Bellows made of TPU

Since 2002 OSSBERGER is offering the new PRESSBLOWER Injection Blow Molding Maschines DSE 140 and DSE 250. The PRESSBLOWER DSE 140 is basically covering the product range of Constant Velocity Joint Boots and Rack & Pinion Boots made of TPE grades while the PRESSBLOWER DSE 250 is destined to make heavier boots and bellows for a maximum weight of up to 250 grs.

In cooperation with the company Plásticos Dúrex at Salamanca in Spain OSSBERGER realised a "TPU project".

It had to be determined what the procedure is and what the processing data are to avoid well-known problems related to the processing of TPU; at the same time it had to be made sure that consistent product quality is guaranteed. For OSSBERGER as the machine maker the following aspects were important:

For the first time a PRESSBLOWER DSE 250 was used to realise a net product weight of about 160 grs. During the trials it turned out that - when following the demanded wall thicknesses for this particular product - a net weight of 162 grs with a tolerance of +/- 1 gr. had been targeted.
A diameter of 160 mm was realised. So far this diameter was just too big for PRESSBLOWER.
Consistent processing of TPU (in this case Elastollan C 90 A) had to be guaranteed.
The trimming of the part on both ends within close dimensional tolerances had to be assured by using the additional top cutting device which is offered as an integrated option for PRESSBLOWER DSE 250.

The photo of this page is showing the bellows which is applied in an air spring system and which Plásticos Dúrex delivers to the system suppler Vibracoustic for the E-Class of Mercedes-Benz. Vibracoustic's decision in favour of TPU (instead of rubber) was made because TPU is highly resilient offering a longer lifetime of the bellows.

For OSSBERGER this project was of high interest because the high precision of the PRESSBLOWER process could be shown when running thermoplastic polyurethane.

A nice side effect for OSSBERGER was that a PRESSBLOWER DSE 250 is now replacing an extrusion blow molding machine which had been used before.