Dakota MMX-6 User Manual

OPERATION MANUAL

P/N P

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142

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0002

Rev 1.

10 / 1.11,

January

200

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DAKOTA ULTRASONICS - MMX -6 MULTI-MODE ULTRASONIC THICKNESS GAUGE

Copyright  2008 Dakota Ultrasonics. All rights reserved.

No part of this publication may be reproduced, translated into another
language, stored in a retrieval system, or transmitted in any form or by any
means; electronic, mechanical, photocopying, recording, or otherwise,
without the prior written consent of Dakota Ultrasonics.

Every precaution has been taken in the preparation of this publication.
Dakota Ultrasonics assumes no responsibility for errors or omissions.
Neither is any liability assumed for damages resulting from the use of
information contained herein.

Any brand or product names mentioned herein are used for identification
purposes only, and are trademarks or registered trademarks of their
respective holders.

1500 Green Hills, #107 Scotts Valley, CA 95066 USA

Tel [phone] Fax [phone]

www.dakotaultrasonics.com

CONTENTS

MMX-6 Ultrasonic Thickness Gauge

INTRODU CTION
OPERATION

THE KEYPAD
THE DISPLAY
THE TRANSDUCER
MAKING MEASUREMENTS
CONDITION AND PREPARATION OF SURFACES
PROBE ZERO
CALIBRATION
SCAN MODE, ALARM MODE, DUAL-MULTI MODE,

RSS232 PORT
TRANSDUCER SELECTION
APPENDIX A: PRODUCT SPECIFICATIONS

1
2
2
6
8

9
11
12
13
18
22
24
28

APPENDIX B: APPLICATION NOTES
APPENDIX C: SOUND VELOCITIES OF COMMON MATERIALS
WARRANTY INFORMATION

30
34
36

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DISCLAIMER – Very Important!

Inherent in ultrasonic thickness measurement is the possibility that the
instrument will use the second rather than the first echo from the back
surface of the material being measured while in standard pulse-echo mode.
This may result in a thickness reading that is TWICE what it should be.

In addition, measurements through very thick paint or coatings while
using echo-echo mode, may result in the paint or coating being measured
rather than the actual material intended. The Responsibility for proper use
of the instrument and recognition of these types of phenomenon’s rest
solely with the user of the instrument.

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INTRODUCTION

The Dakota Ultrasonics model MMX-6 is a multi-mode Ultrasonic
thickness gauge. Based on the same operating principles as SONAR, the

MMX- 6 is capable of measuring the thickness of various materials with
accuracy as high as ± 0.001 inches, or ± 0.01 millimeters. The principle

advantage of ultrasonic measurement over traditional methods is that
ultrasonic measurements can be performed with access to only one side of
the material being measured. The multi-mode feature of the MMX-6 allows
the user to toggle between pulse-echo mode (flaw and pit detection), and
echo-echo mode (eliminate paint or coating thickness).

This manual is presented in three sections. The first section covers
operation of the MMX- 6, and explains the keypad controls and display.

The second section provides guidelines in selecting a transducer for a
specific application. The last section provides application notes and a table
of sound velocity values for various materials.

Dakota Ultrasonics maintains a customer support res ource in order to
assist users with questions or difficulties not covered in this manual.
Customer support may be reached at any of the following:

Dakota Ultrasonics, 1500 Green Hills Road, #107
Scotts Valley, CA 95066 USA

Telephone: [phone]
Facsimile: [phone]
www.dakotaultrasonics.com

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OPERATION

The MMX-6 interacts with the operator through the membrane keypad
and the LCD display. The functions of the various keys on the keypad are
detailed below, followed by an explanation of the di splay and its various
symbols.

The Keypad

This key is used to turn the MMX-6 on and off. When the gauge is
turned ON, it will first perform a brief display test by illuminating all of the
segments in the display. After one second, the gauge will displ ay the
internal software version number. After displaying the version number, the
display will show "0.000" (or "0.00" if using metric units), indicating the
gauge is ready for use.

The MMX-6 is turned OFF by pressing the ON/OFF key. The gauge
has a special memory that retains all of its settings even when the power is
off. The gauge also features an auto-powerdown mode designed to
conserve battery life. If the gauge is idle for 5 minutes, it will turn itself off.

MMX-6 Ultrasonic Thickness Gauge

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The PRB- 0 key is used to "zero" the MMX- 6 in much the same way that
a mechanical micrometer is zeroed. If the gauge is not zeroed correctly, all

of the measurements that the gauge makes may be in error by some fixed
value. Refer to page 12 for an explanation of this important procedure.

The CAL key is used to enter and exit the MMX- 6's calibration mode.
This mode is used to adjust the sound-velocity value that the MMX-6 will
use when calculating thickness. The gauge will either calculate the sound­velocity from a sample of the material being measured, or allow a known
velocity value to be entered directly. Refer to page 13 for an explanation of
the two CAL functions available.

The IN/MM key is used to switch back and forth between English and
metric units. This key may be used at any time, whether the gauge is

displaying a thickness (IN or MM) or a velocity value (IN/µs or M/s).

