Cartridge Heaters Metric Insertion Heaters.com
Cartridge Heaters Configurations Styles and Terminations
Construction of Cartridge Heaters and Features
Optional Features-Cartridge Heaters
Mounting Options-Cartridge Insertion Heaters
Electrical Terminations Cartridge Heaters
Diameter, Tolerances, Actual vs Nominal Diameter-Cartridge Heaters
Installation Tips 2 and Preventive Maintenance-Cartridge Heaters
Evaluating 2 Your cartridge Heater Problems
Heat Calculations Watt Density Catridge Heaters-2
Order Form-How to Order Cartridge Heaters
Split Sheath Cartridge Heaters
Square Cartridge Heaters
Small Diameter, Miniature Pencil Heaters
Bolt Cartridge Heaters
Search this site:
Profile Literature Links Sitemap Contact Us
Construction Cartridge Heaters, Metric Insertion Heaters
Construction of Cartridge Heaters-Metric and Imperial Insertion Heaters:The cartridge heater may be divided in 7 main parts:
Lead Wire Type
Heating Coil- The heating coil is the actual resistance which is where the electrical load occurs. The most common type of metal alloy used for this purpose is a Nickel-Chromium mixture, also known as Nichrome the Nichrome wire is wound around a ceramic core, and the number of spirals per inch vary according to the requested watt density. Potential from an alternating current source, which can either be 2 phase or 3 phase, flows through the coiled Nichrome wire, heating up the wire, which in turn, heats the cartridge heater sheath.
Insulation- is used to prevent the Nichrome coil to contact the sheath. If such event happened, it would ground the resistance and produce a catastrophic short-circuit, resulting in a melted sheath and a major equipment failure. To prevent the coil from touching the sheath, the coil is inserted into the sheath, and immediately filled with Magnesium Oxide (MgO). To ensure the MgO fills the empty space between the sheath and the coil, the cartridge heater is vibratory filled.
Sheath- The sheath is the part of the cartridge heater which makes contact with the material or substance to be heated. Several metal alloys are used, depending on the type of application, such as highly acidic or corrosive environments. The most common types of sheaths are 304 Stainless Steel, 316 Stainless Steel, and Incoloy 800. Incoloy has the highest temperature rating, it is considered a Superalloy.
Sealing- After the cartridge heater has been filled with MgO, a seal is applied to the open end of the cartridge heater (where the Nicrome coil was introduced), this prevents the coil and the MgO from coming out. Also, it prevents contamination, such as plastic debris, air, or moisture, to go inside the heater.
Termination- Since cartridge heaters are installed in a wide variety of machines, manufacturers must design the heaters to meet certain clearances. The cartridge heaters might be terminated with the leads coming out straight, or in a right angle. Also, manufacturer must be careful that the leads are not exposed to temperatures higher than the maximum rating for the lead wire. In order to prevent lead wire damage from temperature, movement or contamination, the lead wire can be protected with metal conduit or braided metal.
Lead Wire Type- Depending on the clearance and the design of the machine where the cartridge heater will be inserted, the type of wire used will vary. Fiberglass is the commonly used for cartridge heaters and other high temperature applications, such as automotive wiring harnesses and industrial equipment. Other variants used are silicone impregnated fiberglass and silicone rubber.
Construction and Features:
Up to 200 w/in2
Efficient heat transfer
Various special features
CSA UL and CE certified
In high-density cartridge heaters the resistance wire loops are positioned as close as possible to the outside shell. Because the MgO powder insulation round these loops is compacted by swaging and transformed into a very hard medium, heat transmission is very efficient. NPH cartridges can have up to 200 w/in2 watt densities. Cartridges are usually supplied with lead wires. The attachment of the leads to the central pins is done internally, in a 3/8" cold section. In excessively hot applications the length of this cold section could be increased. To facilitate installation and avoid excessive air pockets, cartridges are made 0.004" less than the nominal size of the receptacle hole with a tolerance of +/- 0.002". NPH cartridges can be dual-voltage, three phase, and/or be supplied with a ground terminal. With ten different termination styles, mounting attachments and various optional features, NPH high-density cartridges are widely used in numerous high temperature applications.
Cartridge Heaters MetricDescription
A cartridge heater is a device that is usually tubular or square and is inserted into drilled holes of metal blocks for heating. Metric & Imperial high density cartridge heaters are round tubular heaters with electrical terminations on one side. These reliable heaters are made to withstand tough industrial usage. With a tolerance of +/-0.002" on its outside diameter to secure a tight fit inside receptacle holes and rock hard compaction of MgO insulation through swaging, these heaters can attain 1500ºF sheath temperature. High density cartridge heaters are available with various termination styles and mounting attachments. In high-density cartridge heaters the resistance wire loops are positioned as close as possible to the outside shell. Because the MgO powder insulation around these loops is compacted by swaging and transformed into a very hard medium, heat transmission is very efficient. Metric and Imperial cartridge heaters can have up to 200 w/in watt densities. Cartridge heaters are usually supplied with lead wires. The attachment of the leads to the central pins is done internally, in a 3/8 cold section. In excessively hot applications the length of this cold section could be increased. To facilitate installation and avoid excessive air pockets, cartridge heaters are made 0.004 less than the nominal size of the receptacle hole with a tolerance of +/- 0.002. Metric and Imperial cartridges can be dual-voltage, three-phase, and/or be supplied with a ground terminal. With ten different termination styles, mounting attachments and various optional feature, our high density cartridge heaters are widely used in numerous high temperature applications.
Cartridge Heaters Selection Guide
How much wattage is required?
What voltage will be used?
What is the heated length? What is the overall length?
How long are the heater leads or what is the lead length required?
What is the outside diameter of the cartridge heater?
What is the ambient temperature the cartridge heater will see?
What is the maximum temperature required from the heater?
How quickly do you want to reach your operating temperature or set point in hour/minutes?
What is the type and weight (in lbs.) of the material you want to heat?
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.
NPHs 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.
Telephone: 905-859-8225 Facsimile: 905-859-4691
Toll Free: 1-877-674-9744
|Home Profile Products Industries and Applications Technical Resource Center Literature Links Contact Us|
operated by National Plastic Heater, Sensor and Control Inc.
© National Plastic Heater, Sensor & Control Inc. 2010. All Rights Reserved.
The materials on this website are protected by copyright and other laws.