Precision Forming Control Of One Closed Flat End Tubes

Meta: Precision forming control of one closed flat end tubes, covering closed end capping, bending, swaging, inner bore protection and tube shape customization.

1. Core Industry Pain Points

Precision forming defects of one closed flat end tubes are hidden sources of capillary and sensor assembly failure. The one closed flat end structure is produced by capping, stamping or deep-drawing; improper forming causes uneven wall thickness and inner bore shrinkage. Bending and swaging introduce local deformation that narrows the lumen and traps pollutants. Sharp burrs from drilling and slot-cutting fall into the capillary channel and resist removal even after purging. Machining oil and metal powder adhere tightly on the inner wall; insufficient chemical cleaning leaves residual contaminants. Square and rectangular custom tubes have more uneven wall-thickness risk than round tubes. Many factories only control outer dimension and ignore inner lumen integrity after forming.

2. Fundamental Working Principle

Precision forming of one closed flat end tubes aims to realize the customer-defined outline and closed-end structure while preserving a stable, uniform inner lumen. Capping and deep-drawing are plastic forming processes; if strain exceeds material ductility, the inner wall wrinkles or contracts. Burr control reduces the source of metal debris. The flat closed end isolates the sensing chip from the refrigerant flow path. For the capillary section, any change of inner cross-section alters throttling performance. SUS304 and SUS316 have different forming ductility; 316 has better corrosion resistance but higher springback, which must be compensated in fixture design. All formed tubes must remain accessible for three-stage cleaning.

3. Equipment and Category Classification

Machining equipment: CNC turning, grinding, milling, welding station, bending machine, drilling machine, swaging press, flaring tool, slot cutter, stamping press, deep-drawing machine and capping equipment. Material: Stainless Steel 304 and 316. Custom shapes: round, oval, square and rectangular flat closed tubes. Surface treatment options: anodizing, sandblasting, painting, powder coating, plating, brushing, polishing and laser engraving. Quality system: ISO9001:2015 and SGS. Packing: standard carton or customized anti-collision packaging.

4. Standard Operation Guide

First, review the 2D/3D drawing and confirm inner bore tolerance and forming limit before machining. Set different springback compensation for 304 and 316 raw tube. Control bending radius to avoid sharp bends that squeeze the lumen. Steadily adjust swaging and flaring stroke, using step forming instead of one-shot heavy pressing. Remove burrs on the outer edge and prevent burr chips from falling into the lumen. After forming, transfer tubes to the cleaning station immediately. Run standard three-stage cleaning: nitrogen purge, acid-alkali cleaning, pure water rinse, hot air drying and dual-end sealing. For capillary use, test bore uniformity one by one, then tune length by the 1–1.2MPa high-pressure window.

5. On-Site Practical Experience

Most inner bore deformation occurs at bending and swaging stations, not at cutting. Increasing forming speed for output causes hidden wrinkles invisible to the eye. Thin-wall capillary should use a forming fixture with inner support mandrel. Low-residue machining oil is preferred; high-viscosity oil is hard to remove in the acid-alkali bath. For square and rectangular custom closed end tubes, sample four-side wall thickness after deep drawing. Do not stack unsealed formed tubes for long, since workshop dust sticks to fresh surfaces.

6. Conclusion and Value

Standard precision forming control keeps the inner lumen integrity of one closed flat end tubes. It avoids cross-section distortion, burr debris and residual machining compound, creating favorable conditions for cleaning, brazing and pressure tuning. Stable forming tolerance guarantees interchangeability of custom sensor housing parts.

7. Industry Outlook and Suggestions

CNC all-in-one tube forming machines with online bore monitoring will become mainstream. Factories can separate capillary precision forming from general structural tube lines. Customers should mark inner lumen protection requirements on drawings. For high-precision refrigeration sensor projects, specify mandrel-supported bending in the technical agreement.