metal work in China

Archive for 8月 2016

Sheet Metal Cutting (Shearing)

By on 31/08/2016   /   Blog   /   1 Comment

Cutting processes are those in which a piece of sheet metal is separated by applying a great enough force to caused the material to fail. The most common cutting processes are performed by applying a shearing force, and are therefore sometimes referred to as shearing processes. When a great enough shearing force is applied, the shear stress in the material will exceed the ultimate shear strength and the material will fail and separate at the cut location. This shearing force is applied by two tools, one above and one below the sheet. Whether these tools are a punch and die or upper and lower blades, the tool above the sheet delivers a quick downward blow to the sheet metal that rests over the lower tool. A small clearance is present between the edges of the upper and lower tools, which facilitates the fracture of the material. The size of this clearance is typically 2-10% of the material thickness and depends upon several factors, such as the specific shearing process, material, and sheet thickness.

The effects of shearing on the material change as the cut progresses and are visible on the edge of the sheared material. When the punch or blade impacts the sheet, the clearance between the tools allows the sheet to plastically deform and “rollover” the edge. As the tool penetrates the sheet further, the shearing results in a vertical burnished zone of material. Finally, the shear stress is too great and the material fractures at an angle with a small burr formed at the edge. The height of each of these portions of the cut depends on several factors, including the sharpness of the tools and the clearance between the tools.

 

shearing-edge-small
Sheared edge

 

A variety of cutting processes that utilize shearing forces exist to separate or remove material from a piece of sheet stock in different ways. Each process is capable of forming a specific type of cut, some with an open path to separate a portion of material and some with a closed path to cutout and remove that material. By using many of these processes together, sheet metal parts can be fabricated with cutouts and profiles of any 2D geometry. Such cutting processes include the following:

 

  • Shearing – Separating material into two parts
  • Blanking – Removing material to use for parts
  • Conventional blanking
  • Fine blanking
  • Punching – Removing material as scrap
  • Piercing
  • Slotting
  • Perforating
  • Notching
  • Nibbling
  • Lancing
  • Slitting
  • Parting
  • Cutoff
  • Trimming
  • Shaving
  • Dinking
Back to Top

sheet metal fabrication material

By on 30/08/2016   /   Blog   /   Leave a comment

Almost 75% of all elements are metals. Metals are used in electronics for wires and in cookware for pots and pans because they conduct electricity and heat well. Most metals are malleable and ductile and are, in general, heavier than the other elemental substances. Two or more metals can be alloyed to create materials with properties that do not exist in a pure metal.

All metals can be classified as either ferrous or non-ferrous. Ferrous metals contain iron and non-ferrous metals do not. All ferrous metals are magnetic and have poor corrosion resistance while non-ferrous metals are typically non-magnetic and have more corrosion resistance. An overview of the most common ferrous and non-ferrous metals is shown below.

Ferrous Metals

Material name Composition Properties Applications
Low Carbon Steels Up to 0.30% Carbon Good formability, good weld-ability, low cost 0.1%-0.2% carbon: Chains, stampings, rivets, nails, wire, pipe, and where very soft, plastic steel is needed.

0.2%-0.3% carbon: Machine and structural parts
Medium Carbon Steels 0.30% to 0.80% Carbon A good balance of properties, fair formability 0.3%-0.4% carbon: Lead screws, gears, worms, spindles, shafts, and machine parts.

0.4%-0.5% carbon: Crankshafts, gears, axles, mandrels, tool shanks, and heat-treated machine parts

0.6%-0.8% carbon: “Low carbon tool steel” and is used where shock strength is wanted. Drop hammer dies, set screws, screwdrivers, and arbors.

0.7%-0.8% carbon: Tough and hard steel. Anvil faces, band saws, hammers, wrenches, and cable wire.
High Carbon Steels 0.80% to ~2.0% Carbon Low toughness, formability, and weld-ability, high hardness and wear resistance, fair formability 0.8%-0.9% carbon: Punches for metal, rock drills, shear blades, cold chisels, rivet sets, and many hand tools.

0.9%-1.0% carbon: Used for hardness and high tensile strength, springs, cutting tools

1.0%-1.2% carbon: Drills, taps, milling cutters, knives, cold cutting dies, wood working tools.

1.2%-1.3% carbon: Files, reamers, knives, tools for cutting wood and brass.

1.3%-1.4% carbon: Used where a keen cutting edge is necessary (razors, saws, etc.) and where wear resistance is important.
Stainless Steel Stainless steel is a family of corrosion resistant steels. They contain at least 10.5% chromium, with or without other elements. The Chromium in the alloy forms a self-healing protective clear oxide layer. This oxide layer gives stainless steels their corrosion resistance. Good corrosion resistance, appearance, and mechanical properties
Austenitic Steels: Contains chromium and nickel. The typical chromium content is in the range of 16% to 26%; nickel content is commonly less than 35%. Good mechanical and corrosion resisting properties, high hardness and yield strength as well as excellent ductility and are usually non-magnetic Kitchen sinks, architectural applications such as roofing, cladding, gutters, doors and windows; Food processing equipment; Heat exchangers; Ovens; Chemical tanks
Ferritic Steels: Magnetic with a high chromium and low nickel content usually alloyed with other elements such as aluminum or titanium. Good ductility, weld-ability, and formability; reasonable thermal conductivity, and corrosion resistance with a good bright surface appearance Automotive trim, catalytic converters, radiator caps, fuel lines, cooking utensils, architectural and domestic appliance trim applications
Martensitic Steels: Typically contains 11.0% to 17.0% chromium, no nickel, and 0.10% to 0.65% carbon levels. The high carbon enables the material to be hardened by heating to a high temperature, followed by rapid cooling (quenching). Good combination of corrosion resistance and excellent mechanical properties, produced by heat treatment, to develop maximum hardness, strength, and resistance to abrasion and erosion. Cutlery, scissors, surgical instruments, wear plates, garbage disposal shredder lugs, industrial knives, vanes for steam turbines, fasteners, shafts, and springs

