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Milling and Drilling the Tough Materials

8th July 2013
Milling and Drilling the Tough Materials
Milling and Drilling the Tough Materials
For the purposes of mining and drilling, manufacturers of aerospace products often make use of solid high-speed steel or solid carbide tools and manufacturers thereby aspire to achieve the highest level of quality in the products during such machining operations. 
There are certain associated concerns relating to the cost per part and higher priority is often given to production of quality parts and increased productivity comes second.  The aviation industry manufacturers mainly strive for consistency and security through the predictable performances of their machines and tools.  As far as tooling is concerned, the manufacturers must have modern, technologically advanced milling cutters, as well as drills that are capable of delivering enhanced tool life.
With the introduction of modern innovative coatings and the use of geometrics with advanced machining strategies and techniques, modern specialised tools deliver the required process security, increased efficiency and better output.
1. Milling: at present, a strong market for machining Carbon Fibre Reinforced Plastics (CFRP) materials is rapidly growing within the aviation industry.  However, the abrasive and robust nature of materials makes it difficult for the milling tools to machine them.  This challenge is essentially overcome with the use of hard and sharp milling cutters made from solid-carbide and special kinds of surface coatings.  
The mining tools mainly use two types of surface coating treatments, namely Physical Vapour Deposition (PVD) and Chemical Vapour Deposition (CVD) in addition to the advanced Polycrystalline Diamond (PCD) cutting material.  The PVD coatings are done through physical processes and enjoy a thickness of around 3k Vickers.  The CVD coatings, on the other hand, are around three times harder than the PVD coatings and have a thickness of 10k Vickers.
2. Drilling: for aerospace applications, the holes drilled in the composites should be perfectly clean and should not have frayed or ragged fibres that can obstruct or even compromise the following assembly operations.  Delamination failure and uncut fibres, mainly on the drill-exit point of the materials, are the two main challenges of drilling the composites.  
To deal with such issues, the tooling companies aim at reducing the drill feed force against various materials by using different point and helix angles and by providing a C1 diamond coating on the solid-carbide drills.  The drills generating lower feed forces tend to perform better than the ones exerting higher force.  This PCD geometry drill has sharp edges and less feed-force per-revolution for providing far better results than the previously used high-force drills.
Ultimately, employing the most advanced machining solutions is the key to effectively machining tough materials.  This advanced product technology combined with the wealth of knowledge and experience of the engineers also helps significantly in producing ideal and timely results.


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