Thermoplastic material for compression molding
1. How do you prep a Thermoplastic material for compression molding?
a. Thermoplastic resins may be loaded into the mold either in the form of pellets or sheet, or the mold may be loaded from a plasticating extruder. Thermoplastic materials are heated above their melting points, formed and cooled. For both thermosets and thermoplastics, the better the feed material is distributed over the mold surface, the less flow orientation occurs during
2. What are the advantages, Strengths of Rotomolding? List at least 4.
a. Ability to select from a variety of surface textures.
b. Ability to mold in inserts for exceptional pull out strength.
c. Strong outside corners in virtually stress free parts.
d. Process allows for reasonably quick mold changes.
e. Ability to produce double wall parts for additional rigidity.
f. Cheap startup tooling costs compared to injection or blow molding.
3. Describe dry flow and bulk density in Rotomodling
a. Dry flow in Rotomodling is the time it takes 100 grams of resin powder to pass through a funnel of given dimensions. Powder dry flow properties are important throughout rotational molding because they determine how the polymer distributes itself within the mold and how polymer melts into complex shapes. Dry flow depends mainly on particle shape and size.
Bulk density in Rotomodling is the quantity of undisturbed powder than can fit inside a beaker of specified dimensions. It is also a measure of efficiency with which the powder particles are packed together.
Bulk density and dry flow are dependent on particle shape, particle size, and particle size distribution of powder
4. Define a Newtonian Fluid
a. Newtonian fluid is a fluid whose stress versus strain rate curve is linear and passes through the origin. The constant of proportionality is known as the viscosity. It is also any fluid exhibiting a linear relation between the applied shear stress and the rate of deformation.
5.
a. Thermoplastic resins may be loaded into the mold either in the form of pellets or sheet, or the mold may be loaded from a plasticating extruder. Thermoplastic materials are heated above their melting points, formed and cooled. For both thermosets and thermoplastics, the better the feed material is distributed over the mold surface, the less flow orientation occurs during
2. What are the advantages, Strengths of Rotomolding? List at least 4.
a. Ability to select from a variety of surface textures.
b. Ability to mold in inserts for exceptional pull out strength.
c. Strong outside corners in virtually stress free parts.
d. Process allows for reasonably quick mold changes.
e. Ability to produce double wall parts for additional rigidity.
f. Cheap startup tooling costs compared to injection or blow molding.
3. Describe dry flow and bulk density in Rotomodling
a. Dry flow in Rotomodling is the time it takes 100 grams of resin powder to pass through a funnel of given dimensions. Powder dry flow properties are important throughout rotational molding because they determine how the polymer distributes itself within the mold and how polymer melts into complex shapes. Dry flow depends mainly on particle shape and size.
Bulk density in Rotomodling is the quantity of undisturbed powder than can fit inside a beaker of specified dimensions. It is also a measure of efficiency with which the powder particles are packed together.
Bulk density and dry flow are dependent on particle shape, particle size, and particle size distribution of powder
4. Define a Newtonian Fluid
a. Newtonian fluid is a fluid whose stress versus strain rate curve is linear and passes through the origin. The constant of proportionality is known as the viscosity. It is also any fluid exhibiting a linear relation between the applied shear stress and the rate of deformation.
5.