Optimizing tool life and tooling cost containment

Published
April 17, 2019 - 02:45pm

Article from JM Performance Products Inc.

Automotive Industry/Tooling Cost Climate
Automotive industry manufacturers have basic requirements from their suppliers: They want on-time delivery, accuracy and sufficient available stock. They want perfect parts, but they want them to be immediately available at a price they can control. Automotive industry suppliers need to have the ability to maintain production volume and quality, while maintaining a competitive edge through cost containment.


The big automotive companies hold their suppliers to very strict requirements relative to quality while expecting them to be very flexible in response to fluctuating demand, and still produce parts as economically as possible.
Nearly every component manufactured for use in the automotive industry has CNC manufacturing involved in its production. Perhaps it’s time for automotive manufacturers to take a giant step backward and get down to the basics of manufacturing issues that exist on the production floor, which cost the industry billions of dollars per year and go largely unrecognized.


Tooling is a vital and often overlooked process in the production of automobiles, as every single part of a new car requires a unique tool. What if an invisible problem inherent to CNC manufacturing existed? What if an actual flaw in the tooling was robbing manufacturers of the ability to produce parts accurately, and interfering with the production rates and cost containment? One of the major initiatives at the forefront of today’s automotive manufacturing community is to answer these challenging tooling cost containment questions and find progressive solutions therein.

High Torque Inseption/Tooling Cost Revelation
A few years ago, Boeing contacted one of its tooling manufacturers, Briney Tooling Systems, Bad Axe, Michigan, a leading supplier of CNC toolholders and shrink-fit tooling systems in North America, reporting that they had performed testing that revealed a flaw in the V-flange tooling the company was using. Requesting a solution, Briney reached out to JM Performance Products, Inc., Fairport Harbor, Ohio, to elicit their assistance in resolving the problem Boeing described. In turn, within the following week, JMPP began an intrinsic investigation and ultimately designed a gage that mirrors the interior grind of a CNC spindle. This gage measures movement or growth of the toolholder taper down to 7.5 millionths inch in diameter.


JMPP identified that the essential flaw, the invisible problem plaguing CNC manufacturers, as toolholder expansion. Using their gage to perform extensive testing, JMPP proved that toolholder expansion is caused by the installation of a standard retention knob into a V-Flange holder.


Briney had reported expansion of their holders with as little as 13 ft.-lbs. of torque during retention knob installation. This expansion creates a bulge in the holder at the small end, causing the holder to make contact with the small end instead of the large end. This effectively reverses the way the toolholder is designed to fit the spindle, allowing the holder to move randomly within the spindle. This movement results in a loss of contact between the spindle and the toolholder, and causes a laundry list of issues: vibration and chatter, excessive runout, poor finishes, shortened tool life, high power consumption, excessive spindle wear, need to slow down, and the need to reduce the depth of cuts.

Using the taper shank test fixture, JMPP redesigned the knobs, finally reaching a design that eliminated or substantially eliminated toolholder expansion. The company's patented High Torque retention knobs are designed
to thread deeper into the bore of the holder where there is a thicker cross-section of material to resist deformation.

Boeing’s major complaint was associated with the vibration and chatter–that was causing tolerance and finish issues on extremely expensive parts. The introduction of the High Torque knobs effectively eliminated the chatter issues. Once the knobs were made available to the general milling population, JMPP began to get feedback from customers that served to emphasize how rampant and detrimental a problem toolholder expansion represented to the manufacturing community.


Client Cost Containment/Tooling CHallenge Profile
Schuster Mechanical LLC, Detroit, a growing CNC job shop focused on auto test equipment, was investigating new CNC machine investments which included TRAK 2op and TRAK LMP. The TRAK 2op is the first portable (2.5’ x 4’ footprint) VMC to focus on second operations work, featuring an 8-station toolchanger, and 10,000-rpm spindle. The TRAK LMP VMC is a low-volume/high-mix production system that incorporates technologies to markedly reduce the changeover times that plague high-mix, low-volume shops.

Owner Robert Schuster wanted to proactively ensure that his spindle cartridge would last as long as possible to maximize the dependability and productivity of the new machining centers. Schuster engaged with JMPP’s sales engineering personnel at a trade show, who showed him how their knob’s threads ran deeper into the holder, causing less distortion at the small end of the taper. Schuster was immediately impressed that his holders were not damaged by the expansion caused by the standard knobs and could still be used in production with the High Torque knobs–with no spindle damage occurring.

