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First, when choosing a copper tube bending mandrel, you need to consider the following key factors: Bending radius and wall thickness: Choose a suitable mandrel according to the bending radius and wall thickness of the copper tube. For example, when the ratio of the bending radius to the outer diameter of the copper tube R/D is greater than or equal to 3, and the ratio of the wall thickness to the outer diameter S/D is greater than or equal to 0.05, you can choose a coreless bending tube. For copper tubes with a small bending radius or thin wall thickness, you need to use a hard or soft mandrel to bend the tube.   Mandrel type: Choose a suitable mandrel type according to the material and bending requirements of the copper tube. Hard mandrels are suitable for general bending requirements, while soft mandrels are more suitable for copper tubes with small bending radius or thin wall thickness. Soft mandrels can adapt to different bending requirements more flexibly.   Mandrel diameter and gap: The diameter of the mandrel and the gap between it and the inner diameter of the copper tube will also affect the quality and effect of the bending tube. The diameter of the mandrel needs to be appropriate. Too small may cause wrinkles on the inside of the copper tube, while too large or not smooth enough may damage the tube wall. Usually, the diameter of the mandrel should be slightly smaller than the inner diameter of the copper tube to ensure that the copper tube will not be excessively damaged during the bending process. Lubrication: During the bending process, fully lubricating the mandrel and the inner wall of the copper tube is also an important step to improve the quality of the bending. Proper lubrication can reduce friction, make the bending process smoother, and avoid damage to the inner wall of the copper tube.   Choosing a suitable copper tube bending mandrel through the above points can ensure the quality of the bent pipe fittings and meet specific engineering or product requirements. When choosing, you can consider the specific bending requirements and the material, wall thickness and other factors of the copper tube and choose the most suitable mandrel type and specification.   Again, when choosing copper tube, aluminum tube or stainless steel tube bending mandrel, you can follow the following suggestions:   In particular, in the production and manufacturing of air conditioning refrigeration heat exchangers, copper tubes or aluminum tubes with the following outer diameters are generally bent: Φ5mm, Φ6.35mm, Φ7mm, Φ7.94mm, Φ9mm, Φ9.52mm, Φ12mm, Φ12.7mm, Φ14.5mm, Φ15.88mm, etc. The specifications of stainless steel tubes for bending heat exchangers are generally these: Φ7mm, Φ9.52mm, Φ12.7mm, Φ15.88mm, etc. Whether copper tubes, aluminum tubes or stainless steel tubes, there are long U-shaped bends and U-shaped elbow bends. For long U-shaped copper tubes, universal mandrels are generally used for bending. For small-diameter long U-shaped copper tubes such as Φ5mm, Φ6.35mm, and Φ7mm, a dull mandrel or thumb-shaped mandrel is generally used for bending. For U-shaped copper tube elbows, one-way mandrels are generally used for bending, and dull mandrels or thumb-shaped mandrels can also be used for bending. At present, many manufacturers have begun to use aluminum tubes instead of copper tubes in refrigeration heat exchangers. Generally speaking, the aluminum tube bending mandrel is the same as the copper tube bending mandrel, but because the aluminum tube has strong viscosity and high requirements for the surface of the bending mandrel, all bending mandrels need to be PVD treated. The mandrel treated in this way has a very good bending effect. For stainless steel heat exchangers in special environments, stainless steel tubes must be bent. The stainless steel bending mandrel is different from the copper and aluminum tube bending mandrels. It needs to be made of cemented carbide materials or special PVD processing technology. Of course, in the manufacturing process of air-conditioning heat exchangers, whether copper tubes, aluminum tubes or stainless steel tubes, there are many process pipe fittings that need to be bent, and the choice of bending mandrel is the same as the above.

Choosing the pierce punch for a fin die (used in manufacturing heat exchanger fins) is a critical decision that affects tool life, product quality, and production efficiency. Here’s a structured guide on how to choose the right pierce punch:   1. Determine the Fin Material and Thickness Material Type: Aluminum, copper, stainless steel, etc. Material Thickness: Common fin thicknesses range from 0.05–0.3 mm. Punch material and coating must be compatible with the workpiece to reduce wear and prevent galling. 2. Choose the Punch Material Work Material Recommended Punch Material Coating Aluminum SKD11, ASP23, or DC53 TiN, TiCN Copper High-speed steel (HSS), ASP30 TiCN, TiAlN Stainless Steel Carbide or ASP60 TiAlN, DLC Use carbide punches for high-volume or stainless steel applications. 3. Select the Punch Shape and Size Shape: Round, rectangular, oblong, or custom shapes based on fin hole design. Size: Should match the piercing hole in the fin design precisely (plus/minus tolerances as per die design). Work closely with the die designer to determine clearance and punch-to-die fit. 4. Consider the Punch Clearance Clearance is the gap between the punch and die. Recommended clearance: For soft material (like aluminum): 3–5% of material thickness For harder material: 5–8%   Improper clearance causes: Too small: Premature wear, punch breakage Too large: Burrs, deformation 5. Coating and Surface Treatment To enhance performance and longevity: Use PVD coatings like TiN, TiCN, or DLC. Polished or mirror-finished surfaces reduce friction and adhesion. 6. Ease of Maintenance and Replacement Choose punch designs compatible with easy replacement systems. Modular or insert-type punches are preferred for high-volume production. 7. Production Volume High-volume: Invest in durable materials like carbide or powdered metals. Low-volume or prototyping: HSS or tool steels can be more cost-effective.

