Case Industry

Gold Coins

For the metal bellows of thermostatic valves, we manufacture the sleeves from phosphor bronze using deep drawing technology in large series.

The product


Thermostatic valves - i.e. the temperature controllers on the heating system - are found in almost every home. In the head of a thermostatic valve there is a metal bellow, a corrugated pipe, which expands depending on the room air temperature.

The requirements


For these metal bellows the manufacturer required deep drawn sleeves that are very long and thin-walled. The challenge: The sleeves must be matched to the customer's subsequent process under very tight tolerance specifications. Why? Because the sleeves cannot be further processed with deviating geometries. Absolute precision is therefore required.


We can offer absolute precision. The customer commissioned us to manufacture the sleeves. On the one hand, because we meet the special deep drawing requirements. On the other hand, because we can offer a combined, targeted heat treatment for material relaxation in-house.

The solution


In order to guarantee the required further processing, our attention was initially focused on the forming behaviour of the material. The customer decided to use phosphor bronze because of its good thermal conductivity. A specialised press is used to manufacture the sleeve, which makes it possible to manufacture the high length/diameter ratio in a capable manner.


In order to ensure further processing at the customer's premises, we then rely on an annealing process in which the material recrystallises. This creates the desired, extremely uniform material structure. Thanks to this in-house treatment, the customer receives the necessary forming capacity in the component so that the sleeves can be further processed according to the requirements.


Since the components are soft after the annealing process, gentle handling in terms of packaging is then required. In the containers we have chosen, the parts cannot move and damage and corrosion are minimised.

At a glance

  • Manufacture of phosphor bronze sleeves using deep drawing technology
  • Large-scale production
  • Gentle forming to achieve high component lengths with relatively small diameters
  • Continuous annealing furnace integrated in manufacturing for optimum process coordination
  • Customised packaging for damage-free transport and optimum handling at the customer's premises.

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