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Classification And Special Characteristics of Stamping Materials

In daily life, as long as mass-produced products need to use molds. Because of the different characteristics of the products, the materials used in stamping metal products are also different. Today we come to understand the codes, physical characteristics of various commonly used stamping materials, and how to correctly select stamping oil according to the stamping materials.

SUS (Stainless Steel)

Common stamping material number codes: SUS301 (spring steel, magnetic), SUS302 (appearance stainless steel), SUS304 (non-magnetic), SUS430 (magnetic, easy to rust).

Physical properties: Specific gravity: 7.95; Tensile strength: 53kgf/mm² or more.

The surface has a metallic luster and is not easy to rust. It does not require surface treatment and cannot be used as an electroplating base plate, but electrolysis can be used. Generally used in appearance structural parts such as refrigeration, air conditioning, home appliances, and decoration.

Material specifications:

Material thickness range: 0.1~10.0mm, more than 10.0mm need to be customized.

Material width range: the widest 5′(1524mm), generally 4′(1219mm or 1250mm).

According to the appearance of the material itself, it can be divided into matte, shiny, mirror, brushed, and so on. For special products, to protect the surface gloss from being damaged, another layer of PVC film is needed for protection.

Note: The general tolerance of material thickness is +0, -0.08mm, for example, T=2.0mm, the actual measurement is qualified within the range of 2.0-1.92mm. Because stainless steel is widely used, we will focus on understanding it.

• What kind of steel is stainless steel?

Stainless steel is a type of steel. Steel refers to the content of carbon (C) below 2%, called steel, and more than 2% is iron. The addition of chromium (Cr), nickel (Ni), manganese (Mn), silicon (Si), titanium (Ti), molybdenum (Mo), and other alloying elements in the smelting process improves the performance of the steel and makes the steel corrosion-resistant Sex (that is, no rust), is what we often call stainless steel.

• Why are there different steel grades for stainless steel?

In the smelting process of stainless steel, due to the different types of added alloying elements, the amount of addition of different varieties is different.

Its characteristics are also different. In order to distinguish them, different steel grades are added. The following is a table of the “alloying elements” content of different steel grades of commonly used decorative stainless steels for reference only:

• What kind of stainless steel is not easy to rust?

There are three main factors that affect stainless steel corrosion:

1.  the content of alloying elements, generally speaking, the content of chromium in 10.5% steel will not rust easily. The higher the content of chromium and nickel, the better the corrosion resistance. For example, the content of nickel in 304 material is 8-10%, and the content of chromium reaches 18-20%. Such stainless steel will not rust under normal circumstances.
2.  The smelting process of the manufacturer will also affect the corrosion resistance of stainless steel. A large stainless steel plant with good smelting technology, advanced equipment and advanced technology can guarantee the control of alloying elements, the removal of impurities, and the control of the cooling temperature of the billet, so the product quality is stable and reliable, the internal quality is good, and it is not easy to rust. On the contrary, some small steel mills have backward equipment and technology. During the smelting process, impurities cannot be removed, and the products produced will inevitably rust.
3. the external environment, a dry and ventilated environment is not easy to rust. However, the air humidity is high, continuous rainy weather, or the environment with high pH in the air is easy to rust. 304 stainless steel, if the surrounding environment is too bad, it will rust.

• Stainless steel is without magnetism, is it good stainless steel without magnetism? If the microstrip is magnetic, isn’t it 304?

Many customers go to the market to buy stainless steel and bring a small magnet with them. Without magnetism, there will be no rust. In fact, this is a misunderstanding. The non-magnetic stainless steel strip is determined by the structure of the structure. During the solidification process, the molten steel will form “ferrite”, “austenite”, “martensite” and other stainless steels with different structures. Among them, ” Ferritic” and “Martensitic” stainless steels are all magnetic. The “austenitic” stainless steel has good comprehensive mechanical properties, process performance, and weldability, but only in terms of corrosion resistance, the magnetic “ferritic” stainless steel is stronger than the “austenitic” stainless steel. At present, the so-called 200 series and 300 series stainless sheets of steel with high manganese content and low nickel content in the market are not magnetic, but their performance is very different from that of 304 with high nickel content. Instead, 304 has undergone stretching, annealing, polishing, casting, and other processes. Processing will also be micro-magnetic, so it is a misunderstanding and unscientific to judge the quality of stainless steel without magnetism.

