Defense Articles

Radio Frequency Systems has released two new antennas designed for short-haul microwave systems.

RFS says the SB1-520A and the SB1-550A are both 1-foot diameter single-polarized antennas developed to fulfill specific application demands in the 50-to 60-G Hz frequency range.

The RFS CompactLine SB1-520A supports the 51.4- to 52.6-GHz frequency band while the RFS CompactLine SB1-550A is the only antenna on the market to cover the entire 54.25- to 59-GHz range in one product.

Both antennas offer side lobe suppression and also incorporate a short shroud for a low-profile and a modified Cassegrain feed system with a shaped sub-reflector for optimum gain and pattern performance.

Hirschmann Electronics of Germantown, Maryland, introduced three new rooftop-mounted GPS antennas for vehicle tracking: The GPS 2400 CELLULAR (WLAN/Bluetooth, satellite navigation and mobile cellular telephony), and the GPS 400 and 900 V FLEX TETRA models.

The art and science of ultrawideband antennas.

Schantz, Hans.

Artech House

2005

331 pages

$89.00
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Hardcover

TK7871

At the cutting edge of wireless development, ultrawideband (UWB) antennas deserve careful attention at the design stage. Schantz introduces the history of UWB antennas and their use as transducers (in terms of bandwidth, dispersion, and polarization), transformers (impedance and transmission lines), radiators in both time domain and frequency domain (including Maxwell’s equation) and energy converters (including motivation, localization, dipole field energy, and fundamental limits). Schantz also describes the taxonomy of UWB antennas and UWB antennas in systems.

Imagine working for a company with a merchandise inventory valued at $4.2 billion and nearly 1,500 employees working at 22 different locations around the world. Your company’s inventory consists of some 337 different major end items weighing a total of 210,510 tons and is stored at over 150 places worldwide, including stocks afloat on the oceans. Your company’s budget for the next 6 years for replacing the items your customers are anticipated to use is $2.1 billion. Your company must train 450 new employees a year to keep up with personnel turnover, and those employees must be trained to understand and comply with numerous, strict safety regulations imposed by the Federal Government. Finally, there are the customers–over 200,000 of them–whom your company supplies with items from its inventory. They are extremely demanding and unforgiving, and they will not tolerate late delivery or insufficient quantities of items, or items that malfunction or do not work as intended, or shipments that do not contain the items they ordered. Oh, by the way, your customers’ very lives depend on the received items working as advertised.

Welcome to the world of Marine Corps ground ammunition, referred to in the military supply vocabulary as “class V(W).” The management of the Corps’ ground ammunition program, headed by the Program Manager for Ammunition (PM-Ammo) at the Marine Corps Systems Command, is big business. However, managing the Corps’ ground ammunition is not simply a matter of keeping worldwide track of 337 major end items, each with its own Department of Defense Identification Code (DODIC). Many of these items include component items with separate national stock numbers (NSNs). There are literally thousands of NSNs to keep track of, not including the lot numbers assigned to batches of a specific NSN-designated item by its manufacturer. Items with the same lot number are assigned one of 15 condition codes by DOD, and those condition codes can change throughout the life cycle of those items. Items with the same lot number at the same storage location also can have different condition codes. For example, the portable Anti-Personnel Obstacle Breaching System (APOBS) is one of the 337 items managed by PM-Ammo. It incorporates components with different NSNs, including the motor, grenade, fuze, detonation cord, and packaging, and each of those components potentially can have different lot numbers and condition codes.
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To improve the management of ground ammunitions and thus improve support to logisticians and operating forces in the field, the Marine Corps is developing several information systems that will increase the availability, timeliness, and accuracy of ammunition information.

Managing Ground Ammunition

The mission of PM-Ammo is to conduct limited research, development, and acquisition and execute lifecycle management support of all conventional ground ammunition Marine Forces require to train for, and successfully conduct, expeditionary maneuver warfare. PM-Ammo’s corporate headquarters is located at Marine Corps Base Quantico, Virginia, and includes the PM, Deputy PM, and three divisions: Inventory Management and Systems, Ammunition Programs and Budget, and Logistics (see the chart on page 12). PM-Ammo is also the sponsor of occupational field 23, Ammunition and Explosive Ordnance Disposal, for the Corps’ ammunition community, both officer (restricted only) and enlisted. [”Restricted” refers to warrant officers and limited-duty officers. “Unrestricted” refers to the rest of the officer community. All officers in the Marine Corps ammunition community are restricted.]

PM-Ammo is responsible for managing the following types of ground ammunition–

* Small arms.

* Medium caliber.

* Mortar.

* Artillery.

* Tank.

