Deciding the Parting Line/Parting Surface

The parting line or parting surface is location where the component is imagined in two parts 10 correspond to cope and drag. The two patterns are produced depending upon this decision regarding parting line.

A typical box shaped component (100 x 200 x 300) can have three fundamental orientations and can have three optional ways to form the parting like. Each option divides the component into two equal parts. Accordingly, it may appear that these options do not differ in terms of the advantages or limitations. In fact, it is not so. One out of the available choices shall be the best one to have maximum advantages and least limitations. In fact, the selection of the parting line is as per some guide lines or thumb rules which minimize the limitations and maximize the advantages.

1. If any object is defined by three mutual perpendicular dimensions; say X, Y and Z; then the least out the these three is laid vertically and divided into the cope and drag pan. This guideline minimizes the cope and drag heights and minimizes the mould/core release problems. It further maximizes the strength of the mould at its vertical surfaces and minimize defects like sand wash, sand inclusion, mould swelling, etc. Accordingly, the 1 option at the previous sketch seems to be the best option for parting line selection. It shall result into cope or drag height of 50 mm each which is better than 150 mm or 100 mm at the 2nd or 3rd option respectively.

    2. The cope and drag heights are preferred to be equal. However. if the component along its height is odd, then the parting line is preferred at the broadest zone of the component.

As per this thumb rule, the paring line ‘2’ is preferred than the other option ‘1’ fact the selection of parting line 1 will make the cope pattern and mould appear as shown. Such mould is impossible to be released from the pattern at the zone. The release shall result into breakage of the mould at zone ‘P’.

3. If the cope height and drag height are appreciably different than each other, then the smaller height is preferred to be the drag height. It results into falling of the initial liquid metal in the mould cavity through a smaller height and further leads to least damage at the mould surface.

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