermal coupling.
Q: Can you make these with distributed wattage?
A: Yes. For long sealing bars, we can wind the heater with higher power at the ends to compensate for heat loss, ensuring a uniform temperature across the entire knife edge.
Q: What is the lead time?
A: Square heaters require specialized tooling. Lead time is typically 10-12 working days.
