Carbon Fiber Production Slot FurnaceHarper is the industry standard choice in continuous slot furnace technologies for the Carbon Fiber industry. Our involvement in Carbon Fiber began at the market’s inception in the 1970s, and since then we have been helping fiber manufacturers achieve new and ever greater heights with our continual evolution of design innovations. We have designed solutions throughout all line sizes, helping customers scale up from research to large capacity, from research lines to full production scale lines. Additionally, Harper is one of few in the market who push the boundaries of technology in offering Ultra High Temperature furnaces rated to 3000°C.

Harper tailors each design to the customer’s requirements, considering the best possible solution for your needs in terms of element and muffle design, materials platform, and atmospheric considerations to avoid plasma generation for the desired line rates and tow sizes. Our experience spans a variety of precursors including PAN, pitch, nonwoven mat, or discontinuous, loose fiber form.  We have the ability to adapt our technology to process nontraditional precursors throughout the entire thermal process. By using nontraditional precursors such as lignin, rayon, polyethylene, and blends, customers are able to lower their operating costs and reduce the residence time in the oven. To custom engineer a furnace specifically for the client’s needs, we take into consideration the chemistry of the precursor to determine the materials of production. Whether the precursor is unsupported by its weight requiring a belt furnace or is a tow, Harper provides solutions for these emerging precursors throughout the full process.

Harper Slot Furnace Innovations – Energy Utilization

Harper is constantly innovating to serve the evolving Carbon Fiber market’s needs, as demonstrated by our design of gas-fired Slot Furnaces, as well sizing Oxidation Ovens, dryers and air pollution abatement systems, to take advantage of natural gas benefits. Current energy markets and environmental regulations have produced significant advantages to thermal processing equipment that use natural gas for fuel. Capital cost for gas-fired equipment comes at a slight premium and the return on investment (ROI) can vary with the location of the installation. However, we have seen an ROI of less than two years in North America when compared with electrically heated equipment. Additional options for heat recovery to increase efficiency can be implemented in regions of the world that command higher fuel gas prices.

Harper Slot Furnace Design EnhancementsHarper Slot Furnace

  • Unique end seal design delivers excellent process gas flow uniformity
  • Strategic heating element placement to achieve optimal temperature uniformity
  • Advanced insulation designs reducing energy consumption
  • Inboard and outboard louvers used to minimize ingress of air
  • Proven atmosphere purge chambers designs

Harper Slot Furnace Capabilities

  • Unique atmospheres (argon, nitrogen, CO2, steam)
  • Vertical or Horizontal configurations
  • Multiple independently controlled temperature zones (length and width)
  • Highly uniform temperature across the towband
  • Designed to facilitate service and maintenance activities
  • Modular designs minimizing field installation effort

Harper offers specific LT, HT and unique UHT furnace designs for the production of Carbon Fibers:

Harper LT FurnacesCarbon Fibre Slot Furnaces

  • Electric, Gas or Fuel Fired
  • Temperatures up to 1200°C
  • Ceramic fiber based insulation
  • Nitrogen preheating
  • Vent heat tracing
  • Microlines® to large capacities (up to 4 meters; heated lengths to 15 meters)

Harper HT & UHT Furnaces

  • Electric or Gas Fired
  • Temperatures up to 3000°C
  • Materials platform – graphite based
  • Microlines® to large capacities (widths up to 4 meters; heated lengths to 15 meters)


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