Jewelry
The production of jewelry is one industry that has embraced 3D Printing. Many jewelers now use the technology to disrupt the way things were done for hundreds of years. 3D printing is now used to create the patterns for investment casting and to print jewelry directly.
Advantages
- Very complex designs can be created. Historically, jewelry casting patterns were carved from wax using CNC machines. 3D printing is not restricted by the limitations of CNC machining and is able to produce parts that have in the past were impossible to make. Designs can also easily be customized.
- With 3D printing, multiple patterns can be made at once and within a very short time frame. This has significantly reduced lead times as well as cost when compared to traditional pattern making techniques (wax CNC, aluminum molds for casting etc).
- 3D printing also allows multiple designs to be produced in a single print. This means it is very cost competitive pricing for low production volumes.
3D Printing techniques:
3D printing is typically used to create jewelry via 2 methods; investment casting and direct printing
Investment casting
One of the most popular methods of producing jewelry via 3D printing is the investment casting process. Investment casting produces parts through an 8 step process:
Pattern formation
Traditionally this was done by pouring a special casting wax into a metal mold. 3D printing now allows the pattern to directly be printed from wax or a castable resin.
Mold assembly
The molded or printed pattern is then assembled onto a “casting tree”. This allows multiple parts to be cast at once. Some 3D printing methods disrupt this step by printing the part patterns and the tree in a single step.
Shell building
After completion of the pattern assembly, the entire assembly is submerged multiple times in slurry. The slurry coating is then left to dry and solidify forming a ceramic outer layer over the pattern.
Burnout
The structure is then placed inside a furnace and the original wax/resin structure is melted/burnout resulting in a hollow negative mold (cavity).
Pouring
Once all the original pattern material has been removed from the ceramic negative the final casting material is poured into the mold and left to cool and solidify. Parts are often cast in brass and then electroplated in precious metals during the finishing stage.
Knock off
The outer ceramic mold must then be removed. This is typically done by vibrating the mold to knock off the outer shell.
Cut off
After the ceramic shell is completely removed the individual cast items are cut off the mold tree.
Finishing
The cast parts then go through traditional jeweler finishing techniques.
There are several requirements for a 3D printing technology to successfully produce jewelry molds for investment casting. These are:
- The technology must be capable of producing parts with a very high level of detail and minute, intricate features.
- The material used to print the pattern must be able to be completely eliminated at the burnout/melt stage. Leftover remnants of the original pattern material have a detrimental effect on the quality of the final cast part. Because of this there are strict burnout procedures for most 3D printed castable resins.