* Grenade and pyrotechnics.

* Demolition.

* Rockets and missiles.

[ILLUSTRATION OMITTED]

It does not, however, manage Navy-owned aviation ordnance used by Marine Corps aviation units; the Deputy Commandant for Aviation is responsible for those requirements.

Ammunition Knowledge Management Portal

A significant information technology (IT) enabler used to provide meaningful and timely information in the conduct of the Corps’ ammunition business is a comprehensive repository of ground ammunition data with its own Web site known as the Ammunition Knowledge Management Portal (KMP). Access to the KMP is controlled for security reasons.

The KMP includes data on the following ammunition-related subjects–

* Class V(W) ground ammunition assets.

* Life-cycle management.

* Marine Corps stockpile by age.

* Malfunction histories.

* Notice of Ammunition Reclassification (NAR) histories.

* Engineering change proposals.

* Lot manufacture dates.

* Current NARs.

* Muzzle velocity adjustments.

* “Preferred for training lots” ammunition (a classification of ammunition that should be used for training).

The KMP is an evolving service provided to the Marine Corps ammunition enterprise that is updated systematically to provide “added value” to the viewer. Resource links are regularly added to the alphabetized directory located on the KMP home page.

“Knowledge is power when shared.”

In preparation of tank gunnery, crews train on multiple tasks to ensure they are proficient in their job skills, which should guarantee a qualified rating on Tank Table VIII. Throughout the gunnery training phase all tasks are important–individual task training is the key to successful collective tasks.

Collectively, a tank crew wants to acquire, engage, and destroy all targets presented for each engagement. The score for each engagement depends on the time, in seconds, of the last target destruction. To assist in taste, engagement times, experienced tank crewmen emphasize the training of loading the 120mm main gun. During the training phase, the loader will be required to load the main gun until he meets crew standards. In most cases, the loader is allowed to stow the HEAT and sabot rounds in the ready rack where he is comfortable. Since the training sabot weighs 37.8 pounds and the training HEAT weighs 51.4 pounds, the majority of loaders prefer to place HEAT rounds in the upper tubes of the compartment–when the locking mechanism is unlatched for the HEAT round, the weight of the round will assist in the removal and loading process. This is where the armor community falls short in safety issues for crews and equipment.

All M1-series tanks have a ready and semi-ready ammunition compartment in the turret rear and a hull ammunition compartment. The main armament ammunition is stowed in the racks behind sliding armor doors. Each compartment, including the hull, has blow-off panels, a reinforced structure, and ballistic doors to protect the crew in case of projectile penetration in the ammunition storage area. The design specification of the 16-, 17-, and 18-round ammunition racks is the deciding factor in storing HEAT ammunition.
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The initial M1A1 tank from 1985 was assembled with 17-round racks in the turret ammunition compartment and full anti-fratricide protection for all tube locations on both the ready and semi-ready sides. Also, the hull ammunition compartment has full anti-fratricide protection. Because of their design, HEAT rounds are more vulnerable when compared to kinetic energy or canister rounds. Thus, to lower overall system vulnerability, only kinetic energy and canister rounds are to be stowed in the top two rows of the turret ammunition compartments. The lower two rows can hold either kinetic energy, canister, or HEAT rounds. The anti-fratricide protection is provided by wrapping materials around the outside of each tube where the warhead is located. If the jet steam of a HEAT round was to penetrate the amino storage area and detonate a HEAT warhead, the anti-fratricide bars are made to stop the fragmentation and explosive effects from detonating a neighboring round.

The design of the M1 tank evolved into the M1A1 to combat the increased capability of threat forces. The M1A1 tank incorporated modifications that increase the weight of the vehicle. During this period of production, our battle secnario was the tank-to-tank battle as were the tears of the Cold War. This type of battle scenario drove the requirement for more kinetic energy rounds rather than chemical energy rounds. To mitigate the increase in vehicle weight, there were several vehicle weight-reduction initiatives, which included reducing anti-fratricide protected locations within the new 16/18-round ammunition racks. Since the Cold War load plan required a majority of kinetic energy rounds, the reduction in anti-fratricide bars was not considered a reduction in capability.

