Retsch DM 400 User Manual

Operating Manual

DM400 Disc Mill

Original

© Retsch GmbH, 42781 Haan, Retsch-Allee 1-5, Germany 18.07.2014 0001

Copyright

© Copyright by
Retsch GmbH
Haan, Retsch-Allee 1-5
D-42781 Haan
Federal Republic of Germany

Table of contents

4

1 Basic construction .................................................................................................................................. 7

2 Safety instructions and use ................................................................................................................... 9

2.1 Requirements for the user ................................................................................................................ 9

2.2 Intended use ................................................................................................................................... 10

2.2.1 Operating principle ..................................................................................................................... 10

2.3 Duties of the operating company.................................................................................................... 10

2.4 Hazard warnings and symbols used .............................................................................................. 11

2.5 Device safety instructions ............................................................................................................... 15

2.6 Safety equipment ........................................................................................................................... 17

2.7 Danger areas .................................................................................................................................. 18

2.8 Electrical safety .............................................................................................................................. 18

2.8.1 General information.................................................................................................................... 18

2.8.2 Protection against restarting ...................................................................................................... 19

3 Technical data ....................................................................................................................................... 21

3.1 Dimensions ..................................................................................................................................... 21

3.2 Weight ............................................................................................................................................ 21

3.3 Operating noise .............................................................................................................................. 21

3.4 Voltage, power consumption, power input ..................................................................................... 21

3.5 Fuse ................................................................................................................................................ 21

3.6 Material ........................................................................................................................................... 22

3.7 Final fineness ................................................................................................................................. 22

4 Installation ............................................................................................................................................. 23

4.1 Transport ........................................................................................................................................ 23

4.2 Unpacking ....................................................................................................................................... 23

4.3 Positioning ...................................................................................................................................... 24

4.4 Ambient conditions ......................................................................................................................... 25

4.5 Electrical connection ...................................................................................................................... 26

4.5.1 Adjusting the disc mill to the mains network .............................................................................. 26

4.6 Putting into service ......................................................................................................................... 26

4.7 Switching on for the first time / function test ................................................................................... 27

4.7.1 Switching on ............................................................................................................................... 27

4.7.2 Switching off ............................................................................................................................... 27

5 Working with the disc mill .................................................................................................................... 29

5.1 Display and control panel ............................................................................................................... 30

5.2 Menu navigation ............................................................................................................................. 30

5.3 Specifying the zero point ................................................................................................................ 31

5.4 Adjusting the gap width .................................................................................................................. 32

5.5 Reverse operation .......................................................................................................................... 33

5.6 Adjusting the grinding time ............................................................................................................. 34

5.7 Changing the language .................................................................................................................. 35

5.8 Grinding with zirconium oxide grinding discs ................................................................................. 35

5.9 Material feed ................................................................................................................................... 36

5.10 Sample removal.............................................................................................................................. 38

5.11 Final fineness ................................................................................................................................. 38

6 Cleaning ................................................................................................................................................. 39

6.1 Extracting dust after grinding .......................................................................................................... 39

6.2 Grinding chamber ........................................................................................................................... 39

6.3 Housing .......................................................................................................................................... 40

6.4 Cleaning the hopper ....................................................................................................................... 40

Table of Contents

5

7 Servicing ................................................................................................................................................. 41

7.1 Grinding discs ................................................................................................................................. 42

7.2 Replacing the grinding discs (5 + 6)................................................................................................ 42

7.3 Replacing the gear oil ..................................................................................................................... 49

7.3.1 Conducting the gear oil change .................................................................................................. 49

8 Repair ...................................................................................................................................................... 51

8.1 Checklist for troubleshooting ........................................................................................................... 52

9 Disposal .................................................................................................................................................. 54

10 EC Declaration of Conformity ............................................................................................................... 55

11 Index ........................................................................................................................................................ 57

Table of contents

6

Basic construction

7

1 Basic construction

1

Display

2

Control panel

3

Main switch

4

Fill hopper

5

Fixed grinding disc

6

Moving grinding disc

7

Gap set screw

8

Grinding chamber closing mechanism

9

Locking bolts sample material container

10

Sample material container

11

Suction flange lid

12

Height adjustable support

13

Interlock switch

14

Housing cover

1

2

12

10

6

13

3

9 5 4

11 7 8

14

Basic construction

8

a

+ button (change parameters and gap width, menu navigation)

b

- button (change parameters and gap width, menu navigation)

c

Arrow up button (menu navigation)

d

Arrow down button (menu navigation)

e

Start button

f

Stop button

g

Button dust extraction (on/off)

h

Unlocking and locking the grinding chamber

i

Sensor grinding chamber

a b c d e f g h i

Safety instructions and use

9

This Operating Manual is intended for persons commissioned with
the operation and monitoring of the DM400. The Operating Manual,
and in particular the safety instructions, should be heeded by all per­sons working on or with the equipment. Furthermore the regulations
and provisions on accident prevention applicable at the application
site must be observed. The Operating Manual must always be kept
where the DM400 is used.

Persons with health disorders or who are under the influence of medi­cation, drugs, alcohol or extreme tiredness must not operate the de­vice.

The DM400 may only be operated by authorised persons and ser­viced and repaired by trained specialists. Technically qualified per­sonnel must conduct all maintenance, servicing and repair work!
Qualified personnel are people who have been authorised by persons
responsible for the safety of the system to execute the required activi­ties and are able to recognise potential dangers and avoid them
based on their training, experience and instruction, as well as their
knowledge of relevant standards, regulations, accident prevention
regulations and operating conditions (definition of skilled personnel
according to IEC 364).

The instructions in this Manual should be followed in order to prevent
danger to the user.

Faults which can impair the safety of persons, the DM400 or other
material assets should be rectified immediately. The following instruc­tions serve both personal safety of operating staff and the safety of
the described products as well as connected equipment: all servicing
and repair work may only be carried out by technically qualified per­sonnel!

This Operating Manual is not a full technical description. It only de­scribes information required for safe operation and maintenance of
serviceability.

