PLASTIC PROCESSING FUNDAMENTALS:
It is applicable for producing good quality plastic products. First the processor needs to understand the performance requirements for specific and use and accordingly select material. The processing methods select based on the process ability and viability of the selected material as described in below mentioned flow diagram.
Flow Diagram Product Manufacture:
The process selection depends on several interrelated factors:
1. Designing a part to meet performance and manufacturing requirements at the lower cost.
2. Specifying the plastic.
3. Specifying the manufacturing process, which requires
a. Designing a tool around the part.
b. Putting the proper performance fabricating process around the tool.
c. Setting up necessary auxiliary equipment to interface with the main processing machine.
d. Setting up completely integrated controls to meet the goal of the zero defects.
4. Purchasing equipment’s and materials, and warehousing the materials.
Knowledge of all processing methods, Including their capabilities and limitations, is usual to a processor to deciding whether a given part can be fabricated and by which process. Certain process requires high operating pressures on plastics. Such as those used in injection molding where pressures may be 13.8 – 206.9 Mpa. High pressures coupled with the creation of three- dimensional parts make injection molding the most complex process, nevertheless it can be easily controlled, Lower pressure are used in extrusion and compression, ranging from 1.4 – 69 Mpa. Some process such as thermo forming and casting operates at relatively low pressure. Higher pressures allow the higher dimensional tolerances with higher mechanical performances. But there is also tendency to develop undesirable stresses. If the process are not properly understood and controlled. A major exception is reinforced plastics processing at low or contact pressures.
Almost air processing machines can be provided useful products with relative ease. And certain machines have capabilities of manufacturing products to very light dimensions and performances. The coordination of plastic and machine facilitates the process. The interfacing of product and process require continual updating because of continuing new developments in manufacturing operations.
Most products are designed to fit process of proven reliability and consistent production, Various options may exit for processing different shapes, sizes and weights.
Table: Parameters for selecting the right process
Parameters that help one to select the right options are:
1. Setting up specific performance requirements
2. Evaluating material requirements and their processing capabilities.
3. Designing parts on the basis of material and processing characteristics. Considering part complexity and size as well as a product and process cost comparison.
4. Designing and manufacturing tools to permit ease processing.
5. Setting up the complete line, including auxiliary equipment’s.
6. Testing and providing quality control, from delivery of the plastics, through production to the production and
7. Interfacing all these parameters by using logic and experience and obtaining a required update on technology.
Polymers are usually obtained in the form of granules, powder, pallets and liquids. Processing mostly involves their physical change, through chemical reactions sometimes occur.
A wide range of processes are used for converting the raw material in to useful and products.