Vibrating feeder

01

Size the capacity from tray width, depth, density and flow speed

Eriez's heavy-duty feeder brochure gives feeder capacity as Q = W × d × D × v / K, with tray width W, material depth d, density D and flow velocity v; in metric units W and d are in mm, D in g/cm³, v in m/min and K = 16,700, giving t/h. It states that flow velocity depends on particle size, size distribution and moisture, and that rated capacities require ideal conditions. Its catalogue capacities are based on dry sand at 100 lb/ft³ (1.6 t/m³) with a 40° angle of repose, the trough at a 10° downslope and skirtboards fitted for full material depth. [1]

The brochure describes three drive styles: mechanical feeders as two-mass, spring-coupled systems excited by a motor-driven eccentric shaft, with feed rates to 60 ft/min (18 m/min) adjustable by variable frequency drive; electromagnetic feeders with no wear parts and amplitude varying with the applied AC voltage, mounted below hoppers where more precise metering is needed, with standard units rated to 130 °F (54 °C) and high-temperature units to 300 °F (150 °C); and Brute Force feeders with twin eccentric motors that spread conveyed material across the tray ahead of sorters or separators. [1] Eriez's product page adds that the twin counter-rotating motors counteract each other to reduce isolation problems, and lists electromagnetic feeders with capacities of 330 to 1,100 tons (300 to 982 t) per hour. [2]

Editorial calculation: a tray 914 mm wide carrying material 100 mm deep at 1.6 g/cm³ moving at 12 m/min gives Q = 914 × 100 × 1.6 × 12 / 16,700 ≈ 105 t/h. Width, depth and speed are assumed examples; ask the supplier for the flow velocity it expects with your material, slope and drive.

A second maker's grizzly feeder table uses the same 1.6 t/m³ (100 lb/ft³) material basis, at the inclination it specifies: MEKA lists 100–200 t/h for a 620 × 2,500 mm feeder with a 1,000 mm grizzly section and 350 mm maximum feed, 250–400 t/h for 900 × 4,200 mm (600 mm feed), 400–640 t/h for 1,100 × 5,200 mm (800 mm feed), and up to 650–1,000 t/h for 1,600 × 6,000 mm with two 1,000 mm grizzly sections and 1,200 mm maximum feed. Its twin vibromotors run at 1,000 rpm on 50 Hz (900 rpm on 60 Hz), from 2 × 3.8 kW to 2 × 13.9 kW at 50 Hz. MEKA states the capacities are indicative and depend on feeder size, inclination and feed gradation. [3]

Editorial calculation: across that table, feeder width rises 2.6 times (620 to 1,600 mm) length 2.4 times (2,500 to 6,000 mm) and maximum feed size 3.4 times (350 to 1,200 mm), while the upper capacity rises 5 times (200 to 1,000 t/h); compare offers at the same density and inclination basis. [3] [1]

Give the supplier the material (type, bulk density, lump size and size distribution, moisture, temperature, abrasiveness, stickiness), required feed rate range and control signal, hopper or bin arrangement and head load, discharge point and downstream equipment, slope allowed, mounting (base or suspended), power supply, hazardous-area classification, and liners or special trays (grizzly, screen, dust cover).

02

Expect flow velocity to change with frequency and with material condition

A 2021 open-access study from VSB–Technical University of Ostrava (Scientific Reports) ran wood pellets, crushed pellets and oak rods on a twin-motor validation vibrating conveyor with drives tilted 40° to the trough, timing 800 ml of material over a 580 mm transport length at unbalance frequencies of 15, 17.5, 20 and 22.5 Hz. Measured trough vibration above the motors was 0.77–0.84 mm in the direction of motion and 1.34–1.86 mm vertically across that frequency range. [4]

Feed time fell as frequency rose: the pellet mixture took 42.27 s at 15 Hz, 19.88 s at 17.5 Hz, 14.07 s at 20 Hz and 7.50 s at 22.5 Hz, while crushed pellets took 106.70 s, 28.27 s, 15.36 s and 10.53 s. The crushed pellets had an effective angle of internal friction 9.9° higher and an angle of repose 10.2° higher than whole pellets and fell into the cohesive flow class. The authors place the boundary between directed and chaotic particle bouncing at 20 Hz for rods and 22.5 Hz for pellets. [4]

