H.J.UNKEL (THAI) LIMITED

Falling Sand Abrasion Tester

The Falling Sand Abrasion Tester - Model 820 is a popular apparatus used to measure the resistance to abrasion of paint, lacquers and other organic coatings. Abrasion results from abrasive particles falling through a guide tube and impinging the test specimen, until the substrate becomes visible.

Description

Based on a design described in ASTM D 968 and other internationally recognized test standards, the Falling Sand Abrasion Tester consists of an 8" diameter sand reservoir which includes a 60° taper funnel. Standardized abrasive particles placed in the reservoir are released to a guide tube by an abrasive flow gate key. The guide is a 36" straight, smooth-bore tube which contains the abrasive particles as they fall. Specimens are fixed under the guide tube at a 45° angle in a receptacle that includes an opening at the bottom allowing the abrasive particles to be collected in a container. A sturdy base and support system hold the apparatus in a vertical position.

Abradants

Although a variety of abrasive particles have been used, silica sand and various grades of silicon carbide continue to be most popular. To ensure reproducible results, the abrasives must be graded to a particular sieve size.

Note: Silica sand is typically characterized by its roundness of grains and produces a slower rate of abrasion on organic coatings.

It has been noted that for 3 mil dry film thickness, many of the older coatings would require 20 to 200 liters of silica sand to achieve a failure. Today's more durable coatings may require up to 600+ liters of sand to wear-through. For an extremely durable coating, the Taber Rotary Abraser is preferred as the Falling Sand method tends to be laborious and time consuming with the handling of large quantities of abrasive.

Evaluation

Abrasion resistance is often expressed in terms of the volume of abrasive required to wear through a unit thickness of the coating.

Test Methods

The following link provides a listing of test methods the Taber Falling Sand Tester satisfies. Please note, additional accessories may be required.

Oscillating Sand Abrasion Tester

The TABER® Oscillating Abrasion Tester - Model 6160 is best known as an "oscillating sand tester". Described in ASTM F735 (Standard Test Method for Abrasion Resistance of Transparent Plastics and Coatings Using the Oscillating Sand Method), the oscillating sand tester is used to measure the relative abrasion resistance of a material to surface abrasion and / or marring. The primary application of the Oscillating Sand Abrasion Tester is for transparent materials and coatings utilized in windows and lenses, but it might also be used to evaluate organic paints & coatings, plastics, metals and other materials.

Description

Rigid specimens that are 100mm square and less than 12.5mm in thickness are mounted in a holder located in the bottom of a sand tray so the surface is flush within 1mm. The tray is filled to a uniform depth (e.g 12.5mm) with a standardized abrasive media such as quartz silica or alumina. A scotch-yoke drive system reciprocates the tray in a back-and-forth (to-and-fro) motion which causes the entire mass of the abrasive media to shift significantly within the tray. The oscillating movement of the abrasive media results in a random pattern of scratches which simulates normal everyday wear.

Test parameters can be altered with Taber's Oscillating Sand Abrasion Tester, and allow the operator to select the operating stroke length (6.5 to 150 mm) and speed (variable from 100 - 200 cycles per minute). ASTM F735 specifies the sand tray travels a distance of 100mm at a speed of 300 strokes per minute.

In addition to the dry abrasion test, the oscillating sand abrasion tester may be used with abrasive slurry to perform erosion tests. For this application, the optional 4 inch deep tray is suggested along with a specimen tray cover. In place of the abradant, a slurry would be used (e.g. 50 - 50 mixture of solids and distilled water). The abrasivity of the slurry is dependent on the concentration of the solids in the liquid vehicle, along with the characteristics of the solid particles (shape, hardness, size, and friability).

Using a custom specimen holder (not supplied), materials of various shapes may also be tested. To generate useful data, it is important to recognize that the amount and force of abrasive media that contacts the specimen surface will change based on the curvature of the part. Specimens with a severe contour may inhibit the movement of the abrasive media during the test.

An optional kit is available to conduct the Bayer Abrasion Test on contoured lenses. This set-up involves testing a specimen against a control lens for comparative purposes.

