5 Must-Have Features in a Automatic stamping line

Application of press in automatic stamping production line

Automatic Stamping Production Process

In traditional stamping production lines, material handling between the front and rear equipment is performed manually. With the increasing pace of production, manual collection and unloading not only cannot keep up, but also poses potential safety risks.

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Personnel tend to focus on speed, neglecting the dangers posed by moving equipment, leading to frequent accidents involving equipment pressing on hands and causing injuries. To mitigate these risks and improve efficiency, an automated robotic production line was developed.

Automated production involves using equipment instead of manual labor to transport sheets between front and back presses. This not only eliminates the risk of injuries, but also increases production efficiency by around 35%.

After , automated production technology for stamping parts in domestic automobile manufacturing saw significant growth, marking the beginning of an era of automated stamping production. Figure 1 shows a schematic diagram of a stamping automation production line.

Figure 1 Schematic diagram of automatic stamping production line

Main parameters of the press production process

Currently, the most used presses are closed mechanical presses, which can be used for various cold stamping processes, such as stamping, forming, bending, correction and shallow drawing of thin sheet metal parts. Press process parameters are crucial as they not only affect product quality, but also have a significant impact on efficiency, cost and safety.

The following section provides a brief overview of the important parameters and accuracy of some presses:

Press basics

The press foundation must support its weight and withstand the vibrational forces generated when the press is started, and transfer these forces to the ground beneath the foundation. The foundation must be able to safely withstand 0.15 MPa. The strength of the foundation is designed and constructed by the civil engineering department based on the local soil quality. The concrete foundation must be poured in a continuous, uninterrupted operation.

After filling the foundation with concrete, the surface must be smoothed once and then smoothed again with a shovel or sandpaper. To protect against oil, the bottom surface of the foundation must be coated with acid-resistant cement. The basic drawing provides the internal dimensions of the foundation, which represents the minimum space required to install the press.

Resistance indicators such as the brand of cement, the arrangement of reinforcing bars, the size of the foundation support area and the thickness of the foundation must not be changed. The basic bearing capacity must be greater than 1.95 MPa.

Post-sync guide

Indication: It connects the beam gearbox and the slider, transmitting the decelerated movement of the gearbox to the slider to achieve the vertical movement of the slider.

There are generally single point, double point and four point types, that is, one guide post, two guide posts or four guide posts.

Post-sync guide:

It refers to the synchronization accuracy of the two- or four-point pressure guide columns in their upward and downward movement. This parameter is normally established before the printer leaves the factory. The timing accuracy of the guide post should be kept within 0.5mm. Excessive misalignment will result in significant tensile stress on the sliding force, affecting the quality of the product formed at bottom dead center.

Mold mounting height

Mounting height refers to the distance between the bottom surface of the slider and the top surface of the table. There are maximum and minimum limits for mounting height. When designing the die, the possibility of installing and using the mold after grinding must be considered. The closed height of the mold must not reach the maximum or minimum limit values ​​for the height of the pressing mold.

Figure 2 shows a schematic diagram of the press mounting height.

Nominal strength of the press

The rated force refers to the maximum punching capacity that the press can safely handle within its structure. In practice, factors such as material thickness and strength deviation, mold lubrication and wear must be taken into consideration to ensure an adequate margin for stamping capacity.

Figure 2 Schematic diagram of press mounting height

When performing an impact load operation such as blanking, it is recommended to limit the working pressure to 80% or less of the rated force. Exceeding this limit may result in significant vibration and damage to the connection between the slider and transmission, affecting the normal life of the press. Figure 3 shows the nominal load vs. load curve. allowable load.

Figure 3 Permissible load curve of nominal force

compressed air pressure

Compressed air is the main source of energy to ensure the smooth operation of the press and also serves as a source of control circuit for the press's power source. The demand for compressed air pressure varies in different locations. The factory supplied compressed air pressure is based on the maximum demand value of the press. Parts with lower demand values ​​are equipped with pressure reducing valves for regulation.

