Research & DevelopmentOur products undergo strenous testing to ensure that you will enjoy years of service without decline in product quality or performance. The following is an overview of the various tests that each Denver Mattress undergoes.
Leggett & Plat Inc. National Technical Center Testing Department Procedure Overview
Sonar Measuring System Procedures
The Sonar Measuring System provides an accurate method of measuring the actual height and/or loss of height in a set of bedding. The System utilizes an Ocean Motion Sonar XR-1000 ultra sonic transceiver/receiver. One transducer signals in the vertical plane for height measurements with a second in the horizontal plane for transverse location data. The unit is capable of taking a programmable number of readings over a given distance at the operator's discretion. The system's primary use is in determining height loss in sets of bedding, comparing a new or virgin sample to a post tested state and again after a 24 hour recovery time span. The one inch surface flattening or body impression value has become a criteria of sort. Typically a surface change of 1" or less will pose no problem as far as returns for body impression. When evaluated a mild surface flattening will represent less than 1⁄2", moderate flattening up to 1" and large flattening anything over 1". This is not a pass/fail parameter but an indicator that problems might occur.
Indention/Load/Deflection Test Machine
The Indention/Load/Deflection (ILD) Test Machine is essentially a tensile/compression tester, specifically designed and built for Leggett & Platt, Inc. Its primary function is to perform firmness evaluations on innersprings, boxsprings, upholstered mattresses and bedding sets. A standard mattress evaluation consists of an 8" disk platen being depressed into the sample 4" with the 1⁄4" increments recorded and summed to determine a firmness value. Typical positions include shoulder zone, geometric center and calf zone with the geometric center repeated after the conclusion of the physical testing. There is no established pass/fail criteria for this procedure. The typical range for this test a 10% increase in firmness to a 25% softening from a new to post test condition. A recovery run is conducted in the geometric center after a 24 hour time span, with a normal recovery of no change to 10%.
Cornell Testing Machine
The Cornell Testing Machine subjects a set of bedding, or other samples to be tested to a cyclic loading of which force may be set at one's discretion, of a dual hemispheric plunger. Its loading is quite similar to those in actual life of a set of bedding. The Cornell Testing Machine is capable of accommodating up to a queen size set of bedding. The data retrieved is recorded on standardized forms and may be used as comparative analysis of samples tested. The Cornell Testing Machine is capable of running ASTM Procedure F 1566 Standard Test Methods for Evaluation of Innersprings and Boxsprings, Section 9 - Firmness Retention and Surface Deformation as well as other versions of the Cornell Test. The test is a 100,000 cycle evaluation of a buttocks shaped platen loaded vertically into the geometric center of a set of bedding, to a deflection which achieves a 230# load, ran at 160 cycles per minute. Intermediate readings are taken at 200, 6000, 12,500, 25,000, 50,000, 75,000 and 100,000 cycles. Data recorded consists of 1/2" increments load readings from a 5# pre-load zero point, stroke to achieve 230#, and dimple (change in depth to reach the 5# pre-load). Upon completion of 100,000 cycles the support firmness (difference in 4" and 3" readings) percentage difference from 200 cycle to 100,000 cycles is calculated. The dimple readings are added to determine the accumulated dimple. The results, are compared to the historical guidelines of, an accumulated dimple of no more than 1.75? for innerspring bedding or .75? for foam cores, and an allowable support firmness percentage change of -15% to +40%. There are no pass/fail parameters in the current ASTM procedure.
Juggernaut Roller (Rollator)
The Rollator Test Machine is capable of running ASTM Procedure F 1566 Standard Test Method for Evaluation of Innerspring and Boxsprings, Section 7 - Durability Test. The Rollator tests consists of a 230# 6-sided roller, rolling across the width of a set of bedding for 100,000 cycles (200,000 passes) at approximately 1000 cycles per hour. Periodic visual observations are made to report surface flattening and or damage. Mild flattening represents less than 1⁄2" change, moderate indicates 1⁄2" up to 1", and large over 1".