Abradants

In December 2011, Taber Industries learned that the sole source provider of the 4/10 abradant described in section 6.1 of ASTM F735 was sold and the new company discontinued the product. The ASTM subcommittee responsible for this test method is working on initiating a round robin study to characterize / qualify a potential replacement material. The recommended material is a 6/9 Silica Abrasive Media which is available from Taber Industries. If you would like more information, please contact us.

There are a variety of standardized abradants that could be used with this instrument. Besides the silica abrasive media, other potential abradants include alumina (zirconia), silicon carbide, aluminum oxide and glass bead. For repeatable test results, the sizing and shape of the abradant is absolutely critical.

During testing, the abradant may become 'worn' as the sharp edges contact the specimen and other abrasive particles. To ensure reproducibility, new abrasive media should be used for each test. It is also recommended that the abrasive be replaced after 300 cycles for longer cycle tests.

Evaluation

Using a haze meter, the haze and light transmission of a transparent test specimen is measured and recorded. After subjecting the specimen to the specified number of abrasion cycles, the results are measured as a change in haze and light transmission. Abrasion resistance for opaque materials is measured visually or by weight loss.

Test Methods

The following link provides a listing of test methods the Taber Oscillating Sand Abrasion Tester satisfies. Please note, additional accessories may be required.

Crockmeter

The Taber® Crockmeter - Model 418 provides a quick and accurate method to determine the amount of color transferred from textile materials (such as fabric, carpeting, yarn and leather) to other surfaces by rubbing. The Crockmeter has also been employed to perform rub abrasion, scuff and / or mar tests on flat specimens. Plus, it can be used to conduct smudge and smear resistance tests on images produced by a printer or copier. Regardless of specimen material, both wet and dry testing can be performed.

Description

Originally designed to simulate the action of a human finger and forearm, the Crockmeter uses a standard pressure and rubbing motion to provide reliable and reproducible test results. Specimens are positioned on the base of the Crockmeterand held in place with the sample holder. To prevent the specimen from shifting during testing, a sandpaper pad is provided to place under the specimen. A hand crank moves a reciprocating arm a distance of approximately 100mm. The rubbing action is provided by a 16mm diameter acrylic "finger" which moves back and forth in a straight line with each complete turn of the crank. The reciprocating load arm is weighted to provide a constant 9N load on the sample at all times and a mechanical counter keeps track of completed cycles.

Abradants

A standardized crocking cloth is most often used as the abradant for textile applications. This square (or sometimes circular) cloth is wrapped around the acrylic crock "finger" and held in place with a wire spring clip. AATCC Method 8 specifies the cloth should meet the following specifications:

Fiber	100% 10.3 - 16.8mm combed cotton staple, desized, bleached, with no optical brightener or finishing material present
Yarn	15 tex (40/1 cotton count), 5.09 turns/cm "z
Thread Count	32 +/-3 warp ends/cm: 33 +/-3 picks filling/cm
Weave	1/1 plain
pH	7 +/-0.5
Mass/sq. meter	113 +/-5g greige: 100 +/-3 g finished)
Whiteness	W = 80 +/-2

Other abradants that might be used with the Crockmeter include felt, duck cloth, laboratory grade denim, coated abrasives (e.g. Polishing Paper, 281Q 3M WetorDry™), etc.

Evaluation

Typical evaluation for textile Crockmeter tests involve visually comparing the amount of color transfer / staining against a standardized color transfer scale. After rubbing the crocking cloth against a colored test specimen for the prescribed cycles, the crocking cloth is removed from the instrument and the amount of color transferred to it is compared to a known scale and assigned a grade. Two popular scales include AATCC Gray Scale for Staining or the Chromatic Transference Scale. For repeatable and reproducible test results, it is recommended that specimens be evaluated in controlled lighting and at a specified angle.

When using the standard 16mm diameter crock finger to test pile fabrics (such as textile floor coverings), there may be heavier staining on the circumference of the stained area of the crocking cloth. To resolve this, Test Method AATCC 165 describes using a "crock block" measuring 19.0 x 25.4mm.

Test Methods

The following link provides a listing of test methods the Taber Crockmeter (Crock Meter) satisfies. Please note, additional accessories may be required.