Initially, Schuster was considering implementing an HSK toolholder system, but found that it was an expensive system that had too many limitations to justify conversion from V-Flange. The HSK design features a cupshaped
holder that doesn’t provide a long reach, the socket is shallow, and the walls are thin. The High Torque knobs maintain spindle/taper contact, with the benefit of the more affordable V-Flange CAT/BT holder system.

Subsequently, Schuster determined JMPP’s BT30 knobs (JM31109HT) would be a more cost-effective solution to extend the life of the new VMCs. According to Schuster, “Dependability of the machining center is very important, and using the JMPP High Torque retention knobs should reduce the failures associated with traditional retention knobs. I specifically like the low tightening torque required to seat the retention knob into the toolholder. I immediately implemented about 30 of these and plan to use them exclusively on all of my TRAK machines/V-flange systems moving forward.”


High Torque/Carbide Tool Test
Increasingly, the automotive industry is using more carbide tools primarily because they can cut both aluminum
and hard materials such as titanium, carbon, and exotic alloys at high speeds. Carbide tooling is expensive and also fragile, so it’s imperative to watch for microfractures which yield poor surface finishes. If a microfracture occurs, the whole tip may disappear and the inserts can be rendered useless.

Recently, Sandvik Coromant Co., Fair Lawn, New Jersey, a high-tech and global engineering Group with about 42,000
employees, lent out one of their engineering representatives to test the best retention knobs for Caterpillar with a $1,200 solid-carbide tool. The specification included: a toolholder, retention knob, tightening spec, proper placement and then lock it down. The test’s goal was to get the custom carbide tool to run without shattering.

A variety of standard retention knobs did not work. When tested with JMPP’s High Torque knobs tightened to their provided torque specifications, it worked every time with no tool shatter. After witnessing the dramatic testing results, the Sandvik Coromant rep stated, “The JMPP knobs may be the biggest savings to the industry for the
next 10 years. They are better, faster, provide unbelievable feeds, and can reduce set up times by 40% to 60%.”

V-flange tooling by design should be the most efficient, precise and cost effective tooling system available. The fact is, a carbide tip cannot vibrate when it makes contact, or it shatters. Essentially, carbide must smoothly enter into the pocket and maintain its position in the pocket or it breaks. Carbide can last a long time with the right chip load and spindle speed. It could last weeks, but let it vibrate and it could be minutes. JMPP’s High Torque knobs have been proven to extend carbide tooling life.

Ultimately, by making a simple change … moving to the High Torque retention knobs, CNC manufacturers across the board can eliminate the vast majority of issues, improve their milling operations, and get the best results while saving money. Moreover, this solution creates a real opportunity for U.S. tool shops to grow along with their automotive OEM and Tier One customers in creating progressive tooling cost containment solutions.

 

Related Glossary Terms

  • alloys

    alloys

    Substances having metallic properties and being composed of two or more chemical elements of which at least one is a metal.

  • centers

    centers

    Cone-shaped pins that support a workpiece by one or two ends during machining. The centers fit into holes drilled in the workpiece ends. Centers that turn with the workpiece are called “live” centers; those that do not are called “dead” centers.

  • chatter

    chatter

    Condition of vibration involving the machine, workpiece and cutting tool. Once this condition arises, it is often self-sustaining until the problem is corrected. Chatter can be identified when lines or grooves appear at regular intervals in the workpiece. These lines or grooves are caused by the teeth of the cutter as they vibrate in and out of the workpiece and their spacing depends on the frequency of vibration.

  • computer numerical control ( CNC)

    computer numerical control ( CNC)

    Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

  • fixture

    fixture

    Device, often made in-house, that holds a specific workpiece. See jig; modular fixturing.

  • gang cutting ( milling)

    gang cutting ( milling)

    Machining with several cutters mounted on a single arbor, generally for simultaneous cutting.

  • machining center

    machining center

    CNC machine tool capable of drilling, reaming, tapping, milling and boring. Normally comes with an automatic toolchanger. See automatic toolchanger.

  • milling

    milling

    Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.

  • shank

    shank

    Main body of a tool; the portion of a drill or similar end-held tool that fits into a collet, chuck or similar mounting device.

  • tolerance

    tolerance

    Minimum and maximum amount a workpiece dimension is allowed to vary from a set standard and still be acceptable.

  • toolchanger

    toolchanger

    Carriage or drum attached to a machining center that holds tools until needed; when a tool is needed, the toolchanger inserts the tool into the machine spindle. See automatic toolchanger.

  • toolholder

    toolholder

    Secures a cutting tool during a machining operation. Basic types include block, cartridge, chuck, collet, fixed, modular, quick-change and rotating.

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