Track down and correct defects in your cast jewelry with the help of our casting troubleshooting series. Also, learn how to prevent common errors.
14K Pink Casting Grain – made with recycled gold
The casting investment process enjoys wide popularity in the production of commercial and one-of-a-kind art metal objects. However, production practice varies widely. At one extreme, design renderings are turned over to a production shop; at the other, the complete production…
Much of the recent literature on defects that occur in jewellery manufacture is focused on those occurring in lost wax investment casting. However, defects can also occur during casting of ingot and its fabrication into sheet, tube, wire and rod as well as their onward fabrication into jewellery components by processes such as stamping and forging. These defects, along with their causes and prevention, are briefly reviewed in this article, although those defects occurring in the die-striking of findings are described elsewhere in this issue.
As many jewelry manufacturers and goldsmiths know from hard experience, cracking in jewelry can occur at any time during its manufacture. It can also occur much later, after the jewelry has been sold to the consumer or during repair. Cracking can also occur in the processing of the starting materials (the casting grain and mill products from which the jewelry is to be made), and may not be detected until several stages later in the manufacturing process.This article discusses these causes as they relate to cracking and the steps that can be taken to minimize their occurrence. The particular focus is on karat golds, but much is also applicable to silver and platinum jewelry.
A good practice for preventing investment blowout is to measure the height of the trees before investing. The maximum tree height should be between 0.5 inch and (for larger trees with more metal) 0.75 inch shorter than the fill level of the flask. It’s also important to leave a 0.125 inch gap between the top of the investment and the top of the flask if you are using benchtop vacuum casting with a solid flask.
Platinum casting defects are often very difficult to characterize due to the intrinsic complexity of the investment casting process. All defects will fall into one or more of the established seven categories of casting defects. The proper identification of a particular defect is the prerequisite to correcting and controlling the quality of platinum castings. It is contended that a system of defect identification should be based solely upon morphological criteria with no prior assumptions relating to the cause of the defect. The nature of a casting defect can only be determined by correctly categorizing the shape, appearance, location and dimensions of the defect. The importance of a controlled and comprehensive defect analysis program is advanced. Once appropriately classified, the possible causes can be examined and the corrective action can be taken..
Manufacturer spend much time and money diagnosing defects that are believed to originate in the casting process, but actually occur during waxing. Many companies run in circles, changing this gate/sprue, that metal, these temperatures, and screaming at suppliers to try to fix the ‘mystery’ problem. While these areas certainly can be the source of problems, many defects are misdiagnosed as casting defects, and thousands, perhaps millions, of dollars are wasted in search of non-existent flaws in the casting process.
It’s no wonder that as precious metals prices have risen to new heights over the past few years, jewelry castings have gotten thinner and lighter to maintain reasonable price points. It’s not uncommon today for impossibly thin or delicate and…
R&R Plasticast investment provides casters using plastic and wax/ plastic pattern materials with a mold material that meets the high expansion demands of the pattern material while maintaining mold surface and dimensional integrity.
Ultra-Vest Investment offers casters smooth mixing controlled setting clean breakout and excellent surface finish. Ultra-Vest eliminates the watermarking defects seen with many other investments. Ultra-Vest offers superior performance and unmatched consistency. For low temperature mold materials. Rapid prototype cooling.
A design riddled with undercuts and sharp little details just screams casting nightmare the moment the CAD file shows up. But sometimes even the most straightforward looking designs can cause real headaches for the caster. Take for example this three-stone palladium ring design that recently arrived at Jewel-Craft in Erlanger, Kentucky, for casting. It’s a bit unusual, particularly the center setting, which features eight prongs and a raised lip of metal where the stone sits. However, nothing about the design caused alarm.
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