The weld geometry at CD-welding is usually carried out with one projection diameter, or some single projections . Two work pieces are pressed hydraulically, pneumatically, hydropneumatically , or by a servo motor with a pre-load.
Then a measurement of the parts height by the integrated way measurement system takes place. After that the welding force is applied. Generally the pressure unit transfers the force on polymer springs which transmit the force to the upper electrode and further to the work pieces. Once the weld force is reached, the electric energy is discharged from the capacitors through transformers and generates a Joule heating at the contact of the weld projection.