Purpose
To clearly define the inspection methods and quality requirements for the components produced in the sheet metal workshop, ensuring that each product meets the standards before proceeding to the next process.
Scope of Application
This applies to quality control of products processed in the sheet metal workshop.
Responsibilities
1. The technical personnel in the sheet metal workshop are responsible for self-inspection and mutual inspection of the sheet metal processing process.
2. The quality inspectors from the comprehensive quality inspection department are responsible for sampling, supervision, and confirmation of product quality during the sheet metal production process.
3. The comprehensive quality inspection department is responsible for identifying, recording, isolating, and organizing the handling of non-conforming products.
4. The production department of the sheet metal workshop participates in the handling of non-conforming products.
5. The procurement department communicates with suppliers regarding non-conforming sheet metal raw materials received.
Inspection Tools: 5m tape measure, 200mm caliper, protractor, visual inspection.
Cutting Group
1. Review the drawings before starting the construction process. Verify the material thickness, specifications, and quantity required for the project, and strictly follow the drawing requirements for cutting.
2. For standard parts, the dimensional tolerances of the first 5 pieces should be within ±0.5mm for length ≤2000mm and width ≤1200mm. For more than 5 pieces, the dimensions should be exactly as specified in the drawings, with a tolerance of ±0.8mm for length ≥2000mm.
3. For non-standard parts, the dimensional tolerances of the first 5 pieces should be within ±0.8mm for length ≤2000mm and width ≤1200mm. For more than 5 pieces, the dimensions should be exactly as specified in the drawings, with a tolerance of ±1mm for length ≥2000mm.
4. The burr tolerance for both standard and non-standard parts should be within ±0.3mm.
5. For standard parts, the diagonal tolerance should be within ±0.5mm for the first 5 pieces. For more than 5 pieces, the diagonals should exactly match the drawings. For non-standard parts, the diagonal tolerance should be within ±1mm for the first 5 pieces, and for more than 5 pieces, it should match the drawings. For length ≥4000mm and width ≥1300mm, the diagonal tolerance is ±3mm.
6. The surface should be free from scratches, dents, watermarks, oxidation, roller marks, waves, and deformation. For scratches and dents, the width should be >1mm and the depth should be >0.3mm for sheet surfaces ≤2000mm, and the width should be >1.5mm and the depth should be >0.5mm for sheet surfaces ≥2000mm.
7. For standard parts, random inspections should be conducted every 30 minutes. For non-standard parts, random inspections should be conducted every 3-5 pieces.
8. Each order number should be labeled according to the actual situation of the produced sheets, in the same position.
9. Sheets of the same batch, same order number, and same thickness should be stored together.
10. In special cases where the raw materials are insufficient and substitutes are used, detailed labeling should be done on the sheet surface.
11. Handle semi-finished materials with care.
12. The dimensions of the sample should match the width, length, and diagonal requirements specified in the drawings.
Corner Cutting (CNC punching, general punching, engraving, internal assembly, external assembly)
1. Review the surface quality and dimensional accuracy of the workpieces from the previous process before cutting corners.
2. Follow the drawing requirements for punching, cutting, and engraving, ensuring proper positioning of corner codes with a deviation of ±5mm.
3. The dimensional tolerances for the length and width of punched, cut, and engraved parts should be within ±0.5mm.
4. The surface should be free from scratches and burrs. For scratches and burrs, the width should be >1mm and the depth should be >0.5mm for sheet surfaces ≤2000mm, and the width should be >1.5mm and the depth should be >0.5mm for sheet surfaces ≥2000mm.
5. Pay attention to the corner treatment during punching, cutting, and engraving for internal and external assembly.
6. For overlapping plates in tight production, use the technique of long covering short or short covering long.
7. Full inspection for non-standard parts and triple inspection for standard parts (first inspection, in-process inspection, final inspection).
8. Assign dedicated personnel for the production of punched samples.
9. For CNC punching of standard products, check if the programmed graphics match the production drawings. The clamps should match the dimensions. After the first piece is punched, inspect it and proceed with mass production only when it is confirmed to be correct.
10. For CNC punching of non-standard products, pay attention to the correct direction and numbering. If the numbering is punched off, promptly use a marker to add a supplementary label. Inspect each punched product to ensure compliance with technical requirements.
11. For engraving machines, check if the unfolding drawings provided by the technical department match the dimensions in the production drawings before starting production. The edges should be free from burrs. After engraving, check the dimensions and pay attention to the direction. The labeling method should be consistent.
Punching (Outsourced Punching, In-house Punching)
1. Review the drawings before starting the construction process and perform punching operations strictly according to the drawing requirements.
2. Avoid phenomena such as over-punching, under-punching, and deformation.
3. Due to the good stretchability of aluminum, the allowable tolerance for the length and width of the punched sheet is within ±1.5mm.
4. The punched sheet should be free from burrs and undergo flat processing to achieve the best level of surface flatness.
5. Simple treatment should be applied to remove oil stains from the punched sheet.
6. The punched sheet should be free from pressure marks on the surface.
Rolling Arc (Internal and External Assembly)
1. Roll the arc strictly according to the specified radius in the drawings.
2. Pay attention to the direction of forward and reverse rolling during the process.
3. The rolled arc should be smooth without straight line segments, and the rolled radius should be 10mm smaller than the actual radius.
4. Clean the impurities on the rolling drum before rolling.
5. Gradually decrease the radius from the larger radius to the specified radius in the drawings during the rolling process, following a sequence from larger pieces to smaller pieces or vice versa.
