The medical components discussed in this article are defined as parts which must operate within a human body either permanently or temporarily as support for healing.
Challenges lie in the need for precision and high tolerances, as well as working with difficult-to-machine materials, particularly with small parts such as bone screws.
There is an increasing medical trend towards the use of biocompatible materials such as cobalt chromium, stainless steel (316LVM) and titanium.
According to the company, it has its own division called Sandvik Bioline, which specialises in researching and creating medical components. Examples of products which have benefited from research include artificial hip implants such as the ball and cup.
The cup solution is manufactured via spherical turning with round inserts. This process is said to have doubled productivity throughout the industry, and reduced tool costs by a third.
In order to achieve high-tolerance products and good surface finishes with difficult materials, care must be taken to control chips and ensure the material is deburred during manufacture.
The tools must also be chosen carefully to endow the components with the correct characteristics. For example, bone screws are long and slender and each must be designed to integrate with the body. In this case, the tools need to have sharp cutting edges and have high tolerances for turning, grooving and threading the material.
According to the manufacturer, it has developed a specific programme for small part machining which covers an assortment of tools and processes. It supports external and internal machining, milling and drilling.
A quick tool change system for sliding head machines facilitates fast indexing, and machines such as the GC1105 have been specially developed for working with medical component materials. Small tooling solutions provide turning, grooving and threading for drilling diameters down to 0.3mm. Indexable inserts with PVD coating allow sharp edge profiles and high precision.
This article first appeared in Sandvik Coromant’s Metal Working World issue #2/2008.