Laserfiche WebLink
There can be a variation of the ILD from day to day due to minor it <br /> changes in the chemical ingredients. A variation also occurs due to <br /> the daily variation in climatic conditions of temperature and humidity. <br /> Therefore, it is imperative to statistically sample the production to <br /> measure these variations of firmness. This non-uniformity within a t <br /> slab must be recognized by all fabricators. <br /> The normal range allowed for the 25% ILD is 5 pounds. This is the <br /> maximum variation users will accept in a cushion before the difference <br /> Q in comfort becomes objectionable. As indicated here, this large a <br /> variation alone exists within a slab. Additional variations due to the <br /> chemicals and climate add to this problem. <br /> 25% ILD is sometimes referred to as RMA, (an abbreviation of <br /> Rubber Manufacturers Association), a carry over from the nomen- <br /> clature of latex foam. It is obvious why we urethane producers prefer <br /> ILD. ILD is an abbreviation of Indentation-Load-Deflection. The 25% <br /> ILD of urethane foam is the number of pounds required to indent a <br /> 50 square inch circular disc or foot into the sample of foam. The <br /> disc is indented, as I am demonstrating, to a depth or deflection of <br /> 25% of the height of the foam sample (Refer to Figure Number 4). <br /> ILD MEASUREMENTS <br /> III <br /> I <br /> 25%ILD <br /> 65% ILD <br /> I FIGURE 4 <br /> 7 <br />