月: 2023年1月

What Is High Speed Steel?

High Speed Steel is one of the materials used for cutting tools in metalworking.

It was developed to be a material for tools that enable cutting of metal materials at higher speeds. High speed steel is a high carbon steel with alloying elements. It is sometimes referred to as “HSS” for short.

HSS can be used for almost all workpiece materials, but the cutting point temperature must be 600°C or lower because the hardness of the steel decreases rapidly at temperatures above that.

Uses of High Speed Steel

High Speed Steel, as the name implies, is a material developed for high speed cutting. It is often used for cutting tools and blades. At the time of its development, it was designed for high-speed cutting, but today, cemented carbide tools, made from cemented carbide, are more capable of high-speed cutting.

In addition to cutting tools, it is also used for cold working tools and for molds for plastic forming, taking advantage of its superior wear resistance and hardness.

Properties of High Speed Steel

High Speed Steel is the hardest type of steel, but it is softer than cemented carbide, making it resistant to impact during machining. It has the advantage of being less prone to defects such as tool cracking, chipping, and breakage, and is superior when chipping resistance is required or when cost is to be reduced.

On the other hand, it has the disadvantage of being susceptible to heat during machining due to its property of rapidly losing hardness at temperatures above about 600°C. Therefore, care must be taken to prevent heat from being applied to the tool, such as by reducing the cutting speed and using coolant appropriately.

Compared to cemented carbide tools, which excel in cutting speed, wear resistance, and heat resistance, high speed steel has many disadvantages. Especially in the machining of mass-produced products, where machining efficiency directly affects cost, more parts can be machined in the same amount of time using cemented carbide tools.

As a result, even though carbide tools cost more per tool, in many cases, carbide tools are superior in terms of cost because of their longer life and faster machining.

Types of High Speed Speed Tool Steel

High Speed Steel can be roughly divided into two types: tungsten-based (W-based) and molybdenum-based (Mo-based).

1. Tungsten Type

Tungsten high speed steels are high-carbon steels to which tungsten or other elements are added.

18% tungsten is the basic type, also called 18-4-1 type, where 18 stands for tungsten, 4 for chromium (Cr), and 1 for vanadium (V). It is mainly used for lathe turning tools.

2. Molybdenum Type

Molybdenum high-speed steels were developed as a lower-cost version of tungsten-based steels. It contains about 5% molybdenum and 6% tungsten.

Compared to the tungsten type, it is superior in hardness and viscosity, and is used for drills that are subject to impact because of its impact resistance.

The addition of cobalt to both tungsten-based and molybdenum-based steels increases their wear resistance compared to those without cobalt, and they are selected when stronger wear resistance is required.

Other Information on High Speed Steel

Hardness of High Speed Steel

High Speed Steel has a Vickers hardness of 722 HV. S45C, a carbon steel commonly used in general steel products, is 201-269 HV, indicating that it is very hard among steels.

Cemented Carbide has a hardness of 1700-2050 HV, which is about three times that of high speed steel, making it the most frequently used tool in the cutting process.

Therefore, high speed steel, which is inexpensive and easy to regrind with a grinder, is second only to cemented carbide tools in the field of machining.

What Is an Ingot?

An ingot is a mass of molten metal or alloy that is cast into a mold, cooled, and solidified. It serves as the primary material for various metal fabrication processes like rolling, extrusion, and machining.

There are two main categories of ingots based on their deoxidization levels: rimmed steel (insufficiently deoxidized) and killed steel (fully deoxidized). Killed steel is generally higher in quality due to reduced impurities compared to rimmed steel.

Uses of Ingots

Ingots are foundational materials for a wide range of metal products. Killed steel ingots, being of higher quality, are used in applications requiring durability and precision, such as in special steel and structural steel products.

Rimmed steel ingots, while lower in quality than killed steel, are cost-effective and used for general structural steel applications. They are also preferred for thin plates due to their fine cast surface.

Types of Ingots

Ingots vary in size, shape, and use and are categorized into ingots, blooms, slabs, and billets.