Technical Guide Selecting HSS Chipless Cutting Blades for Copper Tubes in HVAC and Heat Exchanger Coils Introduction In HVAC and heat exchanger manufacturing, chipless cutting of copper tubes is essential to prevent metal chips from contaminating refrigeration systems. High-Speed Steel HSS chipless cutting blades provide clean burr-free cuts while maintaining efficiency. This guide explains key specifications including outer diameter OD inner diameter ID thickness and blade angle to help you select the optimal blade for your application. For a full product range visit Machine Die Spare Parts at hairpin bender cutting blade or circular blade. Key Specifications of Chipless Cutting Blades Chipless cutting blades come in various dimensions and angles each suited for different tube sizes and cutting conditions. Below are common specifications Blade Model OD mm ID mm Thickness mm Blade Angle OD32.2xID15x10.2x18 32.2 15 10.2 18 OD25xID15x10.2x16 25 15 10.2 16 OD25.4xID10x8x20 25.4 10 8 20 OD32xID12x8x20 32 12 8 20 OD31xID12x8x20 31 12 8 20 OD31.5xID12x8x20 31.5 12 8 20 Outer Diameter OD and Inner Diameter ID The OD must match the cutting machines blade holder for secure mounting The ID must fit the arbor spindle of the cutting machine Example A 32.2 mm OD 15 mm ID blade fits machines with a 15 mm spindle Blade Thickness Thicker blades eg 10.2 mm provide more rigidity for heavy-duty cutting Thinner blades eg 8 mm reduce material waste but may deform under high pressure Blade Angle Shear Angle 16 to 20 is common for copper tube cutting A smaller angle eg 16 provides a sharper cut but may wear faster A larger angle eg 20 increases durability but requires more cutting force How to Choose the Right Blade for Your Application Match the Blade to the Tube Size For small tubes 25 mm or less use OD25 to OD25.4 blades For medium tubes 25 to 32 mm use OD31 to OD32.2 blades Consider Cutting Speed and Feed Rate Higher blade angles 20 work better for fast cutting Lower angles 16 to 18 are better for precision cuts Blade Material and Coating HSS High-Speed Steel offers good durability for moderate use Carbide-tipped blades last longer in high-volume production Titanium Nitride TiN coating reduces friction and extends blade life Machine Compatibility Ensure the ID fits your machines spindle Check if the OD matches the blade holder Recommended Blades for Common HVAC Applications Application Recommended Blade Model Key Features Small Copper Tubes 25 mm or less OD25xID15x10.2x16 Sharp cut minimal burr Medium Tubes 25 to 32 mm OD32xID12x8x20 Balanced durability and precision High-Speed Cutting OD31.5xID12x8x20 Optimized for fast feed rates Where to Buy For a complete selection of HSS chipless cutting blades visit Machine Die Spare Parts at machine die spare parts Conclusion Choosing the right chipless cutting blade ensures clean burr-free cuts in copper tubes improving HVAC and heat exchanger performance. Key factors include Blade dimensions OD ID thickness Shear angle 16 to 20 Material HSS carbide coated Machine compatibility For best results always verify blade specifications with your tube size and cutting machine requirements. Need a custom blade Contact Machine Die Spare Parts at machine die spare parts for specialized solutions.

1 Understand the Coil Design and Production Requirements Type of coil Serpentine helical finned tube etc Tube material Copper aluminum stainless steel Tube diameter and wall thickness Bending radius and angles Fin type and arrangement if applicable End connections headers fittings brazed joints 2 Select Tools Based on Operations Tube Straightening Tool Tube straightening machine Selection tip Choose based on tube diameter wall thickness and coil material Ensure it avoids tube deformation Tube Cutting Tool Tube cutting machine rotary abrasive or chipless Selection tip Use chipless cutting for high precision and clean edges especially for brazing Tube Bending Tool CNC tube bender or manual bending jig Fixture Mandrel and wiper dies to prevent kinking Selection tip CNC benders for complex or high volume work mandrel support for tight radii Fin Stacking for finned coils Tool Fin press or fin die Fixture Fin alignment jigs Selection tip Match fin die with fin geometry corrugated louvered etc Tube Expansion into Fins Tool Mechanical or hydraulic expander Selection tip Choose depending on coil size and expansion tolerance avoid over expansion that damages fins Brazing or Joining Tool Induction or flame brazing torch Fixture Brazing jig holds tubes and headers in correct position Selection tip Use jigs with heat resistant materials and precise alignment 3 Design Jigs and Fixtures for Consistency General Principles Use modular fixtures where possible to accommodate different coil designs Fixtures should be Rigid to prevent shifting Repeatable for mass production Heat resistant if used in brazing Easy to load and unload for production efficiency Common Jigs and Fixtures Process Bending Fixture Type Tube bending jig Purpose Controls radius and angle Process Assembly Fixture Type Coil assembly fixture Purpose Aligns fins tubes headers Process Brazing Fixture Type Brazing fixture Purpose Holds parts in place at joints Process Leak Testing Fixture Type Pressure test jig Purpose Seals coil ends for testing 4 Consider Production Volume Low volume or Prototype Manual jigs and semi automatic tools are cost effective High volume Invest in CNC machinery and automated fixtures for speed and precision 5 Evaluate and Iterate Conduct trial runs to validate tool and fixture performance Check for Deformation Misalignment Excessive scrap Cycle time Refine jigs and tooling based on actual production issues If you want to know more, please visit All types of heat exchangers line tooling.