For producing metal clad parts, we start with the stereolithography (SLA) process that uses epoxy photopolymer resins, or Plastic Laser Sintering (SLS) that uses nylon based powders, to turn a CAD design into a corresponding physical model by way of additive manufacturing. In addition to being relatively quick to produce, these additively manufactured parts have more complex geometries and thinner walls than subtractive methods such as machining. It has the same advantages over die casting because engineers are not limited by the need design parts to tooling principles.
Of course, the part that results from SL is still plastic. And even though todays SLA resin offerings provide outstanding stiffness and high temperature resistance over other resins, it still doesn't match up to the durability or EMI shielding of a metal part, limiting its usefulness as a prototype for heavy-duty testing or as a production part.
Adding the copper/nickel cladding solves this issue. Once the shape is created, all surfaces are prepped for adhesion with a special wash that places ions onto the plastic. A thin layer of copper is applied by dipping the plastic model in a bath.
Once dry, the nickel layer is applied to the specified thickness. (The copper layer is used to give the nickel something to bond with electrically, since it does not adhere well to plastic.) Again, copper/nickel cladding is a common technology that has been proven in real-world applications for several years.
Neither of these processes is new per se. Both have been used individually in the industry for years. What's new is that the metal cladding of SLA and SLS patterns has evolved to make metal plating work better with SL, creating not just a coating but a true composite. This composite greatly increases the durability of these parts, making them far more useful for both testing and real-world applications.
And while the metal cladding may not prove as durable as a pure metal part over a huge number of cycles, it is more than sufficient for most test labs and even low volume production runs. But durability isn't the only advantage the Metal cladding process offers. Other benefits include:
- Ability to specify thinner walls than with processes such as investment casting - While investment casting offers some of the same benefits, including high durability and fast turnaround with less cost, the tradeoff is that walls cannot go below a certain thickness typically 0.060". Metal Clad Components parts can have much thinner walls (0.010"), opening the design possibilities further.
- Ability to customize expensive parts for greater functionality or branding - Rather than being limited by what can be done with metal bending or even die casting, engineers can design to what they need, e.g. giving a distinctive shape to a housing that allows it to fit into a certain space. Engineers can also create specialty parts inside, such as holders to help route wires internally, that improve the design without adding to the cost.
- Ability to test for ergonomics of metallic hand held products - If you need to cost-effectively simulate exactly what a metallic end-use part will feel like in the user's hand, Metal Clad Components will help you do it. By creating several models with different dimensions simultaneously, you can test a hand-held medical or other device for fit, feel, approximate weight, and ease of use.
- Ability to create prototypes with improved physical properties - Typical plastic parts have very limited physical properties, which can have an effect on both the tests you can run and the results you can achieve. The metal cladding process adds properties such as EMI shielding, fire retardance, solvent resistance, and thermal conductivity that allow engineers to test prototypes more thoroughly as well as specify low volume production run parts that can be used in harsher environments.