Compressed air in the stamping automation production process can be divided into two categories: product quality and action function. The product quality category is used to define the quality of the product, such as air cushion pressure. The action function category is involved in controlling press actions such as clutch pressure.

Using the press of a manufacturing company as an example, Table 1 shows the compressed air pressure values ​​required for each functional module of the press. There are many more printer parameters than the five listed above.

The following is a brief summary and display of the company's printing parameters (Table 2) for your reference.

Table 1 Required compressed air pressure value for each functional module

Table 2 Summary of press parameters

Conclusions

The press is the main equipment in the printing production process. With the rapid growth of the automotive industry, there has been a corresponding increase in demand for high-precision equipment. The development of the stamping process went through three stages: manual production line, automated intermittent production and automated high-speed continuous production. In each iteration of the model update, production equipment plays a crucial role.

Now that we have a basic understanding of the printing press, let's move on to the topic of automatic production lines.

Types of automatic stamping production line

Automatic stamping production lines mainly include: progressive stamping, multi-station stamping, and tandem stamping .

Due to their unique features, these production lines are used to produce different automotive sheet metal parts and play a significant role in automotive automation and efficient production systems. This article compares and analyzes the characteristics of these three stamping automation production lines and provides guidance on how to select a production line based on their characteristics.

This will make it easier for companies to choose a production line that meets the specific characteristics of their parts. With the rapid growth of the automobile industry, the four major stamping industries for automobile manufacturing also flourished. To meet the increase in production, several automated production lines emerged, each with its own characteristics and suitable for different products.

This article categorizes common stamping automation production lines into progressive stamping, multi-station stamping and tandem stamping, and briefly analyzes the characteristics and selection methods of each production line to help companies choose the correct production method for the characteristics of your products.

Progressive Stamping Production Line

(1. Overview:

Automatic production line for progressive stamping is a production line that employs progressive stamping and typically consists of an unwinding feeder, a punch, a progressive die and an automatic cutting line. It automates the process of coil unwinding, strip straightening, strip lubrication, blank stamping and offline collection of finished products.

The most important component is the progressive array, which consists of multiple stations, up to more than 20 stations. Each station is connected to each other to complete different processing tasks, such as punching, cutting, flanging, shaping, trimming and so on. All these tasks are completed with a single press. Upon completion of a stroke, the feeder advances the strip of material in a fixed step, allowing multiple processes to be completed in a single reciprocating press punch.

As shown in Figure 1.

Figure 1 Simplified diagram of the automatic progressive production line

(2) Features:

The production cycle of progressive stamping automation production line is relatively high, generally up to 30 times/min.

1. High production efficiency.
   The progressive die is a multi-tasking process die that can perform punching, bending, forming and drawing within a set of dies, resulting in high productivity. The progressive matrix layout process is shown in Figure 2.

Figure 2 Progressive Matrix Layout Process

2. Easy to automate.
   The progressive die production line allows automatic operation from loading, feeding, processing and unloading of parts, reducing labor costs and increasing production efficiency. Furthermore, it eliminates inconsistencies and abnormalities that may occur during manual operations.
3. Can use high-speed punch production.
   Depending on the product status, a high-speed punch may be considered to achieve greater production efficiency.
4. Safe operation.
   Progressive press equipment has safety doors to optimize the use of the material. The work area is isolated from the operator area to create a relatively enclosed work area, ensuring safety during high-speed production. This results in greater production efficiency compared to traditional series production lines.
5. Save production plant area.
   A machine tool constitutes the processing component of a production line and is capable of producing a product. It has a compact design, simplifies the detection of the transport of materials and semi-finished products and offers high security.
6. Material usage is not high.
   To ensure feed stability and meet various requirements, it is usually necessary to distribute processing tasks evenly at each stage. This may result in some of the material being sacrificed, resulting in a lower material utilization rate.

