Forming rubber-pad

Rubber pad forming is a tooling process that almost any hydraulic press can do. This process u.ses a pressurized elastomer to form sheet metal to the shape of a hard tool. Although the process was developed using rubber, urethane is the material of choice today. 

Tooling for rubber pad forming consists of a block of rubber called the pad, a sturdy steel box called the pad holder, a bolster plate, and the hard tool. The pad holder with pad is attached to the slide of the press, and the hard tool is mounted to the bolster that is attached to the bed of the press. The hard tool and precut sheet-metal blank are pressed into the rubber pad, and the pressure of the rubber forms the blank to the shape of the hard tool. 

One way to reduce tool cost while applying pressure to both sides of the laminate is to use rubber pad forming. Figure 5.7 shows a tool similar to the one presented in Fig. 5.6, but with the upper, machined tool replaced with shaped rubber pad bonded to a metal plate. The metal plate is thick enough to transfer load from the press platen to the laminate. With a single surface to machine, this tool will cost less than a matched tool. 

Beads can be formed to a limited extent in titani im alloy sheet by rubber-pad forming. However, beads are readily formed by superplastic forming. 

Similar to matched metal stamping except that a metal mold half is replaced by a block of solid rubber. Processing material cannot flow to the extent that it can with matched-metal forming. However, more uniform pressure is exerted on the material charge due to the rubber pad. 

Because tooling costs are low, the process is most common in aircraft manufacture and repair, where production runs are short. Also, the rubber pad process works be.st with softer and more easily formed materials such as aluminum. 

Rubberized coir forms for seating in vehicles and has potential for replacement of polyurethane foam in inner sprung mattresses, cushions, geotextile pads, etc. (NR latex added with plant fibres). 

Elastomers are electrically insulating materials, usually in the form of silicone rubber pads, ranging in thickness from 0.001 to 0.20 in. and filled with high-thermal-conductivity materials such as alumina and boron nitride. They require a mechanical pressure to fill the voids. Figure 3.13 shows the variation of thermal impedance vs. pressure of an elastomeric pad for a TO-220 package [19]. 

Figure 6 shows the patterned film formed utilizing rubber pads with varying hardness of 40, 50 and 60A. The rubber-assisted embossing was carried out at a temperature of 120°C and at an embossing load of 670N. The best... 

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