real world success

Simulated Problems, Real Results
Material supplier combines experience and advanced simulation technology to add value to its plastic compounds

By Cristina Beria, Moldflow Corporation

Raw materials represent a key factor in the realization of all products. However, it is not always sufficient to use a quality material, for often several other variables linked to design and production affect the final results. For this reason, the service supplied by Italian material supplier RadiciPlastics begins with a consultation with the customer to define needs, goals, and problems related to the project. The company may perform simulations related to mold filling and product development and, based on the results, suggest solutions to be implemented in terms of materials, equipment, and molding in order to achieve the customer's desired result.

"Through Moldflow Plastics Labs," says Giovanni Pioltini, marketing manager of the Plastics division at RadiciGroup, "we have characterized a set of RadiciPlastics materials in a database which is available for simulations. To this we add the experience developed in the field of plastic materials, which enables us to address the various problems that are submitted to us by suggesting what compound to use. Yet the added value of our service is not restricted to materials alone. Thanks to the know-how we have gained in plastic molding processes, we are able to suggest modifications to be implemented on molds or part geometry thickness changes to solve or prevent possible inconveniences to our customers."

A full range of analysis "Providing mold filling and part warpage analysis thus becomes for us a competitive advantage," says Pioltini. "When we addressed the question of what software to use, we decided to purchase Moldflow products, because they provide a complete analysis package." Pioltini continues, "Equipment plays a major role in terms of time and global costs when developing a project. Hence, it is essential to gather as much information as possible to avoid having to implement modifications subsequent to mold construction. When a customer submits a project to us with its related production problems, including tolerances to be respected, because we have characterized our plastic compounds in order to use Moldflow simulation technology, we can identify the separate effects that cause warpage in the part, and we are able to suggest the necessary steps to counteract such problems. Another advantage of the Moldflow simulation software is the fact that it works in a three-dimensional (3D) environment. Until not long ago, software performed only two-dimensional simulations; therefore, if the part thickness was greater than three millimeters, it was difficult to simulate the behavior of a material during filling of the mold cavity with sufficient accuracy." "When we adopted Moldflow technology," explains Pioltini, "our first experience was to tackle the development of the wheel for a supermarket shopping cart. The customer turned to us because 30 percent of these nylon wheels broke during assembly with a metal locking hook. No problem emerged from 2D simulations, but during testing with MPI/3D analyses, it became clear how the injection of the material at a given point created a turbulence which caused the formation of a bubble and consequently, the failure of the piece during fitting of the hook. We suggested moving the injection point so as to create a different turbulence. The subsequent process has shown a 30 percent reduction in the number of failures, down to just a few parts per million." Through the years, simulation systems have taken on increasing importance. Greater needs in terms of performance and esthetics, especially from highly technical sectors, have driven the need to meet increasingly tight dimensional tolerances, and hence, the need for instruments that can meet these requirements. Technology first Prior to using Moldflow technology, Pioltini says the company's work was based on the tool makers' and mold makers' expertise in locating gates. "Experience is good," says Pioltini, "but that strategy caused problems. The tool and mold makers' experience was used to drive decisions regarding gating. Today, 15-20 percent of our analyses that we perform for our customers are used to check already existing tools — those that were created based on prior experience and no Moldflow analysis. In these instances, the gates have not been well placed and there are filling problems. In my opinion, this problematic situation can be corrected with a more widespread use of Moldflow software throughout the plastic injection molding industry." Today, in order to eliminate any problems, Pioltini relies completely on Moldflow analysis prior to initiating any work for any project. "Experience is key to reading and understanding the analysis, however, we are committed to utilizing Moldflow to help us explore and determine gating locations and part filling schemes," adds Pioltini.

Moldflow analysis results suggest ways to optimize the part design and the molding process. Simulating the behavior of plastic materials enables manufacturing problems to be prevented before production begins. Moldflow MPI/3D analyses effectively simulate all stages of the molding process. By identifying the various causes of part warpage, Moldflow simulations enable problems to be solved appropriately.

Moldflow for development of under-the-hood applications

Diesel engines for cars and large machinery are fitted with a control panel that develops a great amount of heat. Further, diesel oil requires a high operating temperature. Consequently, the idea arose to optimize such factors by creating a heat exchange between the two systems. "The point was to find a material that could resist high temperatures under the hood and in contact with diesel oil," says Giovanni Pioltini. "In addition, the part had a low thickness, up to five or six millimeters, hence the material had to exhibit the least possible warpage to provide adequate dimensional stability and efficient sealing to fuel outflow. On the basis of mathematical data supplied by the customer, we have performed Moldflow mold filling and warpage analyses, to compensate for potential warpage where possible."

"To manufacture the component, we suggested choosing a polyamide 6.6 filled with 30 percent glass fiber, a compound that has been widely tested in these applications. We also recommended that the customer implement some modifications to the initial design to compensate for warpage and favor part flatness. In particular, some ribs were eliminated and some aspects of fuel inlet and outlet inserts were modified to prevent the creation of turbulence and weak adhesion of the material with formation of air bubbles and risks of fuel leakage. At the end of the analysis, the prototype mold was created, implementing the details resulting from the simulation to counteract part warpage."

Despite the usefulness deriving from the use of prototype molds, it is still possible that the switch from the prototype mold to the production mold could reveal some problems. Often the prototype mold has only one cavity, while the production mold may have several. The mold material also may differ between the prototype and the production mold, hence there may be differences in behavior in terms of conductivity, warpage, shrinkage, and so on. Pioltini concludes, "For all these reasons, mold development time has been moved towards the design stages, cutting construction time required. Thanks to the use of Moldflow simulation software, we are able to significantly compress cost and time for mold development, thus avoiding having to implement major modifications on the production equipment."

Quantifiable results

Pioltini says the use of Moldflow is a terrific time savings tool. For example, it can eliminate the need to build a prototype tool. "We can move directly to a production tool as a result of using the analysis. This represents a tremendous savings in terms of time and money," says Pioltini. "Prior to using the software, costs of repairing any tool problems — dimensioning, warpage, or filling — were often more expensive than the tool itself. With Moldflow, we avoid this costly situation, so the time to market and cost of the part are significantly reduced. In addition, we have much more confidence that the final product will be accurate and satisfy our customers' requirements."

For large tools, Pioltini says that the cost of building prototypes is prohibitive, so the first shot has to be right. There are no alternatives. "We can make no mistakes," notes Pioltini. "Moldflow helps the tool makers and the manufacturers reduce new tool start-up costs. The software helps avoid problems that always occur in the production of a new tool, which can cost upwards of tens of thousands of dollars. Indeed, the technology helps us support our customers as well as save valuable time and money."

Founded in 1981, RadiciPlastics is one of the most highly qualified suppliers of polyamide and polyester engineering plastics with operations in Italy, Germany, Spain, the UK, France, Brazil, the USA, and China. For more information about RadiciPlastics, go to www.radiciplastics.com.