Hemp Fiber Production & Processing

Field Production

Hemp belongs to the Moracea family (the Mulberry family) and the commercially cultivated species are Cannabis sativa.  Notes on hemp growing, yields and structure:

  • Sowing:  industrial hemp is usually seeded at approximately 1,000 to 1,350 seeds per hectare (60 to 80 kg of seed/ha.)
  • Growing:  the growing season is usually 95 to 115 days in temperate climates from sowing to harvest.  Usually hemp stalks are 1.5 to 2.5 m high with stalks 4 – 10 mm in diameter.  In some cases, the plants can grow as high as 3- 4 m high and the stalks as thick as 20 to 25 mm.
  • Stalk Yield: is usually 6.5 to 12 tonnes per hectare.
  • Fiber Yield:  23 to 35% of stalk mass under ideal growing and processing conditions and depending on the variety of plant.  Approximately 1.5 to 4.2 tonnes of fiber per hectare.  Note: 1.5 to 4 times higher fiber yield than flax. Only 10 to 20% of cotton fiber yields.
  • Fiber Bundles:  can be as long as 100 to 300 cm.

Processing

Fundamentally, hemp fiber extraction for technical fiber purposes involve the following main steps:

  1.  Retting Harvested Fiber: Keeping the baled fiber in the field for some wet period of time to instill some bacteria-induced delaminating of the bast fiber from the core; once retted, the middle lamella is substantially degraded and the woody plant core is dry and brittle.
  2. Decortication: Processing the field feedstock via special machinery — the Decorticator — to separate the outer bast fiber from the inner core hurd fiber
  3. Refinement of Bast Fiber: Processing the Bast fiber after decortication through special machinery to:
    • Remove non-structural fiber
    • Align the fiber
  4. Treatment & Sizing of Fiber: Using special machinery, as required for applications

Decortication

Decortication is the separation of hemp’s outer layer (bast fiber) from the inner core (hurd). Current decortication uses the same hammer mill or hammer mill-like mechanism that has been used for over a hundred years; which uses a beating action to break down hurd and fiber, significantly damaging both, while creating a substantial amount of dust. This damage is a severe limitation of conventional hammer mills, limiting the hemp fiber produced to low-value markets.

The high-speed kinematic mechanism employed by the HempTrain™ Advanced Hemp Decorticator is far less damaging to the fibers and hurd and creates no appreciable dust. The products produced can be used in high-value markets such as reinforcing fiber, consumer products, and CBD from industrial hemp.

Learn how the HempTrain™ Advanced Hemp Decorticator System brings new innovation to hemp processing!