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.


Metal sleeves (metal cups) and seamless tubes are intermediate products in the manufacturing process of metal bellows, corrugated tubes or expansion joints, but may also be applied in many other fields, such as mechanical engineering, or the automotive industry. Common materials for the production of our metal sleeves and seamless tubes are bronze, brass, stainless steels, special nickel-copper or beryllium copper alloys. Those materials come with different attributes and specifications that have to be considered in the selection.


How seamless cups and tubes are made


The production of a seamless tube starts with a metal strip that undergoes a sheet metal forming process known as “deep drawing”. A piece of metal is considered deep-drawn when its depth exceeds its diameter. Depending on the used material and the designated final size of the tube, it has to be redrawn through multiple dies with decreasing diameter. After each plastic deformation process, the thin-walled seamless tubes have to be annealed to restore the elasticity of the material. Without annealing the material in vacuum furnaces, it would not be possible to continue processing the now very hard material. Using either soap or oil as lubricant, special washing machines are used in order to achieving an immaculate surface. In the case of seamless stainless steel tubing, 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.


The industrial use of seamless tubes


Because of their versatility, metal sleeves and deep-drawn seamless tubes are used by industries all over the world. For example:

  • General Industry
  • Oil & Gas
  • Power Gen
  • Chemical Industry
  • Medical Industry
  • Construction
  • Distribution
  • Automotive


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


We are specialized in manufacturing seamless tubes with extremely thin wall-thickness. If the tube has to be welded in an automatized process on customer side, a consistent dimensional accuracy of the cups (tubes) wall is needed to guarantee a leak-free welding line with the “weld-end” 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 shapes 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) for measurement and controlling devices. Because of their versatility, deep-drawn metal sleeves (cups) and tubes are used in many industries.


Seamless vs. welded tubes


While it is often almost impossible to distinguish with the naked eye a welded from a seamless tube, there are some significant differences 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 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.