The process of nickel electroforming is becoming increasingly important in the manufacture of MST products, as it has the potential to replicate complex geometries with extremely high fidelity. Electroforming of nickel uses multi-component electrolyte formulations in order to maximise desirable product properties. In addition to nickel sulphamate (the major electrolyte component), formulation additives can also comprise nickel chloride (to increase nickel anode dissolution), sulphamic acid (to control pH), boric acid (to act as a pH buffer), hardening/levelling agents (to increase deposit hardness and lustre) and wetting agents (to aid surface wetting and thus prevent gas bubbles and void formation).

Emeritus Professor of Microengineering, Cranfield University, UK

This paper was presented at the PCMI Conference, Chantilly, France on 20th May 2019

As nickel-containing metals are dissolved into ferric chloride etchant, the concentration of nickel ion builds up in solution even when the etchant is being regenerated. Above a critical dissolved nickel concentration, an unacceptable rough surface finish will become apparent in any half-etch areas of parts leading to product rejection and increased costs.

PCM involves many processes in its production process chain and each process has an
associated environmental impact. To remain competitive with rival processes, PCM must
minimise its overall environmental impact as the costs of environmental compliance are
currently increasing at a rapid rate.
This paper reviews the environmental impact of each process in the PCM process chain and
suggests how it can be minimised utilising clean technologies (employing radical revision
and/or innovative modification), waste minimisation through improved quality control,
recycling and ‘end of pipe’ treatments to meet emission requirements.
The costs of environmental impact reduction are also discussed together with the various
financial benefits accrued.

June 2005

Dr. David M. Allen and Dr. Heather J.A. Almond, School of Industrial and Manufacturing Science, Cranfield University, Bedford, UK

Characterisation of Aqueous Ferric Chloride Etchants Used in Industrial Photochemical Machining

Ferric cbloride (FeCI3) is the most commonly used etchant for photochemical machining (PCM) but there is a great variety in the grades of the commercial product.

2010
 
D M Allen, M Simpkins and H Almond
 

A novel photochemical machining process for magnesium aerospace and biomedical microengineering applications

 

Research was carried out to evaluate the feasibility of fabricating perforated (filigree) magnesium microcomponents with metal wire widths of the order of the metal thickness using a photochemical machining (PCM) process.

PCM of nickel and its alloys and the measurement of nickel ion concentration in ferric chloride etchant

Abstract

This paper reviews the nickel and nickel alloy products manufactured by PCM using etchants based on aqueous ferric chloride solutions. The metals include varying percentages of nickel that build up in the etchant as the metal is dissolved.

The etching of stainless steels is a mainstay of photochemical machining (PCM) commerce

worldwide. However, as a class of materials designed to be corrosion-resistant, stainless steels are

not easy to etch. This paper discusses the complex nature of ferric chloride etchant used to etch

stainless steels and the control of its chemistry.

Photochemical Machining: Where has it come from and where is it going?

Emeritus Professor David Allen, Cranfield University, UK

Abstract

The history and development of the photochemical machining (PCM) process is described

together with predicted process developments that should lead to a more robust and versatile rapid

manufacturing process for the future.

In the photochemical machining of micro-parts from nickel-containing alloys, a solution of ferric chloride is used as the etchant. As the alloy is dissolved into solution, the concentration of dissolved nickel will increase to a point where the surface finish of the etched parts will be affected adversely and become rougher.

Electroforming and Chemical Milling of Perforated Products: A Comparison

Spring 1986

Summary

Among the various technologies available for the production

of perforated flat metal products, such as stamping, spark

erosion, laser cutting, mechanical milling, etc., two technologies

deserve a better knowledge because of their unique combination

ofa high quality level with respect to accuracy and reproducibility

combined with relatively low production costs.