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特性以及良好的耐磨性，它在工业上被用于冲压模具，注塑模具和切割工具。硬质合金属于硬脆材料，主要通过磨削工艺制造出不确定的切削刃。用车削和铣削工艺进行加工是困难的，但能够实现有效的制造和增加的几何复杂性。在几何形状限定的切削刃的制造过程中，一个限制因素是增加的刀具磨损，在这项研究中，一种新的切削材料纳米多晶金刚石（NPCD）用于切削硬质合金（WC-Co）。由于材料结构，NPCD实现了与单晶金刚石（SCD）相当的硬度H，而没有共享它们的缺点，例如各向异性。由于金刚石颗粒的颗粒直径在10 nm ≤ dk ≤ 50 nm的范围内，以及没有粘结剂，NPCD具有改善的磨损性能，并有望更有效地加工难切削材料。为了能够将这种切削材料用于硬质合金的特定加工，关于硬质合金切削性能的基本知识，需要掌握NPCD在超精密车削和超精密铣削过程中的工艺行为以及它们之间的相互作用。因此，将获得关于磨损机制和工艺变量的深刻知识，例如由工艺和工艺力Fpr产生的表面粗糙度值。此外，将开发用于描述工具和工件之间的机械相互作用的有限元模拟。在大约24个月的第一个资助期内，将获得车削工艺和工艺模拟的基本知识。在第二个资助期内，也是大约24个月，将传授有关铣削工艺的知识，最后将定义NPCD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.