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Home  >>  Products  >>  Adhesion  >>  Balanced Beam
Balanced Beam Scrape Adhesion and Mar Tester

New and Expanded Design with Hoffman Type Stylus & New Dime Scratch Adapter

Balanced Beam
PA-2197B
  • Exceeds Requirements of ASTM D2197 Standard Test Method for Adhesion of Organic Coatings by Scrape Adhesion
  • Meets ASTM D5178 Standard Test Method for Mar Resistance of Organic Coatings
  • Meets Aircraft Engine Group Spec 50TF61-S1
  • Meets Naval Laboratory Spec WS 12858, Part 4.5.5 Hardness



FEATURES OPERATION PARTS & ACCESSORIES PRICE LIST
 

 

Features

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The most widely-used instrument for evaluating coatings for scratch adhesion and mar resistance is the Balanced Beam Scrape Adhesion & Mar Tester. Originally it was developed at the Bell Telephone Laboratories. It has now been completely redesigned to make it an even more useful instrument.


The geometry of the original design has been retained as shown in the diagram. The stylus is held at 45 degrees from the vertical and the top slopes in the direction of test sample travel. The stylus is held in place by a fulcrum elevated at 22 degrees.
Geometry Diagram

The expanded design includes an auxiliary table, which when in place, accommodates a range of test panel thickness up to 1.0" with either the loop or needle stylus. When removed, this thickness increases from 1.0" to 1.187 or with the Hoffman stylus installed, up to 0.125".
The Stylus load may be varied from 0 to 10,500 grams in 500 gram major steps which may be further subdivided in 50 gram steps. This is accomplished with only two 500 gram weights and one 50 gram weight which may be inserted in differing combinations in any of the ten numbered receiving holes in the weight beam. (The needle stylus should not be loaded in excess of 5250 grams.)
Both the loop and the needle stylus are one inch long and extend 0.36 inches from the holding fixture. They are produced from 1/16 inch tool steel, heat treated to a hardness of Rockwell C 55 - 61. The loop stylus has an outside radius of 0.128 inches. The needle stylus has a 1mm diameter tip. Both the loop stylus and needle stylus are flash chrome plated with plating thickness of 0.0001 inches to .0003 inches. The surface finish is 8RMS. The hoffman stylus's hardened stainless steel contact arc is 0.275 inches in diameter and extends 0.50 inches from the holding fixture for proper placement on the test surface.
All three stylus types are readily interchanged or replaced.
Stylus
It is not possible to rotate the loop stylus out of symmetry as both mounting arms are separately and rigidly held by the holding fixture.
Distance and angle from beam fulcrum to contact of the stylus with the test surface is fixed and the same for each type of stylus.
The weight beam and stylus assembly may be easily locked in an elevated position to prevent any motion, either up or down. The beam counterweight is factory set and there is no need for further adjustment when using the needle or the loop stylus.
Support for the test panel is by floating table which is supported by only three steel balls providing the lowest possible friction against the heaviest possible load.
The floating table for the test panel is 12 inches long. Any portion of this length may be positioned under the stylus except for a half inch from either end.
The Stylus is cantilevered by 2 inches which permits testing up to this distance from the edge of the panel.
The unit is constructed from brushed aluminum except for the weights, fulcrum, locking pin and the stylus. All the weights are machined from stainless steel.
Beam weights are stored directly on the unit when not in use on the beam.
A small base footprint of only 6 x 16 inches requires less than a square foot of work space.

 

Operation

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  1. Insure that the weight beam is locked in the raised position. This is done by placing slight inward pressure on the locking pin and raising the weight beam until the locking pin slides into the recess in the cantilever support member. Also insure that the auxiliary table is in place if required by the stylus - panel thickness combination. The Balanced Beam Tester is furnished with an installed auxiliary table. It is secured to the moving table by two pins permanently attached to the auxiliary table. To remove this table lift and forceably wriggle it to disengage the pins.

  2. Secure desired stylus.

  3. Secure the counterweight, place one or more of the weights in the desired position on the weight beam. Each of the large weights is 500 grams and the small weight is 50 grams. To find the gram load on the stylus, multiply the weight value by the hole number on the beam into which the weight or weights have been placed. For example: If the large weight is in the #8 hole and the small weight is in the #3 hole, then (500 x 8) + (50 x 3) or 4000 + 150 = 4150 grams of weight on the stylus.

  4. Withdraw the test panel support table to maximum travel. This action correctly positions the supporting steel balls between the base and the support table.

  5. Place the test panel on the panel support table with one of it edges against the operating bar of the table.

  6. a. Loosen the two locking screws on the pivot.

    b. Adjust the jacking screw to raise the pivot block so the test panel can fit under the stylus. With tight downward pressure on the sample, adjust the jacking screw (up or down)until the bubble is in the center of the level.

    c. Tighten the two locking screws on the pivot block.

  1. With downward pressure on the sample and support table in the area of the stylus, move the assembly to position the test panel as desired under the stylus. This keeps contact with all of the supporting raceway balls and retains them in position, preventing them from all collecting at one end of the base plate.

  2. With the left hand, lift the weight bar to take pressure off the locking pin, withdraw the locking pin to the extent of its travel with the right hand and gently lower the weight bar to bring the stylus into contact with the test panel.

  3. Slowly move the support table with the test panel (0.5 to 1.0 inches per second). If the coating is removed from the panel, continue the testing, using successively higher weights on the stylus until the coating is not removed. If the coating is not removed in the initial test, continue the testing, using successively higher weights on the stylus until the coating is removed from the support panel. Use an untested area of the panel each time the test procedure is repeated.

