Small-series mold

Whereas aluminum and zinc alloys or low-hardness steels can be used for small-series molds (prototypes and pre-series), the processing of SMC to serial parts is done in heated steel molds. 

Small series of moldings with smooth visible surfaces on both sides are made using the vacuum molding process, Fig. 56. Two mold halves are required. One half can... 

Injection molding machines are characterized according to their clamping force From 50 up to 100,000 kN, for example the production of boat bodies or wet cells of pre-fabricated houses. It is typical that machine sizes in the range of 100 to 30,000 kN are manufactured in small series. 

Applications for hard RIM products are mainly large automotive parts, such as front and rear bumpers, and rocker panels (see Figure 1.135). The most frequently used materials are polyurethanes reinforced with milled short fibers, which are processed in the so-called RRIM process (Reinforced Reaction Injection Molding). The short fibers increase the stiffness and decrease the thermal expansion in the case of temperature changes. They are abrasive, therefore the molds are made from steel (in small series also aluminum). 

Aluminum is the most commonly used material for thermoforming molds. The advantages of aluminum as a mold material are its good thermal conductivity and workability. Specific alloys help meet the stiffness requirements. Modern computer-aided milling techniques allow small series of this material. Large-volume molds are made from aluminum blocks cast under vacuum. 

The direct manufacture of prototype molds using the rapid prototyping process offers significant advantages (see also Section 4.7). By LaserCUSING and adapted processes, molds without restriction for prototype and small-series production can be used. Also, highly filled thermoplastics of up to 70% GF can still be manufactured to several thousand injection molded parts on standard injection molding units. 

Aluminum molds are an economical alternative to injection molds for small series. Milling is performed using predefined CAD data. The manufacture is much cheaper and quicker than for molds made from steel. Very simple and highly complex parts can be manufactured from original material. Aluminum molds (Figure 1.291) are preferably used for part series from 1.000 to 10.000, for tensile- and falling tests or other material tests when original parts are needed. 

Silicone mold Polyamide Molding process through a master model Functional model Prototype Small series part Polyamide Nylon 100 X 900 30-50 2-5 3-4... 

Synthetic resin molds Injection molding Milling and casting process Functional model Prototype Small series part Thermoplastic Thermoset Elastomer 50-300 10-20 2-4... 

Compositional mold through stereolithography Rapid Prototyping Prototype Small series part Thermoplastic Thermoset Elastomer 500 X 500 20-100 5-10 3-5... 

Mold through LaserCUSING Laser melting technology Small series part Thermoplastic Thermoset Elastomer 350 X 350 100-1,000 5-10 2-3... 

Aluminum molds Milling process Small series part Thermoplastic Thermoset Elastomer 1,000-3,000 10-20 1-2... 

For the production of small series, special interchangeable standard molds (Figure 2.34) are offered. These are standard molds with a fixed mold frame and Interchangeable mold inserts including the ejectors. 

Often, only small series are produced, so the standard mold is often left on the injection molding machine while the mold inserts are exchanged for other small series. In these cases, the cavity pressure and cavity temperature sensors have to be automatically decoupled with the mold insert otherwise, the entire mold must be disassembled to replace the sensors. 

RP technologies find application in manufacturing of custom-made parts - including prototypes - and small series parts. Additive manufacturing is not only by far more flexible than conventional molding or casting processes, but may also... 

A series of glycol bis(aUyl phthalates) and bis(aUyl succinates) and their properties are reported in reference 88. In homopolymerizations, cyclization increases in the order diaUyl aliphatic carboxylates < glycol bis(allyl succinates) < glycol bis(allyl phthalates). Copolymerizations with small amounts of DAP can give thermo set moldings of improved impact (89). 

M. Amon and C. D. Denson [33-34] attempted a theoretical and experimental examination of molding a thin plate from foamed thermoplastic. In the first part of the series [33] the authors examined bubble growth, and in the second [34] — used the obtained data to describe how the thin plate could be molded with reference to the complex situation characterized in our third note. Here, we are primarily interested in the model of bubble growth per se, and, of course, the appropriate simplification proposals [33]. Besides the conditions usual for such situations ideal gets, adherence to Henry s law, negligible mass of gas as compared to mass of liquid, absence of inertia, small Reynolds numbers, incompressibility of liquid, the authors postulated [33] several things that require discussion ... 

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