• Ingots
  General raw material cast ingots, sized for versatile melting and processing.
• Bloom
  Blooms, with a rectangular or near-square cross-section, are used for steel strip rolling and as material for steel shapes like H steel.
• Slab
  Slabs, with square cross-sections, are used for rolling into thin sheets and plates at high temperatures.
• Billet
  Billets, mainly cylindrical, are used for extrusion processing to form tubes, rods, and various shapes.

What Is Metal Fiber?

Metal fiber, characterized by its thin, fibrous form, is manufactured in diameters ranging from less than 10 µm to around 200 µm. Production methods include pultrusion, melt spinning, cutting, and recently developed techniques such as chemical vapor deposition (CVD).

Historically utilized for their decorative qualities, gold and silver threads have evolved into a focus on composite materials development, producing fibers from materials like stainless steel, aluminum, iron, nickel, copper, tungsten, molybdenum, and beryllium.

Uses of Metal Fiber

Employed in specialized areas such as composites, reinforcement, filtration, and static elimination, metal fibers like stainless steel are incorporated into fabrics for antistatic purposes. Decoratively, gold and silver retain their traditional roles, while iron in cotton form is used for polishing. Metal fibers enhance the durability and rust resistance of various filters and, due to their conductive nature, serve as electromagnetic wave shields.

Despite their utility, metal fibers’ hardness and potential for skin irritation limit their use in clothing, though they find application in bra cup shaping materials and wires.

Principles of Metal Fiber

1. Drawing Method

The pultrusion method involves stretching metal wire through dies of progressively smaller sizes to form thin metal fibers.

2. Melt-Spinning Method

Metal is melted and extruded through nozzles to produce fibers in the melt-spinning method.

3. Cutting Method

A thin metal sheet is wound around the spindle of a cutting machine, where it is cut into fibers.

Types of Metal Fiber

Metal fibers vary in form, including “tow” (bundles of fibers), “web” (cotton-like), “needlepunched web” (processed into sheets), and “sintered product” (porous materials made by sintering). Sintered products, known for their permeability and resistance to heat and corrosion, alongside other forms like nonwovens and felts, can be converted into yarn for reinforcing composite materials.

How to Select Metal Fiber

Chosen for their electrical and thermal conductivity, tenacity, and resistance to heat, metal fibers are ideal for industrial uses. However, their hardness and susceptibility to metal fatigue when bent repeatedly make them less suitable for direct skin contact applications.

Structure of Metal Fiber

The focused wire drawing technique, a common manufacturing method, involves pulling bundled filaments through a mold to form composite wire, and then dissolving the tubing to yield long fibers. This process produces fibers with minimal thickness variation and enables the production of ultrafine fibers under 200 nm.

What Is Copper Oxide?

Copper oxide is an oxidized form of copper, existing in two types: copper oxide (I) and copper oxide (II).

Copper oxide (I) is produced by reducing an aqueous solution with Fehling’s solution, while copper oxide (II) is obtained by red heating copper in air.

Uses of Copper Oxide

1. Copper Oxide (I)

Used in rectifiers, red pigments, glazes, fungicides, antifouling paints, and glass coloring. Copper oxide (I) paints on ship bottoms prevent barnacle attachment, enhancing fuel efficiency. It is also used in catalysts for photovoltaics, seed sterilization, synthetic resins, and enzyme production.

2. Copper Oxide (II)

Employed as an oxidizing agent, catalyst, pigment, ceramic glaze, and coloring agent for glass. Known for making phthalocyanine blue pigment, it is also used in semiconductors, plating chemicals, paints, rayon manufacturing, and wood preservatives. In ceramics, it contributes to red coloration when reduction is fired with glaze.

Characteristics of Copper Oxide

1. Copper Oxide (I)

Also known as cuprous oxide, it is a red powder (Cu2O) that oxidizes to copper oxide (II) in humid air. It has a molecular weight of 143.08, a specific gravity of 5.88, and is soluble in hydrochloric acid and ammonia solutions.

