Metal Stamping

metal stamping

Metal stamping is a cold-forming process that makes use of dies and stamping presses to transform sheet metal into different shapes. Pieces of flat sheet metal, typically referred to as blanks, is fed into a sheet metal stamping press that uses a tool and die surface to form the metal into a new shape. Production facilities and metal fabricators offering stamping services will place the material to be stamped between die sections, where the use of pressure will shape and shear the material into the desired final shape for the product or component.

1：Basic Concepts of Metal Stamping:

Metal stamping, also referred to as pressing, is a low-cost high-speed manufacturing process that can produce a high volume of identical metal components. Stamping operations are suitable for both short or long production runs, and be conducted with other metal forming operations, and may consist of one or more of a series of more specific processes or techniques, such as: Punching, Blanking, Embossing, Coining, Bending, Flanging.

Metal stamping machines may do more than just stamping; they can cast, punch, cut and shape metal sheets. Machines can be programmed or computer numerically controlled (CNC) to offer high precision and repeatability for each stamped piece. Electrical discharge machining (EDM) and computer-aided design (CAD) programs ensure accuracy. Various tooling machines for the dies used in the stampings are available. Progressive, forming, compound, and carbide tooling perform specific stamping needs. Progressive dies can be used to create multiple pieces on a single piece simultaneously.

2：Types of Stamping Operations:

Progressive die stamping

Progressive die stamping uses a sequence of stamping stations. A metal coil is fed into a reciprocating stamping press with progressive stamping dies. The die moves with the press, and when the press moves down the die closes to stamp the metal and form the part. When the press moves up, the metal moves horizontally along to the next station. These movements must be precisely aligned as the part is still connected to the metal strip. The final station separates the newly-fabricated part from the rest of the metal. Progressive die stamping is ideal for long runs, because the dies last a long time without becoming damaged, and the process is highly repeatable. Each step in the process performs a different cut, bend, or punching operation on the metal, thus gradually achieving the desired end-product shape and design. It is also a faster process with a limited amount of wasted scrap.

 Transfer Die Stamping

Transfer die stamping is similar to progressive die stamping, but the part is separated from the metal trip early on in the process and is transferred from one stamping station to the next by another mechanical transport system, such as a conveyor belt. This process is usually used on larger parts that may need to be transferred to different presses.

 Four-Slide Stamping

Four-slide stamping is also called multi-slide or four-way stamping. This technique is best-suited for crafting complex components that have numerous bends or twists. It uses four sliding tools, instead of one vertical slide, to shape the workpiece through multiple deformations. Two slides, or rams, strike the workpiece horizontally to shape it, and no dies are used. Multi-slide stamping can also have more than four moving slides.

Four-slide stamping is a very versatile type of stamping, as different tools can be attached to each slide. It also has a relatively low cost, and production is fast.

 Fine Blanking

Fine blanking, also known as fine-edge blanking, is valuable for providing high accuracy and smooth edges. Usually done on a hydraulic or mechanical press, or by a combination of the two, fine blanking operations consist of three distinct movements:

1.Clamping of the workpiece or work material in place

2.Performance of the blanking operation

3.Ejection of the finished part

Fine blanking presses operate at higher pressures than those used in conventional stamping operations, hence tools and machinery need to be designed with these higher operating pressures in mind.

The edges that are produced from fine blanking avoid fractures as produced with conventional tooling and surface flatness can exceed that available from other stamping methods. Since it is a cold extrusion technique, fine blanking is a single-step process, reducing the overall costs of fabrication.

3：Types of Stamping Presses:

The three common types of stamping presses include mechanical, hydraulic, and mechanical servo technologies. Usually, presses are linked to an automatic feeder that sends sheet metal through the press either in coil or blank form.

Mechanical

Mechanical presses use a motor connected to a mechanical flywheel to transfer and store energy. Their punches can range in size from 5mm to 500mm, depending on the particular press. Mechanical pressing speed also varies, usually falling between the range of twenty and 1,500 strokes per minute, but they tend to be faster than hydraulic presses. These presses can be found in an array of sizes that stretch from twenty to 6,000 tons. They are well-suited for creating shallower and simpler parts from coils of sheet metal. They’re usually used for progressive and transfer stamping with large production runs.

Hydraulic

Hydraulic presses use pressurized hydraulic fluid to apply force to the material. Hydraulic pistons displace fluid with a force level proportional to the diameter of the piston head, allowing for an advanced degree of control over the amount of pressure, and a more consistent pressure than a mechanical press. Additionally, they feature adjustable stroke and speed capabilities, and can typically deliver full power during any point in the stroke. These presses usually vary in size from twenty to 10,000 tons and offer stroke sizes from about 10mm to 800mm.

