Analysis of common problems in sheet metal processing

Sheet metal processing is an essential component of modern manufacturing, widely used in numerous fields, including automotive, electronics, machinery, and aerospace. However, because sheet metal processing involves multiple processes, including cutting, bending, welding, and surface treatment, and is influenced by factors such as material properties, equipment precision, and operator skills, various problems often arise in actual production. These problems not only affect product quality but can also lead to reduced production efficiency and increased costs. A deeper understanding of these common problems can help companies implement effective solutions and improve the overall quality of sheet metal processing.

1. Raw material related issues

(1) Material specifications do not meet

In sheet metal fabrication, using material specifications that don't match design requirements is a common problem. For example, if the thickness, width, or length of the sheet metal doesn't meet standards, subsequent processing can fail to meet the designed dimensions and precision. This can be caused, on the one hand, by lax procurement processes, where appropriate materials aren't sourced in strict accordance with technical specifications; on the other hand, by poor warehouse management and unclear material labeling, leading to confusion when retrieving materials. Inconsistent material specifications can directly impact the structural strength and assembly precision of sheet metal parts . In severe cases, resourcing materials may be necessary, resulting in wasted time and cost.

(2) Material surface defects

Surface defects such as scratches, rust, pits, and impurities on raw materials are also common problems in sheet metal processing. These surface defects not only affect the appearance quality of sheet metal parts but can also cause further problems during processing. For example, surface scratches can act as stress concentration points, causing crack propagation during bending or stretching. Rust can reduce the material's corrosion resistance and may cause welding defects such as porosity and slag inclusions during welding. Surface defects can be caused by improper protection of raw materials during transportation and storage, or by problems with the supplier's production process.

(3) Material performance does not meet standards

Substandard material mechanical properties, such as strength, toughness, and ductility, can severely impact sheet metal processing. Insufficient material strength can easily deform when subjected to external forces, failing to meet product requirements. Poor material toughness can lead to breakage during processes like bending and stamping. Substandard material properties can be caused by substandard raw material quality, inconsistent production batches, or changes in material properties during storage due to environmental factors.

2. Processing technology issues

(1) Problems in cutting

Dimensional deviation: Inaccurate blanking dimensions are a common problem in the blanking process. Dimensional deviation can occur for a variety of reasons, including insufficient cutting equipment precision, operator marking errors, and programming errors. Dimensional deviations can hinder subsequent bending, welding, and other processes. Even if assembly is possible, they can affect the overall quality and appearance of the product.

Poor cut quality: When cutting with laser or plasma cutting methods, problems such as uneven cuts, excessive burrs, and residual slag may occur. This is primarily due to improper cutting parameters, such as excessive cutting speeds, insufficient power, or inadequate equipment maintenance and severe wear of the cutting head. Poor cut quality not only affects the appearance of sheet metal parts but also increases the workload of subsequent polishing and cleaning, reducing production efficiency.

(2) Problems in the bending process

Bend Angle Error: A common problem during the bending process is when the actual bend angle doesn't match the designed angle. This can be caused by factors such as worn bending dies, unstable press pressure, or improper operator adjustment of the press brake. Bend angle errors can affect the shape accuracy of sheet metal parts, causing the assembled product to fail to meet design requirements and, in severe cases, requiring rework.

Bending cracks: Cracks appear on the surface or inside the material during the bending process. Causes of cracks include poor material ductility, a small bending radius, or excessive bending speeds. High-strength materials are particularly prone to cracking if bending process parameters are not carefully controlled. These cracks can reduce the strength and service life of sheet metal parts, posing a safety hazard.

(3) Problems in welding

Weld quality defects: Common weld quality defects include porosity, slag inclusions, incomplete penetration, and undercuts. Porosity is caused by gases not fully vented during welding, which remain within the weld. Slag inclusions refer to slag that has not fully emerged from the weld and remains in the weld. Incomplete penetration refers to incomplete fusion at the weld root. Undercuts are gaps at the weld edge caused by arc-melted base metal that is not filled with filler metal. These defects can weaken the weld and reduce the reliability of the weld joint.

Welding deformation: During welding, sheet metal parts are prone to deformation due to uneven local heating. This deformation can reduce the dimensional accuracy of sheet metal parts, affecting product assembly and performance. There are many factors that can cause welding deformation, such as improper selection of welding process parameters, an unreasonable welding sequence, and insufficient workpiece rigidity.

3. Quality inspection and management issues

(1) Unclear testing standards

Some sheet metal processing companies lack comprehensive, clear quality inspection standards, resulting in a lack of unified basis for quality inspection. Different inspectors may have different judgments on the quality of the same product, affecting the stability and consistency of product quality. Furthermore, with the development of industry technology and increasing customer requirements, if companies fail to update their inspection standards in a timely manner, their product quality will not meet market demand.

(2) Outdated detection methods

Some companies still rely on traditional manual inspection methods, such as using simple tools like calipers and micrometers to measure dimensions and visually inspecting surface quality. This approach is inefficient, subject to high errors, and can be difficult to accurately detect internal defects and minor cracks. Advanced non-destructive testing technologies, such as ultrasonic testing and X-ray testing, are underutilized in some companies, making it difficult to comprehensively and accurately inspect sheet metal parts.

(3) Imperfect quality traceability system

The lack of a comprehensive quality traceability system makes it difficult to quickly and accurately trace the source and cause of quality issues. This inability to promptly implement effective corrective and preventative measures leads to recurring similar issues, increasing quality costs and production cycles. Furthermore, it hinders companies from continuously improving and optimizing their production processes.

Problems in sheet metal processing involve multiple aspects, including raw materials, processing technology, and quality inspection. Only by fully understanding these common problems, thoroughly analyzing their causes, and implementing targeted solutions can companies effectively improve the quality and efficiency of sheet metal processing and gain a competitive advantage in the fierce market.