About Rubber Molding and Rubber Molding Services Including: EPDM, Molded Rubber, Rubber Grommets, Rubber Seals, Rubber Sheets, Rubber Tubing & Rubber Washers
Rubber
molding is a process that produces a useable molded
rubber product.
Rubber products are made from uncured rubber or elastomers. An elastomer is
any material with sufficient resilience or memory for returning to its original
shape in response to pressure or distortions. Some commonly used examples of
elastomers are styrene butadiene rubber (SBR), ethylene propylene (EPDM), butyl,
hypalon, viton, latex rubber, silicone rubber, nitrile and neoprene. SBR and
nitrile are used for their petroleum hydrocarbon resistance, and EPDM for its
ability to remain unaffected by ozone, sunlight and weathering. Butyl is water,
alkali, steam and oxygenated solvent resistant. Silicone can be used as both
a liquid or solid, and is very durable, and neoprene has a good burn resistance
and is flexible. Rubber and elastomers can be derived from natural sources
to produce latex and polyisprene, although they are mostly synthetic, produced
through highly controlled chemical processes.
Rubber is an excellent material for situations that require a material to give
and return to its original shape. Required information for purchasing molded
rubber products include rubber mold shape, rubber mold size and working
temperature range for the rubber. The hardness, which is the amount of resistance
to distorting forces, is also an important consideration. Specific industries
that benefit from custom rubber molding services are automobile, appliance
controls, lawn and garden, sporting goods, medical, electrical, government
and recreational. These industries and others benefit from the many different
products that can be created by rubber molding services.
While there are variations in specific rubber molding methods, all rubber molding
services use heat and pressure to form molded
rubber products. The four most common methods in the rubber molding process
are injection molding, compression
molding, blow molding and transfer molding.
Each of these rubber molding methods is different, but all involve pouring
liquid rubber material into a mold where it is cured in an oven and cooled,
using pressure, air or temperature to mold, thus creating the finished product.
Some examples of molded
rubber parts include rubber
grommets, rubber
tubes, rubber shock mounts, rubber stoppers, rubber
sheets, rubber hoses, rubber bumpers, rubber washers, rubber grips, rubber
caps, rubber gaskets and rubber
seals.
There are many factors involved in custom rubber molding that affect
tolerances. One is shrinkage, where the rubber product reduces in size in the
mold after cooling to room temperature. The amount of shrinkage is determined
before production and accounted for appropriately in the size of the rubber
mold. Another is trimming and finishing, where the excess rubber that protrudes
from the mold parting lines is removed. Distortion is an important consideration,
as well, because the shape of rubber is flexible and can be changed according
to temperature. For this reason, rubber parts have to be stored at a certain
temperature to avoid distortions and thus, ruined products.
Types of Rubber Molding
- is a less-common process of placing a hollow tube between the two halves of a blow mold. The blow mold then closes, pinching off the bottom half of the tube, and air is injected into the top, forcing the material outwards to the walls of the blow mold.
- is a process that compresses the rubber material in a mold under heat and pressure to achieve the desired shape.
- , or Ethylene-Propylene-Diene Monomer, is an elastomer.
- involves melting rubber in an injection unit and then injecting it into the mold where it stays until after cooling when the finished product is ready.
- is formed through pressing melted rubber into dies.
- are rubber rings inserted into a hole in sheet metal to protect cords or electrical wires from the abrasion.
- are used to prevent leakage at joints.
- are flat pieces of rubber used for a variety of purposes.
- refers to long, hollow cylinders used to transport liquids and gases.
- involves building a "piston and cylinder"-like device in the mold and squirting the rubber into it through small holes. The mold is then closed and under hydraulic pressure the rubber or plastic is forced through a small hole into the cavity where it cures.
Common Terms Related to Rubber Molding
- A rubber compound's
capability to withstand mechanically caused deterioration.
- A test made to replicate in a short period
of time the breakdown resulting from normal working conditions.
- A substance that increases the speed of vulcanization
when used in small quantities in conjunction with vulcanizing agents.
- A compound used to increase the effectiveness of an
accelerator, small amounts at a time.
- Tendency of rubber to cling or bond to any surface it
contacts.
- The continuance of vulcanization, even after the energy
source has been taken away.
- Depressions and marks on the surface of rubber, caused
by air trapped during the molding process.
- Uses steam under pressure to vulcanize rubber products.
- A defect in the molding process, where the rubber near
the parting line sinks below the surface and the parting line ends up
ragged and torn.
- The result of a mixing operation.
- Rubber compound that fills a mold.
- A discoloration of rubber, caused by a liquid or solid
migrating towards the surface.
- The necessary force to start the sliding between
a rubber seal and its mating surface.
- The development of a powdery residue on a rubber surface
as a result of surface breakdown.
- Small cracks on the surface of rubber, usually from
environmental damage.
- The permanent deformation of rubber after removing
the compression.
- Rubber that is able to conduct electricity.
- A chemical bond between polymer chains.
- The date of completion of the molding process for a
rubber product.
- Any of a variety of processes for waste edge removal
from molded rubber parts.
- The application of force used to evenly disperse various
compounds through rubber.
- An instrument that measures the hardness of rubber.
- Applying powder to rubber to prevent adhesion to something
else.
- A seal necessary for the prevention of leaks beyond
parts that are in relative motion.
- A characteristic of rubber, describing its tendency
to return to its initial shape after warping.
- Extension of rubber when exposed to stress.
- A machine that forces rubber through a hole that shapes
it into the finished product.
- The wearing out of elastomers after repeated
deformations.
- The flexing capability of a material with no
permanent deformation or breakage.
- Capability of uncured rubber to move in the mold and runner
system in the molding procedure.
- Rubber processed on a rubber mill
that has a much greater viscosity than liquid silicone rubber.
- The process of mechanical energy changing to heat
in rubber under strain.
- A material that rubber is chemically or physically bonded
to during the molding process.
- Slow recovery rate of rubber after stress.
- The softening of raw rubber by mechanical and atmospheric
forces.
- A chemical compound that is able to endure polymerization.
- A defect that occurs when the rubber does not completely
fill out the mold.
- A line on the surface of rubber resulting from where
the two halves of the mold met.
- A material that is used to quicken the softening of
rubber compounds under heat or mechanical action.
- An insoluble compound that gives rubber its color.
- The degree to which rubber will retain deformation.
- Chemical reaction in which one or more simple
materials are transformed into complex materials that have different
properties from the originals.
- A substance that is added to rubber to increase
its resistance to the harms of the vulcanization process.
- The result when rubber vulcanizes too quickly.
- Extra material that leaks from the mold as it closes.
- The term for the uniting of two parts of vulcanized rubber
to make a whole.
- A thermo-setting
reaction that involves the use of pressure and heat, and results in highly
increased elasticity and
strength of materials like rubber.