• Why does stainless steel rust?

When brown rust spots (spots) appeared on the surface of stainless steel, people were surprised: “Stainless steel does not rust, and rust is not stainless steel. It may be that there is a problem with the steel.” In fact, this is a one-sided misconception about the lack of understanding of stainless steel. Stainless steel can also rust under certain conditions.

Stainless steel has the ability to resist atmospheric oxidation, that is, non-rust, and it also has the ability to resist corrosion in media containing acid, alkali, and salt, which is corrosion resistance. However, the size of its anti-corrosion ability varies with the chemical composition of the steel itself, the mutual state, the use conditions, and the type of environmental media. Such as 304 material, in a dry and clean atmosphere, it has absolutely excellent corrosion resistance, but it is moved to the seaside area, in the sea fog containing a lot of salt, it will quickly rust. Therefore, it is not any kind of stainless steel, which is corrosion-resistant and does not rust at all times.

SPCC, CRS (Cold Rolled Sheet), SPCD (Stretch Cold Sheet), SPCE (Special Cold Sheet For Drawing）

Physical properties: specific gravity: 7.85, tensile strength: 28kgf/mm² or more.

The surface of the material has a gray luster, and the surface is easy to be scratched, and it is easy to rust in contact with the air. In order to prevent contact with the air, the surface of the material is generally coated with anti-rust liquid. It is very suitable as a primer for surface materials, such as electro-galvanized and white zinc. plate)

Material specifications:

Material thickness range: 0.25~3.2mm. Must be customized in advance if the diameter is above 3.2mm.

Material width range: the widest 5′(1524mm), generally 4′(1219mm or 1250mm).

Note: The general tolerance of material thickness is +0, -0.08mm, for example, T=2.0mm, the actual measurement is qualified within the range of 2.0-1.92mm.

AL (Aluminum Plate)

Common material number codes for stamping: A1100P-O (O stands for soft material, no hardness), A1050P, A5052H32P, AL6061T6, AL6063T5, etc.

Physical properties: Proportion: 2.75. Tensile strength: A5052H32P=25kgf/mm² or more, A1100P, A1200P=7 kgf/mm² or more, AL6061T6=27kgf/mm² or more.

The surface of the material itself has a metallic white luster and is very easily corroded by air. It needs another layer of PVC film to protect it. Suitable surface treatments include anode treatment, conductive oxidation treatment, etc.

SPGC

Physical properties: Proportion: 8.25. Tensile strength: above 40～55kgf/mm².

The surface of the material has metallic white luster, has patterns, and is not easy to be oxidized. Once oxidized, white spots will appear. It is not suitable for surface treatment of the bottom plate, and the material itself is not suitable for electroplating.

Material specifications: Material thickness: 0.4~3.2mm, above 3.2mm must be customized in advance.

Material width: the widest 5’ (1524mm), generally 4’ (1219mm or 1250mm)

Note: The general tolerance of material thickness is +0, -0.08mm, for example, T=2.0mm, the actual measurement is qualified within the range of 2.0-1.92mm.

SPHC、HRS

Physical properties: Specific gravity: 7.85, tensile strength: 41～52kgf/mm² or more.

The surface of the material has a black-gray luster, and the surface is hard and will not be scratched, but it is easy to be oxidized and corroded. The surface needs to be removed before production. The material itself cannot be used for electroplating, but it can be used for external surface paint, powder spraying, etc.

Material specifications: Material thickness: 1.4~6.0mm. Must be customized in advance for 6mm or more.

Material width: the widest 5′(1524mm), generally 4′(1219mm or 1250mm).

Note: The general tolerance of material thickness is +0, -0.08mm, for example, T=2.0mm, the actual measurement is qualified within the range of 2.0-1.92mm.