Retsch has prepared and checked this Operating Manual very careful­ly. However no liability can be assumed regarding completeness and
accuracy.

Subject to technical amendments.

2 Safety instructions and use

2.1 Requirements for the user

Safety instructions and use

10

2.2 Intended use

The DM400 is a disc mill for batch or continuous fine grinding of hard
brittle to medium hard solids from the areas of mining and metallurgy,
geology and mineralogy and the glass and ceramics industry.

The maximum feed size is 20 mm edge length; the achievable final
fineness level depending on the gap width set is approx. 12 mm (larg­est gap width) and 0.05 mm (smallest gap width).

The material throughput of the disc mill lies in the range of 20 to 150
kg/h. This depends on the setting of the outlet gap and the bulk
weight and grinding conduct of the sample.

The grinding of the material sample takes place in a grinding
chamber which is dustproof to the outside and in which two
coarsely toothed grinding discs operate against each other.
The moving grinding disc is driven by a powerful, slow running
gear motor.

The sample material is filled through a lockable hopper into the
centre of the upright grinding disc and, after being ground by
compression and shear stress, escapes through the gap be­tween the two discs. The gap width determines the mean parti­cle size of the sample material. The grinding gap can be set to
an accuracy of 0.05 mm using the plus/minus buttons on the
control panel. The gap width can be read off the display (1).

When grinding batches, the sample material is collected in a
sample material container placed in the device (volume: 2l).
The closed design prevents dust escaping. A dust extraction
device may additionally be connected. To clean, the front hous­ing is opened sideways - the grinding chamber is then freely
accessible.

This Manual should be read and understood before using the DM400.
Use of the DM400 demands expert knowledge and should be limited
to commercial users.

Operating personnel must be familiar with the contents of the Operat­ing Manual. It is therefore very important for this Operating Manual to
be actually handed to these persons. It must be ensured that the
Operating Manual always remains with the device.

The DM400 may be used exclusively within the possible uses set out
in this Manual and within the specified regulations in this Manual. In
the event of contravention or incorrect use, the customer assumes full

2.2.1 Operating principle

2.3 Duties of the operating company

Safety instructions and use

11

liability for the functionality of the DM400 or for damage arising from
an infringement of this duty.

Through use of the DM400 the customer agrees and recognises that
defects, faults or errors cannot be entirely ruled out. In order to avoid
the risk of personal injury or damage to property arising from this or
otherwise or of other indirect or direct damage, customers must take
adequate and comprehensive safety measures when working with the
device.

It is not possible for Retsch GmbH to monitor compliance with this
Manual or the conditions and methods used in the installation, opera­tion, use and servicing of the DM400. Damage to property leading to
danger to persons may result from incorrect installation. We therefore
assume no responsibility and liability at all for loss, damage or costs
arising from or in any way associated with faulty installation, incorrect
operation or from incorrect use and servicing.

The applicable accident prevention regulations must be complied with.
Generally accepted statutory and other binding regulations on envi-

ronmental protection must be observed.

Safety instructions

Safety instructions are indicated in this Manual by symbols. The safe­ty instructions are introduced by signal words which express the de­gree of danger.

DANGER!

This combination of symbol and signal word indicates a
direct hazardous situation leading to death or serious
injuries if it is not avoided.

WARNING!

This combination of symbol and signal word indicates a
potentially hazardous situation which can lead to death
or serious injuries if it is not avoided.

2.4 Hazard warnings and symbols used

Safety instructions and use

12

CAUTION!

This combination of symbol and signal word indicates a
potentially hazardous situation which can lead to minor
or slight injuries if it is not avoided.

NOTICE!

This combination of symbol and signal word indicates a
potentially hazardous situation which can lead to
damage to property if it is not avoided.

NOTICE!

This combination of symbol and signal word indicates a
potentially hazardous situation which can lead to
damage to the environment if it is not avoided.

Safety instructions and use

13

Special safety instructions

The following symbols are used in safety instructions to alert to specif­ic hazards:

DANGER!

This combination of symbol and signal word indicates a
direct hazardous situation through electric current. If a
sign with this symbol is not heeded, serious or fatal
injuries will result.

DANGER!

This combination of symbol and signal word designates
content and instructions for intended use of the machine
in potentially explosive areas. If a sign with this symbol
is not heeded, serious or fatal injuries will result.

DANGER!

This combination of symbol and signal word designates
content and instructions for intended use of the machine
with flammable materials. If a sign with this symbol is
not heeded, serious or fatal injuries will result.

DANGER!

This combination of symbol and signal word designates
content and instructions for intended use of the machine
with potentially explosive substances. If a sign with this
symbol is not heeded, serious or fatal injuries will result.

WARNING!

This combination of symbol and signal word indicates a
direct hazardous situation due to moving parts. If a sign
with this symbol is not heeded, injuries to hands may
result.

Safety instructions and use

14

WARNING!

This combination of symbol and signal word indicates a
direct hazardous situation due to hot surfaces. If a sign
with this symbol is not heeded, skin contact with hot
surfaces may cause serious burns to skin.

Safety instructions in
operating instructions

Safety instructions may refer to a specific, individual operating instruc­tion. Such safety instructions are embedded in this operating instruc­tion in order not to interrupt the flow of reading when performing the
action concerned. The signal words described above are used.

Example:

1.

Loosen screw.

2.

CAUTION!
Risk of pinching on the lid.

Close the lid carefully.

3.

Tighten the screw.

Tips and recommendations

This symbol highlights useful tips and recommendations
as well as information for efficient and fault-free
operation.

Other labelling

The following labels are used to emphasise operating instructions,
results, lists, references and other elements in this Manual:

Labelling

Explanation

1., 2., 3. ...

Step-by-step operating instructions



Results of operating steps

Lists without specified order

[Button]

Control elements (e.g. button, switch), indi­cators (e.g. signalling lamps)

"Display"

Screen elements (e.g. buttons, assignment
of function buttons)

Safety instructions and use

15

2.5 Device safety instructions

Please note!

