Liquid Silicone Rubber Plunger Seal, LSR Plunger for Auto Seal
LSR Seal is the simplest part among seals, although it is the best and most
efficient seal. The structure of sealing pat is very simple, for
this reason , it could be used in many fields. It is widely used in
sealing products such as acid resistance, alkaline resistance, many
kinds of pumps. It is popularly used in sealing devices in
petroleum, chemical, medicine, mobile manufacture, war industries,
and metallurgy, printing and dying, food, mechanical and many other
The LSR molding process starts with proper part design. Anyone
familiar with designing parts for injection molding should find
designing an LSR part to be similar. However, the shrink rate on
LSR is fairly high, and the material also tends to flash very
easily during molding. Protomold helps mitigate challenges related
to high shrink rates by planning appropriate tolerances and
incorporating additional features into the mold design to help
reduce flash. LSR typically fills thin wall sections with minimal
challenges and is accommodating to variations in wall sections as
sink is almost nonexistent.
When an order is placed, Proto Labs will then design an LSR molding
tool. Due to the flexible nature of LSR, parts are manually removed
from the mold, and thus, ejector pins are not built into the mold
design. Like a standard Protomold aluminum tool, an LSR molding
tool is fabricated using a combination of CNC milling and CNC
electrical-discharge machining (EDM) to create a high-temperature
aluminum tool built to withstand the LSR molding process. After
milling, the tool is polished by hand to customer specifications,
which allows six standard surface finish options: PM-F0, PM-F1,
SP-C1, PM-T1, PM-T2 or SPI-A2. Others may be available by request.
The finished tool is loaded into an advanced LSR-specific
injection-molding press that is precision geared for accurate
control of shot size to produce the most consistent liquid silicone
rubber parts. LSR molding shares many similarities with
conventional injection molding, but there are a few notable
differences. Unlike thermoplastic resin, which is melted before
injection, LSR is a two-part thermoset compound that is chilled
before being injected into a heated mold and ultimately cured into
a final part. Note that Protomold uses an automated meter mixing
pump to assure the exact combination of the two-part compound;
nothing is hand mixed. Since LSR is a thermosetting polymer, its
molded state is permanent - once it is set, it can't be melted
again like a thermoplastic.
Liquid silicone rubber is a free-flowing, shear thinning thermoset
material that injects easily into a mold and is less prone to many
defects like sink as compared to typical thermoplastic materials.
However, LSR flashes extremely easily and into gaps as small as
0.0002 in. When designing a part for LSR, you should keep in mind
best practices for tooling of standard plastic molds. Though the
materials are different, the molds are constructed in a similar
1) Liquid silicone medical part, as like the capsule, laryngeal
mask capsule, oxygen mask, protective mast, catheter, balloon,
medical belt etc.
2) Liquid silicone auto parts, silicone valve, O-ring, sealing part.
3) Liquid silicone electronics and industrial product, such as the watchband, mobile
4) LSR products, which can be with the insert, as like the plastic
part, steel part etc. As sample: silicone diving mask, electric
silicone drum Stick, silicone handle, silicone vibrators etc.