Tool Life Time Extension with Nano-crystalline Diamond Coatings for Drilling Carbon-fibre Reinforced Plastics (CFRP)

Abstract

Carbon fibre reinforced plastics (CFRP) are delicate to machine as the material is highly abrasive and tends to show multiple workpiece damages like delamination, fibre pull out, uncut fibres and burnt matrix material. In result machining CFRP requires on the one hand tools which can withstand the massive wear, on the other hand geometrical highly adaptable tools to produce flawless workpieces. Diamond coated solid carbide tools can provide an excellent wear resistance in combination with a highly adaptable tool geometry. Nano-crystalline diamond coatings provide a good layer adhesion and can be applied to machining tools. This study focuses on required drilling tool characteristics for a large tool life time of diamond coated carbide tools. The workpiece material used is the M21/35%/370H5/AS4C-6K from Hexcel© which finds its main application in the aircraft industry. The machining tests are being conducted using a Mori Seiki NMV5000DCG at different feed rates and cutting velocities. Two different nano-crystalline diamond coatings are being evaluated regarding wear resistance depending on the drill geometry and tool diameter. The workpiece quality is measured using a microscope. It is shown that the tool geometry influences the wear resistance intensively. A change in wear resistance depending on the tool geometry is not unique for different diamond coatings. Finally, it is shown that cutting velocity and feed have only a small influence on tool life time.

Cutting Performance of Microcrystalline, Nanocrystalline and Dual-Layer Composite Diamond Coated Tools in Drilling Carbon Fiber Reinforced Plastics

“…Tool materials (substrate) and type of coatings have become crucial factors in the final tool characteristics for machining CFRP [4][5][6][7]. Chemical vapor deposition (CVD) diamond coatings are famous for their unique characteristics such as high hardness, good wear resistance, low friction coefficient, and high thermal conductivity.…”

Study of the Effect of Tool Wear on Hole Quality in Drilling CFRP to Select a Suitable Drill for Multi-Criteria Hole Quality

“…Tool wear has been the major focus of study in drilling CFRP with the objective of increasing tool life [11][12][13]. Drilling assisted by vibration [11], drilling using tools coated with diamond, AlTiN [12] and Nano-crystalline diamond coatings [13] are some of the methods used to reduce tool wear.…”

“…Drilling assisted by vibration [11], drilling using tools coated with diamond, AlTiN [12] and Nano-crystalline diamond coatings [13] are some of the methods used to reduce tool wear.…”

Coating of Ultra-Small Micro End Mills: Analysis of Performance and Suitability of Eight Different Hard-Coatings

“…At only slightly below 10,000 HV, it is almost as hard as natural diamond [21]. The nanocrystalline structure of the coating results in a low surface roughness, which means that less material adhesion is to be expected compared to uncoated tools [22]. The low surface roughness also ensures good chip flow and quickly dissipates the heat generated in the contact zone during machining [23].…”