What is the difference between injection molding and extrusion?

Injection molding forms three-dimensional shapes. The injection molding process is based on the molten die-casting method. In the extrusion method, the finished products have a two-dimensional form which are continuous in length and can be cut to multiple lengths and punched or notched.

How does injection Moulding Affect Polymers?

Injection molding machine nozzles and tips present a potentially damaging shear and heat situation. Plastics pass through the nozzle/tip area at very high velocities and pressures during the injection cycle. These parameters can induce large shear forces that may damage the polymer matrix and other components.

What is extrusion in polymer processing?

Extrusion is a technique where molten polymer is forced through a die and is used to produce components of a fixed cross-sectional area such as tubes and rods.

What is extrusion grade plastic?

The polymer grades designed for processing by extrusion are generally characterized by higher molecular weights and high/higher viscosity in the molten state. This will allow to control better the extrusion as profiles (rods, tubes, plates), films, monofilaments, etc.

What kind of plastic is best for extrusion or molding?

Commodity plastics are suitable for most applications and account for 90\% of all thermoplastic use. They are readily available, easy to process, and the least expensive plastic for extruded products. Examples of commodity plastics include polypropylene (PP), polyethylene (PE), and polyvinyl chloride (PVC).

What is polymer injection?

Polymers are long chain molecules composed of many repeated subunits with high molecular weight. When added to water, either as a solution or as powder, they increase the water viscosity. The more viscous polymer-water solution is injected into the reservoir for enhanced oil recovery.

What is the effect of polymer properties on processing techniques?

Cooling Shrinkage and compressibility: When polymers are in molten stage the vibration of the molecules result in the polymer chain being pushed apart so that the volume occupied by a given polymer mass is higher than when the material is solid.

What is the best plastic for injection Moulding?

Polypropylene plastics provide good chemical resistance and retain their shape after torsion or bending. PP also has a high melting point and won’t degrade when exposed to moisture or water. Injected molded polypro, as this plastic is sometimes known, is also recyclable up to four times.

Which grade of polymer is used in extruded polymers?

Hi, In an injection molding, high viscosity rate of material is used, while in an extrusion medium viscosity rate is used. Dear Leelakrishnan, Nice question, subject for attention and practical interest.