AMOCO POLYMERS ELIMINATES MAJOR PELLETIZING PROBLEMS WITH NEW, CUSTOM DIE AND DELIVERS LARGE ORDER AHEAD OF SCHEDULE

Product mix expanded, throughput dramatically increased with cost recovered in 4 days! !

Amoco Polymers, headquartered in Alpharetta, Georgia, produces a broad range of resins including Udel polysulfone, Radel A polyether sulfone, Radel R polyphenyl sulfone, Xydar liquid crystal polymers, Amodel polyphthalamide, Torlon polyamideimide, and a diverse range of polypropylene products.

Significant Processing Problems

Amoco had accepted a very large order of Amodel resin for an overseas customer but was troubled by serious problems with the strand pelletizing process. Amoco found that material was charring because it was 'hung up' in the die, necessitating frequent die cleaning. In addition, the outer strands of material were curling, causing them to stick to the adjacent strands and render them all as waste This permitted processing only of established grades of Amodel resin with acceptable yields. When other grades were produced, it involved changing the face plate, which meant diverting and disposing of sellable product. More importantly, when certain critical Amodel grades are made, the yield results were disappointing. Experiencing a significant, economically non-viable reject rate, Amoco took quick and deliberate action to remedy the situation.

Calling on SPR for Assistance

Amoco contacted Scientific Process and Research (SPR) of Somerset, New Jersey to review their processing problems, recommend a solution, and implement it by designing and manufacturing new dies, if necessary. SPR has 30 years of experience using computer modeling in the design and manufacture of screws, dies and applied equipment to solve extrusion problems and optimize extrusion productivity. SPR invested substantial time in discussions with Amoco' s production and technical staff to ensure an accurate understanding of the resin's physical properties and process parameters. After carefully reviewing Amoco's entire processing system, SPR suspected the root cause of the problem was the die. Using their proprietary simulation software (Diedes), SPR confirmed their conclusion by isolating the problem ( die) and then providing written documentation and detailed illustrations to clearly demonstrate it. "SPR spent a lot of time up front talking with us and being certain they understood the process. They were very patient," said Ken Bowles, Amoco's Senior Production Engineer .

Problems Defined

SPR found the die and strand plate was plagued with a series of dead spaces that impeded the melt flow. These dead spaces caused material hangup and degradation as well as the uneven flow patterns. Using the Diedes program, SPR accurately calculated and demonstrated that this uneven material flow was exposing the strands to high shear at the outside plate positions. In addition, melt was entering the manifold via a flat slope causing nonuniformity in melt distribution. With non-uniform distribution of 20% additional melt being forced to each side of the die, the outer strands were overshearing, causing them to curl and aggravate the material hangup. Solutions Quickly Implemented

SPR rapidly assessed and addressed the problems. They first designed a custom strand plate featuring a symmetrical row of channels. The dead spaces were eliminated by redesigning the flow path, thus permitting even flow distribution to all channels and minimizing the hangup problem. By applying the results of the Diedes program to redesigning the manifold, the uniformity of melt flow was significantly improved.

Immediate Results

The new SPR die delivered immediate results, significantly reducing the reject rate and returning Amoco's investment in only 4 days. In the second year, the reject rate was further reduced. Amoco not only met production requirements but with increased yields, Amoco reduced overall required run time for each product.

Future Flexibility Built-ln

SPR went far beyond the parameters of the die configuration. Not only did the new SPR die solve serious processing difficulties, but the new SPR die was designed to fit into Amoco ' s existing processing line without requiring any significant modifications. For example, the die design utilized 30 heater cartridges and jackets and fit space requirements without requiring any new tooling or complex adjustments. For minor maintenance, SPR insisted on specifying components ‘off the shelf’ to minimize cost and add convenience. SPR even provided Amoco with local distributors who could provide these parts. Furthermore, SPR built independently controlled straining bars into the gate which could be raised or lowered to divert different materials to different channels. This allowed Amoco to quickly adjust the die online and process a wide range of new and existing resins without a die change. In addition, critical safety mechanisms were included to prevent material back up which could increase back pressure.

Amoco Receives More than Their Money's Worth

With the SPR custom designed die, all yields were significantly increased in the first year and additional benefits are still being realized, according to Mr. Bowles. With yield improvements valued in the millions.and with market demand growing substantially for its resins, Amoco now has the ability to meet growing market requirements and capitalize on the potential of its resins. As an added bonus, the SPR die has enabled Amoco to successfully add an additional Amodel grade to production. According to Mr. Bowles, Amoco needed a carefully engineered custom die and not a generic die 'off the shelf’. This is exactly what SPR provided them. "SPR' s ability to precisely model the fluid system and clearly define the problem was paramount for us. Now it's as if the die is invisible." Continued Mr. Bowles, "This is an excellent example of true customer satisfaction. SPR was much more concerned about getting it right then just making a sale. They did a great job for us. "

in the millions.and with market demand growing substantially for its resins, Amoco now has the ability to meet growing market requirements and capitalize on the potential of its resins. As an added bonus, the SPR die has enabled Amoco to successfully add an additional Amodel grade to production. According to Mr. Bowles, Amoco needed a carefully engineered custom die and not a generic die 'off the shelf. This is exactly what SPR provided them. "SPR' s ability to precisely model the fluid system and clearly define the problem was paramount for us. Now it's as if the die is invisible." Continued Mr. Bowles, "This is an excellent example of true customer satisfaction. SPR was much more concerned about getting it right then just making a sale. They did a great job for us. "