Calendering, Extrusion and Press Laminating

No other film and sheet producer in the USA offers calendering, extrusion and press laminating under one roof. Each of these processes produces a range of film and sheet products having distinct qualities. As importantly, film and sheet produced using more than one of these processes can be fused in-line or off-line (with low minimums) to create an unlimited selection of ultra-high performance composite sheet products impossible to achieve using any single production process.


Raw materials in powder form are fused into a homogeneous molten mass through heat and friction shear in a mixing chamber. This molten plastic is fed into a series of heated revolving rollers that squeeze the material to a desired thickness. After leaving the rollers the material passes through a series of surface conditioning and cooling rolls from which it is wound into custom rolls or cut into specified sheet dimensions.

Advantages of Calendered Film and Sheet

  1. Thin gauges for dedicated applications such as card stock, general purpose printing substrate and membrane pressing.
  2. Specialized thin-gauge films intended for capping of thicker-gauge sheet in-line or off-line (with low minimums) to produce composite sheet products offering superior aesthetics, properties and/or economy than monolithic sheet, depending on application
  3. Medium gauges that may be more economical to produce by calendaring than by extrusion, depending on application


Extrusion is a continuous manufacturing process that involves conveying mixed plastic compound through a heated barrel by a specially disengaged spiral shaped screw. The original powder blend is converted into a molten plastic mass that exists through a lip die that flattens the mass into a sheet of designated width and thickness. The sheet then passes through heated embossing rolls that impart a predetermined surface finish prior to trimming to the final sheet dimension. A variety of surface finishes is available.

Advantages of Extruded Sheet

  1. Medium- and heavy-gauge sheet for dedicated thermoforming, membrane pressing, fabricating and machining applications.
  2. Lower minimums than calendering
  3. Custom colors, textures, gauges and blank sizes starting at 500 lbs (227 kg).

Press Laminating

Press laminating is a process in which multiple sheets of calendered or extruded plastic are layered and fused using heat and pressure over relatively long cycle times, to form one solid sheet of material up to 3.0 in. (76.2 mm) thick. Colors can be combined to produce a multicolor edge effect, and other media may be embedded between layers to tailor material for a specific application.

To achieve a given thickness, Boltaron press laminates a relatively large number of thin calendered sheet — generally .016 in. (.040 mm) for uniform heat flow and superior bonding, unlike competitors that press-laminate relatively few layers of thick extruded sheet — generally .125 to .75 in. (3.18 to 19.0 mm)-greatly increasing the likelihood of de-lamination.

Advantages of Press Laminated Sheet

  1. Press laminating allows the production of sheet products in thicknesses that are impractical or impossible to produce by extrusion, particularly in short runs.
  2. Press laminated sheet is generally free of blemishes and is of higher quality than extruded sheet.
  3. While press-laminated sheet is generally monolithic, the individual sheets comprising its layers can be varied to provide coloration, patterns, texture, reinforcement or properties that would be impossible or cost-prohibitive to achieve by heavy gauge extruding of monolithic sheet.


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