Electroforming is an Additive Manufacturing Process used to Make Precision Metal Components

Electroforming (EF) is a highly versatile manufacturing process and is very effective when requirements call for extreme tolerances, complexity, surface finish, or lightweight substrates. Based on the principles of electrochemistry, electroforming is essentially a specialized form of electroplating that allows a high degree of control, precision, and reliability. 

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.

How Electroforming Works

Electroforming is an electrochemical process that involves the deposition of a metal layer onto a conductive template, commonly called the mandrel. The process is based on the principles of electrolysis and utilizes the controlled flow of electrical current to achieve the desired deposition.

The electroforming process typically involves three main components: the mandrel, the electrolyte solution, and the process controls.

The Mandrel: 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 an exact match (at a molecular level) to the surface quality of the mandrel.

Reusable vs. Disposable Mandrels

Surface of revolution components like our parabolic, elliptical, and spherical reflectors, are manufactured with a reusable mandrel. The simple geometries account for a draft angle that allows the part to be separated from the mandrel easily.

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.

Electrolytic Solution: The electrolyte solution is an aqueous bath that contains metal ions in the form of a metallic salt or complex. It is carefully selected to provide the desired metal deposition and other desired properties. 

Process Controls: A number of important processes help control how electroforming works, including power supplies, tooling, masking and shielding. 

The power supply provides the electrical current necessary for the electroforming process. It is typically a direct current (DC) power source, connected to the mandrel (cathode) and an anode (usually made of the same metal as the desired deposit). The power supply drives the flow of electrons through the circuit, causing the metal ions in the electrolytic bath to dissolve and deposit onto the mandrel.

Proprietary tooling is used to effectively secure the mandrel, while masking and shielding techniques are employed to maximize plating uniformity. Thickness of the component is directly related to the amount of time the mandrel is left in the electrolytic bath.

During the electroforming process, the mandrel is immersed in the electrolyte solution, and the power supply is turned on. The DC current causes metal ions from the electrolytic bath to migrate towards the mandrel’s surface. At the surface, the metal ions are reduced, forming a layer of metal atoms that gradually builds up over time.

The deposition process can be controlled by adjusting several parameters, including the current density, temperature, bath composition, and plating time. These parameters affect the rate of metal deposition, the thickness of the layer, and the physical properties of the final electroformed part.

Benefits of Electroforming over other manufacturing techniques:

Electroforming 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.

Key advantages of electroforming:

  • Complex Geometries: Electroforming excels at producing parts with intricate and complex geometries. It enables the creation of fine details, sharp corners, undercuts, and thin walls that may be difficult or impossible to achieve with other manufacturing processes. This makes electroforming particularly suitable for applications requiring high precision and intricate designs.

  • High Dimensional Accuracy: Electroforming can achieve high dimensional accuracy, reproducing the exact shape and dimensions of the mandrel. The process can achieve tight tolerances, making it ideal for applications where precise geometries are crucial.

  • Uniform Thickness: Electroforming allows for the precise control of deposit thickness. The electroplating process ensures a uniform layer of metal is deposited onto the template, resulting in consistent thickness across the part. This uniformity is valuable in applications where precise thickness distribution is critical for functionality or aesthetics.

  • Mechanical Properties: Electroformed parts exhibit excellent mechanical properties, including high strength, hardness, and durability. The electroplating process creates a dense and uniform metal structure, resulting in parts with improved mechanical integrity. This is advantageous for applications requiring robust and reliable components.

  • Scalability: Electroforming is a scalable manufacturing process, suitable for producing both small and large quantities of parts. It can efficiently produce high volumes of parts with consistent quality and repeatability.

  • Cost Efficiency: Electroforming can offer cost advantages compared to traditional manufacturing methods for certain applications. Components electroformed with a reusable mandrels offer high repeatability and precise reproduction of surface detail. Electroforming can also eliminate the need for extensive post-processing or assembly steps, further reducing manufacturing costs.

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”

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