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Shape-Forming Processes
Published in David W. Richerson, William E. Lee, Modern Ceramic Engineering, 2018
David W. Richerson, William E. Lee
Hydraulic presses transmit pressure via a fluid against a piston. They are usually operated to a set pressure, so that the size and characteristics of the pressed component are determined by the nature of the feed, the amount of die fill, and the pressure applied. Hydraulic presses can be very large, but have a much lower cycle rate than mechanical presses.
The Forming of Diaphragms
Published in Mario Di Giovanni, Flat and Corrugated Diaphragm Design Handbook, 2017
Corrugated diaphragms are best formed in a hydraulic press with a minimum capacity rating of 3 tons. Hydraulic presses are more versatile than mechanical presses. Their speed can be adjusted and the forces generated controlled more easily.
Compression Molding
Published in P. K. Mallick, Processing of Polymer Matrix Composites, 2017
Hydraulic presses are commonly used for compression molding operations. As the mold is closed, the upper platen of the press may not remain parallel to the lower platen due to the eccentricity of loading caused by uneven charge placement in the mold or uneven pressure distribution during flow. The clearance in the guidance system of the platens and nonuniform elastic deformation of the press frame also tend to increase the parallelism problem. Nonparallel platens cause thickness variation in the molded part, which in turn can cause fiber misorientation, flow instability, and warpage. One of the ways to correct the problem is to use four independently controlled hydraulic cylinders, one at each corner of the upper platen, instead of only one at the center as in most conventional hydraulic presses. The upper platen is maintained parallel to the lower platen during mold closing by using a control mechanism that includes position sensors mounted at each corner and hydraulic valves that are activated by the error signals from these sensors.
Barriers and enablers for scaled-up adoption of compressed earth blocks in Egypt
Published in Building Research & Information, 2023
Hisham Hafez, Deena El-Mahdy, Alastair T.M. Marsh
Economic enablers to reduce the cost of CEB buildings were identified for the production process of CEBs, and the design of the CEBs themselves. Experts 1 and 3 recommended that CEB producers adopt centralized, factory production of CEB using hydraulic presses – this would reduce CEB unit costs due to three main reasons. Yet, the use of CEB using hydraulic presses – this would reduce CEB unit costs in a factory setup is believed to have a larger cost reduction potential mainly due to three main reasons. Firstly, the ability to mass-produce CEB would result in greater production efficiency, reducing the contribution of baseline operating costs towards the unit cost of a CEB (expert 1). Whilst no data is available for Egypt, a Sri Lankan study found hydraulic press production to yield a per unit area walling cost 8.5% cheaper than when using a manual press (Maïni & Davis, 2018). Secondly, employing a consistent team of skilled labourers in the factory would avoid the additional costs associated with on-site production, in which different sets of workers are trained for each project – this can take up to 10% of a project’s duration (expert 3). Thirdly, in comparison to manual presses used for on-site production, hydraulic presses waste less material and produce stronger blocks which are less likely to break during the curing/storage stages of production (expert 3).
Evaluating the effect of processing parameters on the replication quality in the micro compression molding of silicone rubber
Published in Materials and Manufacturing Processes, 2020
Khosrow Maghsoudi, E. Vazirinasab, R. Jafari, G. Momen
High-temperature vulcanized (HTV) silicone rubber (SR) was used as the process material. A wet-chemical-etching method produced the aluminum (A6061) templates. The aluminum sheets were cut into intended size and cleaned in acetone and distilled water for 20 min ultrasonically. After drying at 70°C for 1 h, they were chemically etched using a 15 wt.% hydrochloric acid solution for 2 h. Then, the templates were cleaned ultrasonically with distilled water for 30 min and dried at 70°C for 1 h. We used a micro-compression molding machine (Carver Inc. USA) having two temperature-adjustable platens. The hydraulic press system is capable of controlling precisely an applied force of 3 to 194 kN. Three-piece flat molds, all having a right rectangular prism cavity of 25 × 25 mm2 with various thicknesses (3 mm, 6 mm, 9 mm), cast the rubber materials. The template was placed on the lower part of the mold into the cavity, and the rubber material was placed onto the template. The top the mold was then closed. The mold was set in the press machine to begin the process. To determine an appropriate process window, we undertook an initial familiarization set of experiments. For this, we determined the most extreme levels at which an acceptable result could be attained. DoE then selected those processing parameters to be assessed for the experimental runs. After the process, the mold was opened, and the cured SR was detached from the aluminum template. Figure 1 schematically represents the direct replication process to create micro-nanostructures on the SR through a micro-compression molding system using a three-piece flat mold. It is worth noting that we used a fluorochemical-based release agent to ensure a flawless demolding for acquiring a high-quality micro-nanostructured surface.