6. The rolled sheet should be free from drum marks, and the radius should undergo initial straightening after burning, welding, and rough grinding, in accordance with the required radius template.
Bending
1. First, check if the products cut and punched in the previous process match the drawings. Before starting the work, prepare the machine for bending strictly according to the drawings.
2. Adhere to the principle of "no drawings, no construction; no drawing review, no construction; no work certificate, no construction."
3. The flatness tolerance of the formed sheet is 2mm for ≤2000mm and 3-4mm for ≥2000mm.
4. For sheets with a length ≤2000mm and width ≤1200mm, the dimensional tolerance for the first 5 pieces should be within ±0.5mm. For more than 5 pieces, the tolerance should match the drawings. For sheets with a length ≥2000mm, the tolerance should be within ±1mm.
5. The angle control for tightly assembled plates should be around 88-89°, except for special cases (the optimal angle for overlapping columns is 88°).
6. The diagonal tolerance for the formed sheet should be within ±1mm.
7. Full inspection should be conducted for non-standard parts, and standard parts should undergo triple inspection (first inspection, in-process inspection, final inspection).
8. For sheets with special technical requirements, assembly inspection should be performed after forming.
9. Keep records of the processed product quantities for easy reference.
Punching (Outsourced Punching, In-house Punching)
1. Review the drawings before starting the construction process and perform punching operations strictly according to the drawing requirements.
2. Avoid phenomena such as over-punching, under-punching, and deformation.
3. Due to the good stretchability of aluminum, the allowable tolerance for the length and width of the punched sheet is within ±1.5mm.
4. The punched sheet should be free from burrs and undergo flat processing to achieve the best level of surface flatness.
5. Simple treatment should be applied to remove oil stains from the punched sheet.
6. The punched sheet should be free from pressure marks on the surface.
Rolling Arc (Internal and External Assembly)
1. Roll the arc strictly according to the specified radius in the drawings.
2. Pay attention to the direction of forward and reverse rolling during the process.
3. The rolled arc should be smooth without straight line segments, and the rolled radius should be 10mm smaller than the actual radius.
4. Clean the impurities on the rolling drum before rolling.
5. Gradually decrease the radius from the larger radius to the specified radius in the drawings during the rolling process, following a sequence from larger pieces to smaller pieces or vice versa.
6. The rolled sheet should be free from drum marks, and the radius should undergo initial straightening after burning, welding, and rough grinding, in accordance with the required radius template.
Bending
1. First, check if the products cut and punched in the previous process match the drawings. Before starting the work, prepare the machine for bending strictly according to the drawings.
2. Adhere to the principle of "no drawings, no construction; no drawing review, no construction; no work certificate, no construction."
3. The flatness tolerance of the formed sheet is 2mm for ≤2000mm and 3-4mm for ≥2000mm.
4. For sheets with a length ≤2000mm and width ≤1200mm, the dimensional tolerance for the first 5 pieces should be within ±0.5mm. For more than 5 pieces, the tolerance should match the drawings. For sheets with a length ≥2000mm, the tolerance should be within ±1mm.
5. The angle control for tightly assembled plates should be around 88-89°, except for special cases (the optimal angle for overlapping columns is 88°).
6. The diagonal tolerance for the formed sheet should be within ±1mm.
7. Handle the formed products with care and place them in the designated positions.
8. Assign dedicated personnel for the production of templates, ensuring that the dimensional tolerances match the drawing requirements and the surface is aesthetically pleasing.
Welding
1. Review the drawings before starting the construction process and perform welding strictly according to the drawings.
2. Before welding, perform initial straightening on the formed angles. During welding, ensure firmness, avoid missing welds, insufficient welds, detached welds, cracks, and ensure smooth and even full welding.
3. Regardless of large angles, small angles, or 90° angles, perform angle correction after welding.
4. The dimensional tolerance for welded fittings should not exceed ±2mm.
5. Assign dedicated personnel for welding and ensure full welding treatment for samples.
6. For large panel group welding, spot welding should be performed.
7. When welding the plates after grooving, perform spot welding regardless of length.
Polishing
1. Review the drawings before starting the construction process and perform polishing on the welded products strictly according to the drawing requirements.
2. Focus on polishing the weld seams, full welds, and surfaces with scratches, abrasions, and unevenness, making them smooth and even.
3. The size of the R angle after full welding should be consistent. For tightly assembled plates, the R angle should be right-angled, while for external decorative plates, the corners should be rounded.
4. File the non-welded overlapping plates to create a smooth angle.
5. When polishing internal and external decorative plates, pay special attention to the edges or hard-to-reach dead spots.
6. The polished products should have a perfect appearance, and they should be handled with care during placement.
7. Assign dedicated personnel for polishing and polishing treatment of samples.
Assembly
1. Review the drawings before starting the construction process and install the corner codes strictly according to the specified height in the drawings. The height tolerance for corner code installation is within ±1mm, and the positional error of the corner codes should be within 5mm. Special corner codes should meet the required height.
2. The corner codes should be made of the same thickness of material.
3. The installation of reinforcement ribs should follow the requirements in the drawings, with a positional and dimensional tolerance within 5mm. When the back ribs are not strong enough, increase the strength while ensuring that the surface remains flat and undistorted.
4. The length of reinforcement ribs, the method of waist hole punching, and the number of nails should be consistent for the same batch of plates.
5. The distribution of reinforcement ribs should be uniform, and when reinforcing, avoid the numbering.
6. Adjust the current size during nail installation according to the actual material thickness of the nails. Pay attention to whether there are nail marks on the surface after reinforcement.
7. After installing the corner codes, check the