 Only use original accessories and original spare parts. Failure to

do so can place the protection of the machine in doubt.

 Safe conduct must be strictly followed during all work.
 The current applicable national and international accident

prevention regulations must be complied with.

Safety instructions and use

16

CAUTION!
Wear hearing protection!

Hearing protection should be worn when a noise level of
85dB (A) is reached or exceeded in order to prevent
damage to hearing.

WARNING!

The maximum workplace concentrations (threshold limit
values - TLV) in valid safety regulations must be
observed, and ventilation must be provided where
necessary or the machine operated under an extractor
hood.

DANGER!
Risk of explosion!

- When grinding oxidable substances (e.g. metals or
coal) there is a risk of spontaneous ignition (dust
explosion) if the fine fraction exceeds a certain
percentage. For this reason special safety measures
must be taken when grinding such substances and
the work must be supervised by a specialist.

- The device is not designed for use in potentially
explosive areas and is not suitable for grinding
explosive materials.

 Do not remove signs.

NOTICE!

Replace damaged or illegible signs without delay.

 Unauthorised modifications to the device lead to loss of the

conformity to European directives declared by Retsch and to loss
of the warranty claim.

 Only use the DM400 in a technically perfect state and as intended,

with an awareness of safety and dangers as specified in the
Operating Manual. In particular have faults which might impair
safety rectified immediately!

 If you have any questions or problems after reading the Operating

Manual, please contact our technical staff.

Safety instructions and use

17

2.6 Safety equipment

Safety equipment must be used as intended and must
not be rendered unworkable or removed.

All safety equipment must be checked regularly for
completeness and function.

The disc mill has a comprehensive safety system:

1.

A grille (4G) prevents contact with the fill hopper (4).

2.

A sensor (i) monitors the closing of the grinding chamber before
operation and prevents the disc mill starting up after it has been
opened.

3.

A second safety device checks whether the grinding chamber has
been closed by means of the motorised closing mechanism (8).

4G i 8

Safety instructions and use

18

4.

The interlock switch (13) pulls in the sample material container
after the start of grinding and locks it using the locking bolt (9) on
the container. During operation the interlock switch monitors
whether the device is closed correctly. It likewise prevents the
disc mill starting up after it has been opened.

The disc mill does not start if the grinding chamber
is open or the sample material container is missing.

CAUTION!

- Risk of crushing on hopper cover

- Risk of crushing when closing the grinding chamber

- Risk of crushing when cover of dust extraction is
removed during operation!

The disc mill is switched on and off with a main switch (3).

 By pressing the switch to I (On):

Disc mill is activated and can be started using the start button (e)

as long as the grinding chamber is closed and the sample material

container is inserted!

 By pressing the switch to O (off) during grinding:

The disc mill comes to a halt and is completely deactivated!
Grinding chamber and sample material container remain locked

when switched “off” and cannot be opened.

13

2.7 Danger areas

2.8 Electrical safety

2.8.1 General information

Safety instructions and use

19

2.8.2 Protection against restarting

The device switches off in the event of a power failure during opera­tion.

 The mill comes to a halt within seconds!
 Sample material container can only be opened with the emergency

release (k) inside the device! To do this the housing cover (14)

must be removed as follows (also see chapter “Positioning” )

DANGER!

Pull the plug out and secure the device to prevent
accidental restarting!

 Open the housing cover (14) by releasing the quick acting

screws placed on either side.

 After releasing the quick acting screws, pull the housing cover

(14) back by a few centimetres. Then lift the housing cover up
and out.

 The emergency release (k) inside the device is then visible.
 To release the sample material container, pull the emergency

release (k) backwards until the locking bolt (9) on the sample

material container (10) is released.
Considerable force is required to release it.

 The emergency release can then be engaged again and the

housing cover closed. The sample material container is pulled in

when grinding next starts.

NOTICE!

Grinding chamber cannot be opened when the grinding
chamber interlock is closed or when switched off.

The disc mill does not start up by itself when supply voltage returns.

 The mill has protection against restarting.
 The motor is started again by pressing the start button (e), and the

mill begins operation.

Safety instructions and use

20

Technical data

21

3 Technical data

52 x 105 x 63 cm (width x depth x height)

228 kg (net) without griding discs
246 kg with tungsten carbide grinding discs

Workplace related emissions value in accordance with DIN EN ISO
3746:2005 LPA .

= 68.9 dB (A) The measurement was conducted with sand as sample
material, particle size 0.5 – 2 mm.

Voltage

400V / 3~ 50Hz

230V / 3~ 60Hz

Power consumption

3.2 A

5.6 A

Power input

1830 W
Under high load (significantly

lower in normal use)

1800 W
Under high load (significantly

lower in normal use)

The device may only be operated on a three phase supply network!
Transient electrical surges according to surge category II permissible

(also see chapter “Electrical connection”)

A thermal circuit breaker (motor circuit breaker) is integrated in the
main switch (3) and triggers on overheating; it is operational again
after a brief cooling phase.

3.1 Dimensions

3.2 Weight

3.3 Operating noise

3.4 Voltage, power consumption, power input

3.5 Fuse

Technical data

22

3.6 Material

 Maximum feed size 20mm (depending on the material)
 Minimum feed quantity 20 - 30ml
 Batch grinding with collecting container (max. 2l)
 Maximum throughput 150kg/h with continuous grinding

The final fineness is between 0.05 and 12mm, depending on the sam­ple material.

3.7 Final fineness

Installation

23

4 Installation

The device is supplied on a transport pallet with wooden cover. We
recommend transporting the packaged device with a pallet truck or
forklift.

DANGER!

Do not walk under the transport pallet during transport.

WARNING!

Incorrect lifting can lead to injury or damage to property.
The machine should only be lifted using suitable
equipment and by appropriately qualified personnel!

Damage caused by incorrect transport does not justify any replace­ment or warranty claims.

 Pull out the nails attaching the cover to the transport pallet. The

cover is the wooden box pulled over the transport pallet.

