Jtp Mould is known as one of the best China plastic mou […]
Jtp Mould is known as one of the best China plastic mould manufacturers and exporters for household items, such as chair mould, crate mould, bucket mould, stool mould and so on. We have advanced plastic molding process, and our plastic moulds are mainly exported to North America, South America, Europe, Australia and middle east countries.
The plastic stool mould design requires a rounded edge at the end of the side wall, so the parting line must be shifted to where the radius meets the outside wall created by the cavity. There is usually no particular reasoning against this design, except that it is somewhat more expensive to produce. For very light products, especially when stripper ejection is used, the radius that is cut into the stripper might cause the product to hang up and not fall free from the mold. Special mold features such as air blow off or mold wipers may then be required to ensure that all pieces have ejected. There is usually no problem with heavier molded pieces weighing maybe 20 grams or more.
The main problem with a rounded edge at the end of the wall is that mismatch is possible between the cavity and core which can result in a small but sharp comer (ridge) . An example is the rim of a drinking cup, where a ridge could be disagreeable on the lips when drinking from such a cup.
There are several methods for avoiding or hiding the mismatch on stool mould:
1. Reduce the significant tolerances of cores and cavities, and on the dimensions affecting the alignment (elements) of the plastic stool mould. This can be very expensive but can (and should) be done with high quality mass production moulds to ensure that all products are as close as possible to the ideal shape and that the mold components are interchangeable.
2. Correct the plastic stool mould after it is completed and tested: the mismatching areas are blended by hand, by grinding the offending ridges. This is frequently done but not recommended because, in multicavity moulds or where a number of identical moulds are used for the same product, each product, from each cavity, may be different .
3. Decide on which side a ridge would have the least disagreeable effect on the end user or on the performance of the product, and then dimension one side different from the other so that, in the worst possible case (all tolerances in the “bad direction), the piece still will be acceptable for its intended use. In this ease ，the half-round recess in the stripper is intentionally slightly smaller than the thickness of the rim. With all tolerances in the “ideal” direction, there will be a minimal ridge. With all tolerances adding in the bad direction, the step of the ridge will be the sum of the tolerances but still is acceptable. In the case of a round container, the dimensions affected are the diameters of the rim in the cavity, the core, and/or the stripper ring.
Similar methods are used to avoid any parting line mismatch, regardless of the plastic stool of the parting line: round, oval, rectangular, irregular, or offset. The more difficult challenge is to foresee where mismatch can occur，and to determine how to dimension the product.
If you have any problems for stool mould or other plastic moulds, welcome to contact JTP Mould company.