Casting molding master

A two-mask process has been used to create a glass master containing two levels of positive photoresist relief structures. The master was used to cast a PDMS chip consisting of the channel/chamber (25-30 pm deep) and weir (7-12 pm clearance) [960]. Another two-mask process was used to create a Si molding master consisting of 3-pm-high Si relief stmctures and 25-pm-high photoresist relief structures [364]. 

Instead of using a planar molding master, a fused silica capillary tube (50 pm i.d. and 192 pm o.d.) was used as a template for casting PDMS channels, and as the fluid inlet/outlet tubes. After PDMS curing, the middle pre-scored section (4 cm) of the capillary was removed to reveal the PDMS channel (192 pm wide and deep) [817]. Similarly, a capillary was used to mold a PDMS channel, and to produce an electrospray emitter. In this case, after PDMS curing, the last 0.5-cm section of the capillary was removed to create a channel [821]. 

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. 

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). 

Generative processes are also used to produce cores and molds for sand casting, lost models, molds for investment casting, and master models for a variety of molding processes, preferably in soft (silicone) molds. Molds for sand and investment castings are not discussed in the context of this book, molding techniques are discussed in Section 1.11. 

One of the oldest methods used with molding, but at the same time the least accurate, is cast molding (e.g., injection molding, casting, etc.) [111]. This method is used both for refractive and diffractive lenses. First, a high-accuracy master is fabricated. It is subsequently used to produce large series of microlenses. The method is especially convenient for work with plastic materials transparent in IR, like TPX (polymethylpentane, polymerized dimer of propylene.)... 

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],... 

Before using a new mold, the dimensions should be checked. The coefficient of expansion of the mold material must be balanced against shrinkage of the cast polyurethane (normally 1.0 to 1.5%). It is normally much easier to remove material from a mold or master piece than to add to it. This should be taken into account when designing the mold. 

Master cast A flawless cast that is set aside to take the place of the specimen, should it need to be molded in the future. 

Master pattern A flawless pattern similar in function to a master cast. The pattern preserves the detail of the mold, as well as the detail of the specimen. There is one master pattern for each side of a mold. 

A liquid preparation with solid polystyrene (0.6 g) dissolved in liquid styrene monomer (1.5 mL) was cast against a mold. Polymerization was accomplished with UV irradiation (21°C, 18 h). Solid PS was included to reduce the degree of shrinkage that occurred when monomeric styrene was photopolymerized [85]. In a similar manner, PMMA dissolved in MMA was cast against a Si master. Upon UV polymerization (with BME as the photoinitiator), a PMMA chip is formed. Nearly 100 PMMA chips can be replicated using a single Si master [223]. 

Nanomold Replication A physical mold is produced that has nanoscales on the order of tens or a few hundred nanometers. To achieve such fine features with precision and repeatability, electrodeposition is used to produce the molds, otherwise referred to as a nanostamp [194], The stamp is then use as a master stamp to duplicate the image or object by casting or embossing the polymeric material. 

Mold Fabrication Fifteen silicone rubber molds were cast from a master stainless steel template machined in the shape of a dogbone with gauge dimensions of 4 X 12 X 25 mm. The grip portion of the sample was terminated in a... 

Plaswite . [Cabot Plastics Ltd.] Uta-nium dioxide masterbaich in polyethylene, polypropylene, or pdys nene carriers some widi lidiopone or caldum carbonate as extenders white master-batch for blown and cast film, inj. mold-it, blow mdding of drug, cosmetic, arid food coniainas. 

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