Coe Press Equipment
Replaces Outdated Air-Feed
Systems to Help Mexican
Stamping Manufacturer
Stay Competitive

Even with low labor rates, Mexican manufacturers must stay competitive against companies offering the same services. Replacing outdated air-feed stamping press equipment with high-precision, servo-controlled systems that offer easier setup and improved reliability and quality is only one way that Small Parts Inc. (Juarez, Mexico) maintains a competitive edge. Other ways to maintain this edge are using advanced equipment and technologies, offering new services, and keeping employees trained.

Small Parts serves a wide variety of markets including consumer electronics, automotive, electrical components, and electric distribution products. They also stamp low-tech products like brackets and handles. But what's important for the company said Terry Littlepage, General Manager, is the company's focus on value-added components. "Being in Mexico, we feel that the ability to handle a part after stamping gives us an advantage. Therefore we do quite a bit of tapping, welding, and metal-to-metal and plastic-to-metal joining including insert molding."

Value-added production accounts for about 25-30% of their business with the rest straight stamping. "We are really the only job-shop stamping operation in Juarez. Most of our competitors are in El Paso on the US side of the border. There are many stamping presses in Juarez, but it's mostly for companies that are making their own products. They have a captive operation that is vertically integrated with a small stamping department," Littlepage added.

Small Parts has 150 employees on one shift, with two shifts running at times in a 120,000 sq. ft. building. They'll ship products within Mexico, to North Carolina and other areas in the US as well as Europe and Brazil.

"Even though our name is Small Parts, we also produce some medium to large parts," said Littlepage. "Our division has presses up to 275-tons in the Small Parts Companies. We also have some hydraulic presses for shallow draw work. The company doesn't produce any complex deep-drawn parts, but we do some tiny reel-to-reel work like terminals, and terminations for electrical components."

"We stamp the parts and then run them onto a reel. In some cases, after putting them on a reel, we'll send them out for service such as metal plating and then bring them back in-house and separate them. Then we send our customers loose terminals rather than the reel. We have a wide variety of different processes we do as well," remarked Littlepage.

With automotive companies demanding quality that meets one defect in a billion instead of a million, producing quality parts is more critical than ever for manufacturers. To produce quality parts, Small Parts uses some of the latest stamping presses and add-on equipment along with other technologies. For stamping quality, several Coe Press Equipment (Sterling Heights, MI) systems are used to straighten and deliver coiled steel to presses.

Coe lines feed two different Stamtech G2-2000 machines and an EP2-100 60" x 30" Elkhart press with a coil reel. Coe feeders used for the lines are a Servomaster CPRF-SM-112 series AC servodrive digital roll-feed processing 12"-wide material, and a Servomaster CPRF SM-118 that handles up to 18"-wide material. Two free-standing Coe power straighteners are used: model CPPS-175-12 for up to 12" wide material and CPPS-225-18 for materials up to 18" wide. The press lines also use Coe model CPR-PO-4018 pull-off coil-reels that can handle a maximum coil weight of two tons, coil width of 18", and a coil OD of 60".

Coe's AC Servo-Drive Digital Rollfeed features sealed-precision roller bearings, funneled-stock path for material threading and operator safety, rigid machined tie-bar construction for precise assembly and a high-performance maintenance-free AC brushless servo drive.

Featuring a fully funneled stock path for material threading and operator safety, the Coe Press Free-Standing Power Straightener also has a three-roll catenary section for proper material support; entrance-side and exit-side pinch rolls; an air-cylinder that raises and lowers upper pinch rolls; and seven straightener rolls for optimum metal straightening capability.

Because automotive companies require that a part is only run on a certified press line and can't be moved to another line if the original one goes down, Small Parts is standardizing their equipment into a universal work cell. "We've got the same feed equipment, presses, and processes so there isn't an issue with moving a part around," Littlepage said. Parts are run across the same process with the same parameters established on every press. While standardizing equipment, we came to the conclusion that Coe was not just about price, they were about service, quality, everything. Coe became our choice. Eventually we will have Coe feed lines on all of the machines."

Along with adding the latest presses and coil feeding equipment, Small Parts is also upgrading presses. They've taken presses and completely rebuilt them with new electronics and sensors in all of the stamping dies.

Another way Small Parts maintains part quality is through the use of sensors in their stamping dies and using vision systems to pick out problem parts. "Our sensor application lab is focused on in-die part inspection," said Littlepage. "We're putting in sensors to interface between our stamping process and with our SPC program.

"We put sensors at different stations of the stamping die to identify critical-to-function dimensions for our customer and measure certain aspects of the part. So as the part's coming off, we're getting a 100% inspected product. We make about 350 different part numbers here, and I would say probably 250 already have in-die sensing," he added. In the near future, Small Parts will have sensor interface units on all its dies. It used to cost the company tens of thousands of dollars to do this to every tool. Now the cost has dropped to just hundreds of dollars.

Small Parts is also building a universal vision system that has the ability to sense bad parts on an assembly belt. Cameras for the vision system operate at 25 milliseconds allowing them to check up to 80 part dimensions in this time frame. Part orientation is not important either. "We can orient the part however it comes down the assembly belt, snap a picture, do a SPC check on it, and take out the bad parts," said Littlepage. Instead of creating 100% good product, they vision sort for 100% non-defective product.

The company's plan is to check every part that has post-processing done to it, either plating or heat-treating. "Obviously we're not there yet, and this is our first venture into this science, but it's actually just now becoming cost-effective," remarked Littlepage.

"We have about 15 different part numbers that we've identified as a candidate for vision sorting. There are 60 different part numbers that we have the ability to do with our equipment and software. We'll start with 15 different parts at first to test it," he added.

Littlepage remarked that Juarez has no job-shop stamping, meaning there are no tooling people to draw from for workers. 'We profile new candidates based on mechanical aptitude, and once we find folks with the proper mechanical aptitude, then we begin to educate them," he said. "Our documented internal program is a combination of science, classroom activities, and on-the-job training. For someone to end up in the tool room, they have to work their way through the press department, quality lab, plant maintenance, and eventually going to the stamping department." Littlepage considers their training as good as any apprenticeship program.

Most of the work Small Parts does is progressive die stamping. They have one cell set up for secondary work such as transfer (non-robotic) or secondary stamping using a common blank that is turned into different part numbers. "We have a secondary stamping tool that's capable of creating different part numbers from the same blank. The secondary stamping operation would create a left or right-hand blank. For instance, where we put a hole could create a left or right-hand blank," adds Littlepage.

Small Parts does about 10% plastic injection-molded parts and 90% metal-fabricated parts. Littlepage said they're focused on the insert molding business. "We look at that more as a value-added service. The straight shoot-and-ship molding business is very competitive, and we're not interested in going head-to-head with these businesses. It's not really our core competency." To service their customers, Small Parts has a fleet of trucks for daily runs to customers. "We also handle all of our own customs and exports for our customers that aren't in Juarez," he adds.

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