General EMHT40 User manual
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TABLE OF CONTENTS
Introduction…………………………………………………………………………… 2-4
Key Features…………………………………………………………………………… 4-5
What’s in the Package………………………………………………………………. 5
Product Overview…………………………………………………………………….. 6-7
Setup Instructions……………………………………………………………………. 7-17
Navigating the Menus……………………………………………………….. 9-17
Operating Instructions……………………………………………………………… 18-20
Interfacing with a PC…………………………………………………………19-20
Specifications…………………………………………………………………………. 20
Operating & Maintenance Tips……………………………………………………. 21
APPENDIX—Non-conventional support rings…………………………………. 21-22
INTRODUCTION
The EMHT40 is a pen-style instrument that uses the Leeb testing method to measure the
hardness of any metal or surface for a wide variety of industrial purposes. The Leeb method is
notable for its accuracy, wide measuring range and operating simplicity.
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Typical applications for the EMHT40 include measuring the surface and coating hardness of
installed machines and components, die molding surfaces and bearings. Up to 1250 test
results can be stored in the EMHT40’s memory and ported to a PC for display as an Excel table
or graph.
Leeb hardness testing produces so-called Leeb hardness values for a target metal (the work
piece). To measure hardness, the user cocks a spring-loaded, pen-shaped plunger and
squeezes a trigger at one end of the instrument to fire the plunger (the impact device) against
the work piece at the other end. A permanent magnet close to the work piece senses the
impact and generates two voltages: one proportional to the plunger’s impact velocity and the
other proportional to the velocity with which the plunger rebounded from the work piece.
To determine the target’s Leeb hardness value—a parameter designated HL—an algorithm
within the EMHT40 divides the voltage representing the plunger’s rebound velocity by the
voltage representing its impact velocity and multiplies by 1000. The following formula is used
for the computation:
HL=1000 × (Vb /Va)
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where Vbis the voltage produced during the rebound of the impact device and Vais the
voltage produced during the impact of the impact device.
Leeb hardness values (HL) can be converted to values using other hardness units such as HV,
HRC, HRB, HB and HS. The EMHT40 can also display readings using several of these hardness
units. However, to maintain the accuracy of measurements all hardness values must describe
not just the testing method but the type of impact device as well.
For example, a hardness value of 510 on the Leeb scale determined by using the “D” type
tungsten-carbide impact device provided with the EMHT40 would be described as 510HLD.
KEY FEATURES
Conforms to ASTM A 956
Compact, easy to use and reliable
Displays minimum, maximum and average values
Wide measuring range, with display of hardness values in any of the following units:
Leeb HL, Rockwell HRB and HRC, Vickers HV, Brinell HB and Shore HS
Impact device works at any angle, even upside down
1250 reading internal memory and USB cable for interfacing to a PC
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2-minute Auto Power Off
2-year limited warranty
WHAT’S IN THE PACKAGE
The EMHT40 comes in a hard plastic carrying case inside a cardboard box. Inside the case
are:
The pen-style EMHT40, incorporating a “D” type impact device.
A standard hardness test block with a nominal hardness value of 777HLD.
A cleaning brush and a conventional support ring in a Ziploc bag.
An 110VAC adaptor with an output of 3.7VDC output available from a full-size USB jack.
A cable with a full-size USB plug at one end and a mini-USB plug at the other. When
used to connect the EMHT40 to a PC, the cable trickle-charges the Lithium-ion battery
that powers the tester.
A mini-disc containing 1) a program for displaying the contents of the EMHT40’s
memory on a PC, 2) drivers for Windows8 (64- and 32-bit), Windows7 (64- and 32-bit),
Windows Vista (64- and 32-bit) and WindowsXP, and 3) installation and operating
instructions for the program and drivers
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This user’s manual
PRODUCT OVERVIEW
The two following images show a typical EMHT40 display and the multiple functions provided
by the three-button keypad on the bottom of the unit. Familiarize yourself with the position of
all indications and the functions of the controls before moving on to the Setup Instructions
and Operating Instructions.
Display
Hardness scale
Measured value
Average value
Maximum value
Minimum value
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Memory location
Remaining battery charge
Number of measurements used for averages
Material
Direction of impact
Keypad
On/Off/Save Setting
Select/Move/Delete
Select/Set/Change display style
SETUP INSTRUCTIONS
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The “D” type impact device built into the EMHT40 will provide optimal results for work pieces
with a surface roughness of 2μm.
A work piece should not be tested: 1) If its temperature is above 176oF (80oC); 2) It is within
a strong magnetic field; or 3) It is less than 0.12 in. (3mm) thick or has a surface-hardened
layer thinner than 0.03 in. (0.8mm).
Work pieces weighing more than 11 lb. (5kg) require no support.
Work pieces weighing between 4.4 and 11 lb. (2 and 5kg), as well as work pieces with
protruding parts or thin walls, should be anchored to a solid support to prevent them from
moving or flexing as a result of testing.
Work pieces weighing less than 4.4 lb. (2kg) should be tightly attached to a non-yielding
support such as a heavy base plate.
Work pieces with a cylindrical or spherical inside or outside surface radius of less than 1.18 in.
(30mm) require the use of the included support ring or a non-conventional support ring. The
Appendix illustrates and describes several key parameters of 12 support rings in common use.
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To power on the EMHT40, press the button. The typical display shown in the Product
Overview section will appear. To power off the EMHT40, press and hold the button for
at least 3 seconds.
NAVIGATING THE MENUS
Briefly pressing (but not holding) the button opens the EMHT40’s main menu screen of 10
items.
1. MEASUREMENT
2. AVG. TIMES
3. MAT. & SCALE
4. TOLERANCE
5. LOCATION
6. MEMORY
7. DATA OUTPUT
8. CALIBRATION
9. CONTRAST
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10. DEFAULT
Although it is not necessary to adjust the settings of all 10 items if you do not intend to store
your measurements or port them to a PC, it is good practice to do so to understand the
options available to you:
To select any item to view or change its setting, use the and buttons to move up or
down and highlight its line. Then briefly press (but do not hold) the button. In most cases,
selecting a main menu item displays either: 1) a default value that can be adjusted by using
the and buttons; or 2) a sub-menu of options that can be navigated using the same
buttons. To save any displayed setting (whether you have changed it or not),briefly press
the button. Doing so resumes display of the main menu screen.
Hint: Try not to take too much time to make your menu selections. The EMHT40 has an Auto
Power Off function that will automatically power off the unit during any 2-minute period
during which no buttons are pressed.
1. Selecting 1. MEASUREMENT displays the full measurement screen on the LCD.
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