Heavy Duty Linear Abraser

The TABER® Heavy Duty Linear Abraser - Model 5800 is used to evaluate material properties of products with a rugged, durable surface finish that require an increased testing load or longer stroke length. Supplied with the 2" diameter Universal Attachment and Scotch-Brite™ scouring pads, the Heavy Duty Linear Abraser is ideal to measure a coating's resistance to scrubbing with an abrasive scouring pad. A popular application includes evaluating non-stick coatings used on cook / bake ware.

Description

Similar to Taber's Linear Abraser, a test attachment is secured to the bottom of a vertical spline shaft and accessory weights may be placed on a weight holder affixed to the top. A precision bearing on the spline shaft creates a "free-floating" test system. As the test arm moves in a linear motion, the "free-floating" system will raise or lower as the test attachment follows the contours of the specimen being tested - curved or flat.

The base load of 500 grams consists of the test attachment, spline shaft and weight holder. Accessory weights of 1000, 2000 and 4050 grams are included and can be added to the weight holder to increase the test load. With a high torque motor, the Heavy Duty Linear Abraser can accommodate a maximum testing load of 20 lbs. (weight sold separately).

Other features of the Heavy Duty Linear Abraser include a slotted roller channel allowing stroke length adjustments up to 330mm (13 inch); five preset speeds including 15, 30, 37, 45, and 60 cycles per minute; and an integrated T-slot table for securing specimens during testing.

With interchangeable attachments, the Heavy Duty Linear Abraser can also be configured similar to the Linear Abraser to evaluate the relative resistance or susceptibility of a material surface to wear and abrasion, scratch, gouge, scrape, rub, and more. In addition, the instrument can be used for both wet and dry testing. To increase test output, an optional second test arm kit may be added to perform two tests simultaneously.

Caution: Not all interchangeable attachments will accommodate the heavy test loads possible with the Heavy Duty Linear Abraser.

Evaluation

Tests conducted with the Heavy Duty Linear Abraser using the Scotch-Brite™ scouring pads are normally performed until the surface coating has been worn down to the substrate material or a portion thereof (breakthrough). Alternatively, tests can be run for a predetermined number of cycles (e.g. 10,000) with mass loss used as the end point.

Test Methods

The following link provides a listing of test methods the Taber Heavy Duty Linear Abraser (Abrader) satisfies. Please note, additional accessories may be required.

Reciprocating Abraser (Abrader)

The TABER® Reciprocating Abraser (Abrader) - Model 5900 is a test apparatus similar to the instrument described in test method ISO 1518. Ideal for flat surfaces, this tester can be configured with optional attachments to evaluate the relative resistance or susceptibility of a material surface to physical damage such as wear and abrasion, rub, scratch, mar, gouge, scrape, plus others.

Click here for information on scratch testing with the Reciprocating Abraser.

Description

Taber Reciprocating Abraser (Abrader) 5900

The Taber Reciprocating Abraser includes a counterbalanced arm which pivots on an adjustable height gantry system. The counterweight allows the user to balance the test arm, ensuring precise test load set-up regardless of the weight of the attachment. Incorporated at the end of the arm is a tool holder to which optional attachments and weights may be secured. A sliding specimen platform moves in a horizontal, reciprocating motion under the stationary tool holder.

Test parameters such as stroke length (6 - 155mm), speed (3 - 75 cycles per minute) and load (1N - 24N maximum, with included weights of 1N, 2N, 2.5N, 5N, 10N & 24N) are adjustable so optimal settings for each material can be established.

To expand test loads, an optional weight support may be affixed to the top of the tool holder. This permits using auxiliary weight discs originally intended for Taber's Linear Abraser 5750 in place of the standard weights supplied with the instrument. Weight discs are sold individually and available as 10g, 20g, 50g, 75g, 100g, 150g or 250g.

The Wearaser® collet assembly comes standard with each Taber Reciprocating Abraser, along with CS-10 and H-18 Wearaser abradants. The size and shape of a pencil eraser, the Wearaser is made using the same high quality Taber abrasive media found in our Genuine Taber abrading wheels. This permits the use of equivalent abrasive materials with the Reciprocating Abraser as well as Taber's Linear Abraser and the Taber Rotary Platform Abraser.

