Density
套餐怎么退订Density is weight per unit volume, weight/volume, and is expresd as lbs/ft3 (pcf).
Density is usually measured in grams/cm3 and multiplied by 62.4 to convert to lbs/ft3 (pcf).
Density can be obtained from any sample size. Density is not related to pore size, i.e., coar pore and fine pore foams can have equal densities.
Density is not a measure of firmness, stiffness, or load bearing capacity. That is defined by Indentation Force Deflection (IFD) or Compression Force Deflection (CFD).
Indentation Force Deflection (IFD)
IFD (previously ILD) is one test method to determine load bearing capacity (firmness or stiffness), and is expresd in pounds force per 50 in.2 at a given percent deflection of th
e foam.
For example: P215-50, FHA grade carpet cushion foam has a target IFD of 50 lbs/50 in2 at a deflection depth of 25% of the original thickness of the sample after a rest period of one minute, 25%R.
无痛分娩真的不痛吗To obtain the 25%R value, a 50 in.2 circular indenter platen is driven into a 15” x 15” x 4” foam sample, stopping when it reaches a deflection of 1”, 25% of the 4-inch thickness. The testing device records the force in pounds required to hold this foam indented after one minute. The higher the force reading, the higher the load bearing capacity of the foam. This result can be reported in metric and the sample size can be varied.
Sag Factor (Modulus) is the ratio of the 65%R IFD to the 25%R IFD values and is expresd in real numbers with one decimal. Sag factor gives an indication of cushioning quality. A high value indicates a resistance to “bottoming out.”
天的成语
Recovery Ratio is the ratio of 25%R IFD relead to 25%R IYD initial when measuring IF
D values at 25% deflection, 65% deflection, and then relead back to 25% deflection. Recovery ratio is expresd as a percentage.
Guide Factor is the ratio of 25% IFD to density and is expresd in whole numbers. Guide factor is uful in determining the relative firmness of foams with different densities. It is also ud to compare the economy of foams. The higher the guide factor, the more economical the foam becau you get a firmer foam with a lower density.
Compression Load Deflection (CLD)
CLD is also a measure of firmness and is expresd in pounds per square inch (psi), at a given percentage deflection.
The sample size is 2” x 2” x 1” thick. The entire sample is compresd under the 50 in2 indenter platen in this test. The procedure is the same as IFD. Record 25%R & 65%R values. It is common practice on foam specifications is to specify only the 25%R-value.
Both IFD & CFD can be tested at 50%R or any other deflection point bad on customer / supplier agreement.
体育与健康论文% Compression Set
公司授权书% compression t is a measure of the permanent deformation of a foam after it has been compresd between two metal plates for a controlled time period and temperature condition. The standard conditions are 22 hours at 70°C (158°F) The foam is compresd to a thickness given as a percentage of its original thickness, usually 50%. Compression t is expresd as the percentage of its original thickness that remained “t”. For example: If a 2” x 2” x 1” sample measured 1.00 inch before compression and 0.95 inch after the test, it is reported to have a compression t value of 5%, i.e., it did not recover 5% of its original thickness.
Tensile Strength
花落时节又逢君Tensile strength is a measure of the amount of force required to break a 1/2 square inch area of foam as it is pulled apart. Tensile strength is expresd in pounds per square inch (psi). The tensile sample is die cut to a dumbbell shaped, 6” x l” x 0.5” thick.
Elongation
Elongation is a measure of the extent to which the foam can be stretched before it breaks and is expresd as a percentage of its original length. Elongation is measured at the same time, as tensile strength is determined; therefore, the sample size is the same.
Tear
Tear strength is a measure of the force required to continue a tear in foam after a split ha
s been started and is expresd in pounds per linear inch (pli).
The sample size is 6” x l” x l” thick.
Tear strength is an important property when the foam will be wed or stapled in an application.
小溪像什么Permeability
Permeability is the measure of the volume of air per minute that can be pulled through a sample of foam and is expresd in cubic feet per minute.
The sample size must be at least 4” x 4” to fit over the opening of the Frazier permeability device.