Multi-station Stamping Automation Production Line

(1) Overview:

A production line with multiple independent mold stations (usually 4 to 5) located on a large tonnage press table uses a destacker or unwind feeder for loading, an automatic feed bar for transferring processed parts, and an automatic conveyor belt for collect finished products offline. As shown in Figure 3.”

Figure 3 Multi-station stamping automation production line

(2) Features

The bottom material can be a roll material or a blank, which provides flexibility and improves the material utilization rate. The production line uses automatic rod feeding and has a lower punching rate compared to the progressive die production line, but a higher rate than the traditional tandem production line, resulting in higher production efficiency.

It can also incorporate sensors such as loading and unloading sensors, dual material detection, adhesion sensors, in-mold sensors, etc. to monitor the position and status of material and product during production, ensuring high safety.

There are strict requirements for the feeding height and stamping direction of molds at each station, and to maintain feeding stability, the states of each process must generally be consistent.

Tandem Stamping Automation Production Line

(1) Overview:

An automated production line is formed by arranging multiple presses in series. Each press table contains a pair of molds, which represent a step in the production process. Loading, transferring of processed parts and unloading and packaging work are carried out by an automatic mechanical arm or robot. As shown in Figure 4.

Figure 4 Automatic production line for tandem stamping

(2) Features

It has a wide range of applications and can be used in the production of various stamping components. There are no strict requirements regarding the size, shape and thickness of these components, allowing great flexibility in the production of large-scale roofing parts.

However, production efficiency is low due to the use of a robotic arm for feeding, which limits cycle time. Compared to progressive production lines and multi-station production lines, this method is less efficient.

On the other hand, mold maintenance and debugging are facilitated. Each mold belongs to a separate press, allowing independent clamping and working parameters. This means that maintenance and debugging of each mold can be carried out separately without affecting other processes.

The disadvantage is that this method requires a large production area. A traditional series production line typically includes 4 to 5 presses, taking up a significant amount of space.

How to Select Stamping Automation Production Line

When choosing the type of stamping production line, the following factors should be taken into consideration:

(1) Product material:

The type of material, its forming performance and hardness must be evaluated to determine the selection of coil or sheet forming.

(2) Material thickness:

Material thickness must be considered along with material type to determine punch press tonnage and feed mechanism support system.

(3) Monthly supply and demand:

Production capacity must be evaluated to determine the production cycle and consider the choice of an automatic line.

(4) Volume and difficulty of stamping products:

The complexity of molding and product quality requirements must be considered to comprehensively determine the mold design method and corresponding stamping automation production method.

Selection and application of stamping automation production line

Progressive Stamping Automation Production Line

According to the characteristics of each process distributed in a strip and the maximum process punches that can be achieved, it can be used for the production of small parts in the car body and can provide a high supply.

Multi-station Stamping Automation Production Line

It can be used for rapid production of medium-sized parts resistant to deformation. Symmetrical parts with complex left and right shapes, as well as products that can be grasped by the automatic lever, can be produced on the automatic line.

Tandem Stamping Automation Production Line

Due to the independent distribution of each process in each press, this production line presents the highest level of flexibility. It is ideal for the production of large and complex parts and facilitates the debugging of individual and independent production processes, making it easier to maintain high product quality control.

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The characteristics of the three production lines are shown in Table 1

The choice between automated stamping production lines can be made based on two priorities: high throughput and high flexibility.

For a large volume of parts, an automated production line with high efficiency and high output should be selected.

If parts are complex and require advanced production technology, a flexible production line should be considered.

This is represented in a simple illustration in Figure 5.

Figure 5 Special intention of 3 production lines

Based on their unique characteristics, stamping automation production lines are widely used in major automobile factories, providing robust support for the growth of the automotive industry and the rapid increase in automobile production.

Understanding and analyzing the automated stamping production line helps in selecting the stamping production method and leverages the strengths of the respective automatic lines to benefit the automotive industry.

