ECM Delivers Productivity Tools for Medical Device Manufacturers

The control on the ECM 500 uses fuzzy logic principles, enabling the machine to adapt itself to the requirements of each material and shape being manufactured.Manufacturing the complex geometry of femoral implants in difficult to machine materials, such as titanium and cobalt chrome, can be both complicated and labor intensive. In addition, any hand finishing or polishing can alter the finished shape, producing small, but important, differences between each implant. Electrosion offers an approach to the precise and rapid machining of these hard metals.

Electrochemical machining (ECM) uses the principles of electroplating in reverse – the workpiece dissolves into the sodium nitrite electrolyte. Up until now, the limitation of the technology has been the large gap required between the electrode and the job – required for electrolyte flushing – making it virtually impossible to produce fine detail with the process. Electrosion developed a solution with its Impulse technique, which oscillates the electrode and pulses the current, simultaneously, enabling the Electrosion ECM 500 to operate with electrode gaps down to 10µm. The small gap enables extremely-fine detail to be transferred from the electrode to the part. Furthermore, the ECM 500 retains the major advantages of electrochemical machining, rapid metal removal rates, zero electrode wear, and high quality surface finish. Steve Duffield, managing director of Electrosion explains, “Our new machine can achieve metal removal rates of 1,000mm3/min, routinely produce surface finishes of 0.10Ra, and with care, 0.03Ra. Because there is no sparking or contact between the electrode and the part, there is zero electrode wear, making it possible to manufacture many parts or cavities with just one electrode.”

Compared with and EDM, ECM is 100 times faster, eliminating the need for multiple roughing and finishing electrodes, and is able to machine any metal, irrespective of its hardness.

The electrodes for the ECM 500 can be made from any conductive material, enabling their rapid manufacturing using conventional machining techniques. Additionally, their long life, and the need for only one to complete both roughing and finishing, produces significant cost savings. The low temperature of the electrolyte, which runs at 20°C, and the absence of contact between the electrode and the workpiece, produces further benefits as it eliminates the localized stresses.

Duffield pictures a wide range of applications in the medical sector for the new technology. “Because of the polished finish that can be achieved straight off the machine, it is possible to produce mold cavities for critical products such as contact lenses and tablets. Thin and fragile parts in hard materials will also lend themselves to manufacturing on the ECM 500, as the low operating temperatures and zero-load on the part will eliminate the possibility of distortion or the introduction of stress.”

The control on the ECM 500 uses fuzzy logic principles, enabling the machine to adapt itself to the requirements of each material and shape being manufactured. By simplifying the operation of the machine, it ensures consistent results in a production environment.

Duffield concludes, “The ECM 500 is a major breakthrough in manufacturing, providing a new and cost-effective way of cutting parts and cavities that would have been either very costly or impossible to achieve previously.”

Electrosion Ltd
Barnsley, United Kingdom
electrosion.co.uk