2. Copper Oxide (II)

Also known as cupric oxide, it is a black powder (CuO) found in natural black copper ore. It has a molecular weight of 79.55, a specific gravity of 6.31, and is soluble in hydrochloric acid, ammonia solutions, and alkaline hydroxide solutions.

1. Oxidation and Reduction of Copper Oxide

Experiments demonstrate the oxidation and reduction principles of copper oxide. Copper transforms into copper oxide (II) when heated, losing properties like metallic luster and conductivity. Reduction methods include using carbon or hydrogen and reverting it back to metallic copper.

2. Copper Oxide Production Method

Copper Oxide (I) is produced through electrolytic and chemical processes. Copper Oxide (II) is obtained through heat oxidation, chemical processes, and direct or indirect wet processes.

What Is a Magnetorheological Fluid?

Magnetorheological fluid, coated with a surfactant 2 to 3 nm thick, is stably dispersed in mediums such as oil or water.

It consists of magnetic fine particles, such as magnetite, blending ferromagnetism of magnetic materials with the fluidity of liquids. This fluid can alter its viscosity and shape under the influence of a magnetic field, provided by a permanent magnet or similar means, exhibiting fluidity with changing magnetic fields. In a magnetic field, its apparent viscosity and specific gravity vary with the field’s strength.

Uses of Magnetorheological Fluids

Magnetorheological fluids are primarily used in magnetic fluid seals, including dust seals in HDDs to prevent static electricity and vacuum seals in semiconductor manufacturing equipment. They are also utilized in speakers and dampers, increasingly in automobile shock absorbers, and as contrast media for cancer diagnosis in the medical field.

Principle of Magnetorheological Fluids

The magnetorheological fluid contains magnetite, acting magnetically only within a magnetic field. Outside a magnetic field, it behaves as a regular fluid but can align like a magnet when exposed to one. Magnetic particles align along the magnetic force lines between the N and S poles, displaying a spiking phenomenon due to the interplay of the orienting force and the fluid’s interfacial tension.

Magnetite particles are oxidized to non-magnetic hematite upon air exposure, necessitating a protective surfactant coating to maintain their magnetorheological properties.

Types of Magnetorheological Fluids

Magnetorheological fluids vary by solvent type, including hydrocarbon oil-based, water-based, and fluorinated oil-based fluids. Key to their formulation is the selection of a compatible surfactant with the base fluid, essential for the intended application.

These fluids can be produced through methods like coagulation, pyrolysis, physical vapor deposition (PVD), laser evaporation, chemical vapor deposition, and continuous vacuum deposition on an active liquid surface, with the latter involving surfactants and oil on a rotating vacuum drum and metal heated to around 2,000°C to form fine particles.

Structure of Magnetorheological Fluids

As a magnetic colloidal solution, the magnetorheological fluid comprises ferromagnetic particles (e.g., manganese zinc ferrite or magnetite), a surfactant layer, and a base liquid like water or oil. The ferromagnetic particles, approximately 10 nm in diameter, achieve a stable dispersion through the interaction with the surfactant and base liquid.

The optimal particle diameter is around 9 nm, with a surfactant molecular length of 1.5 nm, balancing the need to prevent agglomeration and ensure sufficient magnetism by optimizing the metallic magnetic material’s concentration in the fluid.

What Is a Fitting?

Fittings are components used in piping systems for joining, branching, or changing the direction of the flow. There are various types, including bent pipes, branch pipes, and T-pipes made from materials like iron, copper, plastic, and clay. Cast iron and ductile iron fittings are specifically used for water and sewage pipes. Additionally, fittings with non-circular or rectangular cross-sections are also common.

Fittings designed for flow channel alterations and branching come in shapes like bend pipes (with angles ranging from 10 to 180 degrees), cross pipes, Y-shaped pipes, and branching pipes. These are also available in cast iron for water piping systems, and certain standards govern the bend angles. Fittings come in various cross-sectional shapes, including elliptical, semicircular, and grooved.

