Tag: thermoset

Materials

Injection Molding Materials

There are two types of materials(resins) which can be used in the injection molding industry; Thermoplastic and Thermoset. A thermoplastic, or thermo-softening plastic, is a plastic material, a polymer, that becomes pliable or moldable above a specific temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight[1].  A thermoset also called a thermosetting plastic, is a plastic that is irreversibly cured of a soft solid or viscous liquid, prepolymer or resin.[1]

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Figure source: http://www.bbc.co.uk/guides/z9tysg8

Resin selection is a very critical step for the injection molding. There are many material suppliers offering quality materials for the injection molding.

They can formulate a plastic to meet the consumer needs properly. For example, the applications of the product play a key role in the choosing material properties. For High voltage connector, the resin has to provide chemical resistance, excellent tracking defense and heat& humidity resilience. For a Fluid Engineering Components, the resin has to have a good hydrolytic stability, excellent resistance to water and FDA approved. The formulated resin has the processability and consistent properties after molding process and in the final use.

Reference :

  1. https://www.wikipedia.org/
Materials

Injection Molding Materials

There are two types of materials (resins) which can be used in the injection molding industry; Thermoplastic and Thermoset.

A thermoplastic, or thermosoftening plastic, is a plastic material, a polymer, that becomes pliable or moldable above a specific temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight.[1]

A thermoset also called a thermosetting plastic, is a plastic that is irreversibly cured of a soft solid or viscous liquid, prepolymer or resin.[1]

large.png

Figure source: http://www.bbc.co.uk/guides/z9tysg8

Resin selection is a very critical step for the injection molding. There are many material suppliers offering quality materials for the injection molding.

They can formulate a plastic to meet the consumer needs properly. For example, the applications of the product play a key role in the choosing material properties. For High voltage connector, the resin has to provide chemical resistance, excellent tracking defense and heat& humidity resilience. For a Fluid Engineering Components, the resin has to have a good hydrolytic stability, excellent resistance to water and FDA approved. The formulated resin has the processability and consistent properties after molding process and in the final use.

 

 

Reference :

  1. https://www.wikipedia.org/
Terminology of Injection Molding

Y

Yellowness Index: A measure of the color on the yellow scale.

Yield Point: In tensile testing, the yield point is the first point on the stress-strain curve at which an increase in strain occurs without an increase in stress.

Yield Strength: The stress at which a material exhibits a specified limiting deviation from the proportionality of stress to strain.

Young’s Modulus: The ratio of tensile stress to tensile strain below the proportional limit

Terminology of Injection Molding

W

Warpage: Distortion caused by nonuniform internal stresses.

Water Absorption: The amount of water absorbed by a plastic article when immersed in water for a stipulated period of time. All plastics will absorb moisture to some extent.

Weld Line: Where melted material flows together during molding to form a visible line or lines on a finished part that may cause weakening or breaking of the component.

Wisps: Similar to stringing but smaller in size. These also may occur as slight flashing when the mold is over packed or forced open slightly. Mold-parting-line wear or misalignment can also cause wisps.

Terminology of Injection Molding

V

Vacuum Forming: A process whereby a heated plastic sheet is drawn against a mold surface by evacuating the air between it and the mold.

Valve Gating: A type of gate where a pin is held in the gate or channel by spring tension. As the injection stroke moves forward, this gate compresses the plastic in the runner. When this pressure build-up is sufficient to overcome the spring tension, the pin is then pushed back (pulled) and the fast decompression of the melt fills the cavity at extremely high speed.

Vent: A shallow channel or opening cut in the cavity to allow air or gases to escape as the melt fills the cavity.

Vented Barrel: Special barrel unit with a vent port over the compression section of the screw to permit the escape of gases prior to injecting melt into the mold. Often used when molding moisture-sensitive resins.

Vertical Flash Ring: The clearance between the force plug and the vertical wall of the cavity in a positive or semi-positive mold. Also the ring of the excess melt which escapes from the cavity into this clearance space.

Vicat Softening Point: The temperature at which a flat-ended needle will penetrate a specimen under a specific load using a uniform rate of temperature rise.

Virgin Material: Any plastic compound or resin that has not been subjected to use or processing other than that required by its original manufacturer.

Viscoelasticity: This property, possessed by all plastics to some degree, dictates that while plastics have solid-like characteristics such as elasticity, strength, and form-stability, they also have liquid-like characteristics such as flow depending on time, temperature, rate and amount of loading.

Viscosity: Resistance to flow of a liquid.

Void: An unfilled space within a solid material.