- THE MAGAZINE
For more than half a century, The RAM ProcessTM has been used as a forming method in ceramic production operations. Simply defined, the process entails the pressing of moist clay into permeable molds (dies) that are mounted on presses to form ceramic shapes. Gypsum cement (plaster) has been commonly used to make these dies, but more permanent materials have been developed and are being used today. Release of the pressed shape from the die is accomplished by means of fluid pressure (a combination of air and water) forced through the die.
The original concept, which was conceived and patented by two ceramic engineers in Columbus, Ohio, was further developed through the talents of a mechanical engineer who designed and built a special press to complete the system. The three men developed and added new features and improvements to the forming method over the years.
The invention and eventual patents for The RAM Process incorporated the production of dies made from specially prepared plasters using an air system made from woven cotton tubing adapted from the automotive industry. The invention, and its evolution as a tool for production, was patented as The RAM Process; molds became known as "working dies" and were encased in cast iron frames called "die cases." The evolution from molds was complete and, with the RAM press, The RAM Process became a sound method for creating ceramic ware.
Today, many companies in varied fields-such as art ware and novelties, hotel china, semi-vitreous and informal dinnerware, electrical porcelain, and structural clay products-continue to use variations of The RAM Process.
Pressing TechnologyThe technology explosion of the past several decades has enabled component manufacturers to make smaller, more powerful devices for use by engineers and designers in all industries. Ceramic presses and press systems can be very sophisticated, as many enhancements have been made to the presses, dies and materials. While implementing these changes, the next generations of RAM engineers and managers also developed a number of modifications to the original concepts.
Larger systems have been developed that incorporate programmable controllers. Users can now pre-program product-specific operations into their presses and take advantage of complex material handling systems that load raw materials onto the press and automatically unload the finished product.
Presses can be fine tuned to the items being pressed. For example, large deep shapes require a slow pressing speed, longer dwell time and slower opening speed than a relatively flat dinner plate. All of these variations are programmed and the functions are stored in the brain of the press. Based on these commands, the press makes all of the decisions and adjustments necessary to produce the ware to specification.
Aspects of The RAM Process previously left unexplored or simply ignored have been adjusted and improved. In doing so, the life cycle of this forming process continues to be extended. In addition, a decision to develop smaller, less expensive presses broadened the market for RAM Process forming, enabling studios and many other smaller ceramic companies to take advantage of the process.
Die MakingTechnology has also promoted the development of devices to improve die making, such as special valves that are needed to automate purge cycles. As these valves became available, they were incorporated into die-making systems, enabling users to concentrate on other jobs while the dies are purged according to formula. The purge unit measures the temperature of the die and starts the prescribed purge cycle at the correct moment. It escalates the purge pressure as programmed and turns off when the entire cycle is complete. The die maker is free to accomplish other tasks throughout the cycle.
In addition, substitute materials and processes have been developed and used in die making. The ceramic die introduced in the 1970s is one example. It was an alumina-based, hard-fired and porous die. The high selling cost of the ceramic die limited its use to manufacturers requiring extremely long, continuous runs. Intermittent cleaning of the dies using hazardous liquids also limited their use. More recently, other materials have come on the scene and are proving to be flexible, cost effective and very desirable.
In the beginning, The RAM Process was totally dependent on plasters for die making. The most significant advance resulted from work done by US Gypsum and RAM Products, Inc. to tune standard plasters for specific use with The RAM Process. CeramicalTM* evolved from this as the product of choice for making press dies to be used with clay-based bodies. Ceramical maintains detail because it does not wear as quickly as plasters. It also provides better air movement within the working die, which promotes a faster, cleaner release from the die.
The expansion and success of pressure casting using porous plastic or resin materials also brought new life to research and development efforts. Various companies developed porous synthetic products, which led to additional developments in dies used for RAM pressing (see "Synthetic Molds go Mainstream," Ceramic Industry, December 2000).
Porous resins have the added benefit of flexibility. Should die halves come in contact with one another while on the press or off, a slight give in the material will occur, and the die will not fracture as it would if made of plaster or another rigid material. While Ceramical used in RAM press dies may deflect up to .003 in. before cracking, porous plastic will actually bend before breaking.
The newer resin die materials also support short production runs. The dies can be used, cleaned and stored for use at a later date without noticeable deterioration. The resin material can be drilled, tapped, repaired and sanded. Damaged dies have been restored and placed back into service, a trait not shared by less flexible materials, and they can be easily cleaned with solutions that are not hazardous. The dies are stored moist and are therefore not prone to becoming brittle.
Harder and stronger resins have been successfully integrated into the cutoff edge of standard working dies. This marriage of materials provides the normal requirement for airflow and porosity needed to press and release the ware, and wears more slowly on the cutoff edge. Other hard materials have also been integrated into the cutoff edge with similar success. These advances provide working dies with a production life of 20,000 cycles or more, easily twice the capability of synthetics without enhancements.
Air SystemsAlmost as dramatic as the development of these alternative materials is a major modification to the patented air system. The woven cotton material encompassed in the die to direct the flow of air has been eliminated in some molds and dies.
This innovation, which can reduce the time required to make the dies, may have been overlooked in early attempts to bring the new porous materials to the U.S. Ultimately, this and other problems caused the porous resins to meet with less than enthusiastic support by U.S. potteries when they were first released. However, since being coupled with the enhanced capabilities of the presses and improved clay formulations, the resin dies are now making an impact on production.
Additional AdvancementsSuccessful implementation of porous resin molds for pressure casting systems in the U.S. led to favorable attention and interest. These expensive molds and systems led RAM Products to experiment with the concept and build prototype machines. Since the main business for RAM Products was and is the RAM press and The RAM Process, it followed that research and development for pressure casting might also be beneficial.
The desired properties of the pressure cast mold and the RAM press die are similar. Prime objectives include strength of material, porosity, cost per manufactured piece and ease of manufacturing with little or no environmental impact. In addition, the equipment must be easy to operate and release the finished product quickly.
Porous resin die materials wear more slowly and the cutoff edge is maintained over a longer period of time; therefore, the pressed part requires less cleanup, which results in labor savings. Time is also saved because press adjustments are needed less frequently to compensate for the wear of the cutoff edge. Increased uniform product thickness is maintained over longer periods of time.
Experimentation continues with other materials, and companies that mine plaster are developing additives to improve die life. Unfortunately, plaster sold to ceramic manufacturers represents a very small share of their overall sales, and funds for research are limited as margins and profits are minimal. The thrust for substitute die materials must then come from the industry.
Alternative materials used in forming bodies have also been emerging. Armor plate for tanks, cars and personnel is perhaps the best known in today's world, but special bodies have also been created and successfully formed for ovenware, freezer ware and items that can be taken from cold to hot and back.
The Future of FormingThe development of forming systems that are capable of using newer materials will increase competition, and the strategy to grow a middle market base by making lower-cost equipment is sure to continue. It creates new levels of competition and better prices for an industry that struggles with the dream of profit and prosperity. Creating beauty, art and functional products that can compete in the global market will continue to be the driving force for the ceramic industry.
For additional information, contact RAM Products, Inc. at 1091 Stimmel Rd., Columbus, OH 43223; (614) 443-4634; fax (614) 443-4813; e-mail email@example.com; or visit www.ramprocess.com.