Uses of Fittings

Fittings are essential in numerous industrial applications where flow direction changes, branching, or merging are required. This includes piping systems in chemical plants, power generation plants, construction machinery, refrigeration and air conditioning systems, and hydraulic circuits. Cast iron and ductile iron fittings find extensive use in water supply, sewage, and gas pipelines.

Beyond flow paths, deformed pipes of diverse cross-sections and materials are utilized as structural materials in various machinery and equipment like textile, food, and printing machinery, as well as in medical equipment, office automation devices, and office supplies.

Principle of Fittings

The choice of material for fittings depends on their intended use and includes steel, copper, stainless steel, alloy steel, cast iron, ductile cast iron, and ceramics. Ductile cast iron, known for its high strength and toughness due to graphite spheroidization, is especially suitable for fluid pressure applications.

The connection methods for fittings vary and include welding, flange connections, and screw connections, with the choice dependent on serviceability. Mechanical joints are often used to connect cast-iron pipes to polyethylene pipes, with rubber rings and flanged fittings ensuring a secure seal.

For steel and alloy steel fittings, common manufacturing methods involve bending and welding thin plates or cold rolls forming various types of steel pipes. Precision-deformed tubes are produced through a drawing process, providing an accurate finish without the need for internal cutting or fittings. Cast iron fittings are typically cast using molds, allowing for a wide range of shapes.

What Is Carbon Steel?

Carbon steel is a steel variant where carbon is the primary alloying element added to iron. Besides carbon, it may also contain elements such as manganese, silicon, phosphorus, and sulfur. The carbon content significantly influences the steel’s properties, thus earning the name carbon steel.

While pure iron with negligible carbon content (less than 0.02%) is too soft for practical use, adding carbon enhances its hardness and strength. Carbon steel utilizes this property, offering varied carbon content levels to produce steel with desired characteristics.

Uses of Carbon Steel

Carbon steel is employed in numerous structures, machine components, and everyday items. Its mechanical properties depend on the carbon content and are greatly influenced by heat treatment. Hence, carbon steel is adaptable and finds applications across various sectors. It is standardized based on carbon content, intended use, strength, and composition, and is often chosen over alloy steel due to its cost-effectiveness.

Characteristics of Carbon Steel

Steel with a carbon content ranging from 0.02% to 2.14% is classified as carbon steel. As the carbon content increases, so do hardness and tensile strength, but the material becomes more brittle and less ductile, reducing its impact resistance and workability.

Adjusting carbon content and applying heat treatments like annealing, normalizing, quenching, and tempering can alter these properties. Other elements in carbon steel, such as silicon, manganese, phosphorus, and sulfur, impact its overall characteristics. For example, silicon enhances tensile strength, and manganese improves toughness.

Types of Carbon Steel

Carbon steel can be classified as follows:

1. Classification by Carbon Content

Based on carbon content, carbon steel is divided into low (0.02% to 0.25%), medium (0.25% to 0.6%), and high (0.6% to 2.14%) carbon steel. Low and medium carbon steels are often referred to as ordinary steel due to their widespread use.

2. Classification by Hardness

Carbon steel is categorized into mild and hard steel based on hardness. Mild steel typically contains 0.18% to 0.3% carbon, while hard steel ranges from 0.3% to 1.0% carbon.

There are finer distinctions, such as mild steel (up to 0.12%), semi-soft and semi-hard steel (0.2% to 0.45%), and very hard steel (0.8% to 1.7%). The key difference between mild and hard steel is their response to hardening processes.

3. Classification by Standard Name

Standards for carbon steel classify it based on composition, mechanical properties, and names. Examples include:

• Cold-Rolled Steel Sheet (SPC Material): Typically contains less than 0.1% carbon, suitable for light load applications.
• General Structural Rolled Steel (SS Material): Commonly used for structural and machine parts. SS400 is a notable grade.
• Carbon Steel for Machine Structural Use (S-C Material): Harder and stronger than SS steel, suitable for gears and bearings. Examples include S45C and S50C.
• Carbon Tool Steel (SK): Has higher hardness and strength than S-C steel but loses hardness at high temperatures. Ideal for hand tools.