Calculation of Gas Release Distance for Machine Foaming
Given: The small bubble gas release time is 108 seconds, and the conveyor belt speed during foaming is 4.6 meters per minute. We need to calculate the gas release distances for both swinging and trough foaming.
– Swinging gas release distance: (108/60) *4.6 = 8.28 meters
– Trough gas release distance: [(108-18)/60]*4.6 = 6.9 meters
Explanation: For the same formula, the gas release time for machine foaming is shorter than for small bubble foaming. Therefore, the calculated gas release distance is shorter than the actual distance. This method provides a rough estimate, which can assist in adjusting the settling plate. “Troughing 18” refers to the time (in seconds) that the raw material remains in the overflow trough.
Foaming Height Calculation for Machine Foaming
Given: The formula flow rates are: polyether 80 kg/min, white polyether 20 kg/min, TDI 60 kg/min, stone powder 20 kg/min, conveyor belt speed 4.5 meters per minute, mold width 1.65 meters, and foam density is 25 kg/m³. What is the foaming height in meters?
– Total formula weight: 80 + 20 + 60 + 20 = 180 kg
– Formula volume: 180/25 = 7.2 m³
– Conveyor belt base area per minute:
4.5 x 1.65 = 7.425 m²
– Foaming height: 7.2/7.425 = 0.97 meters
Explanation、: This calculation excludes silicone oil, amines, and tin, which balance out the CO2 usage during foaming. Moisture content (MC) is also not considered since it does not increase the foam weight upon vaporization.
Daily Operations for Foaming
Beginners often worry that improper adjustment of the settling plate could cause the liquid from the nozzle to surge forward or backward, affecting foaming. The reaction rate increases within the first two minutes after the machine starts, and sometimes adjustments to the settling plate are necessary. For low-density formulas with high MC, precise adjustment of the settling plate is crucial.
TDI flow rate can be determined by calculating the corresponding scale value, but it is recommended to measure the TDI flow rate during the first foaming cycle. Flow rate is very important—if it is incorrect, everything else will go wrong. The most reliable method is the simplest and most intuitive: direct measurement of flow rate.
When mixing powder, it’s important to leave the stone powder to rest overnight before starting production the next day. For formulas containing melamine and stone powder, it’s recommended to first mix the melamine with the polyether for a while before adding the stone powder.
Foam machines with longer mixing chambers or more teeth on the mixing shaft typically require formulas with less amine and lower material temperatures. On the other hand, machines with shorter mixing chambers or fewer teeth usually have formulas with more amine and higher material temperatures.
For the same formula, when switching between dual spray swing heads and single spray swing heads, if the nozzle cross-sectional areas are similar, the requirements for the mesh fineness and the number of layers are similar.
Small material flow rate adjustments can be made by measuring the return flow rate of small materials, or by dividing the total material usage by the foaming time. If the results from these two methods differ significantly, the data from the second method should be used.
Formulas that produce soft foam with better properties are often in an unstable range, such as a lower TDI index, a lower water-to-MC ratio, a lower T-9 dosage, and a lower silicone oil dosage. Much like in our work, effort is required before reward.