Method of injection moulding ties for e.g. cables

摘要

Balanced injection molding in a multi-cavity mold of a plurality of ties (48. 50) (figures 3A,4A - not shown) hating a uniform maximum thickness (T) between opposite broad sides of the tongue (18) of the tie is accomplished by providing mold pieces (40, 42) in which the relative dimensions (A, B) of projections (52, 54) for forming ratchet teeth (16, 22) on the tongue of the ties in different mold cavities (44, 46) are non-uniform such that when plastic material is injected into the mold cavities, the injected plastic material flows through the different mold cavities at respective flow rates that cause the mold cavities to be completely filled approximately simultaneously with the injected plastic material. In making the mold pieces, the dimensions of the projections initially are larger than required for forming ratchet teeth of a preferred dimension. After measuring the extent to which the different cavities are filled, the relative dimensions of the projections are adjusted such that the projections for at least one of the mold cavities are of a dimension (Ap, Bp) (figure 1 - not shown) required for forming ratchet teeth of the preferred dimension and/or such that the projections for at least one the mold cavities are of a dimension (A L , B L ) larger than required for forming ratchet teeth of the preferred dimension and the projections for at least another of the mold cavities are of a dimension (A S , B S ) smaller than required for forming ratchet teeth of the preferred dimension.