Originally Published MPMN June 2007

ENGINEERING SOLUTIONS

Molder Helps Put a Stop to Coagulation Concerns

IA company specializing in polyurethane molding played a vital role in the development of a plasma-based coagulator

Coagulation of blood vessels and tissues during surgery has presented a distinct challenge for doctors. High voltages employed in the coagulation technique of electrosurgery can be unsafe in such surgical procedures as cardiac and neurosurgery, as well as in laparoscopy, in which surgeons struggle with limited views. Avoiding the use of potentially hazardous high voltages, Plasma Surgical Ltd. (Theale, Berkshire, UK; www.plasmasurgical.com) believes that it has the solution to such a coagulation quandary.

Instead of using electrical current, the PlasmaJet neutral plasma coagulator releases a jet of pure neutral plasma to coagulate the bleeding surface. The high energy of the plasma induces homeostasis by forming a multilayer eschar. Owing to a lack of electrical current and sparks, the use of plasma ensures that there are no holes in the eschar layer to allow residual blood flow.

The coagulator consists of an electronic console mounted on a portable floor-standing service trolley that also houses the argon tank. Plasma Surgical retained Greaves Best Design (Lockerley, Hampshire, UK; www.greavesbest.com), a product and engineering design company, as its technical adviser.

“Initially, we produced 3-D CAD models. Then, we produced what we thought was the largest single-piece SLA model in the UK at that time. A set of rubber tools followed, which we shot with polyurethane (PU) and produced six prototype sets so we could prove-out the process,” explains Greaves Best company partner, Mike Best. “Once we had done this, we needed the input of a PU molder to move the development to the next stage: the manufacture of production mold tools and the molding of an initial 50 sets of parts.”

But in trying to develop a solution for surgeons, Plasma Surgical encountered a challenge of its own in trying to find the vendor best suited for the job at hand. Central to the success of PlasmaJet as a manufacturing project were the two largest moldings—the console housing and the service trolley front panel.

The appointed molding company tasked with producing these parts had to fulfill several prerequisites, including the ability to work closely with the client and its design agency; meet strict deadlines; manufacture tooling and molded components of the highest quality; and provide the most competitive quotation. Midas Pattern Co. (Bedford, UK; www.midas-pattern.co.uk) won the contract based on its ability to match these requirements.

Midas Pattern PU moldings are manufactured using the company’s specifically developed metallized resin injection molding (MRIM) process. A metal-filled composite resin mold tool is manufactured directly from a CNC-machined master model or pattern; this technique ensures that the most complex of forms can be produced accurately and very quickly, according to the company.

Complex forms can be generated using various coring, side action, and even multipart mold tool techniques. Square faces, undercuts, metal inserts, bushes, and features that would normally require machining can all be cast into Midas Pattern’s moldings. Moreover, by manufacturing accurate, hard-wearing tooling, Midas Pattern can offer ongoing repeatability without mold tool deterioration. In fact, the company guarantees its MRIM tooling for the life of the product.

Since being commissioned by Greaves Best to produce PlasmaJet moldings, Midas Pattern Co. has completed the tooling manufacture and to date has delivered further sets of parts on time. “PlasmaJet has massive potential,” Best says. “But this potential could not be realized without the valuable input of Plasma Surgical’s partner suppliers.”

Copyright ©2007 Medical Product Manufacturing News