In a perfect world, lean manufacturing would be a strategic initiative – an end in itself – with the “seven wastes” designed out of every new part and product and process. But sometimes things just need to get done and a better way must be found to build an existing product – now. Or as we recently found while working with a leading medical device manufacturer – a better way to build a family of products.
Our client, a maker of patient monitoring devices, was a victim of its own success. Its line had expanded over time to include eight separate products produced on eight separate manufacturing lines. A lack of product commonality meant customers could not combine features across products or upgrade from one device to another. So our client was losing market share to competitors offering similar products that were easier to manufacture, configure, assemble, and upgrade.
The company’s manufacturing and purchasing teams wanted to design one common platform shared by three product models that would create “lean” efficiencies in manufacturing and purchasing components. At the same time, the company would use this opportunity to add new features such as improved displays, computer connectivity, wireless and printing capabilities, as well as its own patented technology for more reliably reading vital signs. This was a significant project, involving more than two dozens parts, which would determine our client’s ability to compete in a rapidly growing segment of the patient monitoring market and to deliver high-quality, reliable patient readings.
From concept to final design
To start the project, our client provided conceptual CAD models that defined their desired styling and general external shapes, as well as internal constraints for the placement of circuit boards, keypads, and wiring. Leveraging their plastic part design expertise to produce “manufacturing- ready” drawings and models for every part, our engineers worked alongside the client team to carefully analyze and test each new design for functionality and manufacturability. We also helped select the proper resins and produced the required tooling in a timely fashion.
In the end, we designed a common casing “back” that could be shared by all three product models. This replaced the numerous backs used for earlier products. This new part was a single plastic piece molded from a polycarbonate/ABS blend, Sabic Cycoloy, selected for its moldability and ability to withstand chemical cleaners found in healthcare settings. Cycoloy also met the UL flammability standard required by the device’s battery power source.
For the remainder of the casing, we reduced the number of “fronts” and “windows” to two each, which could accommodate the variety of keypads and display screens our client planned to offer to its customers. All of the fronts and windows were compatible with the common back casing. The windows were molded from Sabic Lexan, which could retain its clarity even when exposed to harsh disinfectants.
Flexible, robust and lean
One of the most innovative aspects of the new product design was an interchangeable attachment system that allowed users to connect any of three different types of peripherals to each device. These inserts allow the care-giver to attach the sensor best-suited to the patient’s individual situation or requirements – such as a fingertip attachment, an ear attachment, or an attachment suited to infants. So rather than producing eight products with different “fixed” attachments, our client could now offer fewer models with interchangeable attachments.
This “lean” design cut down on parts, but it also introduced another challenge, since these attachments needed to be robust enough to stand up to rigorous use in moving ambulances and in- and out-patient facilities. Its snap tabs also needed to allow the peripheral adapters to be easily and repeatedly attached and removed without breaking.
Two other innovations were designed to reduce assembly time: 1) a process step was eliminated by designing the window so that when it was ultrasonically welded to the housing, it “captured” or retained the keypad and 2) instead of shipping bulk individual parts to the OEM for stocking a traditional assembly line, they’re shipped as bagged “kits.” Each bag contains all of the plastic parts required to assemble a single unit, so the OEM’s personnel need only snap in their proprietary internal electronic components (circuit board and display) – then fasten six assembly screws to complete the product.
The entire redesign process – from the handoff of conceptual models to production of the first parts – took only 12 weeks. By consolidating manufacturing from eight separate lines to one, labor, and material costs were reduced and competitiveness improved due to more products with proprietary technologies. Once the new units are in full production, the OEM expects to increase overall revenues by $10 million to $20 million per year.