Hydraulic presses are usually used for smaller production runs to create more complicated and deeper stampings than mechanical presses. They allow for more flexibility because of the adjustable stroke length and controlled pressure.

Mechanical Servo

Mechanical servo presses use high capacity motors instead of flywheels. They are used to create more complicated stampings at a faster speed than hydraulic presses. The stroke, slide position and motion, and the speed are controlled and programmable. They are powered by either a link-assisted drive system or a direct drive system. These presses are the most expensive of the three types discussed.

4：Applications:

Stamping is used in a variety of applications, especially those involving three-dimensional designs, lettering, or other surface engraving features. Such stamping products are commonly produced for home appliance manufacturers, automotive companies, the lighting industry, telecommunications services, military and defense, aerospace industries, medical equipment manufacturers, and electronics companies. Odds are you have a product in your home that has parts created through metal stamping because it is a process used in everything from your household appliances to your cars.


The specific products and components can range from simple stamping items, such as metal clips, springs, weights, washers, and brackets, to more complex designs, such as those found in engine bases or friction plates. This process is used for producing both parts for large machinery and also incredibly detailed small parts.  Micro-precision stamping can create parts with diameters of up to 0.002 inches.

Electronic stampings are electronic components manufactured through the metal stamping process. They are used in a variety of industries, from home electronics and appliances to telecommunications and aerospace. Electronic stampings are available in a number of metals, including copper, copper alloys, aluminum, and steel, as well as more expensive metals, such as platinum and gold. Electronic components produced by the metal stamping method include terminals, contacts, lead frames, springs, and pins. They can be created from ferrous or nonferrous materials. Metal stampings find wide use in computers, electronic equipment, and medical devices. Because of the specialized shapes that can be made by the various stamping processes, many electronics are made by this cold forming process.

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General situation and prospect of die casting market

The application of die castings is very wide, involving a considerable number of product areas and industrial categories. Die casting products are mainly automobile and motorcycle parts, followed by hardware, communications and other die castings. At present, the annual production of die castings in China is about 2.1 million tons, with aluminum alloy accounting for about 76%; Zinc alloy accounts for about 16%; Magnesium alloy accounts for 7%; Copper alloys are less than 1%.

The development of automobile market directly drives the development of die casting market. In the die casting market, the consumption of the automobile industry accounts for a considerable share. According to relevant statistics, in China, the proportion of the total volume of die castings supplied to the automobile industry has remained between 65% and 75% in recent years. As for the consumption of die castings in each car, if the consumption of aluminum alloy castings in each car is concerned, it will gradually increase. Relevant data shows that the average consumption of aluminum alloy castings per vehicle was 34KG in 1980 and 157KG in 2009, among which aluminum alloy die castings accounted for more than 65% of all aluminum castings. Zinc alloy, magnesium alloy and copper alloy die castings have also been widely used in the automotive industry.

In terms of the auto market itself, China’s auto market has developed rapidly in recent years. According to relevant data, in 2009, China’s auto production and sales exceeded 13 million, becoming the world’s largest auto production and sales country. In the first three quarters of 2010, China’s auto production and sales exceeded 13 million, approaching the production and sales of 2009. It is conservatively estimated that the auto production in 2010 will reach more than 17 million.

Although the automobile industry has made great progress, the annual ownership has reached more than 85 million vehicles, but it is only close to the current world average. Even if the car ownership reaches 150 million, it still cannot reach the level of Mexico in 2005, so the sustainable development of the automobile industry has an objective market demand potential.

In addition, the light weight of automobiles and the rise of new energy vehicles have also brought greater development space for the die casting industry.

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CNC machines: guide to numerical control

CNC machines

1. What is CNC

CNC (Computerized Numerical Control), or Computer Numerical Control in English, It is a widespread system in engineering to process materials and parts with minimal human intervention. The CNC technique derives from numerical control, an automated system for machine tools that are operated by means of commands through handwheels or levers. However, these machines have evolved and now allow their control through software and a computer in order to further automate the process and offer better performance.

The operation of these CNC systems is quite simple to understand. It is based on the machining of a piece through the use of coordinates that will specify the movement of the tool (cutting, drilling, milling, welding…). Similar to the operation of a 3D printer, which could also be understood as a CNC machine, only instead of machining, what it does is add layers of material to build a part.

And just like 3D printers, you can have multiple axes, like the X, Y and Z, being able to carry out longitudinal, vertical and transversal displacements respectively. Through some servomotors I stepper motors, the tool will be moved to the exact point indicated by the computer software, and the machining will be carried out quickly and with the highest precision.

