When a mold is made in parts from the original object, the going gets complex and can involve some troubles for the mold maker. Following is an attempt to clarify the common problems with solutions.
Mold making is a complex art of creating a negative image of an object. This mold is then used to cast a three-dimensional replica of the original object and results in a carbon copy of the same!
There are different techniques of making molds; even the materials used to make the molds can vary – from simple clay and wax to resins and rubbers. In addition to this, the mold cannot be made in one go at all times. Depending on the shape, undercuts and other detailing of the object, it may require the mold to be made in two or more parts.
Needless to say, multi-part molds are more complicated and time-consuming. The method is not only longer, but can get quite intricate too. Given the elaborate process, mold makers often face different issues in the making of multi-part molds.
There are different techniques of making molds; even the materials used to make the molds can vary – from simple clay and wax to resins and rubbers. In addition to this, the mold cannot be made in one go at all times. Depending on the shape, undercuts and other detailing of the object, it may require the mold to be made in two or more parts.
Needless to say, multi-part molds are more complicated and time-consuming. The method is not only longer, but can get quite intricate too. Given the elaborate process, mold makers often face different issues in the making of multi-part molds.
Let us take a look at the common issues and how to deal with them:
Air Bubbles – When air bubbles form in the mold, they will lead to voids in the final casting. These are more common in two-part molds. Therefore, the mold maker should be careful when mixing the mold making materials and pouring the mix into the mold. Some of them – like resins and rubbers – will require degassing in a pressure pot and vacuum chamber respectively.
Flashing – This refers to the excess material seeping out of the mold and forming a layer around the part. This can be due to problems with the parting line and the mold makers are always advised to design it properly. Errors in the parting line can also cause issues during the demolding process. Do not apply excessive force in the clamping either, as this can also make the mold making material seep outside.
Warping – One of the common reasons for two-part molds to get distorted is lack of proper alignment. It is crucial to align the parts of the mold properly before beginning the casting process. Only when the parts fit together properly, will it lead to a perfect casting.
Voids – It is not just air bubbles that can cause voids in the casting. This can also be due to the simple fact that the material was insufficient to fill the entire mold. Therefore, it is important to ensure that the mold is completely filled and the material seeps into all the undercuts and niches of the mold.
Apart from these, there are other mold defects like chipping, cracks, finger tracks, flow marks and so on. These can usually be corrected in two part molds by way of sanding and smoothening the surface. Other issues like depressions or gouges may require using additional material to fill them before sanding the cured mold.
In sum, as the object is complex, the mold making and casting will require extra attention and caution for sure!
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