3.5  LARGE BALL IMPACT RESISTANCE 

3.5.1  Scope

This test measures the ability of laminate flooring to resist fracture due to impact by a large diameter ball. 

3.5.2  Test Apparatus

3.5.2.1       Impact apparatus as shown in Figure 3-3 or equivalent

3.5.2.2       Polished stainless steel ball weighing 224 ± 3 grams, measuring 38.1 mm (1-1/2 inches) in diameter.  The spherical surface shall have no damaged or flattened surface.

3.5.2.3       Clamping jig capable of holding the test specimen flat.  See Figure 3-4, or the equivalent.

3.5.2.4       Underlayment foam as a closed-cell foam with a thickness of 2.0 mm ± 0.5 mm (0.08 in + 0.02 in) and a density of 35 kg/m³ + 5 kg/m³ (2.2 lb/ft³ + 0.3 lb/ft³) or equivalent.

3.5.2.5       Environmental Chamber maintained at 23^oC + 3^oC (73^oF + 5^oF) and relative humidity of 50% + 5%.

3.5.2.6       Black, water washable marking pen (suitable for overhead transparencies).

3.5.2.7       A clean, damp, soft, white cloth.

3.5.2.8       Overhead white fluorescent lights with bulb(s) positioned parallel to the line of sight and providing an intensity of 800 to 1100 lux (75 to 100 foot-candles) on the specimen surface.

3.5.3  Specimens

3.5.2.1       Specimens shall be 300 mm x 300 mm x thickness (12 in x12 in x thickness).  In cases where material is less than 300 mm (12 in) in one dimension of the face, the specimen shall measure 300 mm x nominal width x nominal thickness (12 in x nominal width x nominal thickness). 

3.5.4  Procedure

3.5.4.1       Condition the samples to constant weight (less than 0.1% deviation per 24 hours) in a conditioning chamber maintained at a temperature of 23^oC + 2^oC (73.4^oF ± 3.6^oF) and a relative humidity of 50 ± 5 percent.

3.5.4.2       Place the specimen on underlayment foam of similar size as the specimen and place the assembly on the clamping base of the apparatus.

3.5.4.3       Loosely clamp the specimen/foam assembly to the base to immobilize the specimen but not compress the foam underlayment.

3.5.4.4       Adjust the measurement scale so that it touches the surface of the specimen.

3.5.4.5       Position the electromagnet at any arbitrary height above the test specimen.

3.5.4.6       Place the ball on the electromagnet and drop the ball. Catch the ball on the first rebound so that multiple impacts do not occur.  Impact positions shall be at least 50 mm (2 in) apart and 50 mm (2 in) from any edge of the specimen.

3.5.4.7       Use the marking pen to ink over impact points caused by the ball.  Use the clean, damp, soft, cloth to wipe each impact point.  Fractures may appear as hairline cracks, concentric circles, or chips.

Figure 3-3

Figure 3-4

 3.5.4.1       Examine the impact spot for cracks and fractures to determine the result.

3.5.4.2       Raise or lower the electromagnet height as necessary and repeat steps 3.5.4.6 through 3.5.4.8 until the maximum height at which no cracks or fractures occur is determined.

3.5.4.3 Drop the ball from the height determined in step 3.5.4.9 two additional times in different locations on the test specimen.  If either drop fails, reduce the height by 25 mm (1 inch) and continue testing until a total of three successful results have been obtained at that height.

3.5.5    Report

3.5.5.1       Reference to this standard.

3.5.5.2       Description of the material under test.

3.5.5.3       Maximum height (mm) achieved in 3 replicate impacts without a visible crack on laminate flooring surface.

3.5.5.4       Any deviation from the specified test method.

3.5.5.5       Date of the test. 

3.5.6  Precision & Bias

3.5.6.1    Table 3-3 is based on interlaboratory studies conducted in 1999 involving 3 replicate tests of 9 materials tested by 6 laboratories.

Table 3-3 

3.5.6.2    In Table 3-3, for the materials indicated:

3.5.7.2.1 Mean is the average of test results for all replicates from all labs.

3.5.7.2.2 S_r is the within-laboratory standard deviation of the mean and I_r = 2.83S_r (see 3.5.7.2.4 for application of I_r).

3.5.7.2.3 S_R is the between-laboratory standard deviation of the mean and I_R = 2.83S_R (see 3.5.7.2.5 for application of I_R).

3.5.7.2.4 Repeatability – In comparing two mean values for the same material obtained by the same operator using the same equipment on the same day, the means should be judged not equivalent if they differ by more than the I_r value for that material and condition.

3.5.7.2.5 Reproducibility – In comparing two mean values for the same material obtained by different operators using different equipment on different days, the means should be judged not equivalent if they differ by more than the I_R value for that material and condition.  (This applies between different laboratories or between different equipment within the same laboratory.)

3.5.6.3    The judgments per 3.5.7.2.4 and 3.5.7.2.5 will have an approximate 95% (0.95) probability of being correct.