Polyurethane molding, often referred to as urethane molding, is an elastic polymer, or elastomer, that contains urethane carbamate links. From a molten liquid state, polyurethane may be fabricated or molded into a variety of material types from the very soft to the very hard, including: low-density flexible foam, low-density rigid foam, soft solid elastomers (gel) and hard solid plastics.
Related Categories
Valued primarily for its uses in rigid and flexible "memory" foams, polyurethane is extremely useful in solid plastic forms as well such as polyurethane rods, urethane sheets, urethane bushings and urethane wheels. Polyurethane moldings are characterized by their high performance; they combine many of the desirable qualities of plastic, rubber and metal with longer service life than plastics, higher impact resistance than rubber, elastic memory, noise reduction, heat and chemical resistance and many other properties. In addition, polyurethane molded parts require little to no secondary finishing. Urethane manufacturers fabricate diverse polyurethane moldings, including a wide variety of pneumatic seals, press tool blocks, electrical potting compounds, conveyor bushings, polyurethane belts, urethane bumpers, bowling balls and parts for a broad spectrum of industries such as construction, automotive, food processing, industrial manufacturing, engineering and athletic equipment. Polyurethane also exhibits excellent adhesion and can easily form strong bonds with most metals and plastics.
The polyurethane molding process is actually a subset of another molding process known as room temperature vulcanization, which is sometimes abbreviated as RTV. For this process, the three most commonly used materials are silicone, wax and polyurethanes. The benefits of this process for polyurethane molding include a high level of detail and an exceptional surface finish. In addition, this process can be used on polyurethane because of its hardness range as well as its ability to withstand high heat of up to 220ยบ F. RTV is a rapid manufacturing and a rapid prototyping chemical process that involves converting materials, such as polyurethane, into more durable materials by means of the addition of curatives, such as sulfur. As a slow vulcanizing agent, sulfur is typically used in combination with other materials in order to increase the stability of the final molded product. In addition, as suggested by the name, the materials that undergo this vulcanization process, including polyurethane, are cured at room temperature. This method of polyurethane molding is most effectively utilized when the manufacturer desires a short run of parts that can closely match the physical appearance of previously produced parts or match the functional capabilities of previously produced parts or materials.
Although all elastomers maintain strength and versatility in many industrial applications, polyurethane elastomers possess several advantages over other elastomers and materials. Many of these advantages have been demonstrated in laboratory tests. Polyurethane has higher abrasion, cut, tear, oil, oxygen, ozone and radiation resistance, greater load bearing ability, broader hardness range and better colorability than rubber; urethane even showed better wear resistance than some kinds of steel. Polyurethane responds so well to compression loading that it can be used to make tires for trucks. Its resistance to petrochemicals is also much better than most rubber materials, and it is also highly oxidation-resistant. Polyurethane has thick section molding and low pressure tooling capabilities and a castable nature. As compared to metal, polyurethane has better noise reduction and resilience, greater abrasion, corrosion and impact resistance, more flexibility and is less costly to fabricate. Polyurethane is also lightweight, easily moldable, non-conductive and non-sparking. Molded urethane serves better than regular plastic in many applications, as it has higher impact, low temperature, cold flow, radiation and abrasion resistance, better elastic memory and noise reduction capabilities, greater resilience and provides lower cost tooling. In addition, polyurethane molding, as a process, offers the benefits of high accuracy, diverse part size capabilities, a fast turn-around and the ability to form parts with undercuts as well as parts without drafts. Also, the cost of polyurethane moulding is on par with the cost of rubber and typical polymer molding, giving urethane an economic advantage as well. - Substance added to a polymer to increase the effectiveness, but not the strength, of the polymer. Examples of additives include flame-retardants, anti-static urethane casting compounds, molded urethane pigments and urethane molding lubricants.
- A discoloration of the molded urethane surface of a polyurethane product-not to be confused with dust from external sources-caused by the migration
of a liquid or solid to the surface.
- Foam producing substance (e.g. carbon dioxide).
- The point of tension at which polyurethane
will rupture in urethane molding process.
- A polymer made up of two monomers in which each repeating unit in the chain consists of molded urethane units of both monomers.
- The chemical linkage of polymeric chains that results in a three-dimensional network of polymers. Crosslinked polymers possess greater strength and durability than linear polymers do.
- The amount of time necessary to complete a urethane molding cycle from urethane mold preparation to demolding.
- A device placed within a urethane mold that prevents the flow of material into cavities of the mold in order to reduce, alter or eliminate a part
of the cast for which the urethane mold was initially designed.
- The amount of time that passes between the dispensation of liquid components into the urethane mold and the removal of the end molded urethane product.
- Chemicals in
liquid or crystalline form used in the production of polyurethane adhesives,
coatings and urethane casting foam.
- A
material capable of returning to its initial length after being stretched
at room temperature up to twice its original length.
- An ion, composed of one oxygen atom and one hydrogen
atom, used in bases, acids and alcohols.
- Energy loss in the form of heat that results from
the deformation of elastomeric material caused by the application of urethane molding
stress.
- The forming of millimeter- or micron-sized parts
through the urethane molding process. Micro molded parts, for which tolerances
must be extremely tight, are increasingly in demand by biomedical, pharmaceutical,
fiber-optic, electronics, telecommunications, office-automation, computer
and automotive industries.
- The most basic polymeric unit, usually a liquid or a
gas, consisting of molecules from the same organic substance.
- Two or more monomers bonded together in a chain through a chemical reaction.
- The urethane molding process in which a chemical reaction links together monomers to form a polymer.
- A chemical compound composed of two or more hydroxyl groups that, in conjunction with diisocyanate, are used in the urethane molding production of polyurethane foam.
- The comparison of the amount of energy needed to create an elastic deformation and the amount of energy needed to recover from such a deformation.
- Category of plastics that have the potential to
soften and reform when heated, hardening again when cooled. During the urethane molding process, the physical makeup of the thermoplastic does not change.
- Category of plastics that cannot be reformed upon reheating. Thermosets remain permanently hard.