The standard specimen table provided with the Reciprocating Abraser is 216mm x 278mm (8.5" x 11") with drilled tapped holes to accommodate specimen clamps or optional specimen fixing plates. To evaluate most flat specimens, specimen clamps or the optional Wide Slot Fixing Plate may be suitable. For flexible materials such as textile products, the optionalSpecimen Fixing Plate Kit might be used. Products with a slight contour can also be secured in place using the specimen clamps provided or a custom fixture.

The Reciprocating Abraser can accommodate two additional test arm kits (sold separately), permitting up to three tests to be performed simultaneously.

Wear / Abrasion Attachments

For information on Wear / Abrasion Attachments for the Reciprocating Abraser, click here.

Evaluation

Due to the wide variety of test attachments that can be used with the TABER Reciprocating Abraser (Abrader), there is no universal method to interpret results. The two most common methods include:

Cycles to a Specific End-Point - The number of cycles required to reach a predetermined end point, or the appearance or condition of the specimen after a fixed number of cycles. The evaluation criteria may include: loss in coating, change in gloss, color loss, or other changes in appearance. In these cases, the abraded sample is usually compared to a known standard of the material tested. When visually inspecting changes in specimen appearance, evaluations should be made using an agreed upon rating system such as a visual grading scale (e.g. five-step) or pass/fail criteria.

Weight (Mass) Loss - This technique measures how much material has been removed by abrasion, and is usually reported in milligrams.

L = A - B

where L = weight loss

A = weight (mass) of specimen before abrasion

B = weight (mass) of specimen after abrasion

Linear Abraser (Abrader)

The TABER® Linear Abraser (Abrader) - Model 5750 has been engineered to test either contoured or flat surfaces, making it ideal to evaluate finished products of all sizes. To expand the versatility of this instrument, the Linear Abraser can be configured with optional test attachments to perform different types of abrasion tests. And can be used for both wet and dry testing.

Click here for information on additional attachments that can be used with the Linear Abraser to evaluate the relative resistance or susceptibility of a material surface to scratch, mar, gouge, and scrape.

Description

The Taber Linear Abraser incorporates a horizontal arm that reciprocates in a linear motion. Attached to the end of the arm is a precision bearing spline shaft that creates a 'free-floating' test system and permits vertical movement. The test attachments are affixed to the bottom of the spline shaft and a weight support is mounted to the top. As the horizontal arm strokes back and forth, the test system raises or lowers vertically as the test attachment follows the contours of the specimen. A laser alignment guide assists with specimen set-up to ensures the abradant travels over the desired area.

Adjustable settings enable the user to select the speed, stroke length and test load. The Linear Abraser includes six preset speed buttons, along with the ability to adjust the speed from 2 to 75 strokes per minute. Eleven stroke lengths are standard ranging from 0.2 inch to 4.0 inch. The base load of the "free-floating" test system is 350 grams and consists of the test attachment; spline shaft; and weight support. Three 250g weight discs are supplied with the instrument and optional weight discs ranging from 10 to 250 grams can be added to the weight support to increase the test load to approximately 2100 grams. Optional accessories can be also be used to decrease the load. For example, an 150mm aluminum spline shaft and plastic Wearaser Collet Kit can bring the minimum load on the sample to as low as 60 grams. Taber's Linear Abraser is programmable to 999,999 cycles, but caution must be used as the abradant may wear prior to the end of the test.

The Wearaser® collet assembly is supplied with each Taber Linear Abraser, along with CS-10 and H-18 Wearaser abradants. The size and shape of a pencil eraser, the Wearaser is made using the same high quality Taber abrasive media found in our Genuine Taber abrading wheels. This permits the use of equivalent abrasive materials with the Linear Abraser as well as Taber's Reciprocating Abraser and the Taber Rotary Platform Abraser.

The Multi-Head Attachment (sold separately), incorporates an additional spline shaft, permitting two tests to be performed simultaneously with the Linear Abraser.

With the diversity of products that can be tested with the Taber Linear Abraser, it is up to the end-user to determine a suitable clamp or fixturing device appropriate to their product. Click here for additional information on specimen mountingavailable from Taber Industries.

Wear / Abrasion Attachments

For information on Wear / Abrasion Attachments for the Linear Abraser, click here.

