Rod Kleiss expects his company's move to a bigger facility will bode well for plastic gears.
As president of Kleiss Gears Inc., he is a visionary trying to turn gear injection molding into a science. Although plastics have made some inroads into gears, Kleiss believes a lot more metal replacement is possible once molders better understand how to design plastic gears and how to mold them precisely.
Kleiss and his wife, Georgianne, founded their company in 1991. After a career in precision manufacturing for aerospace and communications products, Kleiss cut his teeth on gears during a stint with Whirlpool Corp., where he helped design a plastic gear to replace a metal one in a vacuum cleaner. He then joined custom injection molder UFE Inc. of Stillwater, Minn., where he worked on gear design before setting up his own company to specialize in such work.
``I intended in the beginning to be just a gear designer,'' Kleiss said by telephone. But he found all aspects of plastic gear production are important and he wanted control over the whole process. He bought an Arburg injection press and taught himself the complexities of gear molding.
Kleiss Gears will vacate its current, leased 3,000-square-foot facility in Centerville, Minn., this fall and move to a purchased building in Grantsburg, Wis., currently being upgraded to the company's needs. The firm is spending about $750,000 to buy the building, renovate it and to move. That's a big expense considering it amounts up to about half the six-person company's annual sales.
Kleiss said better climate control in the 14,000-square-foot plant should help his firm's use of new materials such as polyetherether ketone to replace metal gears. PEEK is difficult to mold but it is highly wear resistant, surpassing even such standard materials as acetal and nylon.
Kleiss Gears also might gain larger orders in the new operation. Typically its production runs range from 10,000-50,000 parts. The customer base is diverse and recently expanded to include automotive, for which the business molds cruise control gears. Kleiss hopes to add a fourth injection molding press soon after the relocation. His firm is looking at an 88-ton press to complement the two 27-ton and one 144-ton Arburgs it now runs.
For someone who wants more precision in plastic gear production, Kleiss has made a good start on the science of the field. The first thing Kleiss cautions is plastic gears are not like metal gears.
``They are not made the same way, the materials differ significantly, their failure modes are quite often different, and their print specification should be completely different,'' the company explains on its Web site.
Understanding and controlling shrinkage counts for a lot in gear molding. A molder must estimate shrinkage, cut a mold cavity, mold the gear and determine how close the estimate was to actual shrinkage. Measurement of the base circle and tooth thickness are both important.
Currently there is no standard system for directly measuring mold shrinkage, Kleiss Gears maintains. The firm has developed its own system for measurement to help it control all aspects of gear shrinkage.
Kleiss Gears has found that most gears require three plate tooling. Between two of the plates the plastic runner is ejected, and in the second space, the plastic molded gear is ejected, according to company descriptions. Such tools allow the part to be gated in the interior region of its body so that the gear teeth are not near the turbulent region of injected plastic flow. Also, the melt temperature and pressure profiles are more uniform and circular about the axis of the gear, which results in better molded part dimensional stability.
The gear cavity should be replaceable, the company advises, since part shrinkage is not completely known before the tool is used to mold the gear.