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Designing molds

Designing molds is highly specialized and requires skilled engineers experienced in using 3D CAD/CAM technology. This meticulous process considers the shape of the product, the type of plastic to be used, and the shrinkage of the plastic during the injection process. There is air in the cavity of the mold and when injection occurs, the air must be able to escape through minuscule air vents while preventing the flow of molten plastic into these vents. The plastic must spread to all corners of the mold and air should not obstruct this process. A critical aspect of the cycle is cooling the plastic. This must happen relatively quickly, and we utilize water channels within the mold to facilitate optimum cooling of the product. Once the product has cooled and solidified, it must be ejected from the mold using ejector pins, which must work smoothly to prevent damage to the product. We fabricate our molds from ultra-high-quality metals so that they can be highly polished to avoid any unevenness during the production process, especially for glossy or transparent products. If inferior metals are used in the mold, premature wear and tear is possible, which reduces the quality of the product.

Developing & manufacturing molds

For more than 60 years, PIU has been a leader in the design, development, and manufacture of custom-made molds. Our state-of-the-art manufacturing facilities enable us to offer a vast array of development and production possibilities. We focus on each client’s unique requirements and guarantee the quality of every product we manufacture while striving to exceed our clients’ expectations. PIU develops parts or fabricates entire molds for various applications, and molds can be designed for large and small series. Because of our flexible organization and highly-experienced professionals, we can also respond to urgent requests with short lead times to quickly and efficiently fabricate a 3D printed product. The advantage of the 3D printing approach is that we can easily adapt it relative to design, material, and color before producing the mold. Molds are available in various materials, and PIU will work with you to evaluate the materials and production options. Our team leverages its extensive knowledge of the variety of materials available to assist in selecting the most efficient molds that meet your requirements. When developing molds, PIU places the utmost importance on quality, flexibility, professionalism, efficiency, and value.
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Testing the molds

Once a mold is finalized, our process engineering team begins the fabrication process as aligning and tuning of a mold requires special skill. The injection molding process starts with mounting the mold onto the clamping unit of the production machine. The plastic granulate (pellets) is fed by a hopper and heated inside a barrel, transforming it into a molten state. The reciprocating screw inside the barrel acts as a ram which rapidly moves forward to inject the plastic into the mold cavity. Ram pressure is maintained to pack additional melt into the cavity to compensate for contraction during cooling. After cooling, the mold is then opened and the product is ejected and removed. Injection pressure, cooling time, and ram pressure require the highly-specialized expertise and experience of a skilled process engineer. Before full production commences, a test injection is performed so that issues or defects can be identified and possible future production problems can be avoided. The plastic engineer evaluates the functionality of the mold and records any abnormalities. If the mold has to be improved or adjusted, it will be optimized by the mold design engineer. Another test injection is performed and, if the mold is functioning properly, the sampling process will begin. The samples are checked for quality and, when these are optimal, the samples will go to the client for approval.

Molds in production

Once our engineers have developed, built, and optimized our high-quality molds, the injection mold is mounted on one of our powerful, sophisticated precision production machines. The molten plastic is then injected into the mold under high pressure (with a clamping force ranging between 15 and 270 tons per centimeter) and the product is shaped. The water channels inside the mold initiate the cooling process, which causes the molten plastic to solidify, producing the end product. We are capable of injecting 0 to 800 grams (0-28.22 oz.) of material per cycle (shot capacity) with a maximum size of 30×45 cm (11.81×15.75 inch) in virtually any kind of plastic.