Spritzgußwerkzeug (22) zum Spritzen von Kunststoffbauteilen oder Spritzlingen (24), wobei am Fließwegende (2) der in einen Formhohlraum (19) des Spritzgußwerkzeugs (1) eingebrachten Kunststoffmasse zum Entlüften von Verdrängungsgasen eine Entlüftungseinrichtung (26) vorgesehen ist, wobei die Entlüftungseinrichtung (26) als ein mit mehreren Mikrobohrungen (10) perforierter Abschnitt im Wandbereich des Spritzgußwerkzeugs (22) ausgebildet ist,

dadurch gekennzeichnet,

daß die Mikrobohrungen (10) an der dem Spritzling (24) zugewandten Innenseite (11) der Entlüftungseinrichtung (26) einen Durchmesser von kleiner oder gleich 0,06 mm vorzugsweise 0,04 mm aufweisen und daß die Mikrobohrungen (10) einen konischen, sich zu der dem Spritzling (24) zugewandten Innenseite (11) der Entlüftungseinrichtung (26) hin verjüngenden Querschnitt aufweisen.:

An injection moulding tool (22) for injection moulded plastic components, or injection mouldings (24), wherein a venting construction (26) is provided at the end of the flow path (2) of the plastic mass that is introduced into a forming cavity (19) of the injection moulding tool (1) to vent the displacement gases, wherein the venting construction (26) is created in the wall area of the injection moulding tool (22) in the form of a section perforated with multiple microholes (10),

characterised in that

the microholes (10) on the inner side (11) of the venting construction (26) facing the injection moulding (24) have a diameter of less than or equal to 0.06 mm, preferably 0.04 mm, and that the microholes (10) have a conical cross section that tapers towards the inner side of the venting construction that is facing the injection moulding (24). The injection moulding tool (22) as recited in claim 1,
http://www.patent-de.com/20070705/EP1590156.html

Studied venting methods for moulds and learned that such little gaps would be appropriate for these tools, provided that enough gaps exists at the right places (tool split into different parts), but found no translation for “Entlüftungsschliff” and propose therefore a work-around.

Entlüftungsschliff = Entlüftungsschlitz with ground surface (levelling depth 4 - 6 μm) = ground ventilation gap.

In multi-cavity molds or in molds with multiple gating, venting should already start in the runners. This prevents extensive degradation of the material by burning and the gate system can be ground and reused without major loss of quality.
:
There is finally the question left about the size of the venting gap. To avoid flashing a certain gap width, which is plastic-specific, cannot be exceeded after mold clamping.
http://books.google.de/books?id=yTFTlm2PP40C&pg=PA263&lpg=PA...

When molding GE resins it is extremely important for the cavity to be vented effectively to allow air displaced by the melt to escape. Proper venting helps prevent “dieseling” (or super-heating of trapped air) and resulting burn marks at the end of the resin flow. This becomes even more critical in thin-wall parts and when using high injection speeds.
:
The suggested land length is 0.09 inch (2.29mm). The vent relief to the atmosphere should be same width as the vents, with a suggested depth of 0.015 to 0.030 inch(0.38 to 0.76 mm) (Figure 1-20). Vent depths may vary from .0005 to .00075 for various crystalline resins to .003 for glass reinforced amorphous resins.
http://gaetanmabille.free.fr/process/Engineering Thermoplast...

[0007] In a preferred embodiment, the multiple plates have the same inside diameter and the same outside diameter placed strategically across the tread arc of the mold. The plates have a special surface grind on one or both sides to form the gaps or vents.
http://www.patentstorm.us/applications/20070009623/descripti...