Before the invention of the CNC, labor was required to handle the tools manually, but the possible failures they could commit affected quality, repeatability, costs and decreased production. For example, imagine an employee in an aluminum shop who wants to drill frames for a window. This task requires that:

  1. The operator picks up the piece.
  2. Put it on the work table.
  3. Put the appropriate bit in the drill.
  4. And drill.

This to make a single hole is not a problem, but imagine that hundreds or thousands of them need to be made to maintain a considerable production and in the shortest possible time, in addition to all the holes being the same. In that case, the workforce is not adequate, and that is where cnc machines brought great improvements to the industry. In this case, the steps would be:

  1. Make sure the machine is fed with material (sometimes they might even have automatic feeding).
  2. Start it with the necessary programming (it may be necessary only once and indicate the number of repetitions).
  3. And she will be in charge of making the perforations with precision and repeating them as many times as necessary, without the need for the operator to intervene.

In addition, can work faster than an operator and does not get tired, so all are advantages for the industry or workshop.

2. What are CNC machines and how does it work?

An CNC machine is a kind of machining machine operated by computer numerical control.. In this way, process automation is achieved by establishing precise coordinates for cutting, welding, milling, molding, grinding, placing parts, etc., of all kinds of materials, from soft ones such as polymers, foami, MDF, or wood, even harder such as marble, metal, rocks, etc.

Likewise, CNC machines allow for a sophisticated system of feedback that constantly monitors and adjusts the speed and position of the tools used for machining, without the need for such frequent manual maintenance. Even some more advanced ones have intelligent systems to detect problems, control the quality of the work or part, etc., or be interconnected if it is an industry 4.0.

It is important to note that some CNC machines they work differently:

  • point to point control: In this type of CNC machines, the start and end points of each path will be established.
  • paraxial control: in them it is possible to control the movement speed of the pieces.
  • interpolate control: they carry out machining in any way parallel to their axes.

3. What is a CNC machine made of?

When it comes to detailing the parts or components of a CNC machine, the following essential elements can be cited:

Input device

The word input device from a CNC machine to the system that is used to be able to load or modify the data for the machining process. For example, it can be a control panel, a touch screen, etc. That is, an interface to allow the machine operator to activate and control the machine.

Control unit or controller

Is digital electronic system which will be in charge of interpreting the entered data and generating a series of control signals to control the movement of the servomotors to move the work head through the axes and the tool so that they do exactly what the program entered by the user indicates .

Tools

La tool It is one of the most essential components, since it is the one that actually performs the machining, the one that is in contact with the piece that is being processed. It can be a multi-tool head, being able to carry out several different tasks, or also individual fixed or interchangeable tools. For example: drill bit, cutter, milling cutter, welding tip, etc.

In addition, it is important to note that there may be various types of CNC machines in terms of their type and number of axles:

  • 3 axes: are the most common, with an X, Y, and Z axis.
  • 4 axes: like some routers or CNC routers that add an A axis to the previous three. This allows the spindle to move from left to right to process three surfaces at the same time, being able to engrave flat or in 3D. They are ideal for carving wood, metals, complex patterns, etc.
  • rotary axis– It has a rotating spindle for the tool, which allows you to process four surfaces simultaneously. These types of machines are used for machining cylindrical parts, wooden statues, complex metal elements, etc.

Fastening or support system

Is place where the piece is anchored to carry out the machining process without it moving. Depending on the system, it could be of different types, with or without anchors. In addition, some need extras, such as dust collection systems, or water jet cutting, which would require a water tank or reservoir to collect and dissipate the force of the jet once it passes through the part.

These systems are often called also bed or table. Many of them are usually made of materials such as aluminium, when the pieces need to be attached to the table, to process cylinders or complex shapes. Instead, the vacuum bed or table will vacuum the part without clamping it, allowing for a higher degree of precision, less agitation during use, and a greater degree of freedom.

Feedback devices (servomotors)

There are only these types of devices. feedback on CNC machines that use servo motors. In the others it is not necessary.

Monitor

In addition to all of the above, there may also be a information or monitoring system of the machining process itself. This can be through the same interface from which it is operated or independently.

Other parts

In addition to the above, it should be noted two essential elements plus:

  • Engines: are the devices that move or activate the machining tool according to the data received from the control unit.
  • Servo: tolerates high speeds, so you can cut, drill, etc. Ideal for quiet, stable work, and for intricate patterns.
  • Stepper: These stepper motors are priced lower, but are used for more basic engraving or movement. They are easy to control, reliable and highly accurate, making them suitable where maximum precision is needed.
  • Spindle: This element of a CNC machine can have two types of possible cooling or cooling system: By air: They are cooled simply by a fan that cools the spindle, and are cheaper, easier to maintain and use； By water: They use water for cooling. It is more expensive, complex, and difficult to maintain, but it generally lasts longer, is more efficient, and is quieter.

 

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