Scrap Metal Shredder Motors

Whether a machine tears, cuts or hammers metal scrap, its rotor or shafts are turned by an electric motor, and that motor is what we call a scrap metal shredder motor. This group covers very different machines: swarf crushers work with a few kW, twin- and four-shaft metal shredders carry from tens to a few hundred kW, while on large hammer shredders that pound car bodies the main motor reaches the megawatt level and is usually fed at medium voltage. According to manufacturer catalogues, power starts at 5.5 kW on a swarf crusher and reaches 7500 kW on a large hammer shredder.

DRG Motor does not sell these machines, their gearboxes, hydraulic pumps or drives; we supply low-voltage electric motors up to 355 kW. Below we set out clearly which machines our range covers and which fall outside it.

Types of metal shredding machines

In metal recycling, machine choice follows scrap thickness, volume and the required output size. For the motor there are three separate worlds: slow-running cutting shredders, swarf crushers and fast-running hammer shredders.

Twin-shaft metal shredder

Thick cutter discs on two opposed shafts strip empty drums, thin sheet, profiles, appliance shells and aluminium offcuts. In one manufacturer's series the chamber length grows from 300 mm to 2200 mm while motor power rises from 7.5 kW to 220 kW. The drive resembles that of plastic shredders: motor, gearbox and, very often, inverter control with reversing protection.

Four-shaft shredder

Two main shafts cut, two secondary shafts push material back into the cutting zone, and a screen underneath limits output size. This layout gives an even size on e-waste, cable offcuts, mixed light metal and medical waste. Main and secondary shafts can have separate motors: in one data sheet the large models carry four motors, 2 × 45 kW plus 2 × 30 kW; another maker's heavy model reaches 4 × 80 kW with four motors.

Swarf crusher

It breaks long, tangled turning and milling swarf into short, free-flowing chips; a centrifuge then removes cutting oil and the chips can be briquetted. One maker's electrically driven swarf crushers run at 45–76 rpm with 5.5–22 kW motors, while the two largest models are hydraulically driven. On the hydraulic model the electric motor does not turn the crusher shaft but the pump of a separate hydraulic unit.

Hammer scrap shredder

Swinging hammers on a heavy rotor pound car bodies, white goods and light scrap, drawn in by feed rolls, into fist-sized pieces; magnets and air separators then split ferrous, non-ferrous and light fractions. The rotor turns at hundreds of rpm and behaves like a heavy flywheel. These machines are the largest electrical consumer on a scrap yard.

Motor, gearbox and starting

Gearbox and reversing on slow shredders

Twin- and four-shaft metal shredders reduce speed through a high-ratio gearbox. Jams are more frequent with metal than with plastic; when current passes the limit the control stops the shaft and reverses it briefly. The gearbox service factor is chosen for this load, and a bigger motor means checking the gearbox again. On a four-motor machine the main-shaft motors must match each other, and so must the secondary-shaft motors.

Example: swarf crusher shaft torque

Take a swarf crusher turning at 76 rpm with a 15 kW 4-pole DRG-160L-4: 1465 rpm, 97.8 Nm. The gearbox ratio is 1465 / 76 ≈ 19.3; allowing 0.9 for losses, rated torque on the crusher shaft ≈ 97.8 × 19.3 × 0.9 ≈ 1.7 kN·m. The same catalogue gives up to 1.5 t/h of steel swarf for this power class; that figure is the machine's capacity, not a motor property. Models with an ejector for unbreakable pieces in the swarf also have a small hydraulic unit motor.

Starting and load on a large hammer shredder

On a heavy-rotor shredder the motor lets the rotor's kinetic energy take each impact. In a French plant described by a motor maker, a rotor weighing more than 40 tonnes is driven direct from the grid by a ten-pole slip-ring motor of about 3000 kW at 5500 V and 595 rpm; raising the resistance in the rotor circuit lowers speed in a controlled way so that the rotor's energy absorbs the load surge. Another maker cites a 6.6 kV, 1120 kW, ten-pole shredder drive. Industry articles note that squirrel-cage and wound-rotor motors have been used side by side on these machines for decades. A repair case also reports that a slip-ring motor can start a loaded shredder at full starting torque, but that severe vibration can damage brushes and slip rings.

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How many kW for scrap and metal shredding motors?

A) From the smallest to the largest machine: published power

From one motor to the next the spread is huge, about 5.5 kW at the bottom and 7500 kW at the top. The lower and middle part of the range (swarf crushers, twin- and four-shaft shredders) stays within a few hundred kW; the top belongs only to large hammer shredders.

