Originally Published MPMN June 2008
A new molding process was first used to produce a disposable protective cover for a digital thermometer. Tapped to manufacture a reusable digital tympanic thermometer, contract service provider Precision Medical Products Inc. (PMP) was faced with a problem: how to efficiently and cost-effectively produce the single-use protective cover incorporated in the prototype.
The cover consists of three parts, an outer plastic ring, an inner plastic ring, and a circular piece of film material. The inner ring, which covers the tip of the thermometer, is welded to the film, and the film--cut to fit--is welded to the inside edge of the outer ring. "You could imagine using a multistep process to manufacture this part," says George Weaver, the company's vice president of marketing. "Molding, cutting, and welding would be done separately, and it wouldn't be economical."
Instead, the company developed a custom molding process in which the covers are fabricated in one step. Sheets of film are inserted into the molding machine, and parts are simultaneously molded, cut, and sealed. "At the end of the cycle, a finished disposable cover falls out," Weaver says.
The process does not require adhesives, which often have the effect of slowing the regulatory approvals process, according to Weaver. A single material is all that's necessary. In the case of the thermometer cover, polyethylene plastic was joined with polyethylene film.
Both the cover and thermometer required PMP to draw on a range of its manufacturing capabilities, which include in-house insert and injection molding, metal forming and stamping, and assembly. The new molding process has been added to the list. "It's a new tool we now have at our disposal to improve the manufacturability of the customers' prototypes," Weaver says.
The company believes it has developed something more significant than a solution to a single manufacturing problem, and a patent on the molding process is now pending. "I could see this process being used to make, for example, sterile bags, blood bags, other kinds of sterile covers--really any instance where film is being molded to plastic," Weaver says.
Precision Medical Products Inc., Denver, PA