Deep-drawn seamless tubes are made from metal blanks in multiple deformation processes.

 

They can be used for different industrial purposes and the manufacturing of metal bellows.

Common materials for the production of our seamless metal sleeves and thin-walled tubes are bronze, brass, stainless steels, special nickel-copper or beryllium copper alloys. Those materials come with different attributes that have to be considered in the selection to perfectly meet the application’s requirements.

 

How deep-drawn seamless cups and tubes are made

 

The production of our thin-walled tubes starts with a metal strip that undergoes several sheet metal forming processes.

• Blanking: Cutting round blanks from the strip, using hydraulic presses
• Stamping: Producing metal cups (sleeves) – Decreasing diameter while increasing length, wall-thickness stays
• Either soap or oil is used for each operation as lubricant to ensure smooth movements
• Depending on the used material and the designated final size of the tube, it has to be deep-drawn through multiple dies with decreasing diameter, wall-thickness decreases
• Annealing (in vacuum furnaces) after each plastic deformation process to restore the elasticity of the material
• Special washing machines are used continuously in order to achieve an immaculate surface.

If thin-walled stainless steel tubing is requested, our customers benefit of efficient multi-drawing technologies. At Mera Bellows we follow a sustainable approach. Due to our closed water circuits, eco-friendly technologies, and installed oil traps, we ensure that no pollutants are released into nature.

 

Our tooling and techniques enable us to produce thin-walled tubes with very low tolerances

 

We are specialized in the manufacturing of seamless tubes with extremely thin wall-thickness. To guarantee a leak-free welding line with the “weld-end”, a consistent dimensional accuracy of the wall is needed. As an experienced precision bellows manufacturer, we are able to hold such very low tolerances, ensuring max. 0.1-0.4 mm tolerance in diameter and 0.004- to 0.015 mm in wall-thickness. The hydraulic presses allow maximum production lengths of up to 450mm and diameters of ca. 70mm. The closed bottom of our seamless cups and tubes can be designed in customized shape and also the open side may be formed to meet individual requirements. It is also possible to create holes in the bottom – for example stainless steel cups (bonnets) as housing for measurement and controlling devices

Seamless vs. welded precision tubing

While it is often almost impossible to distinguish a seam-welded from a seamless tube with the naked eye, there are some significant differences of stainless steel tubes that matter when it comes to ultra-precise applications. Welded tubes are made from a roll-formed metal strip. The welding process results in an inhomogeneous tube wall that has to be reworked first. Due to different working standards, the quality of the weld area can show great variances in the final product, resulting in a lesser reputation for welded tubes compared to seamless tubes. Since deep drawn seamless tubes are intermediate products in our manufacturing of metal bellows, we do only provide results in a smooth and homogeneous surface. Our seamless precision bellows are key components in highly sensitive systems. Their spring rate must exactly meet the requirements, e.g. for actuators and sensors in cars and aircrafts around the world,