Setup and Control of Molds

Moldflow Plastics Xpert (MPX) process automation and control technology provides machine operators with an easy-to-learn and easy-to-use tool for the setup, optimization, and control of the IM process. Finally, a tool exists that allows a less-experienced operator to set up molds, optimize the process, and control production. 

The SPI kit covers the primary processing machine communication protocol with chillers, blenders, dryers, water systems, discrete mold-temperature controllers, and the like. The protocol provides for centralized setup and monitoring of auxiliaries by the primary machine. The test simulation software that is a key part of the kit ensures uniform interpretation of technical specifications. It is a combination of a detailed technical specification of hardware requirements such as the type of cable, the connector and electrical interface, and software requirements. The kit protocol shows how electronic information moves through the system. 

Recently all of the temperature, pressure, and time controls have been replaced with a single microprocessor-based controller. A number of these are available and they allow for complex pressure and temperature curves to be programmed with multiple soaking levels and variables that can be chosen. Built-in memories recall previous programs and cassettes can store them on the shelf. Interfaces can connect with a central host computer for data collection or actual machine setup and supervision. The result is more flexible, more exacting, and easier to control modern molding equipment (Chapter 3). 

The principle of nanoimprint is quite simple. As shown in Fig. lA, NIL uses a hard mold that contains nanoscale features defined on its surface to emboss into polymer material cast on the wafer substrate under controlled temperature and pressure, thereby creating thickness contrast in the polymer material, which can be further transferred through the resist layer via an O2 plasma-based anisotropic etching process. Nanoimprint has the capability of patterning sub-10 nm features, " yet only entails simple equipment setup and easy processing. This is the key reason that NIL attracted wide attention within only a few years after its inception. 

Sdf-Assembly. Gravitational ass bly was performed on silicon tinplates with 60 pm de holes defined through standard photolithography that were coated with a perfluorodecyltTichlorosilane monolayer. Particles were d x>sited on the coated tonplat which was then placed in a sealed ceU. Ihe entire setup was excited at 60-100 Hz so that the amplitude was just sufficient to fluidize the particles. When all holes in the tinplate were filled with particles, the template was removed, and excess particles were picked up by a carrier that did not touch the assembled particles. Convective assembly (15] was used to order 500 nm polystyrene particles into 2D continuous layers. It was performed on flat PDMS templates previously oxidized by oxygen plasma. Capillary assembly [14] provided 500 nm polystyrene particle ass nblies with full control of the positions on patterned PDMS templates without any surface modification. PDMS templates were fabricated by injection molding on flat or patterned silicon masters [32]. They consisted of a 200 pm thick layer of custom-... 

One of the most surprising ways to affect the dimensions of an injection-molded part is to vary the injection pressure hold time. Generally, the injection pressure is applied and then released after a specified time to allow the injector to recharge for the next shot. Releasing the injection pressure early versus late can have a profound effect on the dimensions of the finished part. This has been observed many times but has not yet been thoroughly studied or quantified. However, on large diameter parts such as O-Rings, this can be the difference between dimension-ally compliant and dimensionally rejected parts. In the initial setup of the injection process, injection pressure hold time should be a variable studied for its effects on the finished parts. If the relationship of injection hold time is established in the initial production approval process, it is more likely to be monitored and controlled in routine production. 

Various tests were performed to quantify energy efficiency gains and process control improvements, using a combination of bench-top setups and production rans on a laboratory injection molding machine. A samphng of the results is presented herein. Additional lab tests are underway and envisioned, as are monitored installations on a spectrum of production machines. 

Only one machine is required to do bodi molding and blowing, easier quality control, since each molding cavity corresponds to a specific blow cavity, and lower installation cost of total setup. 

Setup of the injection and double vacuum-assisted resin transfer Molding (IDVARTM) process proposed by Fan ef a/.The IDVARTM setup controls the preform porosity, compaction and the pressure inside the preform during the resin infusion process by changing the chamber vacuum pressure.The capillary flow effect and the Darcy s flow effect are both utilized in the IDVARTM process to infuse the MWCNTs enhanced epoxy into the glass fiber preform. (This original schematic Is created based on the work reported in reference 38.)... 

In addition to providing sufficient space for the mold, the press must include space for a pressure box and other elements, such as plug assist plates, cavity isolator plates, trim-in-place die plates, and ejector-ring plates. Water and vacuum lines should be properly located and should be easy to disconnect. Programmable logic controls are needed for adjustment of all rate-dependent ancillary features, such as plug assist, cavity isolator, pressure box, and trim-inplace sequence. Many newer machines are equipped with computer controls that provide for rapid setup after mold changeover. The press platens must allow easy mold removal and installation. 

The frame of the hybrid mold has been produced by use of standard 1730 steel. Both mold core and cavity are produced using the DMLS DS50 method. Based on conventional injection parameters for both amorphous and crystalline polymers, the mold has been analyzed by verified FE analyses. After mold design and FE model setup, all boundary conditions were implemented. The model was solved using steady state and transient solver control, by use of the Jacobin solution method and the quadric solver with Chebychev accelerator [5]. 

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