It would be unwise to challenge some companies in the Rockford, IL, area to an engineering contest, when the subject is machining metal parts. This is still home to more engineering firepower than a lot of countries around the world possess and it all results from real-world, hands-on experience, building the machine tools and related equipment that won a couple of world wars, changed the face of American industry, and even helped put a man on the moon. Despite recent hard times and a crippled economy, the master craftsmen and toolmakers in Rockford take those titles quite seriously.

Advanced Machine & Engineering (AME), Rockford, IL, is no exception to that rule. A longtime leader in spindle interface products, fixturing, workholding devices, carbide sawing systems, numerous safety innovations, and other engineered solutions for the machine tool and general metalworking industry, AME engineers brings hundreds of years of experience to the challenges they face. These challenges come from customers, as they seek to help them devise better machining techniques, improved part handling, and transitioning within the metalcutting theater. As an aside, it should be noted AME’s sister company Hennig, also a Rockford area company, is no slouch in this arena, as they are among the world leaders in chip conveyor systems, machine enclosures such as bellows, X-Y-Z covers, telescoping shielding, and more.

Examples abound of how this company applies its extensive knowledge to customer problems in the area of fixturing and workholding devices.

In one recent case, a major Illinois construction equipment builder needed two solutions for its machining inside large MAG centers. The workpieces were assorted shafts and splines, parts of a transmission gearbox assembly. After Alvin Goellner, AME’s vice president for the fixturing group, and Lonnie Miller, project engineer, reviewed and evaluated the challenge, devising a centering vise fixture and hydraulic indexing fixture. These fixtures require mounting on a tapped center plate for a rotary table assembly and machining was to be completed in stages.

Triag workholding fixtures can be used in manual, semi-automatic, or full hydraulic clamping mode, with rotating tables for horizontal machining, vertical machining, turntable, or trunnion mounting. In this case, machining of supercharger bearing plates and sand castings are in a variety of sizes and styles, using AME vertical and horizontal tombstone fixturing.

The key challenges were the numerous diameters and lengths of shafting requiring machining, as well as the substantial volume of chips generated. Devised and engineered by the AME team was hydraulic centering jaws, plus a cradle assembly and chip guard.

Previous handling of each workpiece was manually and individually fixtured, thereby wasting very expensive machine time.

The centers on the vise jaws were kept to ±0.005" while the workpieces requiring securing ranged up to 6.88" diameters. Isolation of all of the hydraulics was in the center plate, another solution configured by the AME engineers, who also devised the entire porting arrangement. Incorporated into the overall design of the indexing fixturing, in order to maximize the accuracy of the cutting and the indexing, regardless of the workpiece diameter machined on any given cycle, was a combination of a steady rest, face driver, and rotary indexer. According to the customer, this solution has proven very successful in decreasing the changeover time from piece to piece, and it has improved accuracy over the length of all individual components, a vital element in the build-up of a transmission or other drivetrain assembly, where gearing and splines are involved.

When assembled into position, this substantial spline-indexing fixture measured a full 84" mounted to a 95" plate.

Another example of AME fixturing expertise is in a vertical machining center built for an automotive engine component manufacturer.

Southland CNC, Cornelia, GA, is a Tier Two supplier to the automotive industry, providing machined aluminum sand-cast components to all three American and the six largest foreign auto manufacturers. The company, which began 19 years ago in President/Owner Keith Armour’s garage on a single machine, has now grown to 30 employees using 21 high-capacity machining centers.

Southland machines a variety of parts that includes production runs of very high volumes and other production runs of relatively low volume. Southland uses dedicated hydraulic clamping fixtures on Okuma Howa vertical machining centers for its high volume production runs, because these fixtures greatly decrease production time, which makes the fixturing highly cost-effective. The dedicated hydraulic fixtures also provide clamping pressure that is consistent and repeatable, which improves machining accuracy. According to Armour, the typical tolerances hold to 20µ true position, with critical dimensions to ±6µ, which he credits largely to the hydraulic fixturing supplied by Southland’s longtime supplier, AME. Because low volume production runs do not justify dedicated fixturing, Southland uses manual fixturing for its adaptability and lower cost of acquisition, when appropriate.

Southland currently has four horizontal machining centers that use hydraulic tombstone fixturing, and three vertical machining centers that use hydraulic tombstone fixturing, all designed and built by AME. Dedication of these fixtures is to high volume production of single parts or single families of parts.

Southland chose AME to provide its first tombstone hydraulic fixture because of the competitively priced and specifically designed fixturing solution answered Southland engineer’s production needs. Delivery, which was very important to Southland’s production scheduling, was significantly better than any other designer/supplier, according to Armour. The first AME fixture specifically replaced the customer-supplied fixturing Southland had been using, which Southland determined did not deliver the required efficiency to meet cost and schedule goals for the high volume production run.

The advantages provided by the AME-designed fixture included reduced load/unload time, reduced cycle time, reduced scrap rates, and error-free loading. The initial application of the fixture reduced Southland’s cycle time by over 50%, which allowed Southland to meet the high production volume without additional machines. On one bearing plate for a supercharger assembly, according to Armour, production has gone from 50 units to 110 units per day with the same superior tolerances and a 1.67Cpk, critical to the Six Sigma conformity for its major automotive customers.

Design of the fixture, which provides automatic clamp and release, is with locating dowels to assure error-free handling. Handling of each component requiring machining is only twice, once as it is loaded into the fixture and a second time, as it is unloaded. Because the fixture is a windowed fixture, the component machines, completely, on all four sides without additional handling. On the vertical machining centers typically, a second loading pallet is used to mount workpieces while another fixture is running in the machine. This further enhances Southland’s throughput.

Armour states that the AME-produced fixturing has been very reliable. One fixture has been in operation 20 hours a day, five days a week for more than seven years without a single problem. Because of this reliability, and because of the cooperation and innovation AME has provided, Southland added a second fixture used on the vertical machining centers, plus a fixture dedicated to horizontal machines.

“The fixture configurations we designed for Southland include cast tombstones as well as welded tombstones. Depending on the intended use for the fixtures, they were provided with external surface mounted hydraulics as well as internally cored hydraulics,” Goellner states.

On one particular part, a bearing plate for a supercharger, the part is aluminum sand-cast, measures 8" x 4" x 1-1/2". A two-operation part per side, the workpieces load in less than 20 minutes on a second fixture, using the secondary pallet on the VMC. Southland produces approximately 30,000 of this part annually for a Tier One supplier to Jaguar, BMW, and Mercedes.

As Armour explains, “The fixture was designed specifically for this part, though it is flexible enough to allow us to use it for other jobs. AME had a very short turnaround time, plus their knowledge of workholding and the components they selected were all first-rate. We have experienced zero downtime because of the fixturing they supplied us for this particular part. Although we tweak the rest pads for enhanced accuracy, which is normal with the machining centers we use.”

He further notes the design and development work was via CAD drawings, and completion of the entire project was on schedule and at the quoted price.

“When we began to go from 50 parts per day to 110 or better, with absolutely no loss of accuracy and finish quality, we knew we had made a wise choice,” Armour explains. Checking of all accuracies is on the in-house CMM at Southland for verification.

Advanced Machine & Engineering
ame.com

Southland CNC
southlandcnc.com