The cutting performance of copper and the selection of sawing parameters, a detailed explanation of the appearance of copper, the cutting performance of copper, etc.
1. Classification of copper
1. Copper
Red copper is pure copper, also known as red copper. It is not necessarily pure copper. Sometimes a small amount of deoxidizing elements or other elements are added to improve the material and performance, so it is also classified as a copper alloy. China's red copper processing materials can be divided into: ordinary red copper (T1, T2, T3, T4), oxygen-free copper (TU1, TU2 and high-purity, vacuum oxygen-free copper), deoxidized copper (TUP, TUMn), adding a small amount of alloy There are four types of special copper elements (arsenic copper, tellurium copper, and silver copper). Appropriate amounts of lead, tellurium, sulfur, etc. can improve machinability.
2. Brass
Copper alloys with zinc as the main added element have a beautiful yellow color and are collectively referred to as brass. Brass alloys containing less than 36% zinc in copper are composed of solid solutions and have good cutting properties. For example, brass containing 30% zinc is often used to make cartridge cases, commonly known as cartridge case brass or 73 brass. Brass alloys containing between 36% and 42% zinc are composed of solid solution and solid solution. Among them, the most commonly used brass is alloy brass containing 40% zinc. In order to improve the performance of ordinary brass, other elements are often added, such as aluminum, nickel, manganese, tin, silicon, lead, etc. Brass is divided into:
1) Ordinary brass, which is an alloy composed of copper and zinc.
The code name is represented by "H + number", H represents brass, and the number represents the mass fraction of copper. For example, H68 means brass with a copper content of 68% and a zinc content of 32%. Cast brass has a "Z" in front of the code, such as ZH62. H90 and H80 are single-phase, golden yellow, so they are collectively called gold, and are called coatings, decorations, medals, etc. H68 and H59 are duplex brass, which are widely used in structural parts of electrical appliances, such as bolts, nuts, washers, springs, etc. Generally, single-phase brass is used for cold deformation processing and duplex brass is used for hot deformation processing.
2) Special brass
A multi-component alloy formed by adding other alloying elements to ordinary brass is called special brass. Commonly added elements include lead, tin, aluminum, etc., which can be called lead brass, tin brass, and aluminum brass accordingly. The purpose of adding alloying elements. The main purpose is to increase the tensile strength and improve the workmanship.
Code: It is represented by "H + symbol of the main plus element (except zinc) + mass fraction of copper + mass fraction of the main plus element + mass fraction of other elements".
For example: HPb59-1 means that the mass fraction of copper is 59%, the mass fraction of lead as the main additive element is 1%, and the balance is zinc.
3. White copper
Copper alloy with nickel as the main added element. The copper-nickel binary alloy is called ordinary cupronickel; the cupronickel alloy with elements such as manganese, iron, zinc, and aluminum is called complex cupronickel.
4. Bronze
Originally refers to copper-tin alloy, later copper alloys other than brass and white copper are called bronze, and the name of bronze is often preceded by the name of the main added element, such as tin bronze, lead bronze, beryllium bronze and phosphor bronze. Code: The representation method is "Q + main plus element symbol and mass fraction + mass fraction of other elements". For cast products, the word "Z" is added before the code name. According to the production method, tin bronze can be divided into two categories: pressure processing tin bronze and cast tin bronze.
2. Appearance of copper
White copper, brass, red copper (also called "purple copper"), and bronze (blue-gray or gray-yellow) are distinguished by color.
Among them, white copper and brass are easy to distinguish; red copper is pure copper (impurities <1%), and bronze (other alloy components are about 5%) is slightly difficult to distinguish. When it is not oxidized, the color of red copper is brighter than bronze, and bronze is slightly cyan or yellowish and darker; after oxidation, red copper turns black, and bronze is greenish (harmful oxidation of too much water) or chocolate color.
3. Copper sawing performance
From the analysis of cutting force, they are divided into bronze, white copper, brass and red copper from large to small.
Copper is often too sticky, making it difficult to remove chips and easily stick to chips. Therefore, bimetallic band saw blades with large rake angles are generally used for sawing. Because its cutting force is relatively small, some manufacturers also use high-speed sawing. The linear speed is generally set at about 800m/min, which is different from the speed of high-speed aluminum cutting, which is generally 2000m/min and above.
Brass has better cutting performance than copper, just like No. 10 steel compared to No. 45 steel. Mainly because its chip breaking performance is better than that of copper.
Due to the addition of nickel, the thermal conductivity of white copper is not as good as the first two, so the heat dissipation capacity is not as good as the first two, and the tool wear will be greater.
Bronze is the most difficult material to cut among these coppers. Some bronzes used for electrodes and wear-resistant parts have a hardness higher than 40HRC. Therefore, a carbide band saw blade can be used to cut bronze. However, easy-to-cut bronze (with added elements that facilitate cold working) can still be cut with a high-tooth bimetal band saw blade or other superior band saw blades.
