4M Knowledge base - papers

T Dobrev, D T Pham and S S Dimov
Manufacturing Engineering Centre, Cardiff University, Cardiff, CF24 3AA, UK

Abstract

Electro-chemical polishing is a process of improving micro smoothness, micro topology, and material brightness by anodic dissolving of the substrate in an electrolyte with an external source of electricity. The resulting surface improvements depend on the uniformity of the material microstructure, the lack of surface inclusions, and the consistency of the surface finish all over the target area. In contrast, laser milled structures are mostly concave features; their roughness is usually higher than that achieved on the other surfaces of the component, and also there is a significant presence of foreign or recast particles on them. Thus, it is important to investigate systematically the effects of electro-chemical polishing on microstructures machined by laser milling.

The paper discusses the effects of electro-chemical polishing on the surface finish of laser milled features. Although ECP displayed some limitations when polishing micro features, it still managed to achieve almost 30% improvements in omparison to the initial roughness after laser milling. Another benefit is that the process also improves the edge quality of the laser machined structures by removing the burrs.

R.K. Leach, C. Giusca
Industry & Innovation Division, National Physical Laboratory, Teddington TW11 0LW, UK

Abstract

There is a clear need in industry and academia for traceable areal surface texture measurements. To address this need traceable transfer artefacts and primary instrumentation are required. The National Physical Laboratory (NPL) is working on two projects – one to develop areal transfer artefacts and one to develop a traceable areal surface texture measuring instrument. The authors describe the development of the artefacts and instrument, and present some of the challenges that are still required to be able to offer an areal traceability measurement service to industry. The instrument has a working volume of 8 mm x 8 mm x 0.1 mm and uses a co-planar air-bearing slideway to move the sample. It also uses a novel vertical displacement measuring probe, incorporating an air-bearing and an electromagnetic force control mechanism. The motions of the slideway and the probe are measured by laser interferometers thus ensuring traceability of the measurements to the definition of the metre. The artefacts were manufactured using a range of machining technologies and in a range of geometries suitable for stylus and optical based instruments.