In roll forming, metal sheets are shaped into various profiles by passing them through a series of rollers. Two common types of tubes produced by this method are open seam tubes and lock seam tubes.
Here’s a comparison between the two:
What is roll forming open seam tubes
Roll forming open seam tubes refers to the process of manufacturing tubular shapes from flat metal sheets or strips using a series of rolling dies, but leaving the edges of the tube unsealed or open. The resulting tube has a gap along its length where the two edges of the metal strip are not joined or connected.
Manufacturing Process of Open Seam Tubes
Step 1: Metal Strip or Sheet: The process starts with a flat metal strip, typically made of materials such as steel, stainless steel, aluminum, or copper.
Step 2: Roll Forming: The metal strip is gradually shaped into a tubular form as it passes through a series of roller dies. These dies bend the metal progressively, forming the desired tube shape.
Step 3: Open Seam: Unlike welded or lock seam tubes, the edges of the metal strip are not joined or sealed during the roll forming process, leaving an open seam along the length of the tube.
Characteristics:
Unsealed Edges: The open seam means the two edges of the metal do not touch or are not connected by welding or mechanical means.
Customizable: The open seam allows flexibility for later modifications such as welding, fastening, or further shaping during assembly.
Shape: Open seam tubes can be formed into various shapes, such as round, square, or rectangular tubes.
Applications:
Fabrication and Construction: Open seam tubes are commonly used where further processing, like welding or fastening, will be done after roll forming.
Machinery Components: Often used as structural components in machinery, where a sealed tube is not necessary.
Flexible Structures: Ideal for frameworks or assemblies where additional operations are needed before the tube is fully closed or joined.
What is roll forming Lock Seam Tubes
Roll forming lock seam tubes refers to a process in which a flat metal strip or sheet is shaped into a tube using a series of rolling dies, and the edges of the metal are mechanically locked together to form a seam without the need for welding. The resulting tube has a closed, secure seam that provides strength and rigidity.
Manufacturing Process of Lock Seam Tubes
Step 1: Metal Strip: The process begins with a flat strip of metal, commonly made from steel, aluminum, or other metals.
Step 2: Roll Forming: The metal is fed through a set of rolling dies that progressively shape it into a tubular form.
Step 3: Locking the Seam: As the metal edges come together, they are mechanically interlocked or crimped to form a seam, creating a sealed tube. This can be done using a series of special rollers or crimping tools designed to lock the edges securely.
Step 4: Final Shape: The result is a tube with a locked seam that is typically stronger and more rigid than an open seam tube, with no gaps between the edges.
Characteristics:
Locked Seam: The edges of the metal are tightly interlocked or crimped, creating a strong, closed seam.
No Welding Needed: Since the seam is mechanically locked, welding is not required, making the process faster and more cost-effective in certain applications.
Customizable: The lock seam tube can be formed into various shapes, such as round, square, or rectangular tubes, depending on the rolling die configuration.
Applications:
HVAC Ducting: Lock seam tubes are widely used in heating, ventilation, and air conditioning (HVAC) systems due to their airtight seam, which is crucial for efficient airflow.
Exhaust Systems: They are also commonly used in exhaust systems, where sealed tubes are needed to contain gases and prevent leakage.
Structural Components: Lock seam tubes are employed in construction and industrial applications where strength and a sealed structure are important.
Fluid or Air Conveyance: Since the seam is sealed, these tubes are ideal for carrying fluids, gases, or other materials that require containment.
Open Seam Tubes vs Lock Seam Tubes
Open Seam Tubes and Lock Seam Tubes differ significantly in their construction, strength, and applications due to how their seams are treated during the roll forming process. Here’s a comparison of the two:
| Feature | Open Seam Tubes | Lock Seam Tubes |
| Seam | Unsealed, open seam | Mechanically locked, sealed seam |
| Strength | Lower strength and rigidity | Higher strength and rigidity |
| Sealing | Not sealed; requires further processing | Sealed, airtight, and watertight |
| Cost | Cheaper due to simple manufacturing process | More expensive due to the locking mechanism |
| Applications | Light-duty structures, temporary frameworks | HVAC, exhaust systems, structural applications |
| Welding | May require welding or fastening later | No welding required |
| Modifications | Easier to modify after production | Harder to modify due to locked seam |
Summary:
- Open seam tubes are more flexible and cost-effective for applications where further modification (like welding) is required, but they offer less structural strength and are not airtight.
- Lock seam tubes provide greater strength and rigidity due to the sealed and mechanically locked seam, making them ideal for applications requiring a closed, sealed, or rigid structure, such as HVAC ducts or structural supports.