Stone Plastics builds customizable Cartesian robots in-house for the production of plastic parts. This allows the company to better control and monitor costs and serve more industries. Stone Plastics uses Rollon linear axes for the linear movements of its robots. Rollon's linear axes play a particularly important role in the removal of plastic parts from the injection molds. Stone Plastics operates 68 injection moulding machines ranging in size from 22 to 1,000 tons, which are mainly used for products in the automotive and consumer goods industries. In addition, there are around 800 different molds, each with up to 16 cavities. In addition to parts for the automotive and consumer goods industries, Stone Plastics also produces plastic parts for other sectors such as furniture manufacturers, leisure facilities and manufacturers of construction machinery and tools.

Stone Plastics' customized three-axis robots with end-of-arm tooling (EOAT) remove the plastic parts from the moulds. The EOAT tool is equipped with suction cups that lift the finished parts and place them on a conveyor belt. The average cycle times are between ten and 30 seconds, depending on the application. Thanks to the use of in-house developments, Stone Plastics can also use its production areas more efficiently. For example, the parts can be removed at the end of the press instead of at the side of the press, as was previously the case. This allows the presses to be moved closer together. In addition, the operating stations for several presses can be arranged close together in order to handle the material efficiently directly in the aisle.

Stone Plastics opted for the Rollon axes from the R-SMART series because of their compact dimensions and high load-bearing capacity. (Image: Rollon)

As downtime is very costly, Stone Plastics needed reliable linear axes. After reviewing their technical characteristics, performance features and capabilities, it quickly became clear that Rollon linear axes were the logical solution. The Rollon R-Smart 120 and 160 axes are the ideal solution due to their high load capacity and small dimensions. The R-Smart series achieves its performance values with two parallel profile rails instead of a single profile rail. Another advantage of the high torque transmission is the fact that a self-supporting gantry can be used when space is at a premium. Instead of a gantry system, the R-Smart can also be used in a cantilevered XYZ system. The S-Smart Z-axis has been selected mainly because of its favorable price/performance ratio. It has a robust and well-designed fixed drive head made of anodized aluminium and a robust profile made of extruded aluminium with a cross-section of 65 millimetres. This high quality linear axis is driven by a polyurethane belt with steel strands in an omega configuration. The loads are easily supported by a single linear profile guide rail with two carriages with recirculating ball bearings. sw