Hennig chip disc conveyor on Niigata machining center at Accurate Gauge.
Hennig magnetic chip disc conveyor dumps chips into hopper.
Chips fall from machining envelope onto auger for transfer onto conveyor and magnetic disc for extraction from fluid.
(l-r) Accurate Gauge Engineering Manager Mark Tario and Maintenance Supervisor John Swift.
Rigorous testing of products is done both inline and offline at Accurate.
Accurate Gauge (Rochester Hills, MI) offers automotive and heavy-duty vehicle part production, with a specialty in transmissions and other housings.
The machining and assembly of large ductile iron castings into components for the heavy truck and military drive train markets is one that demands accuracy at every turn. Accurate Gauge machines over 98% of its workpieces from ductile iron, and the iron sludge build-up in the coolant tank became an all too familiar problem for the production personnel.
"We approach every machine with a keen eye on machine uptime and an absolute ease of maintenance," said Accurate's Engineering Manager Mark Tario. "We had experimented with some systems to handle cast ductile iron fines and got to know their benefits as well as their shortcomings." The company had actually designed two systems in-house to improve the handling of chips and the cleaning of coolant. While the benefits had been appreciable, they felt there was still a shortfall so they began a systematic search for a better solution.
A particular development from Hennig caught the attention of the Accurate team, namely, a magnetic chip disc filtration system that reportedly represented a substantial improvement over the traditional drum screen filtration system. "The relative ease of changeover immediately impressed our engineers, both from the production and maintenance perspectives," said Tario. "Replacing the drum filter screens is not an easy task - in fact it can be downright miserable. The Hennig disc arrangement seemed to us a much easier system to operate and maintain. The incorporation of a rare earth drum and scraper assembly inside the conveyor appeared to be a great solution for minimizing the amount of cast iron fines reaching the coolant tank side of the system. In addition, the heavier-duty mechanical components and drive chains used on the Hennig conveyor provide a greater wear life and reduced likelihood for downtime."
An initial order was placed with Hennig for four Chip Disc Filtration (CDF) conveyors to run in tandem with the company's line of Niigata SPN 701 horizontal machining centers (HMCs). All electrical controls, coolant tanks, pumps and other hardware were provided by Hennig. Tario and his team worked closely with the Hennig mechanical and electrical engineers, as well as Hennig's local representative, John Kaczmarek of Marathon Industrial Sales (Sterling Heights, MI), to complete the first installation. "We have over 40 years of experience in what works and what does not in the machining of cast iron, so we had a very defined list of needs in all facets of the design, electrical functions and the very important aspect of machine to auxiliary equipment communication," said Tario. "The worst scenario in the shop occurs when the machining center is working, but the chip conveyor is not."
Every aspect of the machine-to-conveyor connection was planned out by the Accurate engineering team, including the layout of the coolant tank covers and the access ports. This attention to detail is something in which the company takes great pride. "The Hennig team was very good on this job and they realized that nothing less than their best efforts would satisfy us," said Tario.
Of the many issues Accurate had to overcome, downtime for maintenance was the most prominent. The machining of cast iron, by definition, creates considerable problems arising from the frequent need to replace conveyor chains, drum screens and other mechanical components that get infiltrated by the iron fines and literally lock up. "The conveyor chains on the Hennig system, in contrast, were found to be stronger than the typical styles used on competing brands, which often required adjustments and repairs several times annually and were usually in need of total replacement once a year," said a Hennig spokesperson. "Depending on the severity of the repair or replacement operation, this situation resulted in many hours or even several days to rectify. Practically speaking, the maintenance personnel would get completely soaked and filthy with the coolant and sludge as a result."
On the Hennig CDF system, the discs can be easily removed and cleaned on a workbench, rather than having to reach through narrow access ports to wrestle with a drum style filter. "This entire process is a two-hour operation at most," said Tario. "Simple screen replacements can be done in 30 minutes or less."
Another common problem for the maintenance personnel was coolant related failures. On the HMCs at Accurate, a substantial amount of through the spindle coolant is used to improve productivity. However, this generous use of coolant can create an immediate and dangerous problem if the coolant runs low and the machine has no safeguard/warning device, especially when drilling and tapping. Nearly half of the Accurate systems had no such devices originally, resulting in some damage to the high-speed drills. A third of the later systems used at the company had a communication device to put the machine's CNC into a single block state when the coolant tank ran low, but had no protection to shut off the pump to prevent dry running. "On our third generation systems, we changed from a diaphragm style pump to a screw pump, where dry running would be very bad, to say the least," said Tario. "With our fourth generation Hennig conveyors, however, we have all the protection of the previous generations plus all the necessary controls to shut down the pumps to prevent very costly system component damage."
Accurate has already installed four Hennig systems, just received an additional three and has plans to purchase two more, for a total of nine in the shop. All are connected to Niigata HMCs that have an opening in the back of the machine with a horseshoe-shaped channel where the conveyor fits. The overall machine size is 10' wide by 30' long. The HMCs feature multiple pallets and are used for machining large, heavy workpieces.
Accurate Gauge prides itself on the company motto that says, "The quality is not in the product, unless the quality is in the process." Its customers include Meritor, Axle Alliance, Dana and Mack.
Additional Accurate personnel who contributed to this project include Greg Mann, Plant Manager, Dennis Shepp, Maintenance Technician and Jim Weeks, Shift Supervisor and Maintenance Technician.
For more information contact:
Mark Tario, Engineering Manager
Accurate Gauge & Manufacturing, Inc.
2943 Technology Drive
Rochester Hills, MI 48309
248-853-2400
mark@accurategauge.com
www.accurategauge.com
Kris Drennen
Marketing Admin Assistant
Hennig, Inc.
2500 Latham St.
Rockford, IL 61103
815-316-5277
info@hennig-inc.com