Program 2011/2012 - maxon motor - #49

Explanation of the pages 50 - 134

Dimensional drawings

On the enclosed DVD dimensional drawings

(DXF-files) are available and are suitable for im-

port to any CAD system.

Presentation of the views according to the projec-

tion method E (ISO).

All dimensions in [mm].

Mounting threads in plastic

Screwed connections on motors with plastic

flanges require special attention.

MA Max. tightening torque [Ncm]

A torque screw driver may be adjusted to this

value.

L Active depth of screw connection

[mm]

The relation of the depth of the screw connection

to the thread diameter must be at least 2:1. The

depth of the screw connection must be less than

the usable length of the thread!

Motor Data

The values stated are based on a motor tempera-

ture of 25°C (so-called cold data).

Line 1 Nominal voltage UN [Volt]

is the DC voltage on the motor connections on

which all nominal data are based (lines 2 - 9).

Lower and higher voltages are permissible, pro-

vided set limits are not exceeded.

Line 2 No load speed n0 [rpm] ±10%

This is the speed at which the motor turns at nom-

inal voltage and without load. It is approximately

proportional to the applied voltage.

Line 3 No load current l0 [mA] ±50%

This is the typical current that the unloaded mo-

tor draws when operating at nominal voltage.

It depends on brush friction and friction in the

bearings, and also increases with rising speed.

No-load friction depends heavily on temperature,

particularly with precious metal commutation. In

extended operation, no-load friction decreases

and increases at lower temperatures.

Line 4 Nominal speed nN [rpm]

is the speed set for operation at nominal voltage

and nominal torque at a motor temperature of

25°C

Line 5 Nominal torque MN [mNm]

is the torque generated for operation at nominal

voltage and nominal current at a motor tempera-

ture of 25°C It is at the limit of the motor's continu-

ous operation range. Higher torques heat up the

winding too much.

Line 6 Nominal current lN [A]

is the current that, at 25°C ambient temperature,

heats the winding up to the maximum permissible

temperature (= max. permissible continuous cur-

rent). IN decreases as speed increases due to ad-

ditional friction losses.

Line 7 Stall torque MH[mNm]

is the torque produced by the motor when at

standstill. Rising motor temperatures reduce stall

torque.

Line 8 Starting current lA [A]

is the quotient from nominal voltage and the

motor's terminal resistance. Starting current is

equivalent to stall torque. With larger motors, lA

cannot often be reached due to the amplifier's

current limits.

Line 9 Maximum efficiency r|max [%]

is the optimal relationship between input and

output power at nominal voltage. It also doesn't

always denote the optimal operating point.

Line 10 Terminal resistance R [Q]

is the resistance at the terminals at 25°C and

determines the starting current at a given volt-

age. For graphite brushes, it should be noted that

resistance is load-dependent and the value only

applies to large currents.

Line 11 Terminal inductance L[mH]

is the winding inductance when stationary and

measured at 1 kHz, sinusoidal.

Line 12 Torque constant kM [mNm A1]

This may also be referred to as "specific torque"

and represents the quotient from generated

torque and applicable current.

Line 13 Speed constant k„ [rpm/V]

shows the ideal speed per 1 volt of applied volt-

age. Friction losses not taken into account.

Line 14 Speed / torque gradient

An / AM [rpm/mNm]

The speed / torque gradient is an indicator of the

motor's performance. The smaller the value, the

more powerful the motor and consequently the

less motor speed varies with load variations. It is

based on the quotient of ideal no-load speed and

ideal stall torque.

Line 15 Mechanical time constant

xm [ms]

is the time required for the rotorto accelerate from

standstill to 63% of its no-load speed.

Line 16 Rotor inertia JR [gem2]

is the mass moment of inertia of the rotor, based

on the axis of rotation.

Line 17 Thermal resistance

ancl housing-ambient Rh2 [K/W]

Line 18 Thermal resistance

winding-housing R,hl [K/W]

Characteristic values of thermal contact resis-

tance without additional heat sinking. Lines 17

and 18 combined define the maximum heating

at a given power loss (load). Thermal resistance

R,h2 on motors with metal flanges can decrease

by up to 80% if the motor is coupled directly to

a good heat-conducting (e.g. metallic) mounting

rather than a plastic panel.

Line 19 Thermal time constant winding

, xw [s]

and L '

Line 20 Thermal time constant motor xm [s]

These are the typical reaction times for a tem-

perature change of winding and motor. It can be

seen that the motor reacts much more sluggishly

in thermal terms than the winding.The values are

calculated from the product of thermal capacity

and given heat resistances.

Line 21 Ambient temperature [ C]

Operating temperature range. This derives from

the heat reliability of the materials used and vis-

cosity of bearing lubrication.

Line 22 Max. winding temperature [ C]

Maximum permissible winding temperature.

Line 23 Maximum permissible speed

nmax [rpm]

is the maximum recommended speed based on

thermal and mechanical perspectives. A reduced

service life can be expected at higher speeds.

Line 24 Axial play [mm]

For non-preloadedmotors, this represents the

tolerance limits of the factory-set bearing play.

The latter is included in shaft length tolerances.

Pre-loading cancels out axial play up to the given

axial loading.

Line 25 Radial play [mm]

Radial play derives from the bearings' radial air.

A spring (bearing preload) cancels out radial play

up to the given axial loading.

Line 26 / 27 Max. axial loading [N]

dynamically: axial loading permissible in op-

eration. If different values apply for traction and

thrust, the smaller value is given.

statistically: maximum axial force applying to

the shaft at standstill where no residual damage

occurs.

Shaft supported: maximum axial force applying

to the shaft at standstill if the force is not input at

the other shaft end.This is not possible for motors

with only one shaft end.

Line 28 Max. radial loading [N]

The value is given fora typical clearance from the

flange; this value falls the greater the clearance

Line 29 Number of pole pairs

Number of north poles of the permanent mag-

net. The phase streams and commutation signals

pass through per revolution p cycles. Servo-con-

trollers require the correct details of the number

of pole pairs.

Line 30 Number of commutator segments

Line 31 Weight of motor [g]

May 2011 edition/subjectto change

maxon DC motor 49