Master model

Mass cast tools and composite tools are made from a master model. The surface finish and geometrical tolerance on the mold is then completely determined by the master model. The utmost care must therefore be spent on the master model before the mold is made. This topic is discussed in detail by Morena [33],... 

Two general approaches have been used in low-temperature studies. In the first, the uncompensated resistance, electrode capacitance, diffusion coefficient, and kinetic and thermodynamic parameters describing the electrode reaction are incorporated in a master model, which is treated (usually by some form of digital simulation) to calculate the expected voltammetric response for comparison with experiment [7,49]. 

The master model determines production quantities and inventories per period. 

Epoxy prepreg tapes, with carbon, glass, or aramid reinforcement, have been used for production of tooling. They require an initial cure at 20-80C (68-176F) and offer a maximum service temperature of at least 200C (392F) in air. A low-temperature cure means very low residual stress levels. Low-temperature master models can be used directly without... 

Polyurethane board can include a low density foam block for applications from styling models to cutter path verification, and styling. Low density master models from which vacuum-consolidated RP tools and components can be produced. 

AM is also used to make kernels and molds for sand casting, lost pattern and molds for precision casting, and master models for copying techniques. Tools for lost wax casting and sand casting are not mentioned as well as copying techniques. 

Used for Prototype Tooling or Indirect Tooling, 3D printing quickly leads to not very expensive but not very detailed master models. Because of the poor surface quality and its brittleness that requires infiltration, they are not recommended for copying. If nevertheless taken, intensive surface finishing is required. 

Duplication of prototype master models (made by special techniques such as laser stereolithography, laser powder sintering, LOM etc.) in polyurethane or epoxy resins by the vacuum casting process within the scope of rapid prototyping . 

A bar chart with the height of each bar indicating how many data points were collected within certain interval. The width of the bar provides a measure of the interval. A master model in hardened steel used to sink the shape of a mold cavity into a soft steel block. 

A more detailed examination of the modeling of conqiosite processing will be given in the following sections where each of the submodels mratirmed in this section, integrated into a general master model, wUl be discussed. 

Hob hab [ME hohhe, fr. Hobbe, nickname for Robert] n. A master model of hardened steel that is pressed into a block of softer metal to form a number of identical mold cavities. The hobbed cavities are inserted into recesses in a steel mold base and are connected by a runner system. (2, v) To form a mold cavity by forcing a hardened steel hob, having the inverse shape of the cavity into a soft metal block (that may subsequently be hardened). 

Epoxy resins are widely used as adhesives, surface coatings, encapsulates and casting materials. They are used in industrial tooling applications to produce moulds, master models, laminates, castings, fixtures, and other industrial production aids. This plastic tooling replaces metal, wood and other traditional materials, and generally improves the efficiency and lowers the overall cost or shortens the lead-time for many industrial processes. Epoxy resins are extensively used as a binder for marine paints, which is required to protect the naval structure from the corrosive marine environment. 

Fig. 12.24 The master model is oriented and drilled so that the implant analogues can be placed in it (left), a CAD model of the post-surgical cast (middle), CAD model comparison (right) [32]...

The hob or a master model is usually made of a good quality, hardened steel. Its face is machined to the exact size and contour of the reproduction desired. All surfaces of the hob are highly polished after hardening. The blanks for the impressions are made from soft steel (or beryllium-copper) and are prepared by grinding and polishing the surface that is to come in contact with the hob. Depending on the size and the contour of the hob, it is advisable to remove some of the material from the bottom of the blank. After preparation the blank is placed in a hydraulic press, and the hob is placed in position over the blank before the press is closed. The actual hob pin is done in the press at a very slow rate of speed. The pressure required for hobbing varies from 50 to 150 tons/in of die impression. 

Model Plank, Master models. Tool Chemical Co., Inc. 

Tooling. Tools made with epoxy are used for producing prototypes, master models, molds and other parts for aerospace, automotive, foundry, boat building, and various industrial molded items (261). Epoxy tools are less expensive than metal ones and can be modified quickly and cheaply. Epoxy resins are preferred over imsaturated polyesters and other free-radical cured resins because of lower shrinkage, greater interlaminar bond strength and superior dimensional stability. 

Moving potentially one step further from rapid prototyping to low volume production the vacuum casting process uses a master model, possibly derived from a SLA process, to make a silicon tool. The... 

Molds for the Soft Core Technology 1.8.2.3.1 Master Model... 

The master model (mock-up) (Figure 1.207), also master core, defines mostly the surface of the component to be manufactured. From the original core, further molds can be replicated. The core, as well as the following molds, is subject to modifications. 

The cavity is shaped after the master model (Figure 1.207). The cavity (comparable to the original surface) can also be manufactured through machining based on drawings. The disadvantage is that after wear or mold duplication, a new, expensive machined part has to be manufactured. The mold cavity can be manufactured from different materials. A series of criteria has to be taken into consideration when choosing the material. 

Similar to the soft-core technology, a mold cavity is also needed here however, this cavity must be more solid because of the higher forces occurring during both the layup and the curing process in the autoclave. Therefore, the cavity is made from aluminum or steel, milled in one piece without previous master models. The cores (Figure 1.212), usually divided, are made very accurately from aluminum. 

For the manufacture of silicone molds using models in a cast, a master model will be needed. This master model is produced via stereolithography, selective laser sintering, or milling and is then cleaned and treated with a release agent. Then, the parting line is determined with the help of colored tape (Figure 1.277). 

Silicone mold Polyurethane Molding process through a master model Illustration sample Design sample Functional model Prototype Epoxy resin Polyurethane 1,900 X 900 30-50 2-5 1-2... 

Epoxy resins are used when duplicating models. A casting resin or silicone negative mold is manufactured based on a master model. The casting resin-positive models are now casted in these molds. This procedure is also used when the material of the model is unstable towards the bath solution, e.g., wood, gypsum, leather, and others. 

---