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The UP arrow key has two functions. When the MMX-6 is in calibration
mode, this key is used to increase numeric values on the display. An auto­repeat function is built in, so that when the key is held down, numeric

values will increment at an increasing rate. When the MMX-6 is not in
calibration mode, the UP arrow key switches the SCAN measurement
mode on and off. Refer to page 18 for an explanation of the SCAN
measurement mode.

The DOWN arrow key has two functions. When the MMX- 6 is in the
CAL mode, this key is used to decrease numeric values on the display. An
auto-repeat function is built in, so that when the key is held down, numeric
values will decrement at an increasing rate. When the MMX-6 is not in
calibration mode, the DOWN arrow key switches the display backlight
between three available settings. OFF will be displayed when the backlight
is switched off. AUTO will be displayed when the backlight is set to
automatic mode, and ON will be displayed when the backlight is set to stay
on. In the AUTO setting, the backlight will illuminate while the MMX- 6 is
making a measurement and turn off after several seconds to conserve
battery life.

MMX-6 Ultrasonic Thickness Gauge

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The ALRM key has two functions. By holding down the ALRM key
when powering up the MMX- 6, the audible beeper will be turned on or off
accordingly. After the unit has been turned on, pressing the ALRM key will
toggle the alarm mode to the on/off positions and allow the user to enter a
nominal thickness value. Refer to page 19 for details on how to use the
alarm feature.

The DUAL- MULTI key is used to toggle pulse-echo ( flaw & pit
detection ), and echo- echo ( eliminate paint & coating thickness ). This
enables the user to very conveniently switch between modes depending on
application requirements. Refer to page 20 for a complete explanation of
this feature.

The SEND key is used to send the currently displayed thickness
measurement to an external storage device via the MMX-6's RS232 port.

Refer to page 22 for an explanation of how to use this feature.

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The Display

The numeric portion of the display consists of 4 complete digits
preceded by a leading "1", and is used to display numeric values, as well
as occasional simple words, to indicate the status of various settings.
When the MMX- 6 is displaying thickness measurements, the display will
hold the last value measured, until a new measurement is made.

Additionally, when the battery voltage is low, the entire display will
begin to flash. When this occurs, the batteries should be replaced.

These eight vertical bars form the Stability Indicator. When the MMX- 6
is idle, only the left -most bar and the underline will be on. While the gauge

is taking a measurement, six or seven of the bars should be on. If fewer
than five bars are on, the MMX- 6 is having difficulty achieving a stable

measurement, and the thickness value displayed will most likely be
erroneous.

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When the IN symbol is on, the MMX- 6 is displaying a thickness value in
inches. The maximum thickness that can be displayed is 19.999 inches.

When the MM symbol is on, the MMX- 6 is displaying a thickness value
in millimeters. If the displayed thickness exceeds 199.99 millimeters, the
decimal point will shift automatically to the right, allowing valu es up to

1999.9 millimeters to be displayed.

When the IN symbol is on, in conjunction with the /µs symbol, the MMX-
6 is displaying a sound-velocity value in inches-per- microsecond.

When the M symbol is on, in conjunction with the /s symbol, the MMX-
6 is displaying a sound-velocity value in meters-per- second.

When the + symbol is on and blinking, this indicates that the MMX- 6 is
currently operating in echo-echo ( Thru-paint/coating ) mode.

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The Transducer

The transducer is the "business end" of the MMX-6. It transmits and
receives ultrasonic sound waves that the MMX-6 uses to calculate the
thickness of the material being measured. The transducer connects to the
MMX- 6 via the attached cable, and two coaxial connectors. When using
transducers manufactured by Dakota Ultrasonics, the orientation of the
dual coaxial connectors is not critical: either plug may be fitted to either
socket in the MMX- 6.

The transducer must be used correctly in order for the MMX-6 to
produce accurate, reliable measurements. Below is a short description of

the transducer, followed by instructions for its use.

This is a bottom view of a typical transducer. The two semicircles of the
wearface are visible, as is the barrier separating them. One of the
semicircles is responsible for conducting ultrasonic sound into the material
being measured, and the other semicircle is responsible for conducting the
echoed sound back into the transducer. When the transducer is placed
against the material being measured, it is the area directly beneath the
center of the wearface that is being measured.

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This is a top view of a typical transducer. Press against the top with the
thumb or index finger to hold the transducer in place. Moderate pressure is
sufficient, as it is only necessary to keep the transducer stationary, and the
wearface seated flat against the surface of the material being measured.

Making Measurements

In order for the transducer to do its job, there must be no air gaps
between the wear-face and the surface of the material being measured.
This is accomplished with the use of a "coupling" fluid, commonly called
"couplant". This fluid serves to "couple", or transfer, the ultrasonic sound
waves from the transducer, into the material, and back again. Before
attempting to make a measurement, a small amount of couplant should be
applied to the surface of the material being measured. Typically, a single
droplet of couplant is sufficient.

After applying couplant, press the transducer (wearface down) firmly
against the area to be measured. The Stability Indicator should have six or
seven bars darkened, and a number should appear in the display. If the
MMX- 6 has been properly "zeroed" (see page 12) and set to the correct
sound velocity (see page 13), the number in the display will indicate the
actual thickness of the material directly beneath the transducer.