Abstract: By analyzing the problems encountered in the machining of slot type parts, this paper explores the key factors of cost increase and low machining efficiency caused by tool breakage in slot type machining. A comprehensive analysis was conducted on the types of cutting tools and processing costs, and the existing processing schemes were improved to find suitable processing tools and strategies, thereby reducing processing costs.
Application of High Precision Cutting Tools in Machining
Keywords: groove processing; Cutting tools; Processing strategy; Processing cost; Processing efficiency; machining center
1. Introduction
There is usually a problem of poor chip removal in the machining of slot type parts. Due to the stickiness of alloy materials, it is easy to cause tool chip squeezing and heat dissipation difficulties, resulting in tool clamping and breakage, reducing tool life and processing efficiency, and increasing processing costs. Therefore, it is necessary to select tools and processing strategies reasonably according to the working conditions, improve the processing efficiency of grooves, and reduce processing costs.
This article selects a new 980ML high feed tool and a classic solid hard alloy tool to compare and process multiple groove types of different parts. Data is summarized and analyzed from the aspects of processing time, processing cost, processing efficiency, and metal removal rate. The processing scheme of the new tool is verified, and the existing processing scheme for groove type parts is improved.
2. Characteristics of cutting tools
(1) Tool structure
The overall structure and machining characteristics of the 980ML high feed milling cutter are shown in Figure 1. The kappa of the tool is relatively small, with a maximum of about 15 °, effectively reducing the radial force on the tool, improving the axial force capacity of the tool, protecting the tool ligaments, and increasing the service life of the tool.
The tool adopts a necking design, with a neck diameter D3 smaller than the tool diameter D, which is conducive to chip removal, reduces chip accumulation, facilitates tool heat dissipation, and protects the toughness of the blade. The cutting tool adopts a necking high feed processing method, which facilitates the processing in the depth direction of large overhang working conditions and expands the application range of the cutting tool.
(2) Characteristics of tool processing
The applicability of 980ML high feed milling cutters is more stringent than that of solid carbide cutting tools. The "high feed" machining in its "small cutting depth, high feed" machining strategy requires high high-speed performance of the machine tool, so this tool is only suitable for lightweight high-speed milling machines. The advantages of its processing are as follows:
① The necking structure of the tool and the large circular arc design at the tool tip make the tool mainly subjected to radial force during machining, which facilitates chip removal and heat dissipation. When using the same feed rate, this tool provides a longer service life than solid carbide tools. When using high feed processing, productivity can be significantly improved;
② The processing strategy of "small cutting depth, high feed" requires improving the sharpness of the blade to make it more suitable for processing deep grooves, steel parts, and hardened steel, stainless steel, superalloys, and titanium alloys with a hardness not exceeding HRC62. Reduced production costs and minimized vibration and machine tool wear to the greatest extent possible.
The solid hard alloy end mill has lower requirements for machining conditions and is a relatively universal machining tool. However, in the processing of groove type parts, due to the relatively shallow chip removal groove at the cutting edge and the absence of necking design, it is inconvenient to remove chips during the processing of deep groove type parts, which can easily lead to poor surface smoothness and tool breakage of groove type parts.
3. Comparison of Cutting Tool Processing Examples
Considering the limitations of the 980ML high feed tool on the machining center, high-speed milling experiments were conducted on the MAZAK turning milling composite machining center for comparison.
3.1 Processing of valve seat circular arc groove
Select the circular arc groove of the valve seat for machining testing. There are a total of 57 parts for the valve seat, made of 3Cr13 material. The overall hard alloy tool processing scheme uses PM-4R-D8R1 tool for layered milling, while the high feed tool processing scheme uses 980ML08-MEGA tool for layered milling. The machining of valve seat parts and integral hard alloy cutting tools is shown in Figure 2, and the machining of high feed cutting tools is shown in Figure 3.
(2) Characteristics of tool processing
The applicability of 980ML high feed milling cutters is more stringent than that of solid carbide cutting tools. The "high feed" machining in its "small cutting depth, high feed" machining strategy requires high high-speed performance of the machine tool, so this tool is only suitable for lightweight high-speed milling machines. The advantages of its processing are as follows:
① The necking structure of the tool and the large circular arc design at the tool tip make the tool mainly subjected to radial force during machining, which facilitates chip removal and heat dissipation. When using the same feed rate, this tool provides a longer service life than solid carbide tools. When using high feed processing, productivity can be significantly improved;
② The processing strategy of "small cutting depth, high feed" requires improving the sharpness of the blade to make it more suitable for processing deep grooves, steel parts, and hardened steel, stainless steel, superalloys, and titanium alloys with a hardness not exceeding HRC62. Reduced production costs and minimized vibration and machine tool wear to the greatest extent possible.
The solid hard alloy end mill has lower requirements for machining conditions and is a relatively universal machining tool. However, in the processing of groove type parts, due to the relatively shallow chip removal groove at the cutting edge and the absence of necking design, it is inconvenient to remove chips during the processing of deep groove type parts, which can easily lead to poor surface smoothness and tool breakage of groove type parts.
3. Comparison of Cutting Tool Processing Examples
Considering the limitations of the 980ML high feed tool on the machining center, high-speed milling experiments were conducted on the MAZAK turning milling composite machining center for comparison.
3.1 Processing of valve seat circular arc groove
Select the circular arc groove of the valve seat for machining testing. There are a total of 57 parts for the valve seat, made of 3Cr13 material. The overall hard alloy tool processing scheme uses PM-4R-D8R1 tool for layered milling, while the high feed tool processing scheme uses 980ML08-MEGA tool for layered milling. The machining of valve seat parts and integral hard alloy cutting tools is shown in Figure 2, and the machining of high feed cutting tools is shown in Figure 3.
According to Table 2, when using recommended tool parameters to process the narrow features of the parts, the metal removal rate of the 980ML high-speed milling cutter of the same specification is 3.16 times and 3.22 times higher than that of the VSM-4E tool, effectively improving the machining efficiency of the parts.
4. Conclusion
From actual machining data, it can be seen that when machining groove type parts, the 980ML high feed tool can effectively reduce tool machining costs and improve machining efficiency. This fully confirms the feasibility of the new 980ML tool's "small cutting depth, high feed" machining scheme.
When the working conditions of the machining center meet the requirements of high-speed milling, the cutting strategy of "small cutting depth, high feed" with 980ML high feed tool should be prioritized. For heavy-duty force type machining centers, due to their low feed rate, traditional solid end mills can be used for slot machining. Both types of cutting tools can be used in conjunction with various machining strategies such as "cycloidal milling" and "wafer milling" (see Figure 5), which can not only improve the machining scheme of part shape, groove and cavity, but also solve the problem of tool limitation caused by differences in speed and machine performance of machining centers, providing more choices for machining in different working environments.
