Sintered mold inserts

The uneven heat baiance in the moid is often a reason for distorted parts. Using thermal imaging cameras, which are now affordable, hot spots in the mold, can be seen and valuable support for the optimization, not only for the warpage, is provided. The intensification of the temperature control, by pulsed cooling or sintered mold inserts, for example, often leads to significant cycle time reductions. 

Methods are used to produce the more costly rapid prototypes include those that produce models within a few hours. They include photopolymerization, laser tooling, and their modifications. The laser sintering process uses powdered TP rather than chemically reactive liquid photopolymer used in stereolithography. Models are usually made from certain types of plastics. Also used in the different processes are metals (steel, hard alloys, copper-based alloys, and powdered metals). With powder metal molds, they can be used as inserts in a mold ready to produce prototype products. These systems enable having precise control over the process and constructing products with complex geometries. 

Venting can also be provided within the mold cavity by means of inserts equiped with vent slots, porous sintered plugs, or by holes with a diameter not greater than 0.2 mm. Such holes are machined only to a shallow depth and are relieved by a much larger bore machined from the back of the mold. 

The CO, temperature control can be used in conventional steel molds as well as with inserts made from porous sintered material, which mainly consists of steel (TOOLVAC ). When using sintered steel, the liquid CO, flows through the capillary tubes into the expansion chamber. In the gaseous state, the CO, penetrates into the porous materiai and flows, due to the gas pressure, and is uniformly distributed over the core up to the cavity surface. There, heat can be directly withdrawn from the moided part. 

Two examples for prototype tooling by direct application of generative methods are the AIM-application, Figure 4.141, which can be directly inserted into a mold frame and used on the injection molding machine and the sintered negative of a boot profile (Figure 4.142). 

Injection-Molding Tool Inserts by Laser Sintering or Laser Beam Melting... 

The alternative is to use the laser-sintering process to manufacture form inserts from steel (Section 7.2.6). LDS parts injection-molded with these form inserts can be readied for the LDS process without wet-chemical dipping. On account of the process-related surface roughness of form inserts manufactured by DMLS, there is a slight tendency toward more overmetallization, but this is not generally considered a critical issue. 

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