|
О сайте:
|
Intelligent Injection Molding on Sensing, Optimization, and Control
The term quality has become a “catch all” term used in describing the various characteristics of an object. It is nearly impossible to define the term consistency. The quality is any particular or specific characteristics of a product development design object that contains or relates information about the object. This is primarily a chunk of geometry distinguished by its ability to perform a function with one or more other. In this primary processing conditions are studied from concept development to manufacturing of the product. Effect of different factors studied on the basis of processing parameters. Since quality and productivity are the two important contradictory objectives in any machining process. Some extent of quality has to be compromised while assurance giving for high productivity. Similarly productivity will be decreased while the efforts are channelized to enhance quality. To ensure high quality and productivity, it is necessary to optimize machining parameters. Various responses of quality of injection moulding process has been studied on the basis of performance parameters and methods. This paper aims to present plastic injection moulding process conditions. The processing conditions satisfied quality based product manufacturing.
Temperature control prevents quality issues such as shrinkage, warping and stresses from developing in the injection-molding processes.
From manufacturing personal items like toys and toothbrushes to industrial parts like plastics utilized in automobiles, injection molding is one of the most relevant manufacturing techniques in use today. This article will define what injection molding is, outline the steps involved, and explain the need for temperature control in the process.
Injection molding is a specialized manufacturing technique used for fabricating plastic parts and items. It allows for the mass production of several thousand — or even millions — of identical parts of a specific dimension and quality.
Plastic injection molding involves injecting molten plastic into a mold (or cavity), which defines its molded part’s shape after it solidifies. The basic requirements for the process are the injection-molding machine, raw plastic material and the mold.
The injection-molding machine consists of a hopper, through which pelletized plastics are fed into the machine; a heating barrel with a reciprocating screw; and an injection nozzle. The most common thermoplastics utilized in injection molding are nylon (PA), polycarbonate (PC), polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS). Molds used can be single- or double-cavity type, depending on the application.
Tooling Investment Costs. When a electric car mould part is being manufactured for the first time, the design is first prototyped with a test material to ensure accuracy using techniques such as 3D printing or CNC machining. The mold tool is made of steel or aluminum material and must be designed to precise dimensions.
Prototyping and Testing. With injection molding, manufacturing companies must carry out extensive testing and prototyping of the entire system using replicas. Any subsequent modifications to the final design will require either modifying the tools or scrapping them completely — both of which could add significant costs to the production budget.
Size and Thickness Limitations. Because injection-molding machines and molds typically have limited sizes, injection molding may not be suitable for designing large plastic parts. Also, injection molding tends to create mostly molded parts of a uniform thickness. This characteristic may be undesirable to some manufacturers that require variation in this aspect. This is because injection-molded parts must be created with a sufficient wall thickness (at least 1 mm) to prevent problems with filling the mold.
Many manufacturers use cooling tower water to cool the small channels within the mold with a temperature regulator attached to the injection-molding machine, regulating its temperature. While this technique is effective and incurs a lower operating cost, the mold will be prone to contamination. Cooling towers are open-loop systems. By contrast, an industrial chiller can be used to regulate the temperature via closed-loop cooling, ensuring a higher degree of product purity.
When plastics for the injection-molding process are being heated and mixed inside a machine, a specific temperature limit must be maintained as the temperature of the process will directly impact the quality of the final mixture.
If the temperature is too low, the components may not mix properly. Alternately, when the temperature is too high, the mixture might become burned. Thus, there is typically an ideal point, or a prescribed temperature at which the process must be maintained.
Mold Temperature. The temperature of the precision mold is another essential consideration that affects the quality of the injection-molded part. Getting the best quality mold is a balance between heating the mixture sufficiently to create a homogeneous mixture and cooling it down at an ideal rate. Anything else would be undercooling or overcooling.
Undercooling and Overcooling Issues. Improper polymer flow is a direct consequence of under- or overcooling issues in plastic injection mould. When the mixture is not cooled sufficiently, it may not solidify completely before being ejected. This may leave residual plastic in the mold.
Conversely, excessive cooling causes a lack of uniformity in the plastic material. This may cause further problems down the line such as shearing, cracking and cavities that do not fill up completely. Maintaining the mold temperature at a set temperature will yield the most optimum results.
Temperature Control with an Industrial Chiller System
Close tolerance temperature control units can be used with industrial chiller systems to provide close temperature tolerances for process water. When combined with a compatible and suitably sized industrial chiller, the temperature control unit can maintain the process temperatures at ±0.5°F of the set 33°F value, ensuring a stable injection-molding process without catastrophic freezing failures.
The close tolerance temperature control units come in varying flow variations and configurations and standard models have a pump and heat exchanger with a jacketed tank or a heat exchanger.
Plastic moulding is the process of pouring liquid plastic into a certain container or mould so that it hardens in that customized shape. These plastic moulds can then be used for a wide range of purposed. There are 5 types of plastic moulding that is considered to be the most effective and most popular.
These 5 types are extrusion moulding, compression moulding, blow moulding, injection moulding and rotational moulding. We will look at the details pertaining to each of these methods so that you can decide which one will be the most effective for you to use. The last section provides a summary of and future directions for intelligent injection molding.
The sensing of the injection molding process is focused on the temperature, pressure, position, speed, etc., which reflect the physical state of the process. Temperature and pressure are the two fundamental physical variables that are the most important in the injection molding process.
|