Technical requirements for cutting parting tool operation

Mon Jul 04 11:47:37 CST 2022

In modern metal processing, cutting can be carried out on automated equipment with complex bar feed mechanisms or on state-of-the-art CNC machines. However, if the carbide grade of cutting parting tool is not chosen properly, it may lead to shutdown, tool damage, scraping workpiece, or even destroy the machine tool.

In order to obtain the ideal cutting effect, it is necessary to understand the cutting mechanism in detail. Many of these variables must be considered :(1) workpiece material and shape; (2) machine tools; (3) cutting edge related to the central axis of the part; (4) Type of blade and chip breaker; (5) Hard alloy grade and coating; (6) Other cutting parting tool conditions that affect tool life. Today we're going to talk about the first variable.

Workpiece material and shape

To simplify the problem, three of the most common workpiece shapes are discussed here -- solid, hollow, and irregular shapes requiring intermittent cutting (such as square and hexagonal materials and hollow materials with inconsistent wall thickness).

Materials are generally divided into 7 types. For simplification, they are divided into three types.

1. Material that requires a sharp positive rake cutting edge

It includes superalloys, titanium alloys, aluminum, plastics and other non-ferrous metals, as well as austenitic stainless steel. Sharp cutting edges prevent hardening of these materials. For example, sharp cutting edges allow for high cutting speeds and feed rates, and neatly cut the si-al alloy without leaving a winding edge. It is also suitable for most non-metallic materials (such as plastics, nylon and other soft non-processing materials).

2. Materials that require zero or negative rake cutting edges for cutting

It includes standard carbon steel, alloy steel and cast iron. Zero or negative rake Angle increases the strength of the cutting edge and allows for higher feed rates and prevents edge damage during intermittent cutting. For most materials that produce continuous long chip, this type of cutter with zero or negative rake Angle should be used, which is the type most often used in industrial production.

3. Include materials that require cutting tools with chip breakers

The types of chip breakers are discussed later. These materials, under normal cutting speed and feed rate conditions, will produce filamentous long chips, such as 52100# steel and other high grade steels used in the bearing industry.

Chip breaker is usually required in machine tool processing. When machining soft mild and alloy steels at low feed rates, long and undesirable chips are often produced, requiring frequent operator downtime to remove chips. This reduces productivity and endangers operators because the chips are very sharp. The same problem occurs when some types of superalloys are machined at very low cutting speeds.

When selecting the cutting parting tool, the geometric Angle of the tool can be the same as that used for turning or even milling. Usually if a material is machined with a large forward turning or milling tool, the same geometric Angle can be selected when the cutting operation is performed.