B) What falls inside and outside the DRG range

Motor powers of swarf crushers, twin- and four-shaft metal shredders and the 355 kW main motor of the smallest stationary hammer shredder are inside the DRG range: 0.55–355 kW cast iron, 400/690 V. Large hammer shredders needing more than 355 kW, plants requiring medium-voltage (6/10 kV) or wound-rotor motors, and older DC-driven machines are outside the DRG range; we do not offer main motors for them. The feed conveyor, vibrating chute, magnet drum, fan and pump motors on the same site, however, usually fall within our range.

The 355 kW limit and medium voltage

At low voltage, current grows in step with power, and cable, switchgear and transformer costs climb quickly. The comparison below shows why large shredders are fed at medium voltage:

The machine decides the voltage

A 3000 kW motor would draw about 4,330 A at 400 V, which means parallel cables and very large breakers. The same power is carried at 5.5 kV with about 315 A. That is why large shredder plants install their own medium-voltage switchgear and rotor resistance or starting system with the machine. If your yard needs such a motor, you will need to work with the machine builder or a medium-voltage motor maker.

The part DRG covers

Up to 355 kW at low voltage we can supply the main drive motor; on plants above 355 kW, the motors of the auxiliary equipment. For the pre-shredder, granulator and separation motors of a cable recycling line, see our article cable granulator machine motor selection.

Checklist for motor replacement

• Old plate: kW, rpm, voltage, and whether it runs 690 V star or 400 V delta.
• Squirrel-cage or slip-ring? A standard motor can replace a slip-ring motor only if the machine builder agrees and the starting system is adapted.
• Frame size, foot or flange, shaft diameter and key; gearbox or coupling connection.
• Starting: direct, star-delta, soft starter or inverter; supply capacity for large motors.
• Environment: metal dust, oily swarf, open yard; fan cowl cleaning and a roofed position for the IP55 motor.
• Vibration: on heavy shredders, bearings and fixing bolts are checked regularly.

How is the fit confirmed?

A metal shredder gets a motor proposal from us only after these points have been set against the old plate and the builder's papers; no exact-fit claim comes earlier. Vibration motors used on vibrating feeders and screens are a separate product group; tell us what you need, and our article on vibration motors gives background.

DRG motors: frames suited to metal shredders

DRG Motor is a manufacturer, supplier and seller of electric motors. For swarf crushers and shaft-type metal shredders, these 4-pole cast iron frames are the usual picks:

Our range holds three-phase induction IEC motors; cast iron frames up to 355 kW, aluminium frames up to 11 kW, in 2, 4 and 6 poles. We have no 750 rpm motor, no brake motor and no medium-voltage motor. In the 355 kW class, DRG-400M-4 draws 593 A at 400 V.

Live price table

Prices below are read live from the shop for motors from 5.5 kW up to the 355 kW limit:

DRG MOTOR motors are guaranteed against material and manufacturing defects for 2 years from the delivery date (warranty certificate).

Motors in this power range

• DRG-160L-4 – 15 kW – 1465 rpm – 160L cast iron
• DRG-225M-4 – 45 kW – 1485 rpm – 225M cast iron
• DRG-280M-4 – 90 kW – 1486 rpm – 280M cast iron
• DRG-355L-4 – 315 kW – 1490 rpm – 355L cast iron
• DRG-400M-4 – 355 kW – 1490 rpm – 400M cast iron

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Browse the motors, ask for a quote. Send us the shredder type, the number of shafts and the old motor nameplate; our first reply tells you whether it falls within our range. Suitable codes are under Buy Electric Motors Online; nameplate photos via WhatsApp, a call on +90 (542) 666 11 11.

Frequently asked questions

What kW is a metal shredder motor?

Swarf crushers show 5.5–22 kW, twin-shaft metal shredders 7.5–220 kW depending on series, four-shaft machines 11–80 kW per motor. On hammer shredders that pound car bodies the main motor starts at 355 kW and reaches the megawatt level in large plants.

Can I buy the main motor of a large scrap shredder from DRG?

Yes, if the main motor is up to 355 kW and 400/690 V. If more power, medium voltage or a wound rotor is needed, it is outside our range; we can still supply auxiliary equipment motors.

What speed should a metal swarf crusher motor have?

The crusher shaft turns slowly; the motor is usually 4-pole (about 1500 rpm) and the gearbox brings the speed down. The exact value comes from the machine's nameplate.

Is a scrap recycling motor price listed online?

Yes, for every motor in the table above, each linked to its product page; gearbox, drive and machine are quoted by their own makers.

For scrap recycling motor questions call +90 (542) 666 11 11; equipment lists are welcome at [email protected], and the contact form works too.