A complete guide to sheet metal processing: from material selection to process flow

　　 Material selection

　　Material selection for sheet metal processing is crucial, as different materials have different uses and costs. Here are some commonly used materials and their characteristics:

　　Cold-rolled plate SPCC: mainly used for electroplating and painting parts, low cost, easy to form, material thickness ≤3.2mm.

　　Hot-rolled plate SHCC: material thickness T≥3.0mm, used for electroplating and painting parts, low cost, but difficult to form, mainly flat parts.

　　Galvanized sheets SECC and SGCC: SECC electrolytic plates are divided into N material and P material. N material mainly does not require surface treatment and has high cost. P material is used for spray parts.

　　Copper: Mainly used for conductive materials. Surface treatment includes nickel plating, chromium plating, or no treatment. The cost is high.

　　Aluminum plate: Generally treated with surface chromate, the cost is high, and there are silver plating and nickel plating.

　　Aluminum profiles: The cross-sectional structure is complex and widely used in various plug-in boxes. The surface treatment is the same as that of aluminum plates.

　　Stainless steel: Mainly without any surface treatment, high cost.

　　 Processing process

　　The processing process of sheet metal parts can vary according to structural differences, but in general it does not exceed the following points:

　　Blanking: There are many blanking methods, including shears, punches, NC CNC blanking and laser blanking.

　　Fitter: Including countersinking, tapping, reaming, drilling and other operations.

　　Flanging: Also called drilling and flanging, it is suitable for thin sheet metal processing to increase strength and the number of thread turns.

　　Punch: Processing processes using mold forming, including punching, corner cutting, blanking, convex bulge punching, punching and tearing, drilling, forming, etc.

　　Press riveting: The operation is completed by a hydraulic riveting machine or a punch press to press nuts, screws, etc. onto the sheet metal parts.

　　Bending: Folding 2D flat parts into 3D parts requires a folding machine and corresponding bending molds.

　　 Drawing review

　　Drawing review is an important part of writing part process, and the following aspects need to be checked:

　　Are the drawings complete?

　　Whether the view relationship and labeling are clear and complete, and the dimension units are labeled.

　　Assembly relationships and assembly requirements focus on dimensions.

　　Differences in drawings between the old and new versions.

　　Translation of foreign language pictures.

　　Table office code conversion.

　　Feedback and handling of drawing problems.

　　Material selection.

　　Quality requirements and process requirements.

　　Officially released drawings must be stamped with a quality control seal.

　　️ Expand diagram design

　　The expanded view is a plan view developed based on the parts drawing. The following points need to be noted:

　　The expansion method should be reasonable to save materials and processability.

　　Reasonably choose the gap and hemming method, the gap is 0.2 for T=2.0 and below, and the gap is 0.5 for T=2-3. The hemming method uses the long side to wrap the short side (door panels).

　　Reasonably consider the tolerance dimensions: negative tolerances go to the end, positive differences go half way; hole size: positive differences go all the way, and negative differences go half way.

　　Burr direction.

　　Draw cross-sectional views of the positions and directions of tooth extraction, riveting, tearing, and punching bumps (packs).

　　Check the material, plate thickness, and plate thickness tolerance.

　　Special angles and the inner radius of the bending angle (generally R=0.5) need to be tested and unfolded.

　　There are areas that are prone to errors (similar asymmetry) and should be highlighted.

　　Where there are more dimensions, enlarge the enlarged image.

　　Areas requiring spray protection must be indicated.