Carbide End Mills for Additive Manufacturing Applications

In recent manufacturing trade fairs, many machine builders from around the world are exhibiting new state-of-the-art machinery engineered for additive manufacturing. Although initially used mostly as a prototyping solution in the manufacturing sector, increasing digitalization and government initiatives are driving manufacturers to further accelerate the development of advanced additive manufacturing solutions.

What is Additive Manufacturing?

Unlike conventional processing, where an object is formed by removing excessive materials, additive manufacturing deposits material layer upon layer to form a three-dimensional object. Various substances can be employed for the layering material, such as metal powder, thermoplastics, ceramics, composites, glass and more. Additive manufacturing is agonistic to part complexity and can manufacture unique geometries that would be impossible or unrealistic by using traditional manufacturing methods. Coupled with today’s high connectivity production environment, additive manufacturing is radically revolutionizing the way products are produced by allowing companies to manufacture end products with similar scale and strength to injection-molded parts. In addition, additive manufacturing allows shorter delivery time, lower cost, higher quality parts, and generates minimal waste as compared to conventional manufacturing techniques. Due to these advantages, the adoption of additive manufacturing platforms has greatly accelerated across industries worldwide.

Types of Additive Manufacturing

As illustrated in Figure 1, there are two key categories of additive manufacturing based on material – metal and resin. For this article, we will only focus on metal additive manufacturing. Various metals and metal alloys can be used in additive manufacturing, such as stainless steel, titanium, precious metals and more. Within metal additive manufacturing, there are two main deposit methods – directed energy deposition (DED) and powder bed fusion (PBF). Furthermore, machines used for metal additive manufacturing can be classified into two categories – those that are used solely for deposition; and hybrid machines equipped with capabilities to deposit, heat treat, coat and metal cutting. Major machine builders in Japan have begun the production and sales of hybrid metal additive manufacturing machines. In response to new market demand, OSG Corporation has recently launched a new end mill series engineered for these hybrid machines, especially for the DED method.

As shown in Figure 2, although the DED method offers many advantages, its deposit accuracy is inferior to PBF. This shortcoming has a large effect on secondary operations, especially on the cutting process where cutting tools are used to complete the product. Figure 3 depicts deposited SKD11 (60 HRC) by the DED method. As shown in the photograph, a step difference of over 1 mm can be observed after the deposition. In the cutting process, a change in machining allowance of unevenness exceeding 1 mm greatly affects tool life and is a major cause of tool life reduction.