• Progressive
• Multistation transfer
• Tandem

Abbreviated abroad:：Ｐ.Ｒ.Ｇ /Ｔ.Ｒ.Ｆ/Ｔ.Ｄ.Ｍ

Which stamping automation production method should be selected is generally considered from the following factors:

• Material (material hardness and whether coils are required)
• Material thickness (punch specifications and support considerations for feeder leveling)
• Monthly production quantity (for a large number, continuous molds are available, general or less can use multistation or tandem mode)
• Difficulty stamping product shape (select the corresponding stamping automation method according to the product design mold)

Progressive die automation method

A progressive die is a type of cold stamping die that takes a strip-shaped raw material and performs multiple stamping processes simultaneously in a stamping cycle using multiple stations.

With each punch, the strip moves a fixed distance until the final product is completed.

Multi-station automation method（Transfer）

Multi-station punching technique involves arranging multiple process molds in a punching machine and utilizing the unique reciprocating movement of the punch slider to perform various operations such as stamping, punching, bending, stretching, cutting, etc., simultaneously on the installed molds on the machine tool. The robot transfers the part from one station to another during each cycle to produce a finished part.

It can be classified into two-dimensional and three-dimensional manipulators.

Three-dimensional handling method

Tandem automation method(Tandem)

Multiple punches are arranged in series to create a complete stamping production line, with each punch die corresponding to a separate forming process.

The transfer of materials between punches is done using robotic automation.

This method is mainly suitable for product lines with low production demands, limited processing steps and independent production lines that are highly flexible.

Through the cold-forming process of metal stamping, sheet metal is transformed into different shapes. The metal-stamping process uses a combination of dies and stamping presses to convert pieces of flat metal into usable shapes for a variety of industries.

From the automotive industry to aerospace projects to medical machinery, many industries throughout the globe heavily rely on metal stamping for their equipment. There is an increasing need worldwide for mass-produced quantities of complex parts, and metal stamping is a cost-efficient way to do so.

Metal stamping is a complicated process that can be completed through a variety of
 metal-forming techniques. Some examples include bending, punching, blanking, spinning, hydroforming, or piercing the metal to alter it to the ideal shape.

In this article, we’ve outlined the metal stamping process and some different types of metal stamping techniques to help you get a better understanding of how this process works.

What Is Metal Stamping?

The metal stamping process also referred to as metal pressing, consists of taking flat sheet metal and feeding it into a stamping press. This press then uses pressure and die to transform the metal into the predetermined shape.

Some examples of stamping techniques used include punching, coining, embossing, bending, blanking, and flanging.

To ensure the metal piece turns out the way it is supposed to, stamping professionals need to use the design tool that comes with CAD/CAM engineering technology. These designs must be as accurate as possible for each part to come out looking and operating how it should.

Because the metal stamping process can turn out a high volume of the same part in a short amount of time, it is used in a variety of industries.

Metal stamping can help produce:

• Hardware such as nuts, bolts, screws, hinges, and washers for shelves, custom switches, doors, lighting, etc.
• Specialty stamped hardware that includes products such as household tools, locks, power tools, mounting brackets, etc.
• Electrical components such as cups, covers, fasteners, clips, and sensitive electronic assemblies.
• Durable, high-quality parts for the construction industry that will stand the test of time.
• Fastening solutions such as bolts, hooks, or complicated contact elements.
• Components for appliances such as grills, ice machines, microwaves, cooktops, ranges, fryers, griddles, toaster ovens, disposal systems, and more.

Not only can metal stamping machines stamp, but they can also cut, punch, cast, and shape metal sheets into their desired shape and size. Stamping machines are designed to be as accurate as possible, and they can also be programmed to ensure accuracy.

Types of Metal Stamping Techniques

There are a variety of metal stamping techniques that are utilized for particular applications. We’ve outlined some examples below.

Progressive Die Stamping

This metal stamping technique breaks down the process into a series of stations that each serve a different function. The stock strip carries the part from one station to the next until it is finished and removed from the strip.

The original metal strip travels from its coil and makes its way into the die press. From there, the metal moves horizontally across each station. As soon as the desired bend, punch, or cut is made, the part moves onto the next station until it’s completed.

