Different route to energy efficiency: Polymer-based mold material

Manufacturers that must demonstrate energy savings in their operations can do so by substituting polymer mineral castings for steel structures. The total casting production process is can save up to 80% of the energy typically used to produce a steel weldment.

So says Precision Polymer Casting LLC, Mentor, Ohio. The firm's material, called Castinite, follows a much more efficient manufacturing path than does steel. The raw materials, which can include agricultural content, are mixed in a reactor. The resulting resin is mixed with a hardener and various-sized quartz aggregates. The quartz is surface mined, crushed and sized. The resulting material can be molded and can substitute for structures of welded steel.

The liquid Castinite material pours into the mold and cures at room temperature. Because it is polymer based, the finished part needn't be painted. Parts can also be cast in color. Once a mold is ready, finished parts come in a few days, complete with tapped holes.

In contrast, steel or cast-iron parts start out as ore smelted into pig iron, which is melted and mixed with various elements to produce steel ingots. The ingots are heated and rolled into steel shapes. The steel shapes are then machined to size necessary for producing the weldment. The steel components are welded together, then stress relieved. After stress relieving, they can be machined to the final configuration, after which holes are drilled and tapped.

Cast iron follows a similar path, except billets are formed which are then melted and poured into a mold. The part then must be machined, stress relieved, and finish-machined. A final stress relieve finishing operation may be needed.

In one case a manufacturer of high-speed printing equipment for plastic containers and bottle caps substituted Castinite for the weldments serving as a base for its equipment. The equipment is used to print multicolored images on items ranging from bottle caps, at 600 per minute, to caulk tubes, plastic bottles and plastic pails.

The steel weldments typically measured 2,300×2,300×200 mm. They had to be stress relieved and painted for protection against rust, especially for use in some Asian factories.

The Castinite polymer mineral castings that replace them dampen vibration 40 times better than steel, says PPC. The resulting performance permits faster machine speeds with more accurate resolution and less machine noise. Moreover, the finished Castinite casting was only 40% of the cost for a weldment.

The bases in this application needed a mounting area with a flatness of only 0.010 in, easy to realize even in a wood mold, says PPC. The Castinite part made to this tolerance used an inexpensive mold made with composite materials and which cost less than $5,000.

The Castinite bases were also fabricated with cast-in consumer-grade PVC pipes for wire ways, with outlets located where needed. The steel version had needed external wire ways that were more expensive, easily damaged and required extra wire to reach the proper locations. PVC pipes are also used to run hydraulic lines thru the base, making them less susceptible to damage and producing a much cleaner machine.