The techniques used in the manufacture of sheet metal parts have unique characteristics.
Studying and understanding these techniques can improve the skills of technicians in sheet metal fabrication, leading to the design of more optimized processes and manufacturing plans.
Given the limitations of existing equipment and product structure, it is important to optimize the structure from a process perspective. The main responsibility of a sheet metal technologist is to develop the most efficient process method while considering production efficiency and flexible coordination.
Features of sheet metal parts
Sheet metal parts have unique characteristics, such as being thin and easy to mold into various shapes.
With the use of welding, assembly and riveting, it becomes possible to create multi-structured components.
However, these same characteristics can also result in deformations during manufacturing, such as bending, twisting, and concave or convex deformations, which can affect the size or shape of the component and cause quality issues.
The sheet metal parts production process has its own principles, which allow flexibility in adjusting the manufacturing sequence according to the available equipment and labor. By selecting the appropriate technological process, it is possible to effectively prevent and resolve these types of problems.
Basic Principle of Sheet Metal Technology
The development of a technological route must take into account both the product form and the company's existing processing equipment to meet product quality requirements and achieve maximum economic benefit.
The general principles for creating a manufacturing technique are as follows:
⑴ Meet product quality requirements
⑵ The manufacturing technique is economically viable
⑶ Provides optimization for subsequent processes
⑷ Convenient processing
Technical personnel must consider the quality of the product from both a functional and aesthetic point of view, as well as their knowledge of the processing capabilities of the equipment.
When preparing a technique, it is important to consider the overall machine integration error, optimize product processing methods to reduce difficulties, and establish a relatively stable technological route for batch production.
Cumulative adjustment error of the entire machine
The coordination of cumulative errors is a comprehensive reflection of the cumulative tolerance of the product, and it is necessary to allocate corresponding tolerances during process analysis to ensure that the cumulative error is within an acceptable range.
For example, the AC electrical control cabinet is a typical product that requires careful consideration of cumulative error coordination.
The AC electrical control cabinet can be processed in an assembly cabinet or a welding cabinet.
Mount-style cabinet assembly is common and typically consists of a top frame, a bottom frame, an upright post, a front door, a rear door, and a side door (plate).
If these components are well manufactured, it will ensure the quality of the case.
Typically, customers have certain requirements for the overall size of the cabinet after assembly, with the requirement that the size error of diagonal dimensions X1 and X2, X3 and X4 is less than 2 mm.
Based on installation conditions, customers have control over the width of L3, but there are no strict requirements on height and thickness. This is because the customer's cabinet design often uses the body shape to determine the required size without considering the thickness of the coating film, which may cause size errors in the cabinet dimensions after spraying and assembly.
Therefore, it is necessary to adjust the amount of spray and coverage on each component to meet the width of L3, also ensuring the dimensions L1 and L2.
Typically, the upper frame, lower frame and column are adjusted according to requirements, with different adjustments for different assemblies.
The front door and side door are normally recessed during installation into the upper and lower door lintel, causing the contour dimensions to generally have a negative deviation.
The coating tolerance must be adjusted according to the type of spraying. Considering the mounting clearance and other factors, the spray margin should be readjusted to control the deviation in size (for the door board, a coating layer margin of 0.5 to 1 mm should be left after taking into account the negative deviation).
Optimize product processing method
Processing method optimization involves adjusting the processing sequence or improving the process, which can be demonstrated through a simple example.
If a door panel requires expansion, both quality and time can be considered in single-piece processing.
The typical manufacturing process is as follows:
Scissor cutting → Punching shape and inner hole → Bending by press brake → Welding corners
This process saves time and effort, but in mass production it increases wear on the cutting tool and greatly increases machine maintenance costs. Furthermore, a small programming error can cause irreparable damage.
As the molded area of this type of door is used to install the door handle, a commonly adopted solution for mass production of such door panels is:
Cutting with scissors (cut separately for the three-door jamb) → Inner hole drilling → Corner notching → Bending by press brake → Welding corners and three-door jamb
This improved process not only saves raw materials and equipment maintenance costs, but also significantly reduces the rate of programming errors.
Stability selection of manufacturing technique
The stability of the process route choice must be aligned with the production batch, as the choice of process routes can vary based on changes in production. The development phase focuses on validating the overall product structure and timely processing and is less sensitive to manufacturing cost, while small batch production focuses on validating the process, optimizing individual structures, and preparing a moderate amount of molds.
For small batch production, cost is the top priority and the process is optimized as much as possible to save costs.
For example, consider the small angle bracket:
TechniqueⅠ: Cutting with scissors → Bending by press brake → Punching and threading for markings
TechniqueⅡ: Cutting with scissors (items can be merged) → Bottom hole drilling → Cutting into single pieces → Bending by press brake → Threading
TechniqueⅢ: Making a mold for manufacturing
After comparing these three technology routes, it is clear that all three options effectively meet customer needs, but each has its strengths.
TechniqueⅠ
It requires a lot of labor and is time-consuming (due to punching and threading of markings), leading to significant losses in the process. It is only suitable for single product manufacturing and is not recommended for mass production.
TechniqueⅡ
It uses more machine tools, is faster and can produce several parts at the same time. It is suitable for medium to small batch production, but the cutting process may cause small displacements in the holes.
TechniqueⅢ
It is suitable for series production as it is based on the use of a suitable mold, saving time and effort.
The choice of manufacturing technique is closely linked to the impact of processing loss and batch production and must be made based on comprehensive consideration of various factors. Choosing the appropriate manufacturing plan is especially important given different production conditions.
Conclusion
The processing technology of sheet metal parts is a complex issue.
This post provides a brief overview of the basics of setting up a manufacturing technique for sheet metal parts in general, with the goal of identifying the basic method for setting up a manufacturing technique.
In conclusion, as engineers, it is important to adopt a cost-conscious approach, consider costs throughout the entire process, and view the process configuration from a comprehensive, global perspective.
