Computer Technology Shortens Lead Times For California Manufacturer

A little over two years ago, this company recognized the importance of having complete capabilities to receive and utilize electronic design files. They utilized several technology methods to reach their objectives.

Case Study From: 4/15/1998 Modern Machine Shop

Rimnetics, Inc., located in Mountain View, California, manufactures polyurethane structural foam enclosures for the medical and electronic market. A little over two years ago, Rimnetics recognized the importance of having complete capabilities to receive and utilize electronic design files. Effectively utilizing the Internet's ability to directly transfer large part design files from the designer to the manufacturer can be a big advantage in reducing leadtimes and improving product quality. The fast pace of today's product introduction cycle requires that suppliers meet shortened leadtimes for delivering product. Customers need the confidence that a supplier will deliver as promised. A missed delivery date can have a disastrous effect on a new product's marketing plan.

Rimnetics specializes in reaction injection molding (RIM), a process in which two or more liquid chemical components from separate tanks are fed through supply lines to mix heads, where they enter a chamber to be mixed by high-velocity impingement, and are then injected into the mold at low pressure. They react to form a finished polymer and take on the shape of the mold cavity. The reactants quickly harden and parts can be removed in a few minutes.

Incorporated in 1985, Rimnetics contracted out its tooling needs for the first seven years. Due to poor quality, inappropriate mold designs for the RIM process, and long, unreliable tool delivery schedules, Rimnetics decided to investigate making their own tooling. They started out experimenting with production equipment that they had on hand and quickly discovered that they were on to something worthwhile. The decision was made to set up a separate facility in nearby Concord equipped especially for tool making. This has proven to be a sound business decision. Walter Chew, president of Rimnetics, says "Now our own tool source is an important profit center as well as a substantial business booster for our molding business."

Rimnetics' first CAD/CAM system was a 2D wire frame program that was limited to 2D CAM programming only. The system was used to machine the patterns for pouring epoxy molds. Later, rapid prototypes were used for patterns but tolerances were lost for a number of reasons, particularly because of the multiple stages used in this approach. These parts also did not have a high quality of definition and required too much finishing time. Excessive finishing time went against the initial goal of reducing tooling costs. After analyzing the quality gains and the cost savings to be had from machining aluminum molds directly, Rimnetics began searching for a 3D CAD/CAM system that was powerful as well as easy to use with their existing setups. Epoxy molds and rapid prototype patterns were deemed outmoded technology.

Walter Romanenko, of Tangent Concepts in San Jose, California, introduced Rimnetics to SURFCAM (Surfware, Inc., Westlake Village, California), a PC-based computer-aided design and manufacturing software for Microsoft Windows 95 and NT. Gary Quigley, manufacturing engineer for Rimnetics, determined that SURFCAM met their requirements. "We tried demo packages of other systems and machined sample parts. None suited us to the degree that SURFCAM did, including the short learning curve. Walter of Tangent Concepts proved to be valuable by handling our start-up questions."

Mr. Quigley designed and implemented a full CAD/CAM and DNC network system throughout Rimnetics' machine shop. Rimnetics now uses a network of thirteen PCs, including four Pentium machines and a Dual Pentium Pro to run SURFCAM, SolidWorks and other software. CNC machines run code directly from the computer network, allowing the shop to run twenty-four hours a day, seven days a week. SURFCAM's ability to produce large amounts of error free code permits the shop to run large program files without problems. With the application's solid model verification software, it is no longer necessary to proof programs at the machine. In one instance, a program for roughing out a molding tool ran unattended for over 300 hours.

Another important link in the Rimnetics communication network is their web site. The site was posted about a year ago and has received a very favorable response. The site is set up to receive part data files directly from customers via the Internet. A private, off-line server is used specifically for receiving customer files to provide the necessary security to protect these pre-release designs. The web site is also an effective tool for marketing. It is constantly upgraded to show-case Rimnetics ongoing investment in equipment utilizing the latest technology.

The Rimnetic's system "goes into gear" when a potential customer forwards an IGES or any other design file for review. Tooling and finished molded parts are quoted and any missing design information noted. SolidWorks is often helpful in calculating part volume for weight and material usage. Many Rimnetics' customers have begun submitting SolidWorks design files. Rimnetics encourages this practice since SolidWorks files can be saved directly to the SURFCAM file format for manufacturing.

When a tooling order is received, all required mold features such as water passages, ejector pin locations, base mounts, gating and venting are added using SURFCAM. Machine code is then easily generated. Using this application, manufacturing can now go through the design and "code ready" process in just a few days. As a result, tool machining can now be accomplished in weeks instead of months. The finished code is sent to the computer server for distribution to the shop floor. Rimnetics machining centers run on Microsoft Windows NT using the latest graphical interface and are networked for continuous loading. Both rough and finish cut instructions are included in the same program.

As project file sizes get larger, reliability and speed become increasingly important to Rimnetics. It is not uncommon for a total of 200 megabytes of code to be transferred to complete a tooling order. Reliable, continuous distribution of machine code is key to their twenty-four hour operation.

With all this technology in place, Rimnetics can quickly turn around jobs. On one recent rush order, a file was received electronically on Thursday and code sent to the shop floor by Friday. Two machining centers completed the machining over the weekend and by the following Wednesday, the molds were completed and the tooling was delivered to the molding shop. Molded first article parts were shipped to the customer by the following Thursday, just eight days after Rimnetics first received the design file.

Rimnetics now achieves high-end aluminum tooling at lower costs and can quote substantially shorter leadtimes. Walter Chew says, "The only down side is that we find it difficult to reduce our queue time." In response, Rimnetics will be adding additional machining centers to meet demand. MMS

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