Evaluation

Due to the wide variety of test attachments that can be used with the TABER Linear Abraser (Abrader), there is no universal method to interpret results. The two most common methods include:

Weight (Mass) Loss - This technique measures how much material has been removed by abrasion, and is usually reported in milligrams.

L = A - B

where L = weight loss

A = weight (mass) of specimen before abrasion

B = weight (mass) of specimen after abrasion

Note: There is no standard formula to correlate test results between the Linear Abraser and Taber Rotary Abraser. Due to differences in how the wear paths are generated, testing parameters and the unique wear properties of each material prevents a universal formula from being devised. If you are attempting to correlate the results, Taber recommends correlating through experimentation to determine the appropriate settings.

Taber Abraser (Abrader)

The TABER® Rotary Platform Abrasion Tester - Model 5135 or 5155 is commonly referred to as the Taber Abraser (Abrader) or Rotary Platform Dual (Double) Head Tester. First introduced in the 1930's, this precision built instrument was developed to perform accelerated wear testing. Capable of providing reliable data in a matter of minutes compared to the years that may be required by in-use testing, the Taber Abraser (Abrader) rapidly became the world standard for evaluating abrasion resistance.

Since its inception, the Taber Abraser has been used for quality & process control, research & development and material evaluation. Used to test a wide spectrum of materials, the instrument has been referenced in numerous standards and specifications (including plastics, coatings, laminates, leather, paper, ceramics, carpeting, safety glazing, etc.).

Description

Taber tests involve mounting a flat specimen approximately 100mm square or round to a turntable platform that rotates on a vertical axis at a fixed speed. The standard material thickness that can be evaluated with the Taber Rotary Abraser is 6.35 mm (materials greater than 6.35 mm but less than 40 mm can be tested with optional accessories). Two genuine Taber abrasive wheels, which are applied at a specific pressure, are lowered onto the specimen surface.

Characteristic rub-wear action is produced by contact of the test specimen against the sliding rotation of the two abrading wheels. As the turntable rotates, the wheels are driven by the sample in opposite directions about a horizontal axis displaced tangentially from the axis of the sample. One abrading wheel rubs the specimen outward toward the periphery and the other, inward toward the center while a vacuum system removes loose debris during the test. The wheels traverse a complete circle on the specimen surface, revealing abrasion resistance at all angles relative to the weave or grain of the material. The resulting abrasion marks form a pattern of crossed arcs in a circular band that cover an area approximately 30 cm².

Each turntable has dual abrading arms that are precision balanced. Independently operated, the abrading arms can be raised (or lowered) to mount or inspect specimens. Each arm is loaded for 250 gram pressure against the specimen, exclusive of the weight of the wheel. To increase the load to 500 or 1000 grams, a mount for auxiliary weights is located on the outside of the abrading wheel bearing assembly. This location ensures that weights are concentric with the abrading wheel. A stud on the rear end of the abrading arm is used to carry an optional counterweight (used to reduce the load by 50, 125 or 175 grams).

Taber Abrasers Model 5135 or 5155 offer the following standard features:

Specimen turntable speed control options of both 60 rpm and 72 rpm.
Easy-to-use operator interface that includes tactile feel buttons and a four line digital display. Simple on-screen instructions allow the operator to change the test parameters via the MENU button. An internal memory stores the settings.
A vacuum system is included and is critical for the proper operation of the instrument. The vacuum nozzle(s) is hinged to an adjustable mounting at the rear of the housing. A precision vacuum nozzle adjustment control allows the height to be modified for accommodating varying specimen thickness.
Precision stainless steel weights of 250 grams and 750 grams are furnished to provide standard wheel loads of 500 and 1000 grams. Weights are marked to show total load on each wheel. This marking includes the weight of the abrading arm (250 grams).
A Quick Release Mounting Hub permits quick wheel mounting without the need of a locking nut, increased clearance for the vacuum pick-up nozzle and a larger viewing area for the test specimen. A beveled retaining nut provides a positive locking force on the wheel hub retaining lip making certain that the wheels remain securely fastened until disengaged.
Assembled in a sturdy, sealed aluminum housing.

Models

The TABER^® Abraser (Abrader) is available in two models - single or dual specimen tables. Both offer the same durable design and can be used interchangeably.

