Blender drive motor (geared motor drive for powder blenders)

01

Set output speed and torque from the blender's load

Canaan's specification table for its HTD post bin blenders shows how drive size follows bin size: bins of 100 L to 2,000 L with maximum net loads of 50 kg to 1,000 kg, mixing motors of 1.5 kW to 11 kW, and working speeds of 3–20 r/min for the smaller models, 3–15 r/min for 500–800 L and 3–10 r/min for 1,000 L and above. The HTD1000 lists a 1,000 L bin, 500 kg net load, 3–10 r/min, a 4 kW mixing motor and a separate 3 kW lifting motor. [1]

Canaan describes the bin as held at 30° to the rotary axis, mixing for a set time and speed, then turning to vertical and lowering when the time is up, so the drive has to start, run and stop the loaded bin on every batch. [1]

Editorial calculation: assuming a motor speed of 1,450 rpm at 50 Hz (an assumed nameplate value), an overall ratio of 1,450 ÷ 10 = 145:1 gives the HTD1000's top speed of 10 r/min. On the same ratio, 3 r/min needs about 435 rpm at the motor, roughly 15 Hz on a variable-frequency drive if speed is taken as proportional to frequency. If the full 4 kW reached the bin at 10 r/min, the shaft torque would be 9,550 × 4 ÷ 10 ≈ 3,820 N·m before gear losses. [1] [2]

Give the supplier the blender type and model, bin volume and maximum loaded mass, speed range, run time per batch and batches per day, start–stop and inching needs, supply voltage and frequency, the hazardous-area classification of the room, and the cleaning method.

02

Size the gear reducer with a service factor for the duty

AutomationDirect's IronHorse gearbox manual sets out a selection order: find the load torque and speed, the overall ratio of motor speed to load speed, the gearbox and external ratios, the service factor and overhung-load factor, then pick a gearbox whose thermal and mechanical ratings exceed the real and design torque, and finally a compatible motor. Its worked example divides 1,750 rpm motor speed by 20 rpm load speed for an overall ratio of 87.5. [2]

The AGMA service factor table reproduced in the manual gives, for agitators handling liquids and solids, 1.00 for up to 3 hours a day, 1.25 for 3–10 hours and 1.50 for over 10 hours; concrete mixers are listed at 1.25, 1.25 and 1.50. Tumble blenders for powders are not listed, so ask the reducer supplier which class they use. [2]

Editorial calculation: taking the 3,820 N·m example above and a factor of 1.25 for 3–10 hours a day, the reducer's design torque would be 3,820 × 1.25 ≈ 4,775 N·m. The factor is an assumed classification, not a published rating for blenders. [2] [1]

03

Align motor, coupling and reducer to a stated tolerance

Pruftechnik's practical guide to shaft alignment gives suggested tolerances for short flexible couplings, to be used where no in-house or machine-maker tolerance exists. At 1500 RPM it lists offset of 0.09 mm acceptable and 0.06 mm excellent, and angularity of 0.07 mm and 0.05 mm gap difference per 100 mm of coupling diameter; at 750 RPM the offsets are 0.19 mm and 0.09 mm. It gives a soft-foot limit of 0.06 mm at any speed and states that rigid couplings have no tolerance for misalignment. [3]

The guide notes that tolerable misalignment depends on speed, power rating, coupling type, spacer length, the coupled equipment and the service life expected, and that its acceptable limits were derived from an allowable sliding velocity of 0.5 inch/s in lubricated steel couplings. [3]

Editorial calculation: for a 200 mm flexible coupling at 1500 RPM, the angularity limits become 0.07 × 2 = 0.14 mm acceptable and 0.05 × 2 = 0.10 mm excellent gap difference across the coupling face. [3]

04

Split mixing and lifting drives; account for belt stages

Canaan's HTD blenders use one motor for mixing and another for lifting the bin, each with its own rating. [1] The IronHorse manual covers reductions made partly outside the gearbox, such as V-belt pulleys, which add an overhung-load factor (1.5 for a V-belt in its example). [2]

05

Rate each link of the blender drive train

A loaded bin is only as well driven as the weakest link between motor and bin shaft, so each item below needs its own rating in the order.

06

Nameplate, enclosure and room data for the blender drive

Canaan publishes motor power and bin speed for its blenders; insulation, IP code, efficiency class and noise are not on its table and have to come from the motor and reducer makers for your room.

07

Send the blender, duty and site data together

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

Blender: [type; model; bin volume; maximum loaded mass]
Speed: [range in r/min; ramp; inching]
Duty: [minutes per batch; batches and hours per day]
Drive: [motor kW; reducer ratio; service factor; coupling]
Supply: [voltage; frequency; VFD]
Room: [hazardous-area class; IP; cleaning method]

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