The part is still connected to the metal strip while it is being altered, so each movement must be as accurate as possible. This precision and accuracy assure that the end part is accurate and usable.

Progressive die stamping is a beneficial way to produce mass quantities of parts at a low cost, making it an attractive option for many. The die lasts for a long time and it’s easy to repeat the process as many times as needed. This type of metal stamping also produces minimal wasted scrap.

However, without a high level of precision and accuracy during progressive die stamping, the parts may not be accurately made.

Transfer Die Stamping

Another type of metal stamping is transfer die stamping. It is similar to progressive die stamping, but a mechanical transport system moves the part from station to station instead of an automated strip. This type of stamping is useful for making parts that need to be free from the metal strip during the stamping process.

This may be a single die on its own or it may require multiple dies or machines in a row to create a makeshift production line.

The lower tooling costs associated with transfer die stamping make it an excellent option for production. They are also versatile and can produce features such as cut-outs, ribs, knurls, threading, and pierced holes. This means that no secondary operations are required, further cutting back on cost.

Transfer die stamping is used in markets such as agriculture, automotive, locomotive, electronics, medical, recreational vehicles, and more. It’s beneficial in creating larger, bulkier parts that may require the use of multiple presses.

Fine Blanking

Another type of metal stamping is fine blanking, also referred to as fine-edge blanking. This specialty type of metal stamping is ideal for achieving flatness and a full-sheared edge in a way that other metal stamping techniques cannot.

This technique uses cold extrusion and it is a single-step process, resulting in a lower fabrication cost.

Fine blanking is typically completed using a hydraulic or mechanical press, or a combination of the two. There are three recognizable movements used in the fine blanking process:

1. Using the workpiece’s clamp to hold the workpiece or work material in place
2. Completing the blanking operation
3. The finished part is ejected

The product is manufactured and needs to have complete contact with the surface on the part’s edge to be effective.

One example of a part that is often made using fine blanking is a gear. Gears require flatness in certain areas and every tooth needs to be fully engaged to be effective, making fine blanking the perfect candidate for this type of production.

The fine blanking press runs at much higher pressures than more conventional stamping techniques, so the machinery must be designed to withstand these higher pressures.

Four-Slide Stamping

Four-slide stamping, also referred to as multi-slide stamping, uses four tools simultaneously to form the piece into the proper shape. As the metal sheet is fed through the four-slide, it is quickly bent by each shaft.

It is ideal for producing products that require intricate cuts or complicated bends. While other metal stamping techniques use a vertical slide during production, four-slide stamping uses four different sliding tools to shape the metal piece.

The tool slides used in four-slide stamping are highly productive and straightforward, meaning this is an ideal method for creating complex or multi-part bends, even bends that are larger than 90 degrees. Multiple bends, punches, folds, or cuts can be completed in just one step.

Another advantage of four-slide stamping is the tooling itself is relatively inexpensive and there is minimal waste produced during the process.

Types of Stamping Presses

Stamping presses play an integral role in the process, and there are three common types: mechanical, hydraulic, and mechanical servo. The distinction between the three types comes from the power source.

In most cases, the stamping press is linked to an automatic feeder that moves the sheet metal through the press. We’ll get into detail on each type of stamping press below.

Mechanical

Mechanical stamping presses have a motor that’s connected to the mechanical flywheel. The flywheel then stores that energy to help the machine operate. These presses can produce a variety of punch sizes, ranging anywhere from 5mm to 500mm depending on the specific press being used.

The speed of mechanical presses ranges as well. It can operate as slow as 20 strokes per minute or operate as fast as 1,500 strokes per minute. In the case that additional energy is needed when the speed is lower, the operator can add an auxiliary flywheel to the drive. Mechanical presses are typically faster than hydraulic presses, however.

The press stroke length is kept as short as possible because it has such an impact on speed. On average, each stroke is 2 inches.

