Mold shells hold the two halves of the blow mold in a Sidel blowing station and close them around the preform for every bottle. Sidel stations use a compensated and a non-compensated shell. The compensated shell has a chamber behind it that is pressurized during blowing, pushing back against the blowing pressure so the mold stays tightly closed. Worn or damaged shells can let the mold open slightly, leaving visible parting lines on the bottle, and can make mold changeovers harder.
UM manufactures left and right, compensated and non-compensated mold shells for Sidel Series 1 and Series 2 blow molders. UM can also reverse engineer other mold shell designs, in aluminum or stainless steel.
Our improved aluminum mold shell runs the cooling water through a stainless steel tube, so the water never flows directly through the aluminum. This prevents corrosion inside the shell, while keeping the low weight of aluminum for faster, easier handling.
The compensation system only works if the shell, its seals and the compensation valve are all in good condition. UM also supplies an improved compensation valve for S2, S2+ and Universal machines, built around a standard MAC pilot valve for easier sourcing and more reliable operation.
Provide the machine model and series, the shell side (left or right) and type (compensated or non-compensated), the OEM part number if known, and photos. For older or undocumented shells, a sample lets UM measure and reproduce the design.
Click a reference to open it in our catalog and add it to your cart.
The compensated shell has a sealed chamber behind it. During blowing, air is fed into this chamber to push back against the blowing pressure and keep the mold closed. The non-compensated shell has no chamber. Each station uses one of each, so they are ordered as separate parts.
Cooling water flowing directly through aluminum can corrode the shell from the inside over time. The stainless steel tube carries the water instead, protecting the shell while keeping it light.
Parting lines appear when the mold halves separate slightly during blowing. Common causes are low compensation pressure, a leaking compensation valve or seal, and wear on the mold shells or locking parts.
Send us an OEM part number, a drawing, a photo or a sample and our team will confirm availability and compatibility.