abstract
- © 2018 Elsevier B.V. All rights reserved. Microneedles are an alternative to deliver chemical compounds through the skin for the treatment of several health conditions. In this work, a micro milling process was used to manufacture AISI 316L stainless steel needles arrays with a conical geometry (i.e., a base diameter and height of 1 mm by 1 mm, respectively). An analysis of tool wear on ball nose micro end milling tools with a diameter of ~200 ¿m was performed to evaluate the use of lubricant in the manufacture of those conical surfaces. A tool diameter reduction of 6% and 8% was obtained in dry cutting and wet cutting, after the manufacture of 9 and 54 needles respectively. Geometrical features on the needle tip resulted more affected in dry cutting regime compared with the wet treatment. A maximum needle tip diameter of 188 ¿m was reported on dry cutting versus values lower than 30 ¿m using wet regime. The results indicate that surface roughness increases after machining 36 and 9 needles in wet cutting regime and dry cutting treatment, respectively. However tool breakage occurs after milling 12 needles in dry cutting. A cost analysis shows that the micro milling approach is a competitive method for prototyping of microneedle arrays.