What Causes Tool Wear & How To Reduce Tool Wear In Aluminum Die Casting

When CNC processes aluminum alloy die castings and mold blanks, the tools are worn, and the excessively worn tools can only be discarded, which prolongs the service life of the tools and reduces the cost of the aluminum alloy die casting in a disguised way. The coating technology will be adopted for the current cutting tools to further improve the service life of the cutting tools and significantly improve the machining efficiency. In this article, we introduce the causes of tool wear and how to reduce tool wear for aluminum die casting.

Tool Wear Types

Tool wear usually includes the following types:

① Flank wear

② Scoring wear

③ Crater wear

④ Blunt cutting edge

⑤ Cutting edge collapse

⑥ Cutting edge crack

⑦ Catastrophic failure


What Causes Tool Wear 

In the metal cutting of aluminum alloy die castings or mold blanks, the heat and friction are the manifestations of energy. The high surface load and the heat and friction generated by the high-speed sliding of chips along the tool rake face make the tool in a very challenging machining environment. The cutting force often fluctuates up and down, which mainly depends on different machining conditions. Therefore, in order to maintain its strength at high cutting temperature, the tool is required to have some basic characteristics, including excellent toughness, wear resistance and high hardness.


How To Reduce Tool Wear & Prolong Tool Life

There is no generally accepted unified definition of tool life, which usually depends on different workpiece and tool materials and different cutting processes. One way to quantitatively analyze the end point of tool life is to set an acceptable maximum flank wear limit.

The continuous development of optimal tool substrate, coating and cutting edge preparation technology is very important to limit tool wear and resist cutting high temperature. These factors, together with the chip breaking groove and corner arc radius adopted on the indexable blade, determine the applicability of each tool to different workpieces and machining. The best combination of all these elements can reduce tool wear & prolong the tool life and make the cutting process more economical and reliable.


Select Excellent Coated Tools

The coating also helps to improve the cutting performance of the tool. Current coating technologies include:

① Titanium nitride (TIN) coating: This is a universal PVD and CVD coating, which can improve the hardness and oxidation temperature of tools.

② Titanium carbonitride (TiCN) coating: the hardness and surface finish of the coating are improved by adding carbon to tin.

③ TiAlN and AlTiN coatings: the composite application of alumina (Al2O3) layer and these coatings can improve the tool life of high temperature cutting. Alumina coating is especially suitable for dry cutting and near dry cutting. AlTiN coating has higher aluminum content and higher surface hardness than TiAlN coating with higher titanium content. AlTiN coating is usually used for high-speed machining.

④ Chromium nitride (CRN) coating: this coating has good anti bonding performance and is the preferred solution for anti chip tumor.

⑤ Diamond coating: diamond coating can significantly improve the cutting performance of tools for processing non-ferrous materials. It is very suitable for processing graphite, metal matrix composites, high silicon aluminum alloy and other high abrasive materials. However, diamond coating is not suitable for machining steel parts, because its chemical reaction with steel will destroy the adhesion between the coating and the substrate.

 

In recent years, the market share of PVD coated tools has expanded, and its price is on a par with that of CVD coated tools. The thickness of CVD coating is usually 5-15 μ m. The thickness of PVD coating is about 2-6 μ m. When applied to the tool substrate, the CVD coating will produce undesirable tensile stress. PVD coating is helpful to form beneficial compressive stress on the substrate. Thicker CVD coatings usually significantly reduce the strength of tool cutting edges. Therefore, CVD coating cannot be used for tools requiring very sharp cutting edges.