A typical hydraulic power unit reveals the motor-pump and proportional valve assemblies.
left: Proportional valves right: Pump-motor assembly
Richard Müssler, engineering manager at Maplan Mfg., Ternitz, Austria, gets right to the point, "Because we guarantee our customers' machine availability of up to 99%, we expect the same from our partners." This philosophy puts quite a burden not only on the finished machine, but on its components as well. It should come as no surprise, then, that Müssler relies heavily on the longevity and reliability of hydraulics to help ensure a high rate of success.
Müssler explains, "We began specializing in rubber injection molding machines in 1982. Today, we are ranked second in the world market. We produce about 400 machines a year, and no one machine is identical to any other. Our competitors' machines are very good. In terms of injection molding pressure, cycle times, or clamping surfaces, the standards of their machines are similar to ours. This is why it is essential for us to offer our customers something more — guaranteed reliability."
Maplan guarantees machine availability of 98 to 99%, depending on the calculation methods used. Müssler continues, "This is important because users want high-output machines, and they expect efficient and reliable operation. Why? Because rubber injection molding machines typically run in three-shift operations. Consequently, any equipment failure incurs tremendous downtime costs that cut directly into profits."
Hydraulics take the pressure
Müssler continues, "As the market establishes product prices, it is vital for us to keep our development and manufacturing costs low." To ensure quality as well as low costs, the company relies on a division of labor. Although Maplan concentrates on assembling its machines, specialist partner companies are responsible for producing mechanical components and assemblies. Dorninger Industriehydraulik, a local supplier, has proven to be a reliable and efficient partner in supplying the hydraulics for Maplan's machines.
Müssler explains, "We tell Dorninger what we expect of the hydraulics and they find the solution." Dorninger works together with Maplan engineers to develop the entire control system, and the company supplies all the hydraulic components needed — from reservoirs and motorized pumps to proportional valve assemblies in ready-to-use control blocks. Müssler adds, "We only need to connect the tubes, and we are ready to start operating."
Hydraulics technology plays a decisive role in the functioning of Maplan machines because it is the only actuating force. All movements of molds and tools — including closing, holding, and opening — are done hydraulically. These operations require not only high forces with high precision, but keeping a lid on energy consumption as well.
For example, the clamping unit in Maplan's model MTF1500-250 is fully hydraulic. Standard clamping forces range from 500 kN to 8000 kN, with up to 10 MN by request.
The main clamping piston supports nearly the whole cavity area to guarantee stability of the machine. The fully hydraulic clamping unit offers high stability and maximum platen support-by compensating for curvature. Rapid closing speeds provided by fast-acting cylinders boost production rates.
Information for this article was provided by Bosch Rexroth AG, Lohr, Germany. Additional information is available at www.boschrexroth-us.com.