 Lift the cover from the transport pallet.

CAUTION!
Risk of crushing!

Always lift with 2 people.

 Compare the contents of delivery with your order.

4.1 Transport

4.2 Unpacking

Installation

24

4.3 Positioning

DANGER!

Do not walk under the transport pallet during transport.

To position the disc mill you will need a crane or other suitable means
of transport as well as 2 carrying straps (not included with delivery)
with a minimum length of 40cm and loadbearing capacity of 500 kg.

CAUTION!

Weight of the disc mill is approx. 260 kg with grinding
discs (WC) and transport pallet!

NOTICE!

The disc mill must be placed on an even, stable surface.
It can be screwed to this or to a base plate.

1.

The disc mill is screwed to the transport pallet from underneath
using 3 screws. Loosen screws using a spanner wrench (17
mm).

2.

Open the housing cover (14) by unscrewing the quick acting
screws on either side.

14S

Installation

25

3.

After unscrewing the quick acting screws, pull the housing cover
(14) back by a few centimetres.

Then lift the housing cover up and out.

4.

Two carrying lugs to attach the carrying straps are then visible.

5.

Attach the carrying straps to a crane or other auxiliary equipment.

6.

Now attach the carrying straps to the 2 carrying lugs provided.

7.

With the help of the crane, position the disc mill in the desired
place. Take care while positioning that the device does not swing
when hanging on the crane.

8.

Remove the carrying straps!

9.

Place the housing cover (14) back on and screw tight.

WARNING!
Mains voltage!

- The device may only be used inside.

- The surrounding air must not contain any conductive
dust.

4.4 Ambient conditions

Installation

26

- Maximum relative humidity 80% for temperatures up
to 31°C, decreasing in a linear fashion to 50% relative
humidity at 40°C.

 The room temperature must be between 5 and 40°C.
 Height up to 2000m above sea level
 Degree of pollution 2 in accordance with IEC 664.

Before connection, compare the voltage and current values on the
type plate with the values on the intended mains.

CAUTION!

Electrical as well as mechanical components may be
damaged by failure to heed to values on the type plate.

The DM400 is delivered with supply voltage adapted to suit your coun­try.

The disc mill is supplied with mounted grinding discs. Before grinding
for the first time, check the desired gap width (see chapter “Adjusting
the gap width ”) The device is operational once you have positioned
the disc mill as described under chapter “Positioning“ and have con­nected the plug to the mains socket.

CAUTION!

- Grinding discs must not touch each other.

- The device may only be operated with mounted and
secured grinding discs.

- Smallest gap width 0.05mm

4.5 Electrical connection

4.5.1 Adjusting the disc mill to the mains network

4.6 Putting into service

Installation

27

4.7 Switching on for the first time / function test

Only switch the device on when all work described as from the chap­ter “Installation” has been carried out!

Set the main switch (3) to I! The display (1) switches on and the
STOP button (f) is lit up in red! If the grinding chamber is locked, the
release and locking button (h) is lit up in green.

When the grinding chamber has been electrically closed and the sam­ple material container is inserted, start using the start button (e). The
disc mill starts up. Then actuate the stop button (f), and the machine
comes to a halt. It is then possible to continue with the chapter “work-
ing with the disc mill”.

Set the main switch (3) to 0. The device switches off completely.

4.7.1 Switching on

4.7.1.1 Function test

4.7.2 Switching off

Installation

28

Working with the disc mill

29

WARNING!

No warranty or complaint will be accepted in the case of
damage to the device when grinding tools are used
which are not original accessories of the device.

WARNING!

Before starting the machine, ensure that the grinding
discs are correctly mounted and that there are no loose
parts inside the device. If this is not observed, no
warranty or complaint will be accepted for damage to the
device or personal injury that result.

CAUTION!

- Grinding discs must not touch each other.

- The device may only be operated with mounted and
secured grinding discs.

- Smallest gap width 0.05mm

CAUTION!

Ensure that the suction flange lid or adapter to use the
dust extractor are fitted securely. Never reach into the
opening of the suction flange during grinding

NOTICE!

Do not leave the disc mill to run unsupervised.

NOTICE!

Grinding discs wear during grinding. For this reason the
grinding gap must be checked and regulated if
necessary according to use and the degree of wear.
This is carried out as described in chapter 5.3

“Specifying the zero point” and in chapter 5.4 “Adjusting
the gap width”.

5 Working with the disc mill

Working with the disc mill

30

5.1 Display and control panel

 If the grinding chamber is open, the button (h) to lock the grinding

chamber is not lit up!

 During the motorised closing of the grinding chamber, the button

(h) flashes green until the grinding chamber is closed. It is then lit
up in green.

 When starting up, the start button (e) flashes green. When the

device has started up, it lights up in green.

 After stopping the device, the stop button (f) flashes red until the

disc comes to a standstill. When it is at a standstill it lights up in
red.

 When a dust extractor is connected, the button (g) lights up in

green after its activation.

 The +/- buttons (a, b) are used to adjust values and for menu

changes.

 The arrow buttons (c, d) are used to select menu items and to

make changes in the menu bar.

Menu selection

1.

The Parameter menu is used for the following:

‒ To adjust the gap width between the grinding discs → Gap
‒ To adjust the grinding time in minutes → Time

2.

In the Check/Setup menu you can:

‒ Define the “zero point” → no gap between the grinding discs
‒ Change the direction of rotation of the moving grinding disc (6)

→ Reverse
‒ Set the language → Language

5.2 Menu navigation

Working with the disc mill

31

Menu change

1.

To move from the "Parameter" menu to the "Check/Setup" menu,
actuate the arrow buttons (c, d) until the - and + signs which are
visible on the bottom right of the display are highlighted in black!
Then use the buttons + (a) or - (b) to move to the Check/Setup
menu!

2.

The menu change from the Check/Setup menu to the Parameter
menu takes place in the same way.

Selecting menu items

1.

The menu items within menus are selected using the arrow but­tons (c, d).

