Discharge particle size adjustment range of jaw crusher

Discharge particle size adjustment range of jaw crusher

The discharge particle size of a jaw crusher is controlled by the closed side setting (CSS). CSS refers to the minimum gap between the movable jaw plate and fixed jaw plate at the bottom discharge opening. Changing CSS can adjust the finished product granularity.

Note: The discharge size is not a fixed value. Jaw crusher produces a gradated mixture. The CSS represents the smallest gap, and most finished particles will be less than 1.5 times the CSS.

Typical adjustment range for common PE/PEX jaw crushers

  1. PE coarse jaw crusher (primary crushing)
    • PE 400×600: 40 ~ 100 mm
    • PE 500×750: 50 ~ 100 mm
    • PE 600×900: 75 ~ 200 mm
    • PE 750×1060: 80 ~ 210 mm Coarse jaw models are used for primary crushing, with a relatively wide adjustment range and larger minimum discharge size.
  2. PEX fine jaw crusher (secondary pre-crushing)
    • PEX 250×1000: 20 ~ 50 mm
    • PEX 300×1300: 20 ~ 50 mm Fine jaw crushers have smaller CSS, used for secondary coarse crushing to get finer stone.

Adjustment mechanism

Jaw crusher adopts toggle plate gasket adjustment or hydraulic wedge adjustment:

  1. Gasket adjustment: Add or remove gaskets behind the toggle seat. More gaskets → larger CSS, coarser discharge; fewer gaskets → smaller CSS, finer discharge. Simple and low cost, widely used.
  2. Hydraulic wedge adjustment: Adjust by hydraulic pushing wedge blocks. Fast adjustment, convenient for on-site modification, suitable for large crushing plants.

Important rules

  1. Minimum CSS limit: Do not set CSS below the factory recommended minimum value. Too small gap will cause overload, severe jaw liner wear, material blocking and machine stalling.
  2. Material property impact:
    • Hard rock (basalt, quartz, iron ore): Do not pursue too fine discharge, increase CSS properly to reduce wear.
    • Soft rock (limestone): Can use smaller CSS for finer output.
  3. Wear influence: As jaw plates wear, the actual discharge gap becomes larger, so re-calibration of CSS is required regularly.
  4. Product gradation: Reducing CSS can get finer materials, but the proportion of fine powder rises and processing capacity drops.

Common mistakes

  • Confuse open side setting (OSS) with closed side setting (CSS). Only CSS is the standard index for discharge particle size.
  • Expect jaw crusher to produce sand-sized material. Jaw crusher is coarse/medium crushing equipment, not sand making machine. It cannot reach 0–5mm finished sand directly.