The 16- and 18-round ammunition racks have been used in the Abrams tank since 1990. Whether you have a 16- or 18-round rack will determine where HEAT rounds will be stowed within the turret ammunition compartment. A 16- and 18-round rack has anti-fratricide bars mounted around the rearward portion of the tubes. Refer to Technical Manual (TM) 9-2350-264-10-1, Operator Controls, PMCS, and Operation Under Usual Conditions, page 2-485, for the exact placement of rounds. Generally speaking, to maximize tank crew survivability, stowage of HEAT rounds are to be placed in the two bottom rows and in the inner tube locations of the tun-et ammunition racks. Kinetic energy and canister rounds can be stowed in all rack locations of the turret ammunition compartment. The hull ammunition compartment will accommodate free stowage of kinetic energy, canister, or chemical energy rounds. However, HEAT rounds are considered safer if they are stowed in the inner column of the hull ammunition compartment. If more HEAT rounds are to be uploaded, the TM depicts the tubes that can be used to accommodate your unit’s SOP, but these rounds need to be fired first. The new U.S. Army Field Manual (FM) 3-20.12, Tank Gunnery (Abrams), will address the 120mm ammunition stowage.

Other safety considerations when handling and storing 120mm ammunition include: thoroughly inspecting all rounds prior to uploading according to TM 9-2350-264-10-2, Operations Manual Operation Under Unusual Conditions, Emergency Procedures, Troubleshooting, and Maintenance, page 5-11, Table 5-2; training rounds will not be stored in the hull ammunition compartment due to the vulnerability of the training round propellant; load only enough training ammunition in the bustle compartments to achieve immediate training objectives; do not have, operate, or carry any unauthorized wireless/electronic devices when within three meters of tank ammunition; never operate any tactical or commercial radio on the 200-280 MHz frequency when within three meters of tank ammunition; frequency blocks shall be incorporated in all radios near the tank ammunition; and wear gloves when handling ammunition–the human body could act as an antenna amplifying any signals in area if the center primer electrode is touched.

Everyone knows that ammunition is dangerous. It is designed to inflict damage, usually by hitting a target with great force, exploding, or both. When we look at the bare-bones theory behind ammunition, we see that it revolves around energy. When using ammunition, our objective is to throw “balls of energy” (projectiles, missiles, and bombs) at bad guys and hit them–hard.

To achieve this goal, we somehow have to get these balls of energy from the factories that manufacture them to Soldiers and other military personnel who will use them to protect and defend their units and themselves. Unfortunately, until we perfect ammunition teleportation technology, ammunition is vulnerable throughout the supply system. An article in the March-April issue of Army Logistician, “Preserving Readiness Through Ammunition Packaging,” described the lengths to which packaging engineers go to protect ammunition from problems created by the transportation system and the environment. Readers of that article may be prompted to ask: “What’s being done to protect us from our ammunition?” After all, energetic materials such as propellants and explosives are not discriminating. Give ammunition a good spark, a little fire, or a hot fragment, and most of the energy it has stored up for the bad guys will be hurled at the good guys instead.

Insensitive Munitions
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So what are the Army’s engineers and scientists doing to keep us safe from our own ammunition? The answer is that they are working to make ammunition insensitive. The goal is to develop ammunition that will react in a dangerous way when we want it to and not before.

A reaction is normally most dangerous if it is a “high order” detonation event. In “techno-speak,” this means an event in which a chemical reaction produces high-pressure, high-temperature shock waves that consume the explosive material nearly instantaneously. Shock waves from high-order detonations can travel faster than a mile a second and cause a lot of damage. If we put these already potentially dangerous energetics into a closed container, such as a shell, an armored vehicle, or any other tightly enclosed space or structure, we introduce the effect of confinement to the explosive reaction. Confinement often increases the violence of an explosion because of a buildup of pressure, which eventually bursts the container that encloses it and creates what is essentially a bomb. So not only do we have fire, heat, and a shock wave, we also have flying fragments.

Propellants and Explosives

The ideal approach to making munitions insensitive is to use propellants and explosives that do not react unless they are hit with a specific stimulus. Unfortunately, this is probably the most difficult way to make explosives insensitive. We still want munitions to pack a punch and explode on impact with a target. This means we have to come up with new chemical mixtures that pack similar amounts of energy but react only when we want them to. Scientists and engineers have developed several new materials that are powerful but hard to set off by accident. A word of caution, though: These materials still have more than enough stored energy to do real damage if mishandled, no matter how insensitive they may be.

Containers

One solution to this problem is the use of melt-away panels to protect munitions during transport. In the event of a fire, the panels melt before the ammunition has a chance to explode, leaving behind huge gaping holes in the container. Munitions may react much less violently if their containers are designed so that the munitions cannot build up pressure from confinement. They may burn, but they are not likely to explode. However, a container designed with insensitivity in mind still must be able to protect the munitions and pass stringent handling and environmental testing. This balancing act between insensitivity and ruggedness can be tricky.