The zero point is the gap width at which the fixed and the
moving grinding disc rub slightly against each other so
that no gap is present. All other gap widths are actuated
from this zero point.

The zero point must be reset after every time the
grinding discs are changed. Grinding discs can vary in
thickness according to the degree of wear.

1.

To move from the "Parameter" menu to the "Check/Setup" menu,
actuate the arrow buttons (c, d) until the - and + signs which are
visible on the bottom right of the display are highlighted in black!
Then use the buttons + (a) or - (b) to move to the Check/Setup
menu!

2.

Close the grinding chamber and remove the sample material
container.

5.3 Specifying the zero point

Working with the disc mill

32

3.

To change the grinding gap to adjust the zero point, the zero
point line must be selected in the Check / Setup menu using the
arrow buttons (c, d).

4.

Remove the suction flange lid (11). Check both grinding discs
while they are moving together through this opening. It should
only be possible to see a minimal light gap between the two
discs.

During the process of setting the zero point, no gap
information is shown on the display. You can hear a
mechanical noise of the servomotor and see how
the moving grinding disc (6) is aligned through the
suction flange (11)!

5.

CAUTION!

Risk of crushing between the grinding discs!

To check while adjusting the zero point, rotate the moving grind­ing disc by hand through the opening of the sample material con­tainer. While rotating, reduce the gap using the – button (b) until
slight rubbing of the two discs can be felt and heard!

6.

As soon as the smallest gap width has been set and a minimum
rubbing of the discs is registered, this may be defined as zero
point. Only when the zero point is highlighted in black can the
zero point be fixed by simultaneously pressing the stop (f) and +
(a) buttons.

7.

Reinsert the sample material container.

The adjustment of the gap width takes place automatically using the
Parameter menu item. The zero point must be set first (see chapter
“Specifying the zero point) to prevent damage to the grinding discs.

The gap width is adjusted as follows:

5.4 Adjusting the gap width

Working with the disc mill

33

1.

To move from the "Check/Setup" menu to the "Parameter" menu,
actuate the arrow buttons (c, d) until the - and + signs which are
visible on the bottom right of the display are highlighted in black!
Then use the buttons + (a) or - (b) to move to the Parameter
menu

2.

Close the grinding chamber!

3.

In the Parameter menu, press the c button (arrow up) until the
line to enter the gap width is highlighted.

4.

Using the +/- buttons on the control panel, increase (+) or de­crease (-) the gap width!

5.

The gap width between the discs adjusts automatically if:

☞the menu item is exited or
☞the grinding process is started using the start button (e).

NOTICE!

Grinding discs wear during grinding. For this reason the
gap width must be checked and possibly adjusted from
time to time. This takes place as described in the
chapter “Specifying the zero point and the chapter
“Adjusting the gap width ”.

CAUTION!

Risk of crushing between the grinding discs!

Reverse operation can be selected in the case of one-sided wear on
grinding discs.

5.5 Reverse operation

Working with the disc mill

34

1.

To move from the "Parameter" menu to the "Check/Setup" menu,
actuate the arrow buttons (c, d) until the - and + signs which are
visible on the bottom right of the display are highlighted in black!
Then use the buttons + (a) or - (b) to move to the Check/Setup
menu!

2.

Select reverse using the arrow buttons (c, d), and activate (on) or
deactivate (off) reverse operation with + (c) or - (d) button.

NOTICE!

Grinding discs are subject to natural wear after
longer periods of use and must be replaced where
necessary. If you ascertain that the grinding discs
are worn on one side, they need not be replaced
immediately. Reverse the direction of rotation of the
drive motor using the reverse setting. The crushing
edges of the grinding discs that had been on the
back are then in use. At this point at the latest you
should order spare grinding discs (see chapter
“Replacing the grinding discs (5 + 6)”)

1.

To move from the "Check/Setup" menu to the "Parameter" menu,
actuate the arrow buttons (c, d) until the - and + signs which are
visible on the bottom right of the display are highlighted in black!
Then use the buttons + (a) or - (b) to move to the Parameter
menu!

5.6 Adjusting the grinding time

Working with the disc mill

35

2.

Select the Time menu item using the arrow buttons (c, d) and
then adjust using the + / - button. If no grinding duration has
been specified, the grinding can be started and ended manually
using the start - (e) and stop- (f) button. The maximum time­controlled grinding duration that can be set is 60 min!

1.

To move from the "Parameter" menu to the "Check/Setup" menu,
actuate the arrow buttons (c, d) until the - and + signs which are
visible on the bottom right of the display are highlighted in black!
Then use the buttons + (a) or - (b) to move to the Check/Setup
menu!

2.

Select the language line using the arrow buttons (c, d). The lan­guage (German or English) can be selected using the +/- button
and then set by exiting the menu item.

A number of points must be observed when grinding using zirconium
oxide grinding discs:

1.

Precise adjustment of the zero gap. Under no circumstances
may the discs touch each other during grinding. The localised
heating leads directly to stress cracks on the perimeter. These
cracks occur in a very short time and are easily identified.

2.

Localised heating can also occur if you add so much material that
high pressure grinding takes place permanently in the grinding
gap on the outer edge of the grinding discs. The leads to stress
cracks on the perimeter of the grinding disc or even to it breaking.

5.7 Changing the language

5.8 Grinding with zirconium oxide grinding discs

Working with the disc mill

36

3.

The hardness of the zirconium oxide grinding disc is MOHS 8.5
(HV1350). No sample material that is harder may be ground
because this causes the outer edges of the grinding disc to chip.
Chipping of the edges can also occur with a sample material with
MOHS hardness of 6 or 7.

4.

Proceed very carefully when grinding using zirconium oxide
grinding discs. You should pre-grind your sample material with a
large gap width in the first run before achieving the desired fine­ness with the smallest gap in a second run. You should proceed
in a similar way if you have no information about the grindability
of your material. The grinding discs have a progressive chipping
geometry. Coarse grinding takes place in the inner area, and fine
grinding in the outer area of the grinding disc. The strain is
greatest in the fine grinding area. The chipping described may
occur here with very hard sample material.

