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Electroforming

Electroformed Optics

Additive Manufacturing Using Electroforming

Based on the principles of electrochemistry, electroforming is essentially a specialized form of electroplating that allows a high degree of control, precision, and reliability. The process of electroforming entails preparation of a suitable mandrel and placing it in an electroplating bath. Nickel or other metals are deposited on the mandrel by electrochemical deposition. The outer surface of the mandrel forms the inner surface of the form. The surface of the finished part is rendered in fine detail with respect to the original.

Benefits of Electroforming over other manufacturing techniques:

  • Low Cost Per Part - Exact Replicas
  • Precise reproduction of surface detail
    • Optical Accuracy of ±2 Arc Minutes Slope
  • Production of complex shaped components
  • Production of thin-walled components
    • Thickness Ranging 0.001 inch to 0.25 inch
  • Extensive range of manufactured sizes
    • Capable of electroforming components as large as 36 inches in diameter
  • 66 Electroforming cells to help meet customers demands
  • ISO 9001 certified

How Electroforming Works

Electroforming (EF) is a highly versatile manufacturing process and is very effective when requirements call for extreme tolerances, complexity, surface finish, or lightweight. This process allows high-precision duplication of a mandrel and therefore permits quality production—at low unit costs with high repeatability and excellent process control. In many cases, traditional manufacturing methods (such as machining, forging, stamping, deep drawing, and casting) cannot produce components with the complexity and accuracy that electroforming affords.

A wide variety of shapes and sizes can be made by electroforming, the principal limitation being the need to separate the product from the mandrel. Since the fabrication of a product requires only a single master or mandrel, low production quantities can be made economically.

In special cases, the mandrel may be a sacrificial part due to highly complex or non-drafted geometry. For this class of components, the mandrel is dissolved away after the component is fully formed. While this method raises the unit cost of the component, it removes the primary limitation of separating the part from the tool. The scope of component design possibilities is vast.

Based on our years of experience pioneering this technology, here are some guidelines meant to streamline the design process for components that may utilize the electroforming process

Design Considerations for Manufacturing Electroformed Components

  • For structural integrity, we recommend a minimum radius on all internal edges 2x nominal thickness
  • All critical dimensions should reference the formed surface (surface that contacts the mandrel)
    • Where possible, dimensions to non-formed surfaces should be reference dimensions
  • Overall thickness is typically very uniform for a smooth, continuous surface
    • Thickness may vary up to ± normal thickness/4 near outside edges
    • Non-continuous surfaces and features (i.e. grooves, holes, fins, protrusions) have adverse effects on thickness uniformity
  • Formed features (created during EF process) are highly consistent from part-to-part and can have tight tolerances
  • Secondary operations such as machining, drilling, and EDM may be used to create high precision holes & features
  • For components with features that are difficult or impossible to produce during the EF process or post-processing, pre-machined parts such as mounts, flanges, baffles, etc. may be encapsulated or “grown in”
Figure 1 - Effects of Surface Features on Thickness and Uniformity
GROOVES AND BLIND HOLES
PINS, FINS, AND RIBS
V-GROOVES AND SHARP PROTRUSIONS
DEEP SCOOPS AND LARGE PROTRUSIONS
Electro-Plating-Uniformity

SHALLOW FEATURES ARE EASIER TO CONTROL FOR THICKNESS AND UNIFORMITY

BLIND HOLES ARE TYPICALLY EXEMPT FROM MINIMUM THICKNESS REQUIREMENTS

DEEP AND NARROW FEATURES ARE DIFFICUlT TO CONTROL AND OFTEN REQUIRE SPECIAL MEASURES TO ACHIEVE TARGET THICKNESS.

WIDE FEATURES ARE EASIER TO CONTROL FOR THICKNESS AND UNIFORMITY

HIGH CURRENT DENSITY AREAS TEND TO PLATE THICKER

LOW CURRENT DENSITY AREAS WILL PLATE THIN

TALL AND NARROW FEATURES ARE DIFFICULT TO CONTROL AND OFTEN REQUIRE SPECIAL MEASURES TO ACHIEVE TARGET THICKNESS

SHARP GROOVES ARE TO BE AVOIDED IF POSSIBLE

SHARP PROTRUSIONS SHOULD HAVE GENEROUS RADII TO AVOID EXCESS BUILDUP

DEEP SCOOPS AND CUT-OUTS TAKE MUCH LONGER TO BUILD UP

LARGE PROTRUSIONS ROB MATERIAL FROM SURROUNDING FEATURES

ROUND CORNERS ARE HIGHLY ENCOURAGED WHEREVER POSSIBLE FOR MATERIAL UNIFORMITY AND STRUCTURAL INTEGRITY
LARGE FEATURES ADD A SIGNIFICANT CHALLENGE TO ACHIEVING UNIFORMITY AND INCREASE PLATING TIME DRAMATICALLY
Electro-Plating-Uniformity-2

STRUCTURAL INTEGRITY IS GREATLY IMPROVED BY INTERNAL RADII

IMPROVED UNIFORMITY FROM EXTERNAL RADII

A GENEROUS RADIUS ALLOWS SOME PLATING INSIDE A DEEP V-GROOVE

NOTABLY REDUCED BUILDUP

A GENEROUS RADIUS ALLOWS SOME PLATING INSIDE A DEEP V-GROOVE

LESS EXCESSIVE BUILDUP ON EXTERNAL EDGES CAN REDUCE OVERALL PLATING TIME

LARGER INTERNAL RADII ATTRACT MORE MATERIAL IN A SHORTER TIME

Figure 1 - Effects of Surface Features on Thickness and Uniformity
GROOVES AND BLIND HOLES
Electroforming-Surface-Features-1

SHALLOW FEATURES ARE EASIER TO CONTROL FOR THICKNESS AND UNIFORMITY

BLIND HOLES ARE TYPICALLY EXEMPT FROM MINIMUM THICKNESS REQUIREMENTS

TALL AND NARROW FEATURES ARE DIFFICULT TO CONTROL AND OFTEN REQUIRE SPECIAL MEASURES TO ACHIEVE TARGET THICKNESS

PINS, FINS, AND RIBS
Electroforming-Surface-Features-2

WIDE FEATURES ARE EASIER TO CONTROL FOR THICKNESS AND UNIFORMITY

HIGH CURRENT DENSITY AREAS TEND TO PLATE THICKER

TALL AND DEEP FEATURES ARE DIFFICULT TO CONTROL AND OFTEN REQUIRE SPECIAL MEASURES TO ACHIEVE TARGET THICKNESS

LOW CURRENT DENSITY AREAS WILL PLATE THIN

V-GROOVES AND SHARP PROTRUSIONS
Electroforming-Surface-Features-3

SHARP GROOVES ARE TO BE AVOIDED IF POSSIBLE

SHARP PROTRUSIONS SHOULD HAVE GENEROUS RADII TO AVOID EXCESS BUILDUP

DEEP SCOOPS AND LARGE PROTRUSIONS
Electroforming-Surface-Features-4

DEEP SCOOPS AND CUT-OUTS TAKE MUCH LONGER TO BUILD UP

LARGE PROTRUSIONS ROB MATERIAL FROM SURROUNDING FEATURES

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