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Taking design to the operating room

April 18, 1999

6 Min Read
Taking design to the operating room

This surgical screwdriver, produced for customer OBL, an orthopedic biosystems manufacturer in Arizona, was originally rendered in Cadkey along with the accompanying images. Southmedic relies on visual information to design its products in a team environment.

Engineers are visual thinkers by nature and by training. So when surgeons try to tell designers how a device could be modified for better ergonomics, the outcome is often less than successful. One surgical instrument manufacturer is changing that scenario by sending its 10 salespeople into the operating room, where they observe the way surgeons perform procedures and explain how instrument modifications could make the process easier. They send the visual information back to designers, who then go to work implementing the suggestions.

The company, Southmedic Inc. (Barrie, ON), was established in 1983 by Lee McDonald to manufacture a modified anesthetic equipment device designed by Dr. Sandy McDonald. Today, the com-pany has grown into a leading manufacturer and distributor of a range of medical instruments. Southmedic designs, builds tools, and molds its own components, then assembles them prior to shipping. Says CEO McDonald, "Lots of people produce parts. We are one of few companies in North America able to take a prototype from design to packaging in a very short period of time."

Maurice Lavimodiere, engineering design manager, explains the concept behind Southmedic's unusual design approach. "We receive valuable feedback when our sales staff joins a surgical team. While you can't sterilize a laptop and bring it into surgery, our people do scrub up and observe surgeons. After they see the types of procedures being done and the way in which a surgeon handles an instrument, they are able to give our designers a graphic idea of what the customer wants."

The screwdriver contains two separate parts. Here, a truncated cone shape is shown elevated above the tool used to mold it.

As an alternative to observing surgery, Lavimodiere can begin creating the design at the client's desk. He uses a laptop loaded with Cadkey (Baystate Technologies), FastSurf, and FastSolid to sketch out the 3-D design and to discuss concepts and potential snags. The portable design is then taken back to the shop where final adjustments are made. At the next meeting with clients, Lavimodiere presents the design for final inspection and approval, including any modifications the client might request.

When Southmedic develops a prototype instrument based on the final design, client-surgeons test it on a cadaver. "Only production instruments are allowed into surgery for safety reasons," he explains. All of this close contact between sales, design, and surgical staffs means everyone gets to take part in the discussion from the concept stage. Having this input has helped speed production and improve functionality of Southmedic's products, according to Lavimodiere.

"With a precision digital model, we can illustrate exactly how the design will look," he says. "We can calculate and display the center of gravity on the model and demonstrate that the product will be nose-heavy if a suggested design change is incorporated because the front half of the model would be heavier than the back half. We can also show whether a surgical tool design is going to roll out of the hand or into the hand."

Animated Design
Another time-saving step involves animation. Using Ironcad (Visionary Design Systems), Lavimodiere can show clients how a product will function. This improves communication because Southmedic produces a variety of multifunction products that move in many axes. Healso uses the software to animate the molding sequence, especially on a tool with several actions. "We can add transparency to the tool to see how the mold actions work or how the mold functions in a press," he adds.

Most design work for both parts and tooling at Southmedic is done in 3-D solids. During a recent project involving a product casing, the client had a great deal of difficulty designing it in 2-D because there were only three flat surfaces. Everything else was a complex shape. Lavimodiere completed the design in 60 hours, much of it in front of the client.

The main component of the screwdriver is also rendered with its tool to show customers how the part will be produced.

"We use surfaces as little as possible, because they are an approximation of space and not as accurate as solids. With a straight parting line, in solids, I can just subtract the part out of a plate to design the cavity. For multiple action tools, I slice out the slide or lifter area. Mastercam [CNC machining software from WorkNC] then turns it all into surfaces." Many molds combine inserts in a standard mold base. Southmedic uses mainly Hasco mold bases, which are available from Mastercam's digital library as wireframe files.

Southmedic saves time in the manufacturing process by molding and assembling inside a Class 5000 cleanroom, which eliminates the need for a washing stage prior to sterilization of the products. The cleanroom contains seven molding machines (all from Battenfeld) from 44 to 300 tons. Molding operations are now four years old. "We were getting our parts molded elsewhere. When our molder retired, we bought all of his assets," explains Lavimodiere.

Molded products include a screwdriver for bone implants, medical parts for a drug dispensing unit, electronic parts, cup dispensers, and drug sniffer devices. (Southmedic also does some custom work as well as captive.) The company also purchased a toolmaker several years ago and began developing its own tool designs. "We were fed up with bad designs," he says, "with results on multiple action tooling such as ejector pins going through cooling lines. So we began designing tools using Cadkey, FastSurf, and FastSolid."

Part of the reason for his success, he believes, is that five experienced moldmakers were always there to give their input, troubleshooting designs before they were finalized. Another reason is the software/ hardware combination that speeds design work. Tool designs take, roughly, days at the most. "One of our biggest assets is the speed at which we can design using Cadkey on a Pentium 400 PC," he adds.

Volumes at Southmedic's molding facility can run as high as 400 million parts/year, but typical jobs run at lower volumes. It runs a variety of materials, including Isoplast (Dow Plastics), Delrin (DuPont), PVC, nylon, HDPE, LLDPE, and ABS. Products include the Vapofil anesthetic fluid delivery system, an applicator for a new type of skeletal pin the bone will eventually absorb, renal caps for dialysis, a disposable screwdriver for surgical screws, and a sterile cover for baby soothers. The work spans contracts from large pharmaceutical companies to local hospitals.

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