CMI International, Inc., headquartered in Southfield, Michigan, is a major manufacturer of machined cast and molded products. Principally serving the automotive industry, CMI also produces castings and machined components for the automotive industry. Its product line includes intake and exhaust manifolds, suspension/chassis systems, steering and drivetrain components, and cylinder blocks and heads, produced with a variety of materials and processes.
CMI provides integrated engineering, design, tooling, casting, molding, machining, assembly and product testing. Although CMI is equipped to offer a number of casting and machining options from concept to finished part, prior to the purchase of two Makino machines, CMI outsources all EDM work. Now EDM is done in-house, allowing CMI to reduce cycle time and cut tooling costs.
EDNC106 AND SNC64 PURCHASED TOGETHER
CMI bought both Makino’s EDNC106 and SNC64 in February, 1997. The EDNC106 is a RAM-type EDM, used to burn cavities for metal molds. CMI utilizes the SNC64 as a support machine for graphite EDM electrode manufacturing.
The two Makino machines are primarily producing metal patterns and molds for intake and exhaust manifolds and suspension parts for the automotive industry. CMI’s primary customers include the big three, General Motors, Chrysler, Ford, and various Japanese and European automobile manufacturers as well.
“Besides eliminating outsourcing, what led us into EDM is the difficulty we had machining ribs for suspension parts,” says Butch Vincent, CMI EDM coordinator. “When developing tooling for aluminum suspension parts, the machining of thin ribs becomes very important. Aluminum needs localized reinforcement and the ribs ultimately strengthen the end product. With technology moving towards aluminum, we’re getting a lot more rib work. The EDNC’s ability to machine thin ribs and complex 3D shapes was one of the reasons we went with Makino.”
CMI EMPHASIZES UPFRONT DESIGN
Most EDM work is done at the CMI Tech Center, located in Ferndale, Michigan. CMI puts a great deal of emphasis on upfront design to optimize final product performance and manufacturability. The Tech Center has the capability to provide simultaneous design, engineering, development, and testing for international customers and manufacturing plants.
CMI conducts computer-based engineering analyses during the initial design concept stage to investigate and predict mechanical, thermal, and fatigue stress, as well as fluid flow, heat transfer, and noise/vibration/harshness characteristics. In addition, polymer and metal flow and solidification modeling, and variation simulation analyses are performed to establish the manufacturability of each part.
BENCHWORK ELIMINATED, PROGRAMMING USER-FRIENDLY
When CMI invested in its two machines, it also hired David Bieth, EDM technician, to run them. “In many applications, depending on surface finish, we’ve gotten away with almost no benchwork,” says Bieth. “We’re able to run overnight, weekends, holidays unattended and come in with finished product waiting for us to take off the machines. We’re getting excellent finishes and good life out of the tools, as well.”
Vincent had no experience with EDM prior to purchasing the EDNC106. “After spending some time training during installation, I was able to burn a horizontal cavity that was 5/16 of an inch diameter and 13 inches deep. We also later attended Makino’s Tech Transfer class and found it to be very educational. It gave us a precise understanding of why what they push works,” adds Vincent.
Like Vincent, Bieth attended Tech Transfer, but he also participated in an advanced EDM class at Makino. “They put on an excellent class. All the fundamentals of advanced EDM practices are covered. Rather than tell you what you need to do, they give you a firm understanding of why it should be done. They’re very thorough in their review of all pertinent material. Not one question was added that they couldn’t answer.”
Bieth came to CMI with previous EDM experience, and finds the EDNC106 very user-friendly. Says Bieth, “It follows the most logical steps, as far as programming goes. When you go to the advanced EDM class, Makino goes through the settings so you can make adjustments that are specific to your application. Most of the machines I’ve dealt with don’t program anywhere near as well as the Makino.”
Once the dies are finished in the EDM process, ejector plates and pins are connected as well as any frames that are needed to support the molds. After assembly, the patterns or molds are sent to the foundry. CMI operates five foundries, producing aluminum, ductile iron and steel products. CMI provides customer flexibility by offering a number of different casting and machining options. The principal foundry processes include green and dry sand, investment, squeeze, permanent and semi-permanent mold castings.
SNC64: FAST AND ACCURATE
Both Makino machines are used in tandem. The SNC64 manufactures the electrodes and the EDNC106 uses those electrodes to burn the cavities in the die.
“Repeatability has been the best part,” claims Bieth in reference to the SNC64. “We can take a cut that we made a month ago, put it back on the chuck and machine it without a problem. We know that everything’s going to fall right in place, accurate and within our tolerances.”
“It’s fast, we don’t have to wait on it,” continues Vincent. “With the Super GI, we program it to the max, 200 inches per minute, and let the machine take care of everything in between.” The SNC64 Super Geometric Intelligence Control (Super GI) software allows high-speed data transfer for an accurate feed without data starvation to the 15,000 rpm spindle. This is important because CMI incorporates a direct data transfer network. Once a product’s design is optimized, the same database that was utilized during design and engineering is also used to generate numerically controlled cutter paths to construct production tooling. “The SNC64 is hooked up to the Ethernet network, so the data feed is real close to instantaneous,” says Bieth.
After the tooling is machined at the Tech Center, dimensional integrity is verified using coordinate measuring systems, which have surface-based reverse engineering capabilities. The coordinate measuring systems can also communicate information back through the network to conduct both graphical and dimensional analyses.
CUSTOMER SUPPORT
In addition to the EDNC’s ability to machine thin ribs, Makino’s reputation for reliability, training and support was a significant factor in the purchasing decision as well. “We’re very impressed with the support we’ve gotten from Makino,” says Vincent. “Installation was smooth and painless. Now, any time we call Makino, we get a quick, informative response.”
For more information, CMI can be contacted at (810) 399-9600, Fax (810) 399-3512, 1600 West Eight Mile Road, Ferndale, MI 48220. Or visit their web site at http://www.cmi.com. E-mail can be sent to info@cmi.com. Source: Competitive Mold Maker, Volume 4, Number 1