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The modern orthopaedic implants for applications in hips, knees, shoulders, and spines are composed of hard metal alloys or ceramics. The tribo-logical sub-component is composed of soft materials with good tribological properties – e.g. UHMWPE (Ultra High Molecule Weight Polyethylene). The UHMWPE implants need to be machined into their final shape after the polymerization and consolidation into a blank profile or near-net shaped implant. So machining is a crucial technology that can generate an accurate and precise shape of the implant that should comply with the joints’ function. However, the machining technology can affect the topography and integrity of the surface, and its resistance to wear. The technology, cutting tools, and cutting conditions can impact the physical and mechanical properties of the entire implant, limiting its life span and creating a need to be replaced. The basic machining technologies are turning and milling (each can be used as roughing or finishing). There are many ways to machine these surfaces. Many problems such as low rigidity of the product, poor thermal properties of the material, high melt viscosities, and sticking of the material to the cutting edge (production of built-up edges) have been solved. UHMWPE can be damaged by excessive heat, feed rate, cutting force, and tool micro-geometry. The shapes and dimensions for the customized implants vary broadly for the humans this complicates the machining technology. No standard programs can be used repeatedly so each joint must be designed and produced individually. However, it results in the longer implant life and a better comfort of patients.

The technology of cold wire drawing belongs to an ancient class of technologies, but their use lasts for centuries. Today, special forming machines, advanced tool materials and effective lubricants are used. In this paper, a progressive physical vapour technology (PVD) of coating for inner surfaces is used which resulted in significant prolongation of tool life. The technology of HiPIMS (High-power Impulse Magnetron Sputtering) exhibited excellent performance in protective (Al,Ti)N coating of whole inner surfaces that are in contact with the drawn wire which is impossible to do with other coating techniques. The increase in production of the drawn steel spring wire by the coated die by more than 100% was excellent, and it opens new horizons to some similar technological applications. [ABSTRACT FROM AUTHOR]

The work deals with a machinability of Inconel® 718 construction material (hereafter referred to as "INC 718"). This chromium-nickel alloy has an austenitic structure, which in conjunction with its low thermal conductivity is one of the causes of a worse machinability. The aim of the work was to increase the productivity of the roughing turning process. There are more ways to improve the machinability of the INC 718, starting from the heat treatment of the material and ending with the application of process fluids. This work is based on real requirements of a company and therefore the possibilities of elimination of the worse machinability were limited by economic and technological aspects. For this reason, the main tool for increasing the productivity of the machining process was changing the material of the cutting tool and fine-tuning of the cutting conditions. In another part of the work, an evaluation of the experimentally determined force ratios of the reference and newly designed technology, which is the basis for the stress-strain analysis, have been made. The conclusion of the research highlights the newly designed process in terms of machining times and the volume of material achieved per unit of the cutting edge durability. [ABSTRACT FROM AUTHOR]

The objective of this work is to compare the performance of uncoated micro-end-mills and their effect on micro-milling of the Ti6Al4V titanium alloy that had been manufactured in the technology of Additive Manufacturing (AM). In this work, two different geometries of square-end micro-mills with two and fourcutting fluteshave been used. The effective tool geometry at the real micro-machining is rather problematic, because most of the tools are just down-scaled dimensions of standard cutters, so the cutting geometries might not be working well for all dimensions. The Ti6Al4V titanium alloy was made in technologyof Direct Metal Laser Sintering (DMLS). Micromilling tests were done with use of high precision 5-axis KuglerTM micro-milling centre under dry cutting conditions. The performances were evaluated in terms of surface topography, burrs formation, surface integrity and tool wear. [ABSTRACT FROM AUTHOR]