Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications

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 Tolerances-Cartridge Heaters Installation Tips 2 and Preventive Maintenance-Cartridge Heaters Cartridge Heaters-FAQ's 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

Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications:


Manual Calculation of total heat requirements for insertion heaters applications:


KW = W x C x ΔT W = Weight of material in lbs.

3412 x hrs C = Specific Heat of material ( platen, block etc.)

ΔT= Delta T = Change in temperature, F

KW = Kilowatts

3412 = Conversion factor, Btu to kWh

Hours = Heat-up time in hours to reach set point



Automated calculator tool for calculating heating of solids, fluids or gases within a specific time:



http://www.cartridge-heaters-metric-insertion-heaters.com/calculator-for-heating-solids-fluids-and-gases.asp



Determining, Quantity, Size and Rating - Once total heat requirements are established, the quantity, size and rating of cartridge heaters can be decided. Plan for enough heaters to permit even temperatures through the part during heat-up and operation. The sensor for the temperature control should be placed close to the working surface for accurate control.



Important Formula To Know: How to Determine Watt Density


The term "Watt density" refers to the heat flow rate or surface loading. It is the number of Watts per square inch of heated surface area. For calculation purposes, stock cartridge heaters have a 1/4" unheated length at each end. Thus, for a 3/4" x 10" heater rated 1200 Watts, the Watt density calculation would be as follows:



Watt Density = W / (Π x D x HL)


Where:

W=wattage = 1200 W

Π = pi (3.14)

D= diameter = 0.75 inch

HL = Heated Length = 9.5 inch

Watt Density = 1200/(3.14 x .75 x 9.5) = 53.64 W/in



Use the Watt Density Calculator Below for Quick Automated Results:


Watt Density Calculator

 

Calculate Watt Density and Fit - After the wattage for each heater has been established, the watt density and fit must be calculated. Then, use graph below to be sure that the watt density is within allowable limits. For example a 3/4" x 10" heater rated 1200 watts has a watt density of 53.64 W/in 2 . If it were used in a part with an operating temperature of 1000F with a fit of 0.01", the allowable watt density from the graph would be 90 W/in 2 . Thus, the actual watt density of 53.64 W/in 2 is well below the maximum allowed. A substantial safety margin would exist and high reliability can be expected.

If the heater selected had a watt density higher than that allowed by the graph, consider the following changes.

1. Using more heaters of lower watt density.

2. Using longer or larger diameter heaters.

3. Improving the fit.

4. Reducing heat requirements by reducing heat losses or by allowing for longer heat up time.



Using the Maximum Allowable Watt Density Graph - This graph is useful for choosing type NPH cartridge heaters. The curves should be considered as guides and not precise limits. The graph is based on a 1400F resistance wire temperature inside the cartridge heater, when the heater is installed in an oxidized mild steel block. Watt density values from the graph should be lowered by about 10% or more when other materials are used which have a lower thermal conductivity or lower emissivity than oxidized mild steel. Contact National Plastic Heater Sensor and Control Inc’s Sales office.


Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications

Cartridge Heaters-Specifications:

Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications





cartridge heaters insertion heaters
cartridge heaters-standardOhms Law Calculator cartridge heaters brochureCartridge Heaters, Metric Insertion Heaters-Brochure
slit sheath cartridge heatersTemperature Conversion Calculator cartridge heaters designDesign Your Cartridge Heaters-Here
square cartridge heatersVoltage Engineering Reference cartridge heaters problemsEvaluating Your Cartridge Heater Insertion Heater Problems
miniature small diameter cartridge heaters3 Phase Calculator-Delta & Wye cartridge heaters-installation tips and maintenanceCartridge Heater-Installation Tips & Preventive Maintenance
bolt cartridge heatersCalculator for Heating Solids, Fluids or Gases within a Specific Time cartridge heaters, metric insertion heaters additional informationAdditional Cartridge Heaters Information


Our industrial electric cartridge heaters including metric and imperial heaters...

Consists of the following cartridge/insertion heater categories:

Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Standard imperial and metric round cartridge heaters
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Medium watt density cartridge heaters
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  High watt density cartridge heaters
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Split sheath cartridge heaters
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Square cartridge heaters
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Small diameter/miniature pencil heaters
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Bolt cartridge heaters
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Custom cartridge/insertion heaters

Applications for the above include:

Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Cartridge Heaters for-Extrusion Dies, Liquid Immersion
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Metric Heaters for-Plastic Molds and Injection Molding
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Insertion Heaters for-Plastics Extrusion
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Custom Cartridge Heaters for-Packaging Machinery, Labeling and Sealing
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Square and Round Cartridge Heaters for-Hot Plates and Platens, Hot Stamping
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Cartridge Heaters for-Hot Runner Molds, Various Types of Dies
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  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:


Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Blood warmers used in medical theaters must never fail
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  Battery conditioners for EVA spacesuits on the International Space Station must last ten years      before replacement, due to payload costs
Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications  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.



Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications Heat Calculations & Watt Density for Cartridge Heaters & Other Heater Applications

Telephone: 905-859-8225        Facsimile: 905-859-4691

sales@nphheaters.com

Toll Free: 1-877-674-9744