Voltage Engineering Reference

Consists of the following cartridge/insertion heater categories:

• Standard imperial and metric round cartridge heaters
• Medium watt density cartridge heaters
• High watt density cartridge heaters
• Split sheath cartridge heaters
• Square cartridge heaters
• Small diameter/miniature pencil heaters
• Bolt cartridge heaters
• Custom cartridge/insertion heaters

Applications for the above include:

• Cartridge Heaters for-Extrusion Dies, Liquid Immersion
• Metric Heaters for-Plastic Molds and Injection Molding
• Insertion Heaters for-Plastics Extrusion
• Custom Cartridge Heaters for-Packaging Machinery, Labeling and Sealing
• Square and Round Cartridge Heaters for-Hot Plates and Platens, Hot Stamping
• Cartridge Heaters for-Hot Runner Molds, Various Types of Dies
• Insertion Heaters for- Medical Equipment and Other Industrial Applications

The square cartridge heater configuration simplifies wiring and installation while optimizing performance in a wide range of solid, liquid, and gas heating applications. Tooling applications are particularly well served by the square cartridge heater approach. Typical square cartridge heating applications include platens, molds, sealing bars, sealing plates and dies. Versatile slot style mounting simplifies installation in small tooling components such as bushings and nozzles and is particularly useful when leads must exit at a specific location on the component surface.

Some applications demand much longer heater life, that is where miniature small diameter pencil/cartridge heaters have immense application value. Life expectancies of five, seven or even ten years are not unreasonable for some mission-critical applications:

• Blood warmers used in medical theaters must never fail
• Battery conditioners for EVA spacesuits on the International Space Station must last ten years before replacement, due to payload costs
• Here on earth, high throughput semiconductor chip testers must operate without significant downtime for the 5 year life of the equipment. For these applications, a service life of 50,000 to 90,000 hours is a requirement that is both reasonable and attainable.

Some common issues with most standard cartridge heaters are as follows:

Heater removal: a cartridge heater will oxidize after many hours of operation and maybe difficult to remove. Consider drilling a through hole so the heater can be hammered out or choose a split sheath cartridge heater.

Lubricants: like graphite or silicone facilitate the insertion of the cartridge heater but can carbonize at higher temperature and then the heater will be really stuck.

The NPH split sheath cartridge heateris designed especially for platen, die or mold industrial heating applications where the holes are poorly drilled or worn through age. Independent expansion of each section of the split sheath cartridge heater when energized, creates intimate contact with the wall of the hole.

Through the patented split-sheath design and highly specialized manufacturing techniques, NPH split sheath insertion heaters reduce your total cost of process heating by an average of 40% over other heaters.

NPH’s split sheath cartridge heaters use a unique, patented split-sheath design that expand when energized to maximize heat transfer through greater contact with the wall of the bore. Better heat transfermeans less power is consumed to maintain the set point temperature, reducing operating costs.

Bolt cartridge heaters are used to tighten large bolts that secure heavy machinery and equipment. The shaft of the heater is inserted into the hollow bolt and energized to expand it, which allows further tightening of the nut. Manufactured with a high watt density, they heat up in just a few minutes, resulting in cost savings on reduced man hours removing nuts from bolts and studs. Large bolts can be heated to full expansion in just a few minutes. This heater design is manufactured with specific diameter sheaths to fit industry standard hollow bolts. High watt densities with special heated lengths distribute heat evenly to surrounding bolt.