Holloid Plastics Ltd. (Basingstroke, England) is a family business that began its life with only one injection molding machine. Today the company operates more than 30 molding machines of up to 650 tons in capacity, producing a wide range of components from vehicle registration plates to lighting and office equipment. Holloid is also a major supplier of equipment to the medical industry.
One perpetual problem encountered by all molders is tooling. Customers often have numerous molds of questionable age, quality and design for the molder to use. Incorrect cooling, misplaced gates and ejector pins, and poor flow design are just some of the defects encountered.
Holloid would normally design new tooling, but it recognizes that the cost of replacement tooling can rarely be justified. This is where Stäubli Corp.'s (Duncan, SC) six-axis robots have helped the company overcome some of the tooling deficiencies.
A good example is a case molding for a medical support pack for asthmatics. The tooling supplied by the company was fairly worn, and a thread required in one part of the molding was formed by loose inserts requiring manual intervention during the cycle. This increased cycle time and risked damage due to error. Holloid integrated a RXPlastics130 L six-axis robot. The insert is placed into the mold by the robot. During unmolding, the robot transfers the part to a separate workstation and unscrews the metal insert, leaving a clean thread form in the component. It then moves to a desprueing station. The part is rotated and placed onto the exit conveyor, all within the molding cycle time of the machine.
"The speed and accuracy of the RXPlastics robot has enabled us to overcome this thread problem without extending the machine's cycle time. We are now considering adding subsequent, currently manually performed, drilling and milling operations into the robot's program," says Julian van Wyngaarden, technical director at Holloid.
The ability to easily change actions is one of the most significant advantages of six-axis robots. Molders typically produce a mix of short- and long-run components, and they often must respond to last-minute changes in customer requirements. Molders need to minimize set up times to ensure high machine use. This is where the RX robot's operating software becomes critical. RXPlastics robots are ready for direct connection to the injection molding machine and safety door systems. Signal-handling software is installed and fully integrated with Stäubli's programming software for immediate I/O communication with the injection molding machine. Frequently occurring movement sequences and scenarios are already held in the robot controllers' software. Predefined macros and modules are provided to allow these sequences to be modified to suit any parameters.
"After reviewing the robots available, we selected Stäubli as our robot supplier. Their RX arm is a robust, clean design with high accuracy and repeatability and the user-friendly software enabled us to integrate the robots ourselves," says van Wyngaarden.
For more information on robotics, call 864-433-1980 or visit www.staubli.com.