TABER^® Abraser (Abrader) - Model 5135 (115/230V; 60/50Hz)

Model 5135 features a single specimen turntable.

TABER^® Abraser (Abrader) - Model 5155 (115/230V; 60/50Hz)

Model 5155 features two specimen turntables, allowing you to perform two tests simultaneously (test two different or identical specimens for comparison or contrast). Separate function keys operate the turntables independent of each other.

Click here to view a Taber abrasion test on Exatec® automotive glazing products according to test method ASTM D1044 (video is courtesy of Exatec LLC).

Abradants

For information on Genuine Taber wheels, click here.

Evaluation

There are various techniques used to interpret results generated with the TABER Rotary Platform Abraser (Abrader). The method of evaluation that you select should reflect the type of material that is being tested. If you are following a specification - the method for interpreting test results will be listed.

The most common methods of evaluating results from the Taber Abraser (Abrader) include:

Cycles to a Specific End-Point - The number of cycles required to reach a predetermined end point, or the appearance or condition of the specimen after a fixed number of cycles. The evaluation criteria may include: loss in breaking strength, yarn breakage, loss in coating, change in gloss, color loss, or other changes in appearance. In these cases, the abraded sample is usually compared to a known standard of the material tested. When visually inspecting changes in specimen appearance, evaluations should be made using an agreed upon rating system such as a visual grading scale (e.g. five-step) or pass/fail criteria.

Weight (Mass) Loss - This technique measures how much material has been removed by abrasion, and is usually reported in milligrams.

L = A - B

      where L = weight loss

          A = weight (mass) of specimen before abrasion

          B = weight (mass) of specimen after abrasion

When performing the weight loss method, loose particulate may adhere to specimens during testing. It is critical that you clean off the test specimens as best as possible prior to weighing.

Taber Wear Index - Indicates rate of wear, and is calculated by measuring the loss in weight (in milligrams) per thousand cycles of abrasion. The lower the wear index, the better the abrasion resistance.

I = [(A - B) * 1000] / C

where I = wear index

A = weight (mass) of specimen before abrasion

B = weight (mass) of specimen after abrasion

C = number of test cycles

Volume Loss - When comparing the wear resistance of materials that have different specific gravities, a correction for the specific gravity of each material should be applied to give a true measure of the comparative wear resistance. Calculate the wear index as shown above, and divide the result by the material's specific gravity. The use of this correction factor provides a wear index related to the loss in volume of the material to which it is applied. When comparing materials of different specific gravities, test parameters must be the same including wheel selection and load.

Wear Cycles Per Mil (0.001 inch) - Used to express abrasion cycles required to wear through a coating of a known thickness.

W = D / T

Where W = Wear Cycles Per Mil

D = number of cycles required to wear coating through to substrate

T = coating thickness, mils

Depth of Wear - To determine the depth of wear, use a thickness gauge or other appropriate device to measure the specimen thickness on four points along the path to be abraded, approximately 38 mm from the center hole and 90° apart. Calculate the average of the readings. After subjecting the specimen to abrasion, repeat the measurements and average the readings. Calculate the difference. Alternatively, the depth of the wear can be measured with an instrument such as an Optical Micrometer.

Residual Breaking Force (textile fabrics) - This technique measures the effective strength of the fabric, or force required to break a specific width of fabric. To determine the individual breaking force of the abraded specimen use the procedure described in the ASTM D5034 and D5035 Standard Test Method for Breaking Strength and Elongation of Textile Fabrics. [Note, you must change the referenced distance between clamps to 25mm and horizontally place the path of abrasion on the abraded specimen midway between the clamps.] Report the breaking load to the nearest 0.5kg.

Average Breaking Strength (textile fabrics) - Calculated by averaging the breaking strength of the abraded specimens and the unabraded specimens, as determined by the Residual Breaking Force.

Percentage Loss in Breaking Strength (textile fabrics) - To determine the breaking load of the original fabric and the abraded specimen, use the procedure noted above (ASTM D5034 and D5035). Calculate the percentage loss in breaking strength to the nearest 1% for each lengthwise and widthwise directions.

AR% = 100 * (X - Y) / X

where AR% = abrasion resistance, %

X = breaking force before abrasion, g (lb)

Y = breaking force after abrasion, g (lb)