5.

The adhesive used to adhere the securing bolts in the grinding
disc has a temperature resistance up to 80°C. The grinding discs
should therefore not be heated above 80°C in order to guarantee
the secure fit in the support.

6.

Please observe the chapter “Replacing the grinding discs (5 + 6)”
in the Operating Manual when assembling and removing the
grinding discs!

NOTICE!

Retsch GmbH guarantees that only zirconium oxide
grinding discs of the highest quality leave our company.

Used grinding discs which are cracked, chipped or
completely broken on the perimeter, cannot be accepted
as complaint.

DANGER
Risk of explosion

There is a risk of spontaneous ignition (dust

explosion) when grinding substances which oxidise
(e.g. metals or coal) if the fine fraction exceeds a set
percentage. Special safety precautions must
therefore be taken when grinding such materials and
the work must be supervised by a specialist.

The device does not have an ex-protected design

and is not suitable for grinding explosive materials.

5.9 Material feed

Working with the disc mill

37

Before switching the device on, care must be taken that
the grinding chamber is locked and the sample material
container is placed straight in the insert and is not
twisted!

CAUTION!

Switch the device on before filling material in the hopper.

1.

The cover of the hopper is secured by a quarter turn quick re­lease fastener. To open the lid, turn the quick release fastener a
quarter turn in an anticlockwise direction!

2.

Fill the sample in the hopper

3.

Add only as much material as will allow the hopper cover to be
closed!

4.

To close the cover you must press the pins on the quick release
fastener into the grooves on the hopper and lock again with a
quarter turn in a clockwise direction!

5.

Monitor the grinding process (grinding noise) and determine the
optimum feed quantity! Repeat this with each new material.

6.

Only add more material once the grinding noise has reduced!

7.

The maximum feed quantity depends on the grindability of the
material and the collecting volume of the sample material con­tainer.

8.

Place large lumps of material (max. 20mm edge length) individu­ally in the hopper, close the cover and secure!

Working with the disc mill

38

5.10 Sample removal

NOTICE!

The grinding disc support and the housing are made
from ductile cast iron. This cast steel is not rustproof. If
you grind slightly damp sample material, after grinding
you must dry the back of the grinding disc, the inside of
the grinding disc support and all parts of the housing
which come into contact with the sample. If you do not
do so, corrosion can be expected to occur.

Depending on the volume of the ground material, care
must be taken when removing the sample material
container (10) to remove it with both hands. Risk of tipping
over!

The achievable final fineness depends on the property of the sample
and the selected gap width (approx. 0.05 mm to approx. 12 mm).
Only one dimension of the individual particles in the fine material is
determined by the gap width, e.g. the material crushed in platelet form
in the fine product may well contain larger dimensions in an expansion
direction. Normally, however, after a second run with such materials,
the proportion of the sample with larger dimensions in this expansion
direction will have decreased significantly.

5.11 Final fineness

Cleaning

39

6 Cleaning

DANGER!
Mains voltage!

- Before starting cleaning work, unplug the device and
protect it from restarting accidentally!

- Do not let liquid run into the device.

- Indicate cleaning work using a warning sign.

- Put safety equipment back into operation after
cleaning work.

NOTICE!

The grinding disc support and the housing are made
from ductile cast iron. This cast steel is not rustproof. If
you grind slightly damp sample material, after grinding
you must dry the back of the grinding disc, the inside of
the grinding disc support and all parts of the housing
which come into contact with the sample. If you do not
do so, corrosion can be expected to occur.

After completion of the grinding process, you can vacuum the dust
created during grinding.

NOTICE!

Do not switch on the dust extraction during grinding as
sample material may otherwise also be extracted.

To clean the grinding chamber, open the chamber. Clean the cham­ber using a brush and vacuum cleaner. Where necessary you can
also use liquid detergents (alcohol, benzene). However pay attention
to any rust if you use aqueous liquids.

It is important to allow the disc mill to dry completely.

6.1 Extracting dust after grinding

6.2 Grinding chamber

Cleaning

40

WARNING!
Risk of poisoning and fire!

When using detergents which are flammable or harmful
to health, it is essential to heed the valid safety
regulations (TLV) and where applicable to clean the disc
mill in a ventilated safety zone.

The machine can be cleaned outside when switched off using a soft
damp cloth. A solution of water and mild detergent may be used here.

No not use a solvent for cleaning.

In special cases the hopper may also be removed and cleaned as
described in the chapter “Replacing the grinding discs (5 + 6)”. When
grinding with the same sample, it is sufficient to clean the hopper of
dirt using a brush and dust extraction. For more intensive cleaning,
the protective grille can be removed by unscrewing 4 M3 countersunk
screws. Clean the hopper with the help of a damp cloth!

CAUTION!

Mount the grille again after cleaning!
Never operate the disc mill without hopper or hopper

grille!

6.3 Housing

6.4 Cleaning the hopper

Servicing

41

DANGER!
Mains voltage

- Before starting servicing work, unplug the device and
protect it from restarting accidentally!

- Indicate servicing work using a warning sign.

- Only have servicing carried out by skilled personnel.

- Put safety equipment back into operation after
servicing and repair work.

- We recommend keeping a safety logbook into which
all work (servicing, repairs etc.) to the device are
entered.

- The most important element of servicing is regular
cleaning:

- Cleaning of the entire device must observe the
regulations of the employer’s liability insurance
associations (BGV A3) – in particular when the device
is positioned in a dusty environment or dusty sample
material is processed.

7 Servicing

Servicing

42

Function part

Task

Test

Service interval

Grinding chamber sen­sor

Start inhibitor

Open grinding cham­ber; start; error mes­sage

Always before use

Grinding chamber safe­ty interlock

Start inhibitor

Do not close grinding
chamber electrically;
start; error message

Always before use

Grinding container
protective equipment

Start inhibitor

Sample material con­tainer not inserted;
start; error message

Always before use

Grinding disc gap width

Crush function

Check distance

Always before use

The grinding discs wear after a certain period of time according to
sample material. Check the surfaces at specific intervals. Refer to
the information in the chapter “Reverse operation” and the chapter
below “Replacing the grinding discs (5 + 6)” to change the direction of
rotation or to replace the discs.

