About Engineering & Plastic Technology

  EXTRUDER DIES Extruder Sheet and Cast Film The convention between cast film and sheet is that film is less than 0.01 inch thick and sheet is more than 0.01 inch thick. The key components in a sheet/film extrusion line are: die, three-roll stack or cooling rolls, puller or nip rolls, and windup or sheet stacking system. The sheet die should uniformly distribute the polymer melt across the  entire die width. This is to provide a uniform melt thickness and polymer flow to the three-roll stack. Die width typically range from approximately 24-120 inches (0.6-3 meters. Cast film/sheet is produced using a multiple roll stack. Depending on the thickness, film is wound in continuous rolls and sheet is cut to length and stacked. The die is designed to fit between the rolls in a three-roll stack and lay the sheet down on the roll. Roll diameters generally range between 8 and 16 inches. Roll stack designs are simple 'up' or 'down' stacks to control the entry and exit angle and th...

 INJECTION MOULD DESIGN Injection Mould Injection mold determines the size, shape, dimensions, finish and often the physical properties of the final product. Cross sectional view  Function of mould components The sprue is a channel in the stationary platen that transports the melt from the plasticizing barrel to the runner system. The runner system basically transports the melt from the sprue to the gate. The gate further transports the melt into the cavity. Parting line Every mold has two basic parts to contain the cavities and cores. These are stationary mold-half (on the side from where the plastic melt is injected) and a moving mould-half (on the ejector side of the machine). The line on a plastic part which separates the two mould halves is called the parting line.  Types of injection moulds There are many different types of  molds, designed to meet different product requirements. However, there are six basic types of injection molds for use with thermoplastics....

 Fluid Machines The machine that either add energy to the fluid or extract energy from fluid are called fluid machines. They are classified into two categories Positive displacement machine Turbomachines or dynamic machines POSITIVE DISPLACEMENT MACHINE:- are those machine in which energy transfer is accompolished by volume changes that takes place due to movement of the boundaries in which the fluid is confined. TURBOMACHINES:- Fluid device which direct the flow with blades or vanes attached to a rotating member are termed as dynamic or turbo machine. Eg Francis turbine, Centrifugal pump etc Each of these two category or sub classification as pumps and turbines                 Pump are those machine which add energy to the fluid                 Turbines are those machines which extract energy from the fluid Some example of positive displacement pump are Reciprocating...