With the rapid development of the automotive industry, the stamping industry has also flourished. To adapt to the growing output, various automated production lines have come into being and have been given different production methods in line with the needs of the characteristics of different products. To facilitate the selection of different production methods according to the characteristics of the products, the article classifies the common press automation production lines: progressive die stamping, multi-station stamping, and tandem stamping, and provides a brief analysis of the characteristics of each production line and the selection methods.
Selection factors for stamping automation lines
The following factors are generally considered to select the type of press production line.
(1) Product material: This includes the type of material, forming properties, hardness, etc., to measure the choice of coil or sheet forming.
(2) Material thickness: together with the material, the stamping machine’s cargo, and the feeding mechanism’s form are considered.
(3) Monthly supply and demand: assess the capacity, determine the production schedule and weigh the choice of automatic line.
(4) Volume of the stamped product and the ease of modeling: the complexity of the modeling and the quality of the product are considered together with the design of the tooling and the corresponding automated production method.
Progressive die stamping lines
(1) Overview: A progressive die stamping automation line, i.e., a production line using progressive die stamping, generally consists of an uncoiling feeder, a punching machine, a progressive die, and an automatic unloading line. The automatic process of uncoiling the coil, flattening the strip, oiling the strip, stamping the parts, and collecting the finished parts from the line is achieved.
The important part: is the progressive die, which consists of several stations, up to 20 stations; each station is associated with completing different processing contents, usually punching, trimming, turning, shaping, dropping, etc. A series of different processes are completed in one press stroke. After one stroke is completed, the feeder moves the material belt in the downward direction at a fixed step so that multiple processes can be completed simultaneously in one press stroke.
(2) Characteristics: The automatic production line for progressive die stamping has a high production rate, generally up to 30 times/min or more.
1.High production efficiency. A progressive die is a multi-tasking die that can include multiple processes, such as blanking, bending, and drawing in a single die, resulting in high productivity. The progressive die lays out the sampling process.
Easy to automate. Automatic operation is possible from loading, feeding, processing, and unloading of parts, thus reducing labor costs and increasing productivity while preventing abnormalities caused by inconsistencies in manual operation.
High-speed punching machines can be used for production. Depending on the product’s state, high-speed punching machines can be considered to achieve higher production efficiency.
Operational safety. The progressive press machines are equipped with safety gates, making it possible to work with improved material utilization. The working area is isolated from the personnel operating area, forming a relatively closed working area and providing safety for high-speed production. Traditional tandem production lines allow for higher production efficiency.
Saving of production plant area. A machine tool that forms the processing part of a production line can complete the production of a product with a small footprint while also simplifying the transport of substrates and semi-finished products and testing with higher safety.
Poor material utilisation. Due to the continuity of the material belt and the various requirements, to ensure the stability of the material feed, it is generally necessary to ensure the uniform distribution of the process content in each process state, sometimes sacrificing part of the material, thus failing to achieve a high material utilization rate.
Multi-station press automation line
(1) Overview: A production line with a large tonnage press table on which multiple (usually 4-5) independent stations of molds are placed, with the use of depalletizers or uncoiling feeders for loading, automatic feeding rods for process piece transfer and automatic conveyor belts for collecting off-line products.
The base material can be either a roll or a piece of material, making it flexible and conducive to improved material utilization.
Using automatic rod feeding, the punching times are lower than those of progressive die lines and higher than those of traditional tandem lines, allowing for higher production efficiency.
The machine can be equipped with up and down sensors, double material detection, gripper sensors, and in-mold sensors to detect the position and status of the material and the parts in production, providing a high level of safety.
There are high demands on the height of the die feed and the direction of the press at each station. To ensure the stability of the feed, it is generally necessary to ensure that the status of each process is consistent.
Tandem stamping automation line
(1) Overview: Several presses are arranged in sequence to form an automated production line. Each press is equipped with one mold (i.e., one process of the production process), and automatic robots or arms carry out the loading, transfer of the process parts, and loading and packing.
Wide range of applications, can be applied to the production of various stamping parts, no high requirements on the size, shape, and plate thickness of stamping parts, can be applied to the production of large covering parts, great flexibility.
Lower production efficiency: As the mechanical arm is used to feed the material, the number of beat strokes cannot be higher, and the production efficiency is lower compared to the progressive and multi-station production lines.
Facilitate mold maintenance and debugging, as each mold belongs to each press, the clamping is independent, the operating parameters are independent, and the maintenance and debugging of each molding process can be carried out independently without affecting each other.
A traditional tandem production line usually includes 4 to 5 presses and covers a large area.
Selection and application of stamping lines
Automatic progressive die stamping lines: for the process characteristics of each process being distributed on an integrated material belt and the high number of strokes that can be achieved, they can be used to produce small parts on the body and meet a high supply volume.
Multi-station stamping lines: these lines can be used for the rapid production of medium-sized parts, beams that are not easily deformed, symmetrical parts with a complex left-right co-die shape, and products that the gripper on the automatic lever can hold.
Tandem stamping automatic lines: these lines are the most flexible because the processes are distributed independently in each press; they are suitable for large covered parts with complex production processes, facilitate the commissioning of individual processes and independent production, and facilitate high-quality control of the products.
Table 1 Comparison of 3 automatic stamping lines
Progressive die automation line
1. High stroke, high efficiency, high output
2. Small footprint
1. Low material utilisation
2. Only suitable for small parts
3. Large single moulds, not easy to set up
1.Small structural parts in high demand
Multi-working station stamping automatic production line
1. High automatic efficiency
2. Wide range of products can be produced
3. High material utilisation
4. More automatic safety testing devices
1. Joint installation of moulds, high requirements for the design process of the parts
2. Joint installation of moulds, mould commissioning and maintenance transformation is not convenient
3. Low interchangeability of production lines, special set of moulds designated for a specific production line production
1. Parts in high demand
2. Reinforced parts, baffle parts, parts with a regular shape for easy clamping and where the whole process can be distributed on the same table
Series-automation production line
1. The widest range of products available
2. Flexible transfer of upper and lower parts and processes
3. High interchangeability of production lines
4. Convenient mould commissioning and maintenance
5. High material utilisation rate
1.Maximum floor space
2.Low production efficiency
1.Large parts and overlays
2. Complex and high quality parts
The choice of each stamping automation line can be based on two trends: high output and high flexibility. A highly efficient and productive automation line can be selected for large quantities of parts. A highly flexible line can be selected if the parts are complex and the production process is demanding.