CAUTION!

The device must be connected to the mains to open the
grinding chamber and to adjust the gap width.

7.1 Grinding discs

7.2 Replacing the grinding discs (5 + 6)

Servicing

43

CAUTION!

- Risk of crushing when changing the grinding discs.

- When changing grinding discs, secure them to
prevent them falling down.

CAUTION!

Before inserting the new discs, clean the support and the
back of the discs thoroughly. This is in particular very
important when using the ZrO2 discs and also with
TC+CO discs, so that the discs are positioned without
tension and parallel to each other.

It is also important when tightening the screws that the
tightening torque is not too great (see table) and is the
same for both screws.

Rubber washers (I) which are placed under the steel
washers are used with ZrO2 grinding discs. The nuts are
then tightened until the rubber washer slightly squeezes
out beneath the steel washer. This ensures a tightening
torque of approx. 20Nm.

NOTICE!

When replacing grinding discs, hold them securely and
do not allow them to fall. In the case of zirconium oxide
discs, this can lead to breakage or chipping.

Tools required:

 M20 spanner wrench (r)
 Motor shaft retainer (s)
 30 mm ratchet wrench (t)

6

5

Servicing

44

DANGER!

Ensure that the plug is removed from the socket again
after step 5!

1. Connect the device to the power supply!

2.

3.

Switch the main switch (3) to I (ON)!

To ensure that the hexagon screws at the back of
the movable grinding disc can be reached, the
grinding gap should be moved to the smallest width
(see chapter “Adjusting the gap width”)

4.

Then press the release button (h) on the control panel.

5.

The grinding chamber interlock (8) is released! Now open the
grinding chamber. The grinding discs are visible. The moving
grinding disc (6) is screwed at the back with 2x M20 hexagon
screws.

DANGER!

Pull the plug out and secure the device to prevent
accidental restarting!

6.

In order to be able to remove the moving grinding disc, the hous­ing cover (14) must be removed (see chapter “Positioning”)

3

Servicing

45

7.

8.

Then hold the motor shaft in place with the help of the motor shaft
retainer (s).

CAUTION!

Do not lock the motor shaft retainer (s) by resting on
the component!

NOTICE!

Hold grinding discs securely when changing them and
do not let them fall. This can lead to breaking or
chipping in the case of zirconium oxide discs.

CAUTION!

Risk of crushing when changing the grinding discs.

Ensure that the grinding disc does not fall on the
floor.

Using the spanner wrench (r), unscrew the hexagon screw on the
moving grinding disc and remove.

Servicing

46

9.

The fill hopper (4) must be removed to dismantle the fixed grind­ing disc (5).

10.

To do this, manually close the grinding chamber and remove the
3 cylinder screws shown.

11.

Remove hopper from the front.



The mounting screws on the fixed grinding disc are then visi­ble!

Servicing

47

12.

DANGER!

Risk of crushing when changing the grinding discs.
Ensure that the grinding disc does not fall on the
floor.

Loosen the 2x M20 mounting screws using the ratchet wrench
and open the grinding chamber. Hold the grinding disc in place.
Remove the hexagon screws and remove the grinding disc.

13.

Now take the replacement moving grinding disc and assemble
with the hexagon screws (see Point 5 + 6 in reverse order)

14.

15.

16.

Install the housing cover
Connect the mains plug again.
Switch the device on!

17.

18.

19.

20.

Close the grinding chamber electrically
Adjust the grinding width to at least 12mm as described in the

chapter “Adjusting the gap width”!I
Unlock the grinding chamber and unplug the device!

DANGER!

Pull the plug out and secure the device to prevent
accidental restarting!

Insert the replacement fixed grinding disc and secure with the
hexagon screws. Manually close the grinding chamber and se­cure the disc using the ratchet wrench (t).

21.

Secure the hopper again in reverse order (see Points 10 and 11)

22.

Plug in and lock the grinding chamber again with the help of the
locking button (h).

Zero point must be specified again (see the chapter
“Specifying the zero point”)

Servicing

48

Material

Max. guide
value tightening
torque (Nm)

Density
g/cm³

Abrasion
resistance

Use for sample
material

Hardened steel 11­12% Cr

At least 50

7.9

Good

Hard, brittle samples

Manganese steel
12-13% Mn

At least 50

7.9 - 8

Good

Hard, brittle samples

Tungsten carbide

90.3% TC + 9.5%
CO

At least 50

14.8

Very good

Hard, abrasive sam­ples

Zirconium oxide

92.5 ZrO2

Approx. 20

5.9

Extremely good

Medium hard, abrasive
samples for iron-free
grinding

Servicing

49

The gearbox of the motor is filled with gear oil on delivery (ISO VG

220). A removable fill screw (o) is present in the top of the gearbox
housing to change the gear oil. To reach this the housing cover must
be removed.

This oil must be changed after approx. 5 years.

1.

Run the DM400 for approx. 15 minutes so that the gear oil inside
warms up and drains off better.

2.

3.

Switch the device off and unplug.

DANGER!

Pull the plug out and secure the device to prevent
accidental restarting!

Unplug the device and remove the cover (see chapter “Position-
ing”)

4.

Remove the motor securing screw (m) under the oil drain plug (n)
using an M10 Allen key!

The gearbox contains approx. 0.22 litres of ISO VG
220 gear box oil!

7.3 Replacing the gear oil

7.3.1 Conducting the gear oil change

Servicing

50

5.

Hold a flat container underneath the oil drain plug (n) and un­screw this using an Allen Key No. 5 until oil flows out.

6.

Allow all of the oil to drain from the gearbox (approx. 0.22 l).
Watch the size of the collecting container and empty at intervals
where necessary, screwing the oil drain plug back in to do so.

