Binderless nano-polycrystalline diamond (NPCD) as cutting material for precision machining cemented carbide

由于硬质合金的硬度和强度以及良好的耐磨性能，它在工业上被用于冲压模具、注塑模具和切削工具。碳化钨属于硬脆材料，主要是通过磨削加工制造的，切削刃不明确。车削和铣削加工是困难的，但可以有效地制造和增加几何复杂性。在具有几何定义切削刃的制造过程中，一个限制因素是增加刀具磨损。本文研究了一种新型切削材料纳米聚晶金刚石（NPCD）用于硬质合金（WC-Co）的切削。由于材料结构的原因，NPCD达到了与单晶金刚石（SCD）相当的硬度H，而不具有单晶金刚石的各向异性等缺点。由于颗粒直径在10 nm≤dk≤50 nm范围内的金刚石颗粒以及不含粘结剂，NPCD具有改善的磨损性能，并且有望更有效地加工难切削材料。为了能够使用这种切削材料进行特定的硬质合金加工，需要了解硬质合金切削行为的基本知识，以及NPCD在超精密车削和超精密铣削过程中的加工行为及其相互作用。因此，将获得关于磨损机制和过程变量的深刻知识，例如由过程产生的表面粗糙度值和过程力Fpr。此外，将开发用于描述工具和工件之间机械相互作用的有限元模拟。在第一个为期24个月的资助期内，将获得车削工艺的基本知识和工艺模拟。在第二个资助期（也计算为24个月），将转移有关铣削工艺的知识，最后将定义具有NPCD的超精密车削和超精密铣削工艺的基本应用。

Due to the hardness and strength properties as well as the good wear behaviour is tungsten carbide industrially used for punching moulds, injection moulds and cutting tools. Tungsten carbide belongs to the group of hard-brittle materials and is mainly manufactured with undefined cutting edges by grinding processes. The machining with turning- and milling processes is difficult but enables an effective manufacturing and increased geometry complexity. A limiting factor during the manufacturing with geometrical defined cutting edges is increased tool wear.In this investigation a new cutting material nano polycrystalline diamond (NPCD) is used for the cutting of cemented carbide (WC-Co). Due to the material structure NPCD achieves a hardness H comparable to single-crystalline diamond (SCD) without sharing their disadvantages such as anisotropy. In consequence of the diamond particles with particle diameter in a range of 10 nm ≤ dk ≤ 50 nm as well as the absent binder NPCD has an improved wear behaviour and promises a more efficient machining of hard to cut materials.In order to be able to use this cutting material for specific machining of cemented carbide basic knowledge about the cutting behaviour of cemented carbide, the process behaviour of NPCD during the ultra-precision turning and ultra-precision milling process, as well as their interactions needs to be acquired. Therefore, profound knowledge about the wear mechanisms and process variables, such as the surface roughness values resulting from the process and the process forces Fpr, will be acquired. Furthermore, finite element simulations for description of the mechanical interactions between the tool and the workpiece will be developed. In a first funding period about 24 month the basic knowledge with the turning process and the process simulation will be achieved. In the second funding period, which is also calculated about 24 month, the knowledge is transferred on the milling process and at the end fundamental applications for the ultra-precision turning and ultra-precision milling process with NPCD will be defined.