Common Knowledge and Usage of Metal Cutting Tools

When selecting the angle of the cutting tool, multiple factors need to be considered, such as workpiece material, cutting tool material, processing properties (rough and fine machining), etc., and must be selected reasonably based on the specific situation. The commonly used tool angle refers to the marked angle used for manufacturing and measurement. In actual work, due to different installation positions of the tool and changes in the cutting direction, the actual working angle and marked angle may differ, but the difference is usually very small.

The materials used for manufacturing cutting tools must have high high-temperature hardness and wear resistance, necessary bending strength, impact toughness, and chemical inertness, good processability (such as cutting, forging, and heat treatment), and are not easily deformed.

Usually, when the material hardness is high, the wear resistance is also high; When the bending strength is high, the impact toughness is also high. But the higher the hardness of the material, the lower its bending strength and impact toughness. Due to its high bending strength, impact toughness, and good machinability, high-speed steel is still the most widely used tool material in modern times, followed by hard alloys.

Polycrystalline cubic boron nitride is suitable for cutting high hardness quenched steel and hard cast iron, etc; Polycrystalline diamond is suitable for cutting non ferrous metals, alloys, plastics, and fiberglass; Carbon tool steel and alloy tool steel are now only used as tools such as files, dies, and taps.

Hard alloy indexable blades have now been coated with hard layers of titanium carbide, titanium nitride, alumina, or composite hard layers using chemical vapor deposition. The developing physical vapor deposition method can not only be used for hard alloy cutting tools, but also for high-speed steel cutting tools, such as drills, hobs, taps, and milling cutters. Hard coatings act as barriers to chemical diffusion and heat conduction, slowing down the wear rate of cutting tools, and increasing the lifespan of coated blades by approximately 1-3 times compared to uncoated blades.

Due to the increasing number of difficult to machine materials used in parts working at high temperatures, high pressures, high speeds, and corrosive fluid media, the automation level of cutting and the requirements for machining accuracy are becoming increasingly high. In order to adapt to this situation, the development direction of cutting tools will be to develop and apply new cutting tool materials; Further develop the vapor deposition coating technology for cutting tools, depositing higher hardness coatings on high toughness and strength substrates to better solve the contradiction between the hardness and strength of cutting tool materials; Further develop the structure of indexable cutting tools; Improve the manufacturing accuracy of cutting tools, reduce differences in product quality, and optimize the use of cutting tools.

According to the cutting motion mode and corresponding blade shape, cutting tools can be further divided into three categories. General tools, such as turning tools, planers, milling cutters (excluding formed turning tools, formed planers, and formed milling cutters), boring cutters, drill bits, reamers, and saws; Forming tools, such as forming turning tools, forming planers, forming milling cutters, broaches, conical reamers, and various thread processing tools, have the same or nearly the same shape as the cross-section of the workpiece being processed; Generative cutting tools are used to process the tooth surface of gears or similar workpieces, such as hobs, gear shapers, shaving cutters, bevel gear planers, and bevel gear milling cutters.

The structure of various cutting tools is composed of a clamping part and a working part. The clamping and working parts of the overall structure of the cutting tool are all made on the cutting body; The working part (tooth or blade) of a toothed cutting tool is embedded on the tool body.

There are two types of clamping parts for cutting tools: with holes and with handles. Holed cutting tools rely on inner holes to be installed on the spindle or spindle of the machine tool, and transmit torsional torque through axial or end face keys, such as cylindrical milling cutters, sleeve type face milling cutters, etc.

There are usually three types of tools with handles: rectangular handles, cylindrical handles, and conical handles. Turning tools, planers, etc. are generally rectangular shanks; The taper of the conical handle bears axial thrust and transmits torque through friction; Cylindrical shank is generally suitable for smaller Fried Dough Twists drills, end mills and other tools. During cutting, the torsional moment is transmitted by the friction generated during clamping. Many cutting tools with handles are made of low alloy steel, while the working part is welded with high-speed steel to form the two parts.

The working part of a cutting tool is the part that generates and processes chips, including the blade, the structure that breaks or folds the chips, the space for chip removal or storage, and the channel for cutting fluid.

The working part of some cutting tools is the cutting part, such as turning tools, planers, boring cutters, and milling cutters; Some cutting tools include cutting and calibration parts, such as drills, reamers, internal surface broaches, and taps. The function of the cutting part is to remove chips with the blade, while the function of the calibration part is to polish the machined surface that has been cut and guide the tool.

There are three types of structures for the working part of the cutting tool: integral, welded, and mechanically clamped. The overall structure is to make cutting edges on the tool body; The welding structure is to braze the blade onto the steel blade body; There are two types of mechanical clamping structures, one is to clamp the blade onto the blade body, and the other is to clamp the brazed blade onto the blade body. Hard alloy cutting tools are generally made into welded structures or mechanically clamped structures; Ceramic cutting tools all adopt mechanical clamping structures.