Blow moulding
In extrusion blow moulding, hollow plastic bodies for technical applications are manufactured in a coreless process. The process can be classified as highly efficient as only pressurised air (approx. 8 – 20 bars) is used to inflate the extruded tubular plastic parison against the internal contours of the moulding die.
Using this process, we realise the main part of our manufacturing volume at our etm facilities. Further processes (injection moulding / extrusion) can be applied to combine the articles or semi-finished components to make innovative products. For example, etm uses insert moulding technologies to manufacture charge air pipes with complex geometries and sophisticated bracket and fastening systems.
Additionally, blow moulding can be used to secure inserts (brackets/grommets) in/on blow-moulded components by insert moulding.
2d blow moulding: Process sequence (conventional blow-moulding)
- Melting on and potentially storing of plastic in an extrusion unit with parison die.
- Cycle start: vertical ejection of a defined tubular and viscoplastic parison between the open die halves by gravity.
- Moulding by centric closing of the die halves.
- After closing the die halves, the parison is immediately internally pressurised using a blow mandrel (from the top or bottom) or a blow pin. In this process, the parison is expanded (biaxially) and pressed against the cooled cavity for moulding.
- Cooling the moulded component under internal pressure.
- Venting of the moulded component.
- Opening the die halves and removal or ejection of the moulded component from the cavity.
- End of cycle.
3d blow moulding: process sequence (suction blow moulding)
- Melting on and storing of plastic in an extrusion unit with parison die.
- Cycle start: vertical ejection of a defined tubular and viscoplastic parison in a closed die with open cavity.
- After closing the die halves, the parison is moulded by direct suction into the cavity.
- After ejection, the cavity is closed on both sides by means of moveable sliders.
- The parison is then immediately pressurised internally (pressurised air) using a blow pin. In this process, the parison is expanded (biaxially) and pressed against the cooled cavity for moulding.
- Cooling the moulded component under internal pressure.
- Venting of the moulded component.
- Opening the die halves and removal or ejection of the moulded component from the cavity.
- End of cycle.
Usually, the final geometries of the articles (e.g. tube end, attachment surfaces) need to be finished accordingly. This and many of the additional finishing processes are implemented by dedicated process layouts.