Non-Ferrous Metals

Material name Composition Properties Applications
Aluminum / Aluminum alloys Pure metal / Easily alloyed with small amounts of copper, manganese, silicone, magnesium, and other elements Low density, good electrical conductivity (approx. 60% of copper), nonmagnetic, noncombustible, ductile, malleable, corrosion resistance; easily formed, machined, or cast Window frames, aircraft parts, automotive parts, kitchenware
Brass Alloy of copper and zinc, 65% to 35% is the common ratio Reasonable hardness; casts, forms, and machines well; good electrical conductivity and acoustic properties Parts for electrical fittings, valves, forgings, ornaments, musical instruments
Copper Pure metal Excellent ductility, thermal and electrical conductivity Electrical wiring, tubing, kettles, bowls, pipes, printed circuit boards
Lead Pure metal Heaviest common metal, ductile, and malleable, good corrosion resistance Pipes, batteries, roofing, protection against X-Rays
Magnesium / Magnesium Alloys Pure metal / Used as an alloy element for aluminum, lead, zinc, and other nonferrous alloys; alloyed with aluminum to improve the mechanical, fabrication, and welding characteristics Lightest metallic material (density of about 2/3 of that of aluminum), strong and tough, most machinable metal, good corrosion resistance, easily cast Automobile, portable electronics, appliances, power tools, sporting goods parts, and aerospace equipment
Nickel / Nickel Alloys Pure metal / Alloys very well with large amounts of other elements, chiefly chromium, molybdenum, and tungsten Very good corrosion resistance (can be alloyed to extend beyond stainless steels), good high temperature and mechanical performance, fairly good conductor of heat and electricity The major use of nickel is in the preparation of alloys or plating – frequently used as an undercoat in decorative chromium plating and to improve corrosion resistance; applications include electronic lead wires, battery components, heat exchangers in corrosive environments
Titanium / Titanium Alloys Pure metal / Easily alloys with aluminum, nickel, chromium, and other elements Low density, low coefficient of thermal expansion, high melting point, excellent corrosion resistance, nontoxic and generally biologically compatible with human tissues and bones, high strength, stiffness, good toughness Aerospace structures and other high-performance applications, chemical and petrochemical applications, marine environments, and biomaterial applications
Zinc / Zinc Alloys Pure metal/ Metal is employed to form numerous alloys with other metals. Alloys of primarily zinc with small amounts of copper, aluminum, and magnesium are useful in die-casting. The most widely used alloy of zinc is brass Excellent corrosion resistance, light weight, reasonable conductor of electricity Used principally for galvanizing iron (more than 50% of metallic zinc goes into galvanizing steel), numerous automotive applications because of its light weight
Back to Top

Sheet Metal Forming Stretch Forming

By on 29/08/2016   /   Blog   /   Leave a comment

Stretch forming is a metal forming process in which a piece of sheet metal is stretched and bent simultaneously over a die in order to form large contoured parts. Stretch forming is performed on a stretch press, in which a piece of sheet metal is securely gripped along its edges by gripping jaws. The gripping jaws are each attached to a carriage that is pulled by pneumatic or hydraulic force to stretch the sheet. The tooling used in this process is a stretch form block, called a form die, which is a solid contoured piece against which the sheet metal will be pressed. The most common stretch presses are oriented vertically, in which the form die rests on a press table that can be raised into the sheet by a hydraulic ram. As the form die is driven into the sheet, which is gripped tightly at its edges, the tensile forces increase and the sheet plastically deforms into a new shape. Horizontal stretch presses mount the form die sideways on a stationary press table, while the gripping jaws pull the sheet horizontally around the form die.

stretch-forming-small

Stretch formed parts are typically large and possess large radius bends. The shapes that can be produced vary from a simple curved surface to complex non-uniform cross sections. Stretch forming is capable of shaping parts with very high accuracy and smooth surfaces. Ductile materials are preferable, the most commonly used being aluminum, steel, and titanium. Typical stretch formed parts are large curved panels such as door panels in cars or wing panels on aircraft. Other stretch formed parts can be found in window frames and enclosures.

Back to Top
第 1 页，共 3 页123

Latest Posts

  • Machining
    Machining
    Machining is a term used to describe a variety […]...
  • Shell mold casting
    Shell mold casting
    Shell mold casting is a metal casting process s […]...

Showcase

Testimonials

We are extremly happy with CNCT. I would like to take a minute to thank CNCT for being a great partner.the CNCT team is so helpful, proactive, and organized that they made the products perfect. CNCT allows us to be more productive and don't have to worry about things like quality, deliver time.
--Grant stevens

ADDRESS

Jiangmen City, Guangdong Province, China
Tel: +86-750-3162699
Fax: +86-750-3162691
Website: http:www.c-nct.com
Email: echoliu@c-nct.com