Serrated tools for processing molds

The series of end mills with serrated cutting edges and chip breakers developed by Iscar Japan include indexable ISO inserts, spiral-edge milling inserts (independently developed), integral end mills, and ball-end vertical milling cutters. Milling cutters, circular blade machine clamp-type end mills, etc. Among them, the round insert clamp-type end mills with chip dividing grooves and chip breakers and the fine milling end mills with alternating rough and fine cutting edges have shown excellent cutting performance in mold processing.

1Clamp-type end mills with round blades and chip breakers

Most of the rough machining of molds use round-blade machine clamp-type end mills, which are characterized by circular blades and high strength; when the cutting depth is small, the chip can be thinned and the feed rate can be increased. However, when machining molds, if the tool overhang is large, problems such as high cutting resistance and high-frequency vibration will occur. The clamp-type end mills with round blades with chip breakers and chip breakers are the first end mills with serrated cutting edges and round blades, which better overcome the above-mentioned defects.

(1) Features of Milling Cutter

①Adopt serrated cutting edge: The serrated cutting edge can break the chips into fine chips; the direction of the cutting force is dispersed and the occurrence of high-frequency vibration is suppressed; the contact length of the serrated cutting edge with the workpiece is longer than that of the ordinary round blade machine The clip-on end mill is longer, which can make the chip thinner, thereby increasing the feed per tooth. This tool is suitable for milling of molds with a long overhang (the overhang of a 63mm end mill can reach 400mm), and it is recommended to use medium and low speed (80～120m/min) processing. The clip-on end mills with round blades with chip breakers are recommended for mold processing with overhang length of 150mm or more.

②The structure of the sipe: the positioning of the blade is determined by the combination of the quadrilateral shim where the shim is installed and the two sides of the bottom of the blade; the cutting force acting on the tip is determined by the positioning of the two sides of the bottom of the blade and the shim It can withstand the surface, so stable cutting can be realized.

③The phase of the cutting edge: the cutting edge of the round insert clamp end mill with chip breaker and chip breaker is composed of 12 convex cutting edges, and the corresponding included angle between each two cutting edges is 30° . For a 5-tooth end mill with φ63mm, the phase misalignment angle of the cutting edge from one insert to the next is 30°/5u003d6°. Therefore, the cutting force direction is dispersed while the chips are broken, thereby suppressing the high-frequency vibration caused by the large overhang of the tool.

④Common circular blades can be used: the structure of the circular blade machine clamp end mill with chip splitter and chip breaker is also suitable for the installation of ordinary circular slices, that is, two circular blades can be used on one type of milling cutter.

(2) Precautions for use

①Cutting width: Under the processing conditions with large tool overhang length, setting the cutting width to more than 60% of the usual cutting width can achieve stable processing. If the diameter of the milling cutter is φ63mm, a cutting width of 38mm or more can be selected; if the cutting width is reduced to less than 50%, high-frequency vibration will occur. When the overhang length of the tool is large, the deflection of the tool holder increases. When a cutting width of more than 60% is selected, the direction of deflection can make the cutting resistance act in the opposite direction to the cutting force, which is balanced with the feed force to achieve stability. If the cutting width is reduced below 50%, the pressure angle becomes a negative angle, and the cutting resistance is inconsistent with the feed direction, which will cause vibration. It can be seen from the results of the cutting width influence test that the depth of cut can be increased when the cutting width is larger.

②Machining deep mold cavity: When processing deep mold cavity on vertical machining center, if chip removal is not smooth, the phenomenon of chip entanglement will occur. At this time, should we use strong compressed air to blow out the chips, or use cutting fluid to prevent the chips from being entangled? These issues should arouse sufficient attention.

(3) Comparison with ordinary circular blade machine clamp-type end mills

Comparative cutting results of clamp-type end mills with chip-breaking round inserts with chip-breaking grooves and ordinary clamp-type end mills with round inserts show that the life of the new tool is increased by 6 times (extended from 20 minutes to 120 minutes) , The number of tools required for processing a workpiece is reduced from 12 to 2, thereby reducing the number of tool changes and improving processing efficiency. Since the chips can be divided into fine chips, the chip evacuation is more smooth.

2Fine milling end mills with alternating rough and fine cutting edges

The number of chip pockets of this end mill is an even number, and an end mill is staggered with fine milling cutting edges and serrated rough milling cutting edges.

The characteristics of the milling cutter are: ①Rough milling and finishing milling can be completed with one tool, reducing the number of tools used; ②No high-frequency vibration will be generated when milling the shoulder of thin-walled parts, and stable cutting can be achieved ③The difference between the rough milling cutting edge diameter and the finishing milling cutting edge diameter is 0.05mm, and there will be no rough milling marks on the machined surface.

Compared cutting results with this end mill (EFS) and ordinary solid carbide end mills show that compared with ordinary end mills, the depth of cut is doubled, the processing time is reduced by half, and the tool life Increased to 7 times, no rough milling marks are left on the machined surface, and the finish machining is perfectly realized.