Rotational molding machine

What issues arise when using multi-armed rotational molding machines when each arm produces a different sized part ... 

For the folloiving products manufactured by rotational molding, indicate whether they would be made with a rock-and-roll or standard rotational molding machine ... 

ABS structural foam can be processed by injection molding, through conventional or low pressure injection machines (Chapter 4) by expansion casting in rotational molding machines (Chapter 13) or conveyorized oven systems or it can be extruded into profiles through conventional extruders (Chapter 5). 

The term dispersion refers to how well the pigments are wetted out in the plastic matrix (see below), whereas distribution refers to the uniformity of color in the part. Finally, in referring to the parts fabrication process, the term molder is used below to represent any the following pieces of equipment injection molding machine, injection or extrusion blow molding machine, or rotational molding machine. 

RMB Products, Inc., has developed a tank that has been rotomolded ] around fins to improve heat transfer to and from the tank. The fins were first electrostatically coated with the resin powder before being placed in the rotational molding machine. The precoating of the fins was found to improve resin adhesion. The polymer of choice for this tank (Fig. 6.44) was PFA or ECTFE, which allows the tank to be used to store aggressive chemicals. 

FIGURE 2.78 Basics of continuous-type three-arm rotational molding machine. 

Modern rotational-molding machines enable large parts to be molded (e.g., 500-lb car bodies and 500-gal industrial containers). For producing small parts an arm of a carousel-type machine may hold as many as 96 cavities. 

Rotocast, Rotational molding machines. Ferry Industries Inc. 

The basic rotational molding machine must be able to satisfy these three stages of the rotomolding process (typically simultaneously) while providing controlled rotation of the molds being used. 

Figure 9.2 An example of a biaxial rotational molding machine.

The eompound was fabricated into a tube lining by first sandblasting the surface with alumina followed by baking a primer on the tube surface. Next, the tube was lined at 2 mm wall thickness in a two-axis rotational molding machine aeeording to the conditions in Table 9.9. 

A rotational molding machine looks somewhat like a crazy ride at an amusement park. The molds are usually made of iron or steel, but since there is no pressure involved, they can be simple shells. The process is suited only for certain materials, those that will melt and coat the mold, and also withstand the heat for the full duration of the molding cycle (which can be several minutes). It is well suited for making simple, hollow parts (things like chocolate Easter bunnies and rubber duckies). 

A ZN-PE was rotomolded on the biaxial rotational molding machine at different heating times and oven temperatures. Table 3 demonstrates the effect of different oven time on the percent crystallinity and roughness values for ZN-PE molded parts. A general trend can be seen. With increasing oven time the crystallinity and... 

---