The key role of end mills in mold manufacturing

End mills are core processing tools in mold manufacturing, and their performance directly determines the precision, efficiency and service life of molds. The following is an analysis of their key roles from three dimensions: technical realization, process adaptation and quality assurance:

First, the executor of the precision in the processing of complex surfaces

High-precision engraving of three-dimensional curved surfaces

In the surface processing of automotive body panel molds, solid carbide end mills, in combination with five-axis linkage machine tools, can achieve continuous interpolation cutting of curved surfaces. For example, when processing bumper molds, A ball-end end mill with a helix Angle of 45° and a cutting edge arc radius of 0.2mm is adopted. Through the contour milling strategy with a step distance of 0.05mm, the contour error of the profile surface is controlled within ±0.02mm, meeting the requirements of grade A surface smoothness.

Efficient forming of fine structures

In the manufacturing of precision electronic molds, micro-diameter end mills (with a diameter of ≤0.5mm) can be used to process 0.3mm wide heat dissipation grooves for the middle frame of mobile phones and 00-level concentric steps for camera holes. For example, when processing the mold for the back cover of a certain brand of mobile phone, a coated hard alloy end mill with a diameter of 0.3mm is used, combined with a feed rate of 10μm, which can complete the processing of a fine flow channel with a depth of 0.1mm in one go, avoiding the cumulative error caused by multiple clamping.

Stable processing of deep cavity structures

For the deep cavity structure of the mold core (with a depth-to-diameter ratio > 5), long-edge end mills achieve rigid processing by optimizing the core thickness and chip removal groove design. For instance, when processing the cooling water channels of injection molds, using a helical groove end mill with a diameter of 8mm and an effective cutting length of 80mm, combined with the directional injection technology of coolant, can ensure that the cutting force fluctuation at the bottom of the deep cavity is less than 15%, and the surface quality of the core reaches Ra0.8μm.

Second, a processing hub that is compatible with multiple processes

The process connection between roughing and finishing

In the processing of mold blanks, coarse-toothed end mills (with 3-4 teeth) can quickly remove material allowances by combining a large cutting depth (0.8-1.2mm) with a low rotational speed (800-1200rpm). For instance, when processing a mold for a certain automotive instrument panel, a coarse-toothed end mill with a diameter of 25mm was used, and a single pass could remove 80% of the allowance. Subsequently, a fine-toothed (with 6-8 teeth) finish mill was adopted for semi-finishing with a 0.1mm allowance, resulting in a surface flatness error of less than 0.05mm.

Efficient cutting of hard materials

For quenched die steel (HRC50-55), coated carbide end mills achieve efficient processing of high-hardness materials by optimizing the coating structure and cutting parameters. For example, when processing the quenched slider of a certain mobile phone mold, PVD-TiALN-coated end mills were adopted, combined with a cutting speed of 120m/min and a feed rate of 0.08mm/ tooth. The material removal rate reached 80cm³/min, which was 15 times higher than that of traditional high-speed steel tools, and the tool life was extended to 2000 pieces.

Multi-material composite processing

In the manufacturing of compound molds, end mills need to handle the processing of both steel and non-ferrous metals simultaneously. For example, when processing a certain automotive seat mold, a combined tool with a hard alloy coating at the front end (for processing steel) and a diamond coating at the back end (for processing aluminum alloy) is adopted. The compound processing of the core and the insert is completed in one clamping, avoiding secondary positioning errors and keeping the mold assembly clearance within 0.02mm.

Third, the guarantor of mold quality and service life

Direct control of surface quality

The edge design and coating technology of end mills play a decisive role in the surface quality of molds. For instance, when processing optical molds, using nanostructured AlCrN-coated end mills in combination with micro-cutting of 0.02mm per tooth can achieve a surface roughness of Ra0.1μm for the molds, reducing the subsequent polishing workload by more than 50%, and at the same time avoiding the deformation of the mold surface caused by polishing.

Thermal deformation and stress release control

In large-scale mold processing, end mills control processing thermal deformation through layer-by-layer cutting and cooling strategies. For example, when processing the mold of a certain automotive engine cylinder block, a coarse-toothed end mill with a diameter of 50mm was adopted, combined with a cutting depth of 0.5mm per layer and intermittent cooling technology, which made the overall thermal deformation of the mold less than 0.03mm, reducing the deformation by 70% compared with the traditional continuous cutting method.

The source guarantee of mold life

The machining accuracy of end mills directly affects the fit clearance and motion accuracy of the die. For example, when processing the slider mechanism of precision injection molds, a fine-toothed end mill with a diameter of 10mm and a cutting edge arc radius of 0.05mm is adopted. This enables the fit clearance between the slider and the guide rail to be controlled within 0.01mm, increasing the mold life to over one million times, which is 30% longer than the conventional processing method.