Freeform surfaces, also called sculptured surfaces, have been widely used in various engineering applications. Freeform surfaces are primarily manufactured by CNC machining, especially 5-axis CNC machining. Various methodologies and computer tools have been developed in the past to improve efficiency and quality of freeform surface machining. This paper aims at providing a state-of-the-art review on recent research development in CNC machining of freeform surfaces. This review primarily focuses on three aspects in freeform surface machining: tool path generation, tool orientation identification, and tool geometry selection. For each aspect, first concepts, requirements and fundamental research methods are briefly introduced. The major research methodologies developed in the past decade in each aspect are presented with details. Problems and future research directions are also discussed.

Review: Recent development in CNC machining of freeform surfaces: A state-of-the-art review

Recently, a large amount of new research related to numerical control (NC) tool path generation has appeared in the literature Unfortunately, finding information on a particular topic can be difficult Not only does path generation span several disciplines, but the material tends to vary both in content and focus In this paper, the literature is partitioned into categories and papers related to path generation classified according to the topics they cover This should be useful to those looking for references on specific topics as well as those seeking an introduction to the literature as a whole

https://www.cgl.uwaterloo.ca/smann/Papers/survey2.pdf

A classified bibliography of literature on NC milling path generation

Robotic polishing of free-form surfaces using scanning paths

https://www.smu.edu/~/media/Site/Lyle/RCAM/Publications/Automated%20Torch%20Path%20Planning%20Using%20Polygon.ashx

Automated torch path planning using polygon subdivision for solid freeform fabrication based on welding

Due to the wide diffusion of 3D printing technologies, geometric algorithms for Additive Manufacturing are being invented at an impressive speed. Each single step, in particular along the Process Planning pipeline, can now count on dozens of methods that prepare the 3D model for fabrication, while analysing and optimizing geometry and machine instructions for various objectives. This report provides a classification of this huge state of the art, and elicits the relation between each single algorithm and a list of desirable objectives during Process Planning. The objectives themselves are listed and discussed, along with possible needs for tradeoffs. Additive Manufacturing technologies are broadly categorized to explicitly relate classes of devices and supported features. Finally, this report offers an analysis of the state of the art while discussing open and challenging problems from both an academic and an industrial perspective.

From 3D Models to 3D Prints: an Overview of the Processing Pipeline

Several methods have been developed for the computerized generation of space-filling curves, but these curves have never been used for NC tool-path generation. The paper discusses the application of space-filling curves as tool paths for sculptured-surface machining. Tool paths that are space-filling curves, single-direction conventional paths, and 2-direction conventional paths are compared. The efficiency ratings of the paths require further testing, but the preliminary conclusions are favourable for space-filling curves.

Eric L. Mulkay

Papers

Space-filling curves in tool-path applications