Metering Products produce varying densities of foam.

Press Release Summary:




Hydraulic Driven 2-Position Orifices for Multi-Density Metering(TM) Technology switches mix head between 2 different throughputs/ratios. High and low throughput positions are programmed into shot profile data on machine. Hydraulic Operated 2-Position Clean-out Piston allows mix head to be tuned for optimal mixing with stops to lock in alternate settings. Servo Controlled Clean-out Piston allows infinite throughput/ratio variations as fast as 0.5 sec while maintaining pour pressures at ±50 psi.



Original Press Release:



Linden Industries Introduces Three New Multi-Density Metering(TM) Technologies at the 2004 Polyurethanes Conference



October 2004 - API Conference Las Vegas, Linden Industries introduced three new technologies for processors who wish to produce varying densities of foam from a single mix head/machine. Advanced high-pressure polyurethane metering equipment provides the capability of modifying polyol and isocyanate ratios on-the-fly. Multiple density foams allow processors the flexibility to produce different products with different densities on a production line in addition to single products such as seats that require a soft center and firm sides.

NEW Hydraulic Driven 2-Position Orifices for Multi-Density Metering(TM) Technology
This technology was developed for processors who need to automatically modify the throughput/ratios in the mix head but do not have the budget for computer controlled servo orifices. Linden has developed a hydraulically operated mechanism attached to the mix head that can switch the mix head between two different throughputs/ratios. The high and low throughput positions are programmed into the shot profile data on the machine and can be selected as required. Hydraulic two-position orifices can be easily and inexpensively added to existing machines that have variable frequency drives. The modification involves reprogramming the machine to use alternate settings.

Multiple Density Mixing Problems
With multiple density foams from the same mix head, the variation in polyol to isocyanate ratios can be as much as 4-to-1. Mixing difficulties can be experienced particularly when variations in the material viscosities exist. By using an L-style mix head, the position of the mix head's clean-out piston can be adjusted to impede the flow of material and create additional turbulence and mixing. The clean-out piston position will typically be set to optimize the mix for the higher throughput pour. This may not always provide the optimal mix for low throughput ratios and cause mixing challenges. If the backpressure from the impedement rises too much, it may cause crossover between the material orifices.

NEW Hydraulic Operated 2-Position Clean-out Piston
Linden has developed a two-position clean-out piston, operated by the existing mix head hydraulics. The mix head can be tuned for optimal mixing of both the high and low throughput situation with stops to lock in the alternate settings. As with the orifices, the two-positions are programmed into the machine's shot profile data and utilized when required. The capability for a two-position clean-out piston can be easily and cost-effectively added to existing machines that have variable frequency drives.

NEW Infinite Ratio Variations With Servo Controlled Clean-out Piston If the processor requires more than two combinations of ratios/throughputs such as production lines manufacturing a wide range of products in varying densities, servo controlled systems involving closed-loop pressure feedback are typically used. Linden introduced servo controlled orifices in 2000, which allow infinite through-put/ratio variations as fast as 0.5 seconds while maintaining pour pressures at +/- 50 psi. To optimize the mixing with servo orifices, Linden developed the technology to program and servo control the position of the clean-out piston based upon closed-loop pressure feedback. Molders can now run a variety of formulations and output ranges on the same production line with a single metering machine and optimized mixing.

Each of the above technologies developed and presented by Linden Industries are a result of the need for increasing flexibility and improved product quality in high-production polyurethane processing. For additional information, readers should contact Mr. Theron Sherman, Sales Manager, Linden Industries, Inc., 137 Ascot Parkway, Cuyahoga Falls, Ohio 44223, p. (330) 928-4064 f. (330) 928-1854 e-mail: tsherman@lindenindustries.com, www.lindenindustries.com.

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