Metal mold insert

Once the PMMA deep structures are made by X-ray lithography, the electroplating of metal and replication from the metal mold insert are all standard processes. The most commonly used metal for electroplating is nickel, because electroplating of nickel is a mature technique... 

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. 

Other recent modifications include lost-core injection molding and gas-assisted injection. The former involves inserting in the mold a low melting metal alloy insert over which the polymer is injected. After solidification and ejection of the part, the insert, which has a melting point lower than that of the polymer, is melted away to yield a hollow part. Gas injection also makes it possible to manufacture hollow parts. After injection of a small volume of polymer, but before its solidification, gas is injected in the mold through a different gate. The gas pushes the molten material... 

Uses Coupling agent esp. for polyolefins and polyolefin elastomers, min.-and glass-filled formulations, sealants (acrylic, SBR), rubbers (butyl, neoprene, isoprene, fluorocarbon), as primer coal for metals in insert molding... 

Hardening is not necessary, and chrome plating is not customary. For large-volume parts with a content of 4 cu yd (3 cu m) and up, welded machined steel plate construction can be considered. Cast metal is of no value for the mold bases. Given the right care, the life of steel molds is the longest, at over 10 parts per mold. Inserts subject to wear and tear have to be either refurbished or exchanged at intervals of 10 or 10 cycles (Table 4-10). 

Zhang N, Chu JS, Byrne CJ, Browne DJ, Gilchrist MD (2012) Replication of micro/nano-scale features by micro injection molding with a bulk metallic glass mold insert J Micromech Microeng 22 065019... 

Post-molded inserts come in four types press-in, expansion, self-tapping, and thread forming, and inserts that are installed by some method of heating (e.g., ultrasonic). Metal... 

Fourth, molded-in metal parts should be avoided whenever alternate methods will accomplish the desired objectives. If it is essential to incorporate such inserts, they should be shaped so that they will present no sharp inside comers to the plastic. The effect of the sharp edges of a metal insert would be the same as explained in the first point above, namely, brittleness and stress concentration. The cross-section that surrounds a metal insert should be heavy enough that it will not crack upon cooling. A method of minimizing cracking around the insert is to heat the metal insert prior to mold insertion to a temperature of 250 to SOOT so that it will tend to thermoform the plastic into its finished shape. The thickness of the plastic enclosure will vary from material to material. A reasonable guide is to have the thickness 1.75 to 2 times the size of the insert diameter. 

If metal inserts are to be molded into a plastic product, their shape would present no sharp edges to the plastic, since the effect of the edges would be similar to that of a notch. A knurled insert should have the sharp point smoothed, again to avoid the notch effect. The practice of molding inserts in place is usually employed to provide good holding power for plastic products, but there are drawbacks to this method it is dangerous to have an operator place an arm between the mold halves while the electrical power to the machine is turned on. It normally takes a pin to support the insert, and since this pin... 

In this technique, the micro structure is either directly or through masks incorporated into a suitable material, which is usually located on a carrier plate using UV lithography, lithography with synchronic radiation, or X-ray lithography. The machined interspaces are then filled with metal by an electroplating process. The actual mold inserts are then manufactured from these metal parts. 

The different thermal conductivity of metals can be used for temperature control of injection molds. In this way, heat can be removed from critical or difHcult to access areas. Mostly, copper elements (beryllium copper) are used and are integrated as a segment into the mold insert. 

If the manufacturing practices show that the walls of the part are uneven, a remedy can be found through the installation of auxiliary panels made from sheet metal, through painting with aluminum colors, or through wall thickness modifications of rotational mold. Inserts made from plastic material or steel can be fixed into the walls of the molded parts, but must be preheated to initial temperature of the mold. It is important that the pins, which are necessary for the acceptance, are properly installed so that no plastic can leak at these points during the rotation. 

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