Contained munitions can build pressure so fast that common solutions such as pressure-relief valves will not work. One solution to this problem is the use of melt-away panels. These panels protect munitions during transport, but, in the event of a fire, they melt away, leaving huge gaping holes in the container before the ammunition has a chance to explode. When the ammunition finally explodes, the pressure has somewhere to go; it does not turn the container into a bomb.

Several other techniques also are being tried. Most of them offer some way to weaken the structure of the container so that it will vent at precise spots under pressure. Ideas such as scoring the wall of the container or weakening the welds have been studied, but these approaches pose challenges for quality control and manufacturability. It is difficult to develop a container that is strong enough to pass all packaging tests but strategically weak enough to pass all IM tests.

IM Testing

All munitions acquired by the military services must be examined to determine if they meet established IM requirements. This is true whether the munitions are developed by the services or procured from commercial or foreign sources. This examination normally involves a series of six tests designed to assess the ability of munitions (typically in their shipping configuration) to withstand shock, heat, and impact. The specific tests are identified during a threat hazard assessment conducted by the acquiring service. The six tests normally include fast cookoff, slow cookoff, sympathetic detonation, bullet-impact, fragment-impact, and shape-charge jet impact tests. These test requirements, methods of conduct, and passing criteria can be found in Military Standard (MIL STD)-2105, Hazard Assessment Tests, Non-nuclear Munitions, and in various North Atlantic Treaty Organization Standardization Agreements (STANAGs).

By the early 1980s, the technology was in hand to define “smart weapons” that could fill at least three important military purposes. First, guided weapons could provide theater-range artillery fire accurately across an entire battle area, when linked with a theater-wide surveillance system to identify and locate targets. Second, advanced surveillance systems could be used to mount an effective theater-wide air defense using surface-to-air missiles. Third, electronics could be employed in handheld anti-tank weapons that would make it possible to activate and deactivate these weapons from a central location, making possible wide distribution, even to militias, without fear of their misuse. How have these possible applications played out?

Substantial elements of a real-time, theater-wide surveillance system capable of covering a region 1,000 kilometers (roughly 600 miles) across already existed in the mid-1980s. These elements would be supplemented by a robust theater-wide communications system. Surveillance would be carried out in part by forward observers on the ground and in part by small drone aircraft, equipped with global positioning system (GPS) navigation and with television cameras or other sensors that could obtain precise knowledge of the target position. Once a target was identified and located, attacking weapons were available that could be guided to the target by using a navigation grid common to the sensors and to the weapon.
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As demonstrated in U.S. actions in Afghanistan in 2001 and in Iraq in 2003, this capability has been functionally achieved. The laser-guided bombs used during the Vietnam War have been augmented by the addition of highly accurate Joint Direct Attack Munitions (JDAMs). These devices are guided by GPS systems and do indeed “bomb by navigation” on coordinates provided by ground observers, aerial surveillance, or satellite observation. A typical JDAM is a 2,000-pound Mk 84 bomb. A much larger JDAM, a 21,000-pound device called Massive Ordnance Air Blast, or MOAB, was used in Iraq after its first test in 2003.

Despite the advances demonstrated by the U.S. Navy and Air Force, the Army has not yet seen the merit of largely replacing tube-fired artillery shells by GPS-guided rockets. Developing such weapons would be possible within the constraints of the Intermediate Range Nuclear Forces Treaty, which prohibits the United States and Russia from possessing ground-based ballistic or cruise missiles with a range between 500 and 5,500 kilometers. A ballistic missile with a range of 480 kilometers would give the Army the ability to mass accurate fire from secure areas onto targets across an entire theater. In contrast with a conventional howitzer, which has a range of only about 40 kilometers and might miss its target by as much as 150 meters, the probable error for GPS-guided rockets of any range is likely to be in the 5-meter range. The rockets also can be arranged for simultaneous arrival on target, with final approach from any desired angle.

The contribution of JDAMs has been realized in conjunction with an integrated targeting and communication system, including the possibility of changing the target coordinates in the individual weapons while the delivery aircraft is in flight. Similar in accuracy to laser-guided bombs, JDAMs offer the important capability of being able to work in cloud or smoke, and they can attack dozens of individual targets in a region tens of kilometers across from a single release of multiple bombs by a B-52 or other large aircraft.

Only extra care will prevent guided bombs from “accurately” destroying the wrong targets by mistake, as happened with the Chinese embassy in Belgrade. But it would be highly desirable in any case to add a feature to ensure that such weapons explode in the air rather than on the ground if their guidance system malfunctions or if surveillance shows a civilian bus approaching the target area.

The problem with missile defense

The Bush administration has placed great emphasis on National Missile Defense (NMD), focused on a possible North Korean attack on the United States using intercontinental ballistic missiles (ICBMs) bearing nuclