Knife over roll coaters

The knife-over-roll coater is one of the first coating methods developed for the web converting industry, first introduced for the textile industry. Simple to operate, and relatively inexpensive compared to other roll coating methods, KOR coaters are frequently selected for both water based and solvent based coatings, typically for applying relatively thick wet layers of more viscous coatings.

While KOR configuration is the most popular, Pyradia offers a complete range of knife coaters, designed according to the highest quality standards for long life and easy maintenance: KOR Knife-Over-Roll, KOP Knife-Over-Plate, KOA Knife-Over-Air and Comma coaters.

KOP and KOA coaters will be considered for textile applications, while KOR coaters will be selected for their higher coating thickness precision. The precision ground back-up roll is commonly chrome plated and can be driven or not, depending on the substrate tensile strength. Coating width can be easily adjusted using rail mounted edge dams, while coater knifes can be rapidly removed for cleaning, thanks to our proprietary toolless knife clamping system.

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While pre-metered coating methods apply a uniform coating thickness regardless of substrate variations, coating thickness of a KOR coater will be dependent on substrate thickness variations, along with back-up roll and coater blade uniformity. Various knife shapes are available, from square edge typically selected for thin coatings, to radius edge that generates less shear force and produces smoother thick coatings. A hook type knife, incorporates a groove on the blade back-side, minimizing coating accumulation and defects. Comma is essentially a KOR coater equipped with a large radius knife, best suited for lower viscosity coatings.

With over 50 years of experience, extensive process knowledge, modeling software and pilot equipment, Pyradia engineers will analyse your specifications and recommend the ideal production line configuration for optimal process efficiency.

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Features

  • Pyradia gravure knife-over-roll features:
  • Solvent-based, water-based or hot melt
  • Wet thickness: 2.0 – 30.0 mils
  • Viscosity range: 500 – 50,000 cps
  • Line speed: up to 400 FPM (or more for specific applications)
  • Substrate width: 12in to 120in or larger
  • Coating uniformity: around 10% by weight (substrate dependent)
  • Simple to set-up and operate
  • Aftermarket services
  • CSA and cCSAus certification
  • NFPA 86, OSHA & FM standard compliant

    • Options

  • The following options are available on Pyradia knife-over-roll coaters:
  • Sheeting, radius or hook knife geometry
  • Reciprocating coating dispensing
  • Nip roller
  • Tension control
  • Driven back-up roll
  • Cleanroom configuration
  • Fluid delivery
  • Knife deflection compensation
  • Knife servo gap adjustment
  • Coater enclosure
  • Scada and remote communication systems
  • Installation and start-up services
    • Technical data sheet

    Heat treating furnaces applications:

    Nonwovens

    Adhesive coating-laminating

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