Crushing, Screening and Washing Technical Terms Glossary

In brief: buyer-oriented explanations of the core technical terms you meet when selecting crushing, screening and washing plants. It helps you size your plant with the right capacity, settings and wear strategy.

At General Makina we manufacture crushing, screening and washing machines. This glossary summarizes the core technical terms you encounter when selecting and configuring the right machine. Our aim is to define each term together with how it directly affects the sizing of your plant and your specification decisions.

Machine Types

Jaw crusher: A primary crusher that breaks material by compression between two jaws, one fixed and one swung by an eccentric shaft. It is chosen as the first stage for large, hard feed; its intake opening sets the maximum feed size the plant can accept.
Impact crusher: A crusher working on the impact principle, where high-speed rotor hammers strike the material and hurl it against breaker plates. Because it delivers high reduction and cubic product, it is chosen as a primary or secondary stage for low-to-medium abrasive material such as limestone.
Cone crusher: A secondary/tertiary crusher that breaks material by progressive compression between an eccentrically gyrating mantle and a fixed concave. With its wear-resistant design it is chosen for hard, abrasive material when high capacity and an adjustable gradation are required.
Vertical shaft impactor (VSI): A vertical-shaft impact crusher that breaks material by hurling it from a high-speed rotor in rock-on-rock or rock-on-metal impact. Because it delivers superior cubicity and sand (0-5 mm) production, it is chosen at the tertiary/quaternary stage when particle shape and fines output are critical.
Vibrating screen: A machine oscillated by eccentric or vibrator motors that separates material by particle size across its screen decks. Deck count, screen area and inclination are selected according to the target number of fractions and capacity to achieve gradation control.
Screw washer: A washer that scrubs and dewaters sand with rotating spiral(s) in an inclined tub while overflowing fine clay and slimes off the top. It is chosen to clean high-clay material while limiting the loss of fine sand.
Bucket wheel washer: A washing/dewatering machine that lifts washed sand out of the tank and dewaters it with perforated buckets on a rotating wheel. It is chosen in the sand-washing line when clean sand with lower fines loss than a screw is required.
Log washer: A heavy-duty washer that scrubs tenacious clay off aggregate with paddles on two counter-rotating shafts in a horizontal trough. It is chosen when aggregate contains high-plasticity, sticky clay that demands intensive scrubbing.
Feeder: A feeding machine that delivers material from the hopper to the crusher or screen at a controlled, steady rate. Because it ensures balanced feed to the plant’s first stage, it is sized and selected according to capacity and feed size.
Wobbler feeder: A feeder built from shafts of rotating elliptical discs that conveys coarse material while pre-scalping soil and fines through the graded gaps. It is chosen when clay- or soil-laden feed needs fines removed ahead of the crusher.
Conveyor (belt): A system that carries material point to point on a belt running over drive and tail pulleys. Belt width and speed are selected according to capacity, conveying distance and incline to ensure flow between plant units.
Mobile crushing plant: A plant that combines crusher, screen and feeder on a wheeled or tracked chassis, rapidly set up and relocatable on site. It is chosen for changing quarries and short-term projects where installation flexibility and low set-up cost are wanted.
Concrete batching plant: A plant that batches aggregate, cement, water and admixtures by weight and mixes them to produce fresh concrete. It is sized by choosing a stationary or mobile type and mixer capacity according to the target m3/hour output and site conditions.

Technical Parameters

Capacity (tons/hour, t/h): The amount of material a machine can process per unit of time, varying with the feed's density, size and setting. It is the first decisive selection criterion; the target t/h determines crusher size, motor power and conveyor capacity together.
Reduction ratio: The ratio of feed size to product size, showing how much a crushing stage reduces the material. The total required reduction determines how many crushing stages (primary, secondary, tertiary) you will need.
CSS — Closed Side Setting: The gap between the crusher jaws or mantle/concave at their closest position, directly governing the finest product size. Because CSS drives product gradation and capacity, the setting range is a critical specification during selection and commissioning.
OSS — Open Side Setting: The gap at the widest position of the jaws in the crushing cycle, equal to the sum of stroke and CSS. It is used to estimate the largest particle size in the product; the OSS-CSS relationship is considered when guaranteeing gradation.
Wear parts (jaw plate/mantle/concave/hammer): Components in direct contact with material that wear and are replaced periodically. Since alloy quality and profile affect both product shape and operating cost, part life and spare-parts availability should be evaluated during selection.
Feed size (F80): The screen aperture through which 80% of the feed passes, defining the maximum particle size the crusher can accept. Feed larger than the intake opening causes blockage, so F80 directly guides crusher size selection.
Product gradation: The particle size distribution obtained after crushing, expressed by a sieve-analysis curve. Because target fractions (0-5, 5-12, 12-22 mm, etc.) determine the machine and screen configuration, it sits at the center of the specification.
Abrasivity / silica content: The abrasive level of the material; a high silica (quartz) content means rapid wear. Abrasivity directly affects the choice of wear-part alloy and crusher type (impact vs. cone).
Screening efficiency: The ratio showing how much of the fine material that should pass actually reaches the lower deck. Low efficiency leaves excess fines in the product; screen area, inclination and deck count determine this value.
Amplitude / stroke: The oscillation amplitude of the screen or crusher body, governing how much the material moves within the bed. Because the right amplitude-frequency combination determines screening performance for coarse or fine material, it is defined during machine selection.
Moisture and washing: The water content in the material and the washing applied to remove clay. High moisture and clay cause blinding in dry screening, so they determine the need for washing screens, sand washers or log washers.
Manganese steel (Mn): A high-manganese steel alloy that work-hardens at the surface under impact, used in jaws, mantles and concaves. Since the manganese content (14-22%) is chosen by application, the alloy should match the material hardness and impact conditions.
Cubicity / particle shape: The degree to which product particles approach a cubic, non-flaky, non-elongated geometry. Because concrete and asphalt aggregate require cubic product, the cubicity requirement guides the choice of impact or cone crusher and a tertiary stage.
Installed power (kW): The total nominal power of all motors in the plant, determining energy consumption and transformer/generator sizing. Installed power is evaluated together with target capacity and crushing resistance to shape the machine and energy-infrastructure selection.