Editorial calculation: 580 mm in 42.27 s is about 13.7 mm/s (0.82 m/min) and 580 mm in 7.50 s about 77 mm/s (4.6 m/min) for the pellet mixture; crushed pellets at 15 Hz move at about 5.4 mm/s (0.33 m/min). Because flow velocity v enters Eriez's capacity formula directly, [1] a degraded or finer version of the same material can cut capacity by more than half at the same drive setting, so state the material's condition (including fines from degradation) in the enquiry and ask how drive frequency or stroke can be adjusted. [4]

03

Design the hopper, gate and skirtboards with the feeder

Eriez states that an improperly designed hopper or transition section can reduce feeder capacity by as much as 30%. Its guidelines: the hopper bottom almost as wide as the tray with about 25 mm (1 in) clearance; a throat opening of 2½–3 times the largest particle for random-sized material, or 3–4 times for near-sized material, but not more than 30% of the tray length, or head load may overpower the feeder; a gate height of 1.2–1.5 times the material depth needed and 1–2 times the throat; a rear transition wall at 60° or more, with the front wall 5–10° shallower. [1]

Skirtboards on both sides from the gate to the end of the trough contain a burden deeper than the tray sides; they should flare and taper by at least 40 mm per metre of feeder length and keep at least 25 mm clearance from the tray. Eriez notes that some installations have raised capacity by more than 50% with a 10° downslope and gives a rule of thumb of about 2% more delivery per degree of downslope, while more precise repeatability and less over-feed come with less downslope. [1]

For grizzly feeders under primary hoppers, MEKA describes a fully welded, post-weld heat-treated body with a 20 mm S355JR steel base plate and 12 mm side plates, replaceable bolted AR400 wear liners 12 mm thick on the base and side walls, and feed rate set by a frequency converter from the control desk or a PLC. It notes that grizzly feeders can be installed inclined, that horizontal installation favours separation efficiency, and that the angle can be raised by a few degrees for more capacity without loss of separation efficiency. [3]

Editorial calculation: for random-sized rock with a largest lump of 150 mm, the throat should be about 2.5 × 150 = 375 mm to 3 × 150 = 450 mm; keeping that within 30% of tray length needs a tray at least 375 / 0.3 = 1,250 mm to 450 / 0.3 = 1,500 mm long. Lump size is an assumed example.

04

Who sells grizzly, motor-driven and electromagnetic feeders

SBM (Shibang Industry & Technology Group Co., Ltd.) lists heavy grizzly vibrating feeders and motor vibrating feeders for crushing plants; JXSC Machine and Anhui Vrv Industrial Technology Co., Ltd. list electromagnetic vibrating feeders; Qingdao Kefid Machinery Co., Ltd., Henan Xingyang Mining Machinery Manufactory, Henan Pingyuan Mining Machinery Co., Ltd., Henan Excellent Machinery Co., Ltd and Jiangxi Changyi Mining Machinery Co., Ltd. list vibrating feeders with crushing, screening or conveying equipment; Henan Hongxing Mining Machinery Co., Ltd. shows an HST vibrating feeder in its solution cases. Ask each for drive type, capacity basis, amplitude and frequency, tray size and liners.

05

Tray, drive, springs, isolators and the gate above them

06

Eriez and MEKA figures to set against a feeder offer

Capacity figures are only comparable on the same basis: Eriez quotes dry sand at 1.6 t/m³ on a 10° downslope, MEKA 1.6 t/m³ at the inclination it specifies. Weight is not given in either source.

07

Send the material, rate and hopper data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Material: [type; bulk density; lump size; moisture; temperature]
Rate: [t/h range; control signal]
Hopper: [throat; gate; head load; skirtboards]
Installation: [slope; base or suspended; discharge to]
Drive: [electromagnetic, mechanical or twin motor; power supply]
Options: [liners; grizzly; screen; dust cover]

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