7.

When the gear oil has been completely emptied, remove the oil
drain plug!

8.

Wipe any spilt gear oil with a paper towel and clean the contact
surface of the oil drain plug.

9.

Screw the oil drain plug with washer tight again.

10.

Assemble the motor securing screw again

11.

The fill screw (o) is then removed!

12.

Place a funnel in the hole and fill the gearbox with 0.22 litres of
gear oil ISO VG 220.

13.

Screw the fill screw (o) with clean sealing ring tight again.

14.

Assemble the housing cover.

Repair

51

8 Repair

DANGER!
Mains voltage!

- Before starting repair work, unplug the device and
protect it from restarting accidentally!

- Indicate repair work using a warning sign.

- Have all repair work conducted by skilled personnel.

- Put safety equipment back into operation after
servicing and/or repair work.

Repair

52

8.1 Checklist for troubleshooting

Malfunction

Possible cause

Rectification of fault

Mill does not start

No mains connection

Plug in

Mains switch is off

Switch the mains switch on

Grinding chamber safety switch open

Correctly connect the grinding chamber

Sample material container safety switch
open

Correctly insert the sample material container
Thermal circuit breaker has triggered

Wait until the device has cooled down

Fuse in the control circuit has triggered

Have the fuse replaced by qualified specialists.

Discs do not rotate

Gap width set to 0

Adjust the gap width! See chapter “Working with
the disc mill”

Sample is blocking the disc

Open grinding chamber and remove the sample

Mill stands still during operation

Overload! Switch off by motor circuit
breaker switch (main switch)

Allow the mill to cool. Remove sample material,
reduce feed of sample material

Grinding chamber overfilled. Too large /
hard sample material has become stuck

Open the grinding chamber and empty

Mill produces poor grinding
result

Grinding discs are worn

Change the direction of rotation or replace grind­ing discs. See chapter “Reverse operation” or
chapter “Replacing the grinding discs (5 + 6)“

Grinding discs are not installed in parallel

Remove grinding discs, clean the support and
reinsert (see chapter “Working with the disc mill” )

Sample materials escapes

Grinding chamber seals and sample
material container seals dirty or faulty

Clean or replace seals
Collecting container overfilled (max. 2l)

Remove container and clean the inside

Error message sample material
container
Sample material container not recognised

Slide container in centrally

Soiling of the container guide

Cleaning

No release of the sample
material container after STOP

Release mechanism on sample material
container faulty

Release by emergency actuation inside the
device; see chapter “Protection against restart-
ing”. Contact Retsch!

Automatic gap adjustment not
possible

Control panel is faulty

Replace the control panel

Gap adjustment is faulty

Contact Retsch
Temporary problem solution using the set screw

(7) on the bottom right-hand side at the front!
Adjust the precise gap width manually!

Discs have got stuck

With the help of the set screw (7), loosen! Rea­lign the zero point!

Error message

Gap width, grinding chamber, sample
material container

Actuate the STOP button

Repair

53

Disposal

54

9 Disposal

Observe the respective statutory regulations when disposing of the de­vice.

Information on disposal of electrical and electronic devices in the Euro­pean Community:

The disposal of electrical equipment within the European Community is
specified by national regulations based on EU Directive 2002/96/EC on
Waste Electrical and Electronic Equipment (WEEE).

Accordingly all equipment supplied after 13.08.2005 in the business-to­business area may no longer be disposed of with the municipal or
household waste. They are labelled as follows to document this:

Fig. 1: Disposal label
Since the disposal regulations may differ from one country to an-

other within the EU, we ask you to contain your supplier where
necessary.

In Germany this labelling duty has applied since 23.03.2006. As
from this date the manufacturer must offer a reasonable possibility
for returning all equipment supplied as from 13.08.2005. The last
user is responsible for correct disposal for all equipment delivered
before 13.08.2005.

EC Declaration of Conformity

55

10 EC Declaration of Conformity

EC Declaration of Conformity

56

Index

57

11 Index

A

Accident prevention .............................................. 9

Adapting to the mains network ........................... 26

Adjusting the gap width ...................................... 32

Adjusting the grinding time ................................. 34

Authorised persons ............................................... 9

B

Basic construction ................................................ 7

C

Changing the language ...................................... 35

Checklist for troubleshooting .............................. 52

Cleaning after grinding ....................................... 39

Cleaning the grinding chamber .......................... 39

Cleaning the hopper ........................................... 40

Cleaning the housing .......................................... 39

Control panel ...................................................... 30

D

Dimensions ......................................................... 21

Display ................................................................ 30

Disposal label ..................................................... 54

E

Electrical connection ........................................... 26

Electrical safety .................................................. 18

Explanation of signs ........................................... 11

M

Material feed ....................................................... 36

Menu change ...................................................... 31

Menu navigation ................................................. 30

O

Operating noise .................................................. 21

Operating principle .............................................. 10

P

Positioning the device ......................................... 24

Power consumption ............................................ 21

Power input ......................................................... 21

Putting into service ............................................. 26

R

Remove motor cover .......................................... 24

Replacing the gear oil ......................................... 49

Requirements for the user .................................... 9

Reverse operation .............................................. 33

S

Safety equipment ................................................ 17

Safety instructions .............................................. 11

Sample material .................................................. 22

Selecting menu items ......................................... 31

Servicing ............................................................. 41

Specifying the zero point .................................... 31

F

Final fineness ............................................... 22, 38

Function test ....................................................... 27

Fuse .................................................................... 21

H

Hazard symbols used ......................................... 11

Hazard warnings ................................................. 11

L

Locking the hopper cover ................................... 37

T

Timer ................................................................... 34

V

Voltage ................................................................ 21

W

Weight ................................................................. 21

Z

Zirconium oxide grinding discs ........................... 35

Index

58

FB-EW-805-042 Änderungsstand D 01.2014

Copyright

® Copyright by
Retsch GmbH
Haan, Retsch-Allee 1-5
D-42781 Haan
Federal Republic of Germany