The Cornell Type Tester test the long term capacity of bedding to resist cyclic loading. There are several different methods evaluate the quality of innersprings and boxsprings. Such as testing for measurements regarding firmness, firmness retention, durability, effect of impact etc. Our Cornell type Tester is trusted by leading mattress brands. For Instance, Sealy.
The machine consists of a double hemispherical ram head on a manually adjustable shaft. A load cell on the ram head measures the force being applied to the mattress. The shaft is connected to an adjustable eccentric which is rotated by an electric motor at up to 160 cycles per minute, variable.
Bedding/ Mattress Testing using Cyclic Loading
The testing method starts by placing the mattress below the ram. Then, adjusting eccentric and shaft position. So that the specific load is possible to apply. That is maximum load of 1025N and the minimum load of 22N. This is when the eccentric rotates to the lowest and highest positions respectively. The machine measures the psoition of ram head automatically. This is with the help of position transducer.
Then, eccentric rotates slowly, raising and lowering the ram head. Thus, recording load or position data for a few cycles. The firmness of mattress is measured from the load readings. Which is between 75mm and 100mm respectively. This procedure is performed at the start of the test and the subsequently at the end of each of seven stages. These stages are reached when 200, 6,000, 12,500, 25,000, 50,000, 75,000 and 100,000 cycles have been completed at 160 cycles per minute. The duration of the cyclic testing will take nearly 10.5 hours, simulating 10 years of mattress use.
At the end of each stage, the position of the ram head is noted when a load of 22N is applied to the mattress. A change from the previous static reading is referred to as a dimple and this is recorded. An operator prompting computer program measures both the load and ram head position from the two transducers throughout the total test stages and produces a full test report upon completion.
Firmness, firmness retention, durability, impact Testing
The Cornell Type Tester uses a custom software to produce the test results and dispalys results in the form of load deformation, cyclic load limits, etc. These are produced in graphs, tables for better intrepretation.
- Cycle: List shows the number of cycles to be tested at each stage.
- Units: All measurement units throughout the software program, including on screen information and recorded information, can be viewed as either Metric (N, Kg, mm.) or Imperial (lbf, lb, inch).
- Peak/Trough Load: denotes the working range of the load cell. This can be adjusted to suit customer requirements.
- Peak/Trough Tolerance: are the allowable tolerances over/under set loads that can be exceed before warnings will appear.
- Stroke Tolerance: is the acceptable tolerance of stroke length in one deformation curve to the next.
- Disp Range: is the maximum displacement selected for the recordings of the mattress firmness
- Firmness Start/Firmness End: relates to the position of which firmness is calculated between two points of a stroke in each load deformation result of each stage during the test. These points may be adjusted to suit.
- Test speed: This is where you can set your maximum cycle speed of your machine when testing. The recommend speed for this test is 100 cpm.
- Jog speed: Is the speed set for when the machine is cycling for developing the load deformation results. This is set to 10 RPM.
- Load Average: selects the amount of readings data is averaged over. (ie: set at 50, data would be averaged over every 50 load readings)
- Indicator Update: selects how fast the indicators of the software are updating and displaying relevant information.
Mattress Firmness Retention Test
The Cornell Type Tester is used to test the long term capacity of bedding to resist cyclic loading. The machine consists of a double hemispherical ram head on a manually adjustable shaft. A load cell is located at the ram head to measure the force being applied to the bedding.
The shaft is connected to an adjustable eccentric which is rotated by an electric motor at up to 160 cycles per minute. The bedding is located below the ram, and the eccentric and shaft position adjusted so that the maximum load of 1025N (230lbf) and the minimum load of 22N (5lbf) is applied when the eccentric is rotated to the lowest and highest positions respectively. A position transducer (wire activated potentiometer) is located so the position of the ram head can be measured automatically when the manual adjustments are complete. A static scale is manually adjusted to zero when the ram head measures 22N (5lbf) load.
Mattress Testing Procedure
After adequate conditioning, place the selected bedding on a flat rigid surface in the relevant position under the ram head. Midpoint with respect to ends and size for a twin/single size mattress and midpoint with respect to ends and quarter point with respect to sides for full/queen/king size mattresses. The centre line of the ram head should be positioned so it runs parallel to the mattress ends. To ram head direction is adjustable to allow most suitable placement of mattresses. By using the Software Program, the following procedures are easily progressed through with on screen prompts for the operator from the initial hysteresis graph to the completion of 100000 cycles with all relevant stops for necessary recordings at appropriate cyclic counts of 200, 6000, 12 500, 25 000, 50 000, 75 000 and 100 000.
ASTM F1566 - Standard Test Methods for Evaluation of Innersprings, Boxsprings, Mattresses or Mattress Sets
These test methods cover recognized methods for testing mattress innersprings, boxsprings, and finished mattresses or mattress sets, or both, to ensure uniformity of results. These test methods are applicable to un-upholstered mattress core units including but not limited to innersprings, air chambers, and foam cores, un-upholstered foundations including but not limited to boxspring and build up foundations, finished foundations and mattress constructions. Data developed is for comparative analysis with no pass/fail criteria applicable.