More than most industries, today’s aerospace, defense, and automotive-component manufacturing is challenged with machining a lot of exotic alloys and hard metals. This can take a toll on the carbide cutting tools used, and the result is that the tools must be changed out more frequently as they dull or break. Tool replacement, not to mention loss of production time due to frequent changeover, can escalate costs as well.
Founded in 1978, Preco Manufacturing (Riverside, California) has built a reputation as a leading aerospace manufacturer of precision machined components for military, government, and commercial customers around the world. A minority-owned company; Preco is helmed by President Martin Munguia and is consistently driven by its ability to provide customers with optimal engineered parts solutions at the right cost. To fulfill this commitment and maintain a competitive edge in the marketplace, the company recently replaced all of its machines with new state-of-the art equipment to take full advantage of today’s sophisticated manufacturing technologies.
The ISO9000:2008 and AS9100 registered company’s goal is to control costs and provide a shorter turnaround by manufacturing all phases of a component from start to finish — regardless of its critical tolerances. To achieve the result of holding tight tolerances, the company invested approximately $1.6 million in the MAM72- 35V Matsuura 5-Axis Machining Center (Matsuura Machinery Corporation Fukui-city, Japan) —which is synonymous with state-of-the-art unmanned (no need for operator oversight) simultaneous production for integrated close tolerances.
The MAM72-35V provides the advanced integration of a multi-pallet stacker, tool carousel, and close tolerance machining center. It also features a 35-tower pallet system with an exceptionally high option of a 520-tool matrix magazine base. This robust configuration was able to meet the manufacturing challenges of Preco’s predominantly exotic material castings (stainless steel, titanium, aluminum alloys, etc.) — which creates a unique set of production machining hurdles when considering that it typically requires high speeds in excess of 20,000 RPMs. The MAM72-35V features a 20,000 RPM Hi-Tech spindle, coupled with hand-built precision, which makes for an accurate and robust unattended solution for complex work like Preco’s.
In this realm of optimizing machining to its limits via hard torque, Preco was experiencing frequent broken retention knobs, which resulted in costly downtime, poor finishes, and were challenging the bottom-line cost efficiencies. Additionally, they would experience excessive chatter at high RPMs because the tooling wasn’t balanced — therefore finding a solution for manufacturing high-speed aluminum parts with chrome finishes at 20,000 RPMs was key.
The immediate goal for Preco was to find a “fool-proof/no-excuses” retention knob solution that wouldn’t fail. This would allow it to avoid increased costs per part and negate impact to its ability to move toward its goal of “max-capacity/max-efficiency” aerospace manufacturing.
JMPP/High Torque finish/system solution
Imperatively, a retention knob solution had to be found to improve the contact, reduce the spindle loads, and increase the speeds and feeds — all while improving the capacity to remove more cubic inches of metal per minute. In seeking out recommendations on knobs, Preco contacted JM Performance Products, Inc., a leading manufacturing innovator of CNC mill spindle optimization products since 2009. The companies’ patented High Torque retention knobs were the only knobs on the market to fully address the gamut of vital and costly CNC V-Flange tooling production issues that can negatively affect tool life.
Notably, JMPP’s High Torque retention knobs are specifically designed to eliminate the toolholder expansion responsible for costly and ongoing CNC milling and boring issues. Toolholder expansion caused by standard retention knob installation can reduce the toolholder to spindle contact by 70 percent or more. Key to the design is a relief beneath the precision pilot that forces the threads of the knob deeper into the threaded bore of the toolholder — where a thicker cross-section of material resists the expansion and deformation.
“Fundamentally, JMPP’s knobs also work as an integrated system that starts at the connection of the spindle and the knob,” said JMPP Plant Manager Craig Fischer. “The system includes precision-cut threads, which take into account the mechanical functionality of each thread, magnetic particle testing that will reveal any faults and cracks in the material, installation torque specifications based on draw bar force and taper size, as well as replacement recommendation specifications.”
Preco results/finishes/conclusion
Preco was using more than 100 tools on their MAM72-35V machine, so they tested a High Torque knob for every tool including drills, face mills, taps, etc. The same knobs were used across multiple tools — from a 1” reeler, 2” base mill, 32K end mill, etc.
“The benefits were immediately deep and far reaching as better taper connection resulted in spindle load reduction, increased speeds and feeds, and the ability to remove more cubic inches of metal per minutem,” Munguia said. “Most visibly, we were able to achieve a combination of higher quality chrome finishes on parts, which is essential in aerospace/defense applications.”
“Achieving better surface finishes also eliminates additional benching operations that add to the cycle times,” said Sam Flores, Preco’s machinist-operator. “We’ve had experiences with poor finishes in the past, but now we can run deep 4” bores with six finish with no taper on the end mill.”
With these empirical results in hand, Preco moved swiftly to converting all of its 5-axis machines and milling centers to JMPP’s knobs and have had them in operation for more than two years.
“In the aerospace and defense industries, price is a factor, but the customer is more interested in top quality parts delivered on time,” Munguia said. “We wouldn’t dare change back to standard retention knobs.”
“It started with the new Matsuura machine, which proved out the overall great finishes even when running heavy tools on some parts,” Flores said. “In essence, we now exclusively use the High Torque knobs on every tool on our machines. They have better concentricity, fit exactly, and the tools perform better across the board. Most importantly, with the heavier milling we do with titanium and stainless-steel parts, there are no issues with the retention knobs.”
“In implementing our High Torque knobs over the long haul, Preco will continue to increase speeds and feeds that deliver better cycle times to realize superior finishes and substantial savings for their demanding aerospace applications,” JMPP’s Fischer said.