  4. At the conclusion of the test, raise the weight beam sufficiently to permit the locking pin to secure the assembly in the elevated position. Inspect the stylus to insure that it is clean and has not been damaged in any way. If any defect is noted, the stylus should be replaced. Remove the test panel from the support table.

  5. Record the designation of the material tested, panel surface preparation, coating curing schedule, thickness of the coating, the stylus type and stylus load required to impose failure of the coating and other information pertinent to the particular test.

 

Stylus Change Procedure

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1. Remove all weights from the weight beam, except the counterweight, and place them in the postions provided on the cantilever arm.

Stylus
2. Withdraw the panel support table on the extent of its travel.

3. Release the weight beam mechanism locking pin while holding on to the Balanced Beam securely, to prevent the counterweight from striking the base and elevate the weight beam to the extent of its travel. This action exposes to the maximum possible the stylus and the securing allen head screws.

4. Loosen the securing screws and remove the stylus. Note that the needle stylus and the Hoffman stylus can be placed in either of the receiving holes in the assembly.

5. When inserting a stylus, insure that it travels to the base of the receiving holes, or with the Hoffman that it seats against the assembly, prior to tightening the securing screws. By so doing, the tip of the stylus is positioned at the correct distance from the fulcrum. Tighten the securing screws.

6. Lower the weight beam so that the locking pin holds it in the elevated position. Return the test panel support table to its central position. The Balanced Beam unit is now ready for the next series of tests.

 

Parts & Accessories - Model PA-2197B

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Diagram 1 Diagram 2
  A Counterweight   O Weight Beam
  B-C 500g Weights   P Bubble Level
  D 50g Weight   Q Pivot Block & Locking Pin
  E Locking Pin   R Auxiliary Table
  F Jacking Screw   S Securing Screws
  G Adjustable Pivot Block   T Stylus
  H-I Pivot Block Locking Screws    
  J-N Allen Wrenches    

Parts List - One 50 gram weight, One Counterweight, One Needle Stylus, Two Allen Wrenches, Two 500 Gram Weights, One Loop Stylus, Five Allen Wrenches

 

New Dime Adapter

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For Use with the GARDCO Balanced Beam Scratch, Adhesion & Mar Tester


The Balanced Beam Dime Adapter is a new device originally developed as a quality control tool for determining the ease of removability of special "scratch-off" coatings applied to lottery tickets made by the lottery industry. It has been found to be equally useful in testing properties of paint, coatings, and other materials that include paper and paper products.

The Dime Adapter is a small block of machined aluminum (0.69" x 0.53" x 0.40") with two pins for insertion into receiving holes where any other stylus is normally held. The adapter has a machined channel that accommodates a coin the size of a dime, and allows the user to test the resistance of his coatings to scratch and mar from the milled edge of a dime.

New Dime Adapter

 

In adhesion testing, sometimes the edge of a Hoffman type stylus may be too sharp, and the loop or needle stylus may not be sharp enough. In this case, the edge of a dime may have just the right edge. Not only will a dime provide a different type of cutting edge, but the adapter also allows the user to insert practically any type of test coupon desired (such as a thin wafer), as long as it has roughly the same dimensions as a dime.

With the Dime Adapter, employ the normal operating procedure. However, the actual load at the edge of the coin is only 72% of the normal applied load. This is due to a small change in the placement of contact relative to the pivotal fulcrum.


Dime Adapter Dime Adapter, Spacer Plate, Two Bolts
Dime Adapter Dime Adapter, Spacer Plate, Two Bolts

 

5 Gram Precision Weight

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An Accessory For Balanced Beam Scratch-Adhesion & Mar Tester

A NEW five gram (5g.) precision weight is now available for use with the Balanced Beam Scratch-Adhesion and Mar Tester. It allows the user to perform tests at loads less than fifty grams, which was previously the lowest allowable weight. The five gram precision weight was developed for use with the Balanced Beam Dime Adapter to measure the scratch resistance on paper lottery tickets at very low amounts of force. The piece is machined from steel like all other Balanced Beam accessory weights, and has a recessed top that allows the five gram weight to achieve total loads in multiples of five grams, up to 550 grams.
5 Gram Precision Weight

 

Prices

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Prices subject to change    Prices listed in US dollars for domestic shipments within US, Canada, & Mexico only    Export orders require quotations - click here for a quote     For more info call us 1-800-762-2478 or 954-946-9454.
Item Number Item Prices

Auxiliary table, Two 500 gram weights, One 50 gram weight, Loop stylus, Needle stylus, Counter weight
PA-2197B Standard Balanced Beam Scrape Adhesion and Mar Tester with infinite adjustment up to 1.0" $3,895.00
Accessories
PA-2197A/SH Hoffman Stylus 105.00
PA-5089 Hoffman Cutter, Carbide Tipped 205.00
PA-5090 Hoffman Cutter, Hardened Tool Steel 149.00
PA-2197/SL Loop Stylus, Tool Steel, RC 55-61, 8 RMS Finish 55.00
PA-2197/ST Needle Stylus 34.00
PA-SG-8103 Steel Needle for MIL-DTL-7788H & MIL-P-7788F 43.00
PA-2197A/SP Spacer Plate and Bolts to elevate range of test panel thickness by +0.19 inches (.502" total) (for old model A only) 248.00
PA-2197A/AD Dime Adapter for Gardco Balanced Beam Scratch-Adhesion & Mar Tester (for old model A only) 468.00
PA-2197B/AD Dime Adapter for Gardco Balanced Beam Scratch-Adhesion & Mar Tester (for model B only) 414.00
PA-2197B/AN Nickel Adapter for "B" model 485.00
PA-2197A/W4 5 Gram Precision Weight 49.50



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