CU (Copper Plate)

Common material number codes for stamping: C1020P-O (O stands for soft material, no hardness), C1020P-1/2H (Vickers hardness HV75～120) 1/4H HV=60～100 H HV=80 and above.

Physical properties: specific gravity: 8.9, tensile strength: O material = more than 20kgf/mm², 1/4H material = 22-28 kgf/mm², 1/2H material = 25 ~ 32kgf/mm², H material = more than 28 kgf/mm² .

The copper material has very good electrical and thermal conductivity, an excellent stretching process, and excellent weldability and corrosion resistance. It can be used for wire drawing, polishing, pickling, electroplating, etc.

Material specifications: Material thickness: 0.3mm or more. Material width: generally 2’, that is, 610mm, if it exceeds the range, it must be customized in advance.

Note: The general tolerance of material thickness is +0, -0.08mm, for example, T=2.0mm, the actual measurement is qualified within the range of 2.0-1.92mm.

How to Choose Stamping Oil For Stamping Materials of Different Materials?

The application of stamping oil is very wide, but not every stamping plant will use stamping oil. In order to save surface cost, some factories may use waste oil, engine oil, etc., seldom use professional stamping oil in order to save surface cost. . In the stamping process, due to the different materials to be stamped, the working speed of the stamping machine used is different, the stretch coefficient of the workpiece is different, the shape of the workpiece is different, and the subsequent process requirements are different. These factors also determine the stamping oil they use. It’s different.

Therefore, when selecting stamping oil, you must carefully investigate the following issues:

1. What kind of stamping process: punching? Deepen? Deep drawing and thinning? bending?
2. The material of the workpiece: what kind of steel? Aluminum, copper, alloy, silicon steel sheet?
3. What is the stretch coefficient? How many times to deepen?
4. What is the tonnage of the punching machine? Speed of work?
5. What is the shape of the workpiece? When trying to deepen, what is the problem that the scrap shows?

To understand the actual situation of customers in response to these specific problems, can we more accurately select the appropriate stamping oil. At present, the stamping industry is still accustomed to using oil-based stamping oil. In most cases, the oil-based stamping oil formula must be selected according to the factory’s usage habits.

For some common stamping materials and materials, what are the specific requirements when selecting stamping oil?

1. If the silicon steel sheet is stamped, the silicon steel sheet is a material that is relatively easy to punch. Most of them require that the surface of the workpiece be quickly dried after punching, and no oil remains. At the same time, it is necessary to prevent burrs during punching and prolong the service life of the mold. Therefore, if it is the stamping oil of silicon steel sheet, choose a stamping oil that has a slightly higher viscosity and can be volatile, does not produce carbon deposits after annealing, and has a certain anti-rust performance.
2. If you are stamping tin-plated steel, you should consider choosing a stamping oil that does not contain chlorine to prevent the surface of the workpiece from whitening.
3. If it is stamping aluminum or aluminum alloy, stamping oil containing chlorine and sulfur additives cannot be used, otherwise it is very easy to be oxidized. Generally, it is recommended to use a stamping oil with a neutral pH.
4. If the stainless steel plate is stamped, work hardening is likely to occur during the stamping process. It is required to use stamping oil with high oil film strength and good sintering resistance, and the stamping oil must have a certain viscosity and good cooling properties.
5. If you are punching copper or copper alloys, you cannot choose punching oils containing chlorine and sulfur additives, but you should choose punching oils with oily agents and good fluidity.
6. If you are punching stainless steel, it is generally recommended to use stainless steel special punching oil, which requires high extreme pressure, and the workpiece has no burrs and has a significant protective effect on the mold.

According to whether volatility is required, stamping oil can be simply divided into non-volatile stamping oil and volatile stamping oil. Volatile stamping oil is especially suitable for high-strength operations such as punching, stamping, tapping, and tapping. At the same time, it is also very suitable for plastic forming. The operator should determine which formula is more suitable according to the requirements of stamping materials, process characteristics, and process characteristics after processing.

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