Electric injection molding machines have quickly become a normal sight in many injection molding plants. After a somewhat slow start, the advantages of all-electric molding machines have accelerated their implementation. The reasons for the growing popularity of all-electrics are many. Among the most important reasons are consistency, repeatability, and accuracy.
Electric injection molding machines operate with digital control systems. The various components of electric molding machines are mechanically driven. Electric injection molding machines tend to run with a high level of consistency. Nearly all of the components that hydraulic injection molding machines rely on for their operation are eliminated in electric molding machines. So there aren’t any hydraulic hoses that may change diameter due to pressure or heat. Electric molding machines also do not have the valves found on hydraulic molding machines. These valves are prone to sticking. And of course, there is no hydraulic fluid to put pressure on or heat up. It is not unusual for injection molders to find that their electric injection molding machines are producing good parts by as little as the 3rd, 4th or 5th shot. Once the process is stable, electric machines can often run without attention for the entire production.
Electric molding machines also tend to be much more predictable in their operation and injection molding cycle (i.e. consistency, repeatability and accuracy). This translates into higher quality parts once a consistent injection molding process has been reached. Because of the consistency factor, the same plastics processing parameters and molding machine set-up can be used over and over. One example – the position of the screw for filling and packing the mold cavities is controlled digitally which makes it very precise. Because of this precision any problems with over-packing and molded-in stress are greatly reduced. Another benefit of electric injection molding consistency is that the machines can run unattended overnight or even over weekends. This reduces direct labor costs and increases profits. Now your skilled molding technicians can focus on their more important tasks and not have to put out as many “fires”.
Electric molding machines also tend to have an overall lower per part cost. All-electric molding machines can run at faster cycle times. This is primarily due to the fact that the clamp and injection functions are independent. The molder has very precise control over the shot size. This control reduced material usage and also reduced any colorants or additives that may be used in a particular molding job.
We’ll talk more about the advantages of all-electric injection molding machines in a future blog post.