Beckwood Press Company, a leading manufacturer of custom hydraulic presses & automation systems, recently partnered with a leading aerospace company to develop a custom hydraulic heated platen press, used in the high-density compression molding of aircraft cabin interiors. The press was integrated with a hot oil heating system for accurate and uniform heating across the 60” x 108” bed and ram.
The 800 ton capacity custom made hydraulic press is equipped with 48″ of stroke, dwell capability for holding precise pressure on the part for extended periods of time and mirrored light curtains to ensure operator safety. The custom press system features Beckwood’s Productivity Package control system which includes full recipe functionality. Operators have the ability to program and save pressure & position values, temperature specifications, desired dwell time and bump sequences for the controlled release of gases which build up during the thermoforming process.
More information about the press can be found by visiting the company’s website and typing in 411 in the press example search, located at the bottom left side of the homepage.
In lieu of traditional two-post hydraulic presses, which feature two housing posts & are optimal designs for shallow-bed applications, slab-side designs are often the smarter frame configuration.
In a slab-side design, two solid plates of steel are used in place of the posts. This change from post to slab-sides increases the ease of assembly & can result in a net decrease in price of the press. Also, this substitution often allows for the use of less expensive, non-lubricated guide bushings on those presses which feature guided rams.
While the slab-side configuration is most often used on smaller, low tonnage systems, it has also been implemented successfully on larger units well in excess of 200 tons. Finally, the lighter, compact design of a slab-side press lends itself well to applications featuring small heated platens for use in laboratory-type environments.
by Josh Schroeder
When selecting a heat source for your heated platen press application, you should first consider your process requirements followed by the total cost of ownership. In your evaluation there are advantages and disadvantages you should consider for each method of heat transfer.
Heat Transfer (Fluid) Systems
The advantages of a Hot Oil or Heat Transfer System are that it produces the most accurate and uniform temperature control across the surface of the platens. Accuracy is typically from 1 to 5 degrees Fahrenheit depending on the platen design. Process temperature ramping can also be controlled consistently with this type of system and large heat loads are possible. The maximum operating temperature is around 700 degrees Fahrenheit.
Another advantage is that cooling of the platen can also be achieved utilizing the same circulating system. This will allow product to be removed from the press at a safe operating temperature for personnel. This can also be used to provide an end of shift cool down for equipment.
Maintenance of these systems can be considered both an advantage and disadvantage. The heat system is external to the press and therefore routine maintenance and electrical connections can be serviced without disrupting the press. The down side is that the oil is a flammable medium and can be a fire hazard if proper industrial hygiene and preventative maintenance are neglected.
These systems are very accurate and provide uniform temperatures even with large heat loads. The cost for this level of accuracy is much higher than metal sheath style heaters and maintenance of these systems can be demanding but if your process requires tight tolerances these systems are the best choice.
Metal Sheath Insert Heaters
The advantages of metal sheath insert heaters are that they can produce fast heat up and recovery times. They provide efficient energy usage with the heaters inside the platens and can achieve high temperatures up to 1,200 Fahrenheit. The initial cost is also much lower than the hot oil systems and maintenance cost would be considerably less. The risk of fire is greatly reduced as well.
The disadvantages are that temperature uniformity across platen surfaces is not as accurate. The delta range is typically from 15 to 30 degrees. Also the physical dimensions of the platen may limit the amount of KW that can be installed.
Maintenance on these systems is relatively low in comparison to hot oil however should a heater failure occur often the heater must be drilled out of the platen. This may lead to extended downtime.
Metal Sheath Insert Heaters provide efficient energy usage and fast heat up and recovery times coupled with higher temperature capabilities but they do not provide the same level of accuracy or uniformity. If you are looking for a lower cost option and your process does not demand the higher accuracy or uniformity of the hot oil systems then insert style heaters would be the best choice.