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In the field of heat exchanger manufacturing, the choice between mechanical expansion and hydraulic expansion depends directly on the thickness of the tube sheet. When the tube sheet thickness exceeds 45 mm, hydraulic expansion joining becomes the preferred method due to its characteristic of uniform stress distribution ； When the thickness is less than 45 mm, mechanical expansion joining offers better operational advantages. Classification of connection types and applications: The strength expansion joint system as a connection method requires it to fulfill three functions simultaneously: withstanding axial loads, ensuring sealing performance, and compensating for thermal stresses. Its key parameters include a tensile strength of ≥4 MPa, a shear strength of ≥2 MPa, and the ability to withstand temperature fluctuations above 200°C. The key points of the expansion bonding process are primarily used to eliminate minor gaps in tube holes, with a control accuracy within the range of ±0.05 mm; the operating pressure is usually 60-70% of that used for strong expansion bonding. The slotting process specification for mechanical expansion joining calls for a slot depth of 0.5 mm, with the typical slot configuration being a 3-6-3 stepped structure. For hydraulic expansion joining, it is necessary to calculate a specific groove width: L1=（1.1-1.3）×√(d×t), with a maximum value not exceeding 13 mm; the 8-6-8 groove layout is commonly used. The material compatibility requirements for manufacturing simulated tube sheets dictate that such sheet must exactly replicate the material properties of the actual product tube sheet: a Rockwell hardness error of ≤3HRC, a thickness tolerance of ±0.1mm, and a hole diameter deviation of ±0.02mm. Key points of structural design: For triangular arrangements, a 7-hole reference model is used, while the recommended size for rectangular simulation plates is 300×200 mm. The outer diameter of the circular steel simulation plate must be determined using the plastic displacement verification formula: μ