Jewelry Industry

An unexpected use of 3D printing is in the apparel industry. 3D-printed jewelry has become a popular niche for those looking for a unique look. With the advent of 3D printers, jewelers can experiment with designs and not limited to using conventional jewelry-making methods. In addition, 3D printers make it cheaper to manufacture individual, unique pieces of jewelry or customize pieces for customers. Jewelry manufacturing is one industry that embraces 3D printing. Most jewelers now use technology to challenge the way things have been done for decades. Usually 3D printing is used to make jewelry using two methods: investment casting and direct printing.

Investment Casting

The investment casting process is one of the most common methods of producing jewelry via 3D printing. Parts are created by investment casting through an eight- step process:

  • 1. Pattern formation: This was traditionally done by pouring a special cast of wax into a metal mold. The 3D printing also allows direct printing of the pattern from wax or castable resin (Figure 7.3).
  • 2. Mold assembly: The molded or printed pattern is then assembled on a “casting tree.” This allows multiple parts to be cast at the same time. Some 3D-printing methods disrupt this step by printing part patterns and a tree in one step (Figure 7.4).
  • 3. Shell building: Upon completion of the pattern assembly, the entire assembly is immersed in slurry several times. The slurry coating is then left to dry and solidify, forming an outer ceramic layer over the pattern (Figure 7.5).
  • 4. Burnout: The structure is then put inside the furnace and the original wax/ resin structure is melted/burned resulting in a hollow negative mold (cavity) (Figure 7.6).
  • 5. Pouring: When all the original pattern material has been removed from the negative ceramic, the final casting material is poured into molds and left to cool and solidify. Parts are often cast in brass and electroplated in precious metals during the finishing stage (Figure 7.7).
Pattern formation process

FIGURE 7.3 Pattern formation process.

Mold assembly process

FIGURE 7.4 Mold assembly process.

Shell building process

FIGURE 7.5 Shell building process.

Burnout process

FIGURE 7.6 Burnout process.

Pouring process

FIGURE 7.7 Pouring process.

  • 6. Knock off: The outer ceramic mold must be removed. This is usually done by vibrating the mold to knock off the outer shell (Figure 7.8).
  • 7. Cut off: Once the ceramic shell has been fully removed, the individual cast objects are cut off from the mold tree (Figure 7.9).
  • 8. Finishing: The cast parts then go through traditional jeweler finishing techniques (Figure 7.Ю).

There are many criteria for 3D-printing technology for the efficient development of jewelry molds for investment casting. These are:

  • • Engineering must be capable of manufacturing products with a very high degree of detail and minute, intricate features.
  • • At the burnout/melt stage, the material used to print the pattern must be completely removed. The remains of the original pattern material have a negative effect on the consistency of the final cast product. Due to this, strict burnout procedures are in place for most 3D-printed castable resins (Figure 7.11).

Direct Printing

A much less common method of manufacturing jewelry by 3D printing is the direct printing of parts made of metal powder. Parts may be printed by means of gold,

Knock off process

FIGURE 7.8 Knock off process.

Cut off process

FIGURE 7.9 Cut off process.

Finishing process

FIGURE 7.10 Finishing process.

silver, or platinum alloys and then require a large amount of post-processed finishing. Direct jewelry printing is generally more expensive than investment casting, even for single pieces, and requires a very high level of precious powder management. DMLS/SLM, direct metal laser sintering (DMLS), or selective laser melting

A cast jewelry tree before removal of the parts from the tree

FIGURE 7.11 A cast jewelry tree before removal of the parts from the tree.

Jewelry produced via metal 3D printing still attached to the build plate and showing support material

FIGURE 7.12 Jewelry produced via metal 3D printing still attached to the build plate and showing support material.

(SLM) are powder bed melting techniques used in the production of metal parts. For the accurate production of DMLS/SLM pieces, a large amount of support must be provided during printing. High temperatures result in high levels of stress, meaning that parts are often susceptible to warping or deformation. This leads to the need for significant post-processing to remove the support and finish the surface where it was attached (Figure 7.12).

 
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