Polyurethane is a material that is valued for its uses in “memory foam” products due to its flexibility and rigidity. Polyurethane is also a valuable material for products such as solid plastic forms, polyurethane rods, urethane wheels, urethane brushings, and urethane sheets. Polyurethane moldings have an excellent reputation for their high performance. Their longevity is greater than that of plastic, and are more impact-resistant than rubber. It also has elastic memory, reduces noise, and is resistant to heat and chemicals. It possesses many of the good qualities of metal, rubber, and plastics, and is capable of forming strong adhesive bonds with most plastics and metals.
Polyurethane molded parts require little to no additional finishing. This process is used by manufacturers to fabricate a wide array of moldings, parts, bowling balls, urethane bumpers, polyurethane belts, conveyor bushings, electrical potting compounds, press tool blocks, and pneumatic seals. Polyurethane products are used extensively in industries such as athletic equipment, engineering, manufacturing, industrial, food processing, automotive, and construction.
Raw polyurethane materials exist in a liquid state, as far as castable urethane is concerned. Because of this liquid state, the raw material can be easily measured and mixed and prepared for molding. Read More…
There are two types of molding processes that can be used: open urethane casting and closed casting. In preparation for the main polyurethane molding process, a silicone mold and a master pattern is developed. Once the mold is formed, the raw polyurethane materials react and form a pre-polymer solution. During the urethane molding process, the polymeric transition is completed when a curative is mixed with the pre-polymer solution. The mixture is then accelerated by pressure or heat as it is poured into a mold cavity. In this stage, coloration and other chemicals may be added for aesthetic purposes. Finally, the mixture is cured to form the final polymer product.
During the process of open polyurethane molding, the pre-polymer and curative are heated and mixed. Next, the mixture is poured into an open mold cavity, and the curing process does not involve the application of pressure. Closed polyurethane molding processes such as injection molding involve heating the curative and pre-polymer, mixing it together, and injecting it through small holes into a closed mold cavity. One example of a type of polyurethane molding is knowns as polyurethane foam molding. Polyurethane foam molding is a foam molding process which is frequently used by manufacturers to make soundproofing insulation. The final product is an excellent coefficient of friction, and possesses exceptional, flexibility, compression, and tension properties. Furthermore, urethane products are highly stable, enabling them to maintain their hardness over their entire operating lifespan.
The polyurethane molding process is a subset of a broader category of molding process called room temperature vulcanization, the acronym of which can be RTV. This process often involves using materials such as polyurethanes, silicone, or wax. This process has a few benefits, including the ability to achieve a excellent surface finish and a high level of detail. Polyurethane is a popular material for this process because of its hardness and its ability to withstand temperatures up to 220F (approx. 104C). The rapid manufacturing and prototyping chemical process of RTV involves adding curatives such as sulfur in an effort to convert materials such as polyurethane into a compound that is much more durable.
Sulfur is a slow vulcanizing agent, and is often used alongside other materials to improve the final product’s stability. Furthermore, materials such as polyurethane that undergo the room temperature vulcanization process are cured at room temperature, as stated in the process’s name. The RTV process is ideal in projects in which the manufacturer requires a short run of parts that must be similar in physical appearance or functional capabilities compared to parts or materials that have been previously produced.
Polyurethane elastomers have several laboratory-tested advantages compared to elastomers made from different materials. Polyurethane is highly resistant to radiation, ozone, oxygen, oxidation oil, tear, cut, and abrasion. Additionally, has a greater load bearing capacity, a broader range of hardness, and is easier to color than rubber. Urethane has also been proven to resist wear and tear more effectively than some types of steel. Polyurethane can be used for applications such as tires for trucks, due to how well it can handle compression loading. Compared to most rubber materials, polyurethane has a higher resistance to petrochemicals. Polyurethane can be effectively used in casting, and has the capabilities for low pressure tooling and thick section molding. Compared to metal, polyurethane is more resilient and more capable of reducing noise. It is highly flexible, inexpensive to fabricate, and is highly resistant to impact, corrosion, and abrasion. Polyurethane is light in weight, non-conductive, easy to mold, and doesn’t generate sparks.
Molded urethane is often times favored over regular plastic in a multitude of applications, as it is much more resistant to abrasion, radiation, cold flow, low temperatures, and high impact. Polyurethane provides lower cost tooling, has an excellent elastic memory, and is highly capable of noise reduction. Lastly, the polyurethane molding process is capable of forming parts without drafts or with undercuts. It is highly precise, is capable of working with a wide range of part sizes, and has a fast turn-around time. Polyurethane molding also has an economic advantage, as it costs roughly the same as polymer molding and rubber molding.