In many manufacturing businesses the time from the initial customer contact to the release of components or systems for production is a critical path. Current processes and tools in place in many manufacturing processes, in particular, injection molding processes cannot support the order volume desired by the manufacturers.
Injection molding is a process by which some malleable material is forced under pressure into a closed mold. The material solidifies and retains the shape of the mold. Thermoplastic materials, thermosetting materials and some ceramic materials can be processed in this way. In a typical injection molding process, a material is melted and injected into a mold that has been clamped shut. The material freezes in the relatively colder mold and is then ejected.
At the beginning of the molding cycle, the molten material is injected into the mold through a sprue bushing, runner, and gate. During injection, the molten material (the “melt”) is subject to a cooling effect by contact with the relatively lower temperature surface of the mold, but is also subject to a heating effect due to viscous dissipation in the melt. If the cooling effect is greater than the heating effect, the plastic may solidify before the mold is filled, resulting in an unfilled mold, i.e. a “short shot”. If the heating effect dominates, the molding cycle may be unnecessarily extended for added cooling time. Because of the high volume rates of operation, even small gains or losses of time can be significant. The melt temperature and injection rate must be chosen so that neither of these problems occurs.
At the end of the injection period, the flow in the mold stops, the pressure rises rapidly, and the material begins to cool. As the material cools it shrinks slightly and more material may be forced into the cavity to the hold pressure acting on the melt. This portion of the molding cycle is called the “hold” or the “packing stage”, and it continues until the hold pressure is released or until the gate freezes. After the gate has frozen, the material in the mold continues to cool, which at first causes a reduction in pressure, followed by shrinkage of the material in the cavity. When the molded part has cooled sufficiently to remain rigid, the mold may be opened and pins eject the molded part, runner, and sprue from the mold.
Over the last decade, the techniques for designing, building, and ordering injection molding processes have been improved to increase productivity. There are systems in place that support electronic versions of catalogs of injection molding components such as, those offered by Mold Masters Limited, the assignee of this invention, Hasco Yudo, Dynisco, Heatlock, Mastip and the National Tool and Manufacturing Co. Further, interactive systems for selection of components from standard component lists such as Eurotool offered by Navigator are known in the art. There are systems also in place that support automatic drawing generation of injection molding systems. Further, there are systems available that integrate a computerized business system with a computerized manufacturing system.
However, even with recent improvements, the current injection molding systems have several drawbacks. Specifically, problem areas include the inadequacy of specification and order systems. For example, such systems are typically confined to only limited off-the-shelf components and information. Further, some systems presently allow the user to specify and order injection molding systems, such as hot runner systems, even though the person ordering has insufficient knowledge or experience to specify the product design. The resulting product may not function or may even result in a safety concern. In addition, current systems still require manual human intervention downstream by the manufacturer's personnel such as, for example, by the engineers. Further, typically the current manufacturing systems include the manual generation of the manufacturing information, such as the tooling information.
Accordingly, it is desirable to automate and integrate the design, specification, configuration and order systems with the business and manufacturing systems to enable a real-time automated configuring and manufacturing system which overcomes the problems associated with the prior art.
Hot runner systems for injection molding are well-known in the art. Hot runner systems generally comprise a manifold plate with a plurality of injection nozzles. The manifold plates used in such hot runner systems come in a variety of different shapes, configurations, and styles, depending on customer and/or manufacturing preferences. For example, the manifold plate may have a straight bar shape, X-shape, H-shape, Y-shape, Y-plate shape, or H-plate shape. In addition, the manifold plate may be configured with a wide range of lengths (e.g., 150 millimeters to 600 millimeters) and thickness (e.g., 25 millimeters to 40 millimeters), and the flow channels of the manifold plate may be configured with a wide range of diameters (e.g., 3 millimeters to 12 millimeters).
The number, pitch spacing, and type of nozzles used with the manifold plate may also vary depending on customer and/or manufacturing preferences. For instance, anywhere from 2 to 8 nozzles (or more) may be used with a manifold plate, and each nozzle may be spaced (i.e., nozzle pitch) anywhere from 30 mm to 250 mm away from the melt inlet of the manifold plate. Moreover, the nozzles may have a number of different shapes, sizes, tips styles, gate configurations (e.g., thermal or valve gating), and shot weight ranges.
Obviously, it would be very impractical and expensive, if not impossible, to pre-manufacture and pre-assemble all of the possible existing combinations of hot runner systems, and have them stored in inventory for delivering to a customer upon placing an order. In contrast, it would be undesirable to unduly limit the shapes, configurations, styles, types, and/or sizes of the manifold plates and nozzles used in hot runners systems, and restrict customers' ability to customize their hot runner systems. Thus, in order to accommodate their various designs and customers' custom specifications, hot runner systems are typically not manufactured or assembled until after customers have placed orders for the hot runner systems and specified their design requirements. Consequently, the manufacturing and assembling of such hot runner systems can take several weeks, if not several months, to complete, since all of the work is done after the customer places an order.
A typical hot runner system is manufactured and assembled with the following prior art method. In the first step, a customer's order is taken by the hot runner maker, including the customer's specifications for the ordered hot runner system. Based on the customer's specifications, the raw material for the manifold is selected in the second step, and the manifold plate is manufactured in the third step by cutting and grinding the raw material into the desired manifold plate dimensions. Next, in the fourth step, a heating element is added to the manifold plate, and in the fifth step, the main and auxiliary flow channels are drilled in the manifold plate. Then, in the sixth step, holes for attachments to the manifold plate are drilled, bored, and/or machined, and the specified injection nozzles are manufactured in the seventh step. Finally, in the eighth step, the specified components, including the injection nozzles, are attached to the manifold plate, and the customized hot runner system is completed and delivered to the customer in the ninth step. As previously mentioned, this prior art method can take several weeks, if not months, to complete.
Accordingly, it would be desirable to provide a method for speeding up the manufacturing and assembling processes involved with hot runner systems to allow customers to receive their hot runner systems in a shorter period of time (i.e., in a matter of days, rather than weeks), yet still provide customers with the flexibility to customize their hot runner systems. The present invention accomplishes this desire and overcomes the problems with the prior art by providing a method for quickly manufacturing and assembling customized hot runner systems using a wide selection of standard manifold plates, nozzles, and other stock components, such as manifold heating elements and plugs. The method of the present invention enables hot runner systems to be rapidly assembled from partially manufactured components, while still allowing customers to choose from a broad range of options for manifold plates and injection nozzles, and to specify the requirements for their hot runner systems.