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Balanced Beam
Scrape Adhesion and Mar Tester
Operating Instructions
Balanced Beam
Scarpe Adhesion &
Mar Tester
Operating Instructions
English
PE-5780
BYK - Gardner USA
9104 Guilford Road
Columbia, MD 21046
USA
Phone 800-343-7721
301-483-6500
Fax 800-394-8215
301-483-6555
www.byk.com/instruments
BYK-Gardner GmbH
Lausitzer Str. 8
D-82538 Geretsried
Germany
Tel. 0-800-gardner
(0-800-4273637)
+49-8171-3493-0
Fax +49-8171-3493-140
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Table of Contents
Section 1: Description ...................................................................................4
Section 2: General Information .......................................................................5
Section 3: Operation ......................................................................................6
Section 4: Evaluation ...................................................................................... 8
Description
Description
This instrument, is used for scrape-adhesion
testing of coatings according to ASTM D 2197,
D 5178, and for testing coatings and surfaces of
other materials for their hardness or resistance
to being scratched or marred by a pointed, sharp
edge or blunt tipped stylus.
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General Information
General Information
A pivoted beam is supported horizontally above
a sturdy base plate. Near one end of the beam is
an adjustable length stylus holding rod mounted
through the pivoted beam at 45° A weight
platform is positioned on the beam such that
weights mounted on the platform exert their force
on the stylus. The weight platform is equipped
with a post to help retain slotted weights. On the
opposite end of the beam is a counter-weight that
can be moved to balance the weight of the stylus
holding rod and weight support structure. The
base plate is equipped with a level and adjustable
feet used to level the instrument. A separate level
is mounted on the beam and is used to verify that
the beam is horizontal. On the base plate under
the stylus rod is a sample platform supported on
bearings and freely movable. Rotation of a knob
near the center of the beam will raise amd lower
the stylus holding rod. A movable support bar with
two pegs can be inserted in holes in the sample
platform at one end of the sample to assist in
positioning the sample.
The instrument is supplied with slotted weights
for placing a load on the stylus. The Loop Stylus
for ASTM scrape adhesion and mar resistance.
The Needle Stylus is for testing hardness as
resistance to scratching. The Loop Stylus is a
0.0625“ drill rod bent 1800 to a „U“ shape with a
0.256“ outside width dimension. It is hardened,
buffed and nickel plated. Available as options are
the Scratching Tool of the Hoffman Scratch Tester,
rod stylus, ball-tipped styluses of 1/16“ and 1/8“
diameter and a Spit Stylus.
Operation
Operation
Level the base plate using the bubble level and the
three adjustable feet. Secure the desired stylus in
position in the appropriate end of the holding rod.
The Loop Stylus ts into the end of the rod with
the two-hole stylus clamp. The Needle Stylus can
be placed in either of the two holes, as can the
Rod, Spit and Ball-tipped styluses. The Hoffman
Tool is mounted in the single-hole end of the
rod. Styluses are held secure at either end by
tightening a screw. Turn the instrument so that the
stylus end is toward the operator and the counterweight is pointing away. The sample platform
may then be pulled or pushed freely using both
handles.
The test specimen for this instrument must
be at and smooth. When a coating is tested,
its substrate must have this form. The sample
platform measures 4-3/4“ x 8“ (12.1 cm x 20.3
em). The sample can be as wide as 5“; although
it can be somewhat longer than the bed, the the
Needle Stylus onto the sample and then with a
uniform motion pull the sample and inch or two
using a very light initial load (about 50 gm) on the
weight holder. Make successive passes across
the sample, increasing the load by a convenient
increment (perhaps as little as 10 gm) until the
needle cuts through the lm to the substrate. The
coating should be penetrated with less than 1 kg.
A load of 1.5 kg or more may damage the Needle
Stylus. Where relatively heavy loads are needed
for scratch testing, the sturdier Hoffman Tool or
Rod Stylus can be used in the same manner.
Low power magnication may be required for
determining whether the Needle Stylus exposed
the substrate, especially when the coating is
transparent or the same color as the substrate.
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Operation
The uncoated surface of any rigid material may be
tested for hardness by nding the load required to
make a visible scratch on the surface. The Needle
Stylus, Hoffman Tool or Rod Stylus are used for
this purpose.
The two Ball-Tipped styluses may not actually
scrape or scratch, but will depress a coating or
other material under sufcient load, creating a
groove in the surface. As with scratch resistance,
resistance to „grooving“ is a practical test because
the product may be subjected to forceful contact
with sharp and blunt objects.
The resistance of a surface to penetration by
too sharp and too blunt objects mayor may not
correlate.
The Spit Stylus is used for rubbing tests. A soft
object supplied by the user is impaled upon the
stylus and then rubbed against the test surface
under a certain load. Examples are rubbing an
eraser against printed characters on paper or a
piece of shoe leather against a polished oor tile.
Evaluation
Evaluation
Since the variety of materials that can be tested
with the instrument is unlimited, we cannot offer
denitive conclusions as to what constitutes
acceptable hardness or scrape adhesion. The
user, based on his knowledge of the material, its
history and end use, must make this decision.
Evaluating a coating for scrape adhesion or
hardness is usually objective because the
substrate is exposed or not exposed. Testing
uncoated surfaces for resistance to scratching,
marring or other types of deformation can be more
subjective in that the operator must decide what
is acceptable or the type of and extent of damage
that constitutes failure.
When the approximate weight to achieve a
certain end point has been found, time is saved
by starting the testing of each sample just a few
increments below this value. The end point load
may cover a range of force with some materials
due to differences between samples. Knowledge
of the end point value and the end use of a
material can help establish a value for a single
stroke, pass-or-fail test.
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253 017 659 EDFIS 0408 Europe
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