Injection Molding Automation: From Concept to Flawless Volume Production in One Go

The industrial Moulding industry is growing daily, as our use of plastics has increased 1000 fold over the last 10 years. The injection molding industry claims 5000 companies on the North American continent. Out of these 5000, only the top 100 companies regularly take advantage of Computer Aided Manufacturing in all of its aspects.

Design and Development in Injection Molding: The design of products and the molds that make them is key to a good injection molding business. The quality of the mold design directly affects the quality of the process that makes the products, along with the products themselves. Many injection molders allow the customer to perform the design work, taking what the customer gives them. On the upper end of the scale are molders that do all of the design work themselves. Most customers to injection molding are beginning to realize the benefits of early supplier involvement.

Automation in Injection Molding:  Complex automation systems are unusual in custom injection molding facilities. This is due to the nature of the industry. With tooling changes occurring daily, fully automated part production is not feasible. However, in "captive" injection molding companies (companies that mold products that the company then uses in another production operation), automation is economically viable.

The first stage of automation unloaded the molding machine using a pneumatic parts removal system. The robot then dropped the parts onto a stationary table, where a machine operator picked the parts up and individually transferred them to a nest on a rotary dial. The parts were then individually hot stamped with the appropriate logos and then the cover was transferred to nest that contained the base. The two parts were then either snapped together or pinned. The final automated step was to transfer the assembled, decorated compact to a conveyor via a point to point robot. The conveyor then transported the compact to an operator that packaged the product.

The second stage of automation unloaded the molding machine using a pneumatic parts removal system that dropped the two plastic parts onto vibratory belts. The vibratory belts conveyed the parts to an X-Y, pick and place robot. The robot placed the parts into the individual nests on the rotary dial. The operations from that point forward were identical to stage one.

The third stage brought a revolutionary idea. It consisted of automation that used a walking beam concept as opposed to the rotary dial. This was necessitated by the difficulty in hot stamping one of the products. This particular compact had a different logo, thus making the contour matching difficult.

Stage four was started due to visual concerns with the products. The vibratory conveyors were "rough" on the products, sometimes causing visual defects. A method was needed to eliminate this concern. This compelled the use of electric robots on the parts removal system. By using electric robots, positioning of the parts was much finer than with the pneumatics.

The final stage of automation developed to date is generally the same as all the other stages, but includes an additional operation. Some makeup compacts require a mirror. By automating the mirror insertion, operators could be eliminated from the system. Four additional stations were required on the rotary tables. The first additional station inverts the cover after hot stamping. Hot melt glue is then shot into the mirror well of the cover. A mirror is placed in the mirror well and pressed down by a pick and place robot, finally the cover is then reinverted for assembly.

Computer Integrated Manufacturing:  CIM is growing in importance in injection molding. Progressive companies are now using CIM computers to schedule their production, monitor cycle times, perform statistical process control and count production. This data is often dumped into a company business system to maintain inventories, account for raw materials and provide production management reports.Ten years down the road, I doubt you'll be able to mold without CIM.

To maximize capacity utilization and production efficiency, while improving quality, manufacturers need integrated manufacturing solutions that facilitate continuous process improvements and ultimately make them more competitive.