The operator of the mechanical press will use electronic control, a clutch, and a brake to help engage and disengage the press drive as necessary.

Mechanical stamping presses are most often used to create simple and shallow parts made from coils of sheet metal, most notably for large production runs for transfer and progressive stamping.

Hydraulic

As the name implies, hydraulic stamping presses use the hydraulic fluid as the power source. The technology used in hydraulic presses has significantly improved over time, with each improvement offering an upgrade in electronics and valves.

The hydraulic pistons release fluid that has a proportional amount of force to the piston head’s diameter. This allows for a high level of control over how much pressure is applied at any given moment. Despite so much flexibility in its stroke and speed capabilities, hydraulic presses can still deliver full power at any point in the stroke.

The pressure used in hydraulic presses may be preset by the user. The velocity can also be tweaked to adjust how fast the slide travels while the die closes. When the right pressure level is achieved, the valve helps activate pressure reversal to avoid overloading.

Hydraulic presses range anywhere from 20 tons to 10,000 tons. Their stroke sizes are anywhere from 10mm to 800 mm. This type of press is ideal for creating small, intricate parts thanks to its changeable stroke length and consistent pressure.

Mechanical Servo

Mechanical servo stamping presses don’t use flywheels as their power source. Instead, they rely on high-capacity motors to ultimately create intricate designs at a faster pace than standard hydraulic presses.

Servo presses are highly programmable, making it easy to have control over the stroke, slide position, motion, and speed of the press. These machines operate on a link-assisted drive system or a direct drive system.

Their high speed and high levels of customization make mechanical servo presses the most expensive option out of the three.

Types of Stamping Dies

Now let’s discuss the dies used in metal stamping. There are two types of dyes used: single-station dies or multi-station dies.

A single-station die is made from compound dies and combination dies; a compound die is capable of performing multiple operations in a single press. For example, if a steel washer needs to be made in a single press, it would need multiple cuts, thus requiring compound dies.

Combination dies use cutting and non-cutting operations in one stroke. For example, a combination die may produce both a cut and a flange when shaping a metal blank.

The other type of die used in metal stamping is multi-station dies. Progressive dies and transfer dies are included in this category. Examples of operations resulting from this die-set include cutting, punching, or notching.

Another noteworthy die used in stamping presses is steel rule dies, commonly referred to as knife dies. This type of die was first used on soft non-metal materials such as paper, cardboard, or leather. Over time, knife dies have also been utilized on copper, brass, and aluminum.

Metal Stamping Advantages and Disadvantages

Let’s now compare the pros and the cons of metal stamping.

Advantages of metal stamping include:

• Compared to other stamping processes, the costs of metal stamping are low.
• High levels of automation compared to other presses.
• Not as expensive to produce or maintain compared to those used in other processes.
• More affordable secondary costs such as plating or cleaning.
• Can use highly technical computer programs to provide increased precision.
• Overall faster production and turnaround time with metal stamping.
• Low cost of labor thanks to how automated this process can be.

On the other hand, there are also some downsides to metal stamping. Disadvantages of stamping include:

• The presses themselves are extremely expensive and heavy to transport.
• It’s not always easy or fast to acquire the dies needed in metal stamping.
• If custom dies are used, the pre-production process takes longer.
• If dies need to be changed in the middle of production due to a change in design, it can be difficult to achieve.

Applications of Metal Stamping

Now that we’ve covered the basics of metal stamping, let’s look at how this process is used and applied. It is used in a variety of ways, especially for the creation of three-dimensional designs. Chances are high that there are appliances or light fixtures in your home that were created through metal stamping.

It is utilized in the automotive industry, the lighting industry, the automotive industry, the medical field, the electronic industry, telecommunications services, and so many more. From simple components to extremely intricate machines and parts, metal stamping has seemingly endless applications.

Conclusion

Metal stamping is a widely used process that has applications relevant to your daily lifestyle. If you’re interested in learning more about metal stamping or any of our other metal capabilities, Schaumburg Specialties is happy to assist you.

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