This news article was originally written in Spanish. It has been automatically translated for your convenience. Reasonable efforts have been made to provide an accurate translation, however, no automated translation is perfect nor is it intended to replace a human translator. The original article in Spanish can be viewed at Los bronces de aluminio y las aleaciones de cobre de alta conductividad térmica en los moldes de inyección de plástico

They allow the workshops to offer molds of higher productivity and lower costs with a better quality

Aluminium bronzes and copper alloys of high thermal conductivity in plastic injection molds

Ampco Metal07/05/2008

So far, the manufacturers of molds have been reluctant to use alloys of copper's high conductivity for the moulds, because the cost of these alloys is supposed to be superior to conventional tool steels. An alloy of copper's high conductivity, in the context of this article, is a material with a copper base which, through a combination of alloy and manufacturing techniques, maintains high thermal conductivity of copper, but with a degree of hardness that allows to be used at the stage of machining in a production environment.

Let's first of all the benefits of a high conductivity copper alloy.

You are there are several reasons that may decide to use copper alloys in the plastic injection moulds:

The cycle time can be reduced by up to 20 percent (some clients have indicated up to 80 percent of reduction), which means getting a cooling rate faster, thanks to the high conductivity of copper alloys.
Productivity It may increase in at least 25 per cent, and some users in the industry of production of headlamps of cars have indicated up to a 500 percent increase, simply because the reduction of the cycle time means that more components can be produced per turn.
You can reduce much the deformation of the pieces, because with improved cooling, molded components remain at high temperatures for less time, thereby decreasing the number and severity of the "hot spots" in the mold and part quality improves significantly.
Less deformed pieces means a more consistent quality, injection after injection.
Thanks to the best thermal transfer of copper alloys of high conductivity (usually 10 times more than the steel), heat you can remove sensitive parts of the mold at a speed that allows to reduce, or eliminate altogether, the need for complex cooling channels in the immediate vicinity of the molded component.
As the number of required cooling channels in the tool is less, the cost of the molds machining can be reduced dramatically: up to four times less than the cost of a cast steel with a speed of comparable cooling.

Applications

Here are a few applications which choose high conductivity copper alloys is a good choice:

Moulds for injection of plastic, souls and cavities, nuclei of needle and cooling plates
Matrices for the extrusion of forms and complex of plastic profiles. In this case the use of high-conductivity copper alloys represents an improvement in productivity thanks to its thermal transfer and dimensional stability.
Moulds for the production of bottle-blowing. The inserts of high conductivity copper alloys in the mold, especially at the base of the bottle and in the neck, will result a very good productivity and a high quality of the component.
Grout injection. When high conductivity copper alloys are used, it is possible to maintain a constant temperature which will make it possible to simplify the system of overall control, thanks to the reduced time of heat transfer and reduction of energy costs.

Examples of specific products

Production of plastic buckets: manufacturers of plastic buckets used molds containing high conductivity copper alloys and, depending on the desired level of results, some used alloys of copper beryllium for las Animas and the cavities. However, when the beryllium-containing alloys can not be employed, the chosen material is a beryllium-free alternative alloy.
Production of plastic: plastic bottles of mineral water plugs are produced with considerable success using bores and pockets of high conductivity copper alloys. An alloy CuCoBe to 0.5 per cent, depending on the polymer that is shaping, with a coating of electroless nickel is sometimes employed. Again, the reluctance to use alloys of beryllium has led to develop alternatives without beryllium's high efficiency.
Production related to the automotive industry: the automotive industry has introduced the aluminium bronze inserts in its steel production of bumper molds, and some employ souls of high conductivity copper alloys to produce their bumpers. The dashboards of automobiles are also produced with molds that contain inserts of aluminium bronze, which increases the conductivity of heat compared to steel in three.

Conclusion

To enable manufacturers of molds today to compete with areas of low-cost in the world where there is a low cost of manufacture, it is important to consider the use of copper alloys of high conductivity in the manufacture of plastic injection moulds. High conductivity copper alloys will allow workshops offer molds of higher productivity and lower costs with a better quality.

Is can greatly reduce the deformation of the pieces, because with an improved cooling, molded components remain at high temperatures for less time, thereby decreasing the number and severity of the "hotspots in the mould" and the quality of the part improves significantly

The specific advantages of high conductivity copper alloys include:

Thermal diffusion

High conductivity copper alloys absorb the wave of heat in a cast as inject the plastic part. The initial absorption of the heat wave is a crucial factor. The Elimination of the heat from the bottom of the mold with cooling system leaves enough time to do so. It is here where high conductivity copper alloys show their worth, absorbing the initial heat wave, injection after injection.

Polishing

Excellent ability of polished high conductivity copper alloys has been demonstrated in the manufacturing of packaging for contact lenses, which requires a transparent package so that the quality of the lens can see through the packaging. Such packaging quality is achieved with inserts of finely pulimentados high conductivity copper alloys. It has been shown that the time of polished these inserts is four times smaller than the of the inserts of steel, and the cycle time is reduced by 57 per cent.

Coatings

To increase the wear resistance, high conductivity copper alloys are may be easily with electroless nickel, chromium hard or even with PVD (physical vapour deposition) and CVD (chemical vapor deposition) coatings

The electroless nickel makes the lining to penetrate in each and every one of the holes with a constant thickness, which does not occur in a galvanic process, such as the laminate with hard chrome. You can get a hardness of 60 to 70 HRC.

So that the plastic piece retires with greater ease of the mold, the electroless nickel can be combined with Teflon (PTFE) or boron nitrate. These parts of mold, thus covered, have a surface that, to the touch, seems covered in SOAP, so molded parts do not stick to the mold and it can be removed easily.