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Cutting Characteristics of Different Metal Materials

In metal cutting, there will be different materials used to produce CNC machining parts. Different materials have different cutting formation and removal characteristics. How can we master the characteristics of different materials? ISO standard metal materials are divided into six different type groups, each type has unique characteristics in terms of machinability, this paper will summarize them respectively.

Metal materials are divided into six categories

(1) Steel

(2) Stainless steel

(3) Cast iron

(4) Nonferrous metals

(5) Heat resistant alloy

(6) Hardened steel

1. What is steel?

-Steel is the largest material group in the field of metal cutting.

-The steel can be non hardened or quenched and tempered (hardness up to 400HB).

-Steel is an alloy mainly composed of iron (FE). It’s made by melting.

-The carbon content of non alloy steel is less than 0.8%, only Fe and no other alloying elements.

-The carbon content of alloy steel is less than 1.7%, and alloying elements such as Ni, Cr, Mo, V and W are added.

Application: Steel is the largest material group in the range of metal cutting, because it covers several different industrial fields.

The material is usually long chip material, which can form continuous and relatively uniform chips. The specific chip form usually depends on the carbon content.

Low carbon = tough viscous material.

High carbon content = brittle material.

Processing characteristics:

-Long chip material.

-Chip control is relatively easy and stable.

-Low carbon steel is sticky and needs a sharp cutting edge.

-Unit cutting force Kc: 1500 ~ 3100 n / mm 2

-The cutting force and power required for machining ISO P materials are all within the limited range.

2. What is Stainless Steel?

-Stainless steel is an alloy material with at least 11% ~ 12% chromium.

-The carbon content is usually very low (as low as 0.01% maximum).

-The main alloys are Ni, Mo and Ti.

-A dense layer of Cr2O3 is formed on the surface of the steel to make it corrosion resistant.

Application fields: most of the applications belong to oil and gas, pipe fittings, flange, processing industry and pharmaceutical industry. Stainless steel CNC machining services are offered at Junying.

Chip shape: the material forms irregular flake chips, and its cutting force is higher than that of ordinary steel. There are many different types of stainless steel. Chip breaking performance (from easy to almost impossible) varies with the alloy characteristics and heat treatment.

Processing characteristics:

-Long chip material.

-Chip control is relatively smooth in ferrite, but difficult in austenite and duplex.

-Unit cutting force: 1800 ~ 2850 n / mm 2

-High cutting force, chip build-up, heat and work hardening are produced during machining.

3. What is Cast Iron?

-There are three main types of cast iron: gray cast iron (GCI), nodular cast iron (NCI) and vermicular cast iron (CGI).

-Cast iron is mainly composed of Fe-C with relatively high silicon content (1% ~ 3%).

-The carbon content is more than 2%, which is the largest solubility of C in austenite.

-The addition of Cr (CR), Mo (MO) and V (V) to form carbides increases the strength and hardness, but decreases the machinability.

Application: Cast iron is mainly used in auto parts, machine manufacturing and ironmaking.

Chip shape: the chip shape of the material varies from approximately powdery chips to long chips. The power required to process this material group is usually small. *Note: there is a great difference between gray cast iron (usually the chip is nearly powdery) and nodular cast iron, and the chip breaking of the latter is often similar to that of steel.

Processing characteristics:

-Short chip material.

-It has good chip control under all working conditions.

-Unit cutting force: 790 ~ 1350 n / mm 2

-Abrasive wear occurs when machining at a high speed.

-Medium cutting force.

4. What is Nonferrous metal?

-This category includes non-ferrous metals and soft metals with hardness less than 130 Hb.

-The non-ferrous metal (AL) alloy containing nearly 22% Si is the largest part.

-Copper, bronze, brass. If you are requiring brass machining or copper parts, quick turn CNC services are provided here.

Application fields: aircraft manufacturing industry and aluminum alloy automobile wheel manufacturers occupy the leading position.

Although the power required per cubic inch is low, it is necessary to calculate the maximum power required to achieve high metal removal rate.

Processing characteristics:

-Long chip material.

-In the case of alloys, chip control is relatively easy.

-Nonferrous Metals (AL) are viscous and require sharp cutting edges.

-Unit cutting force: 350 ~ 700 n / mm 2

-The cutting force and power required for machining ISO n materials are within the range of finite values.

5. What is Heat Resistant Alloy?

-Heat resistant alloys (HRSA) include many high alloy iron, nickel, cobalt or titanium based materials.

Annealing, rolling, solution treatment, casting, aging treatment.

Characteristics: higher alloy content (cobalt is higher than nickel) can ensure better heat resistance, higher tensile strength and higher corrosion resistance.

Application: this type of alloy with difficult processing are mainly used in aerospace, gas turbine and generator industries. The range is wide, but there is usually a high cutting force.

Processing characteristics:

-Long chip material.

-Chip control is difficult (serrated chip).

-Negative rake angle is needed for ceramics and positive rake angle is needed for cemented carbide.

-Unit cutting force:

For heat resistant alloy: 2400 ~ 3100 n / mm

For titanium alloy: 1300 ~ 1400 n / mm

-The cutting force and power required are very high.

6. What is Hardened Steel?

-From the point of view of processing, hardened steel is the smallest group.

-The group contains quenched and tempered steels with hardness > 45 ~ 65 HRC.

-Generally, the hardness range of hard parts is 55 ~ 68 HRC.

Application fields: the hardened steel is used in various industries, such as automobile industry and its subcontractors, as well as machine manufacturing industry and mold business.

Chip shape: usually continuous, red hot chips. This high temperature helps to reduce the KC1 value, which is very important to help solve the application problems.

Processing characteristics:

-Long chip material.

-Relatively good chip control.

-Negative rake angle required.

-Unit cutting force: 2550 ~ 4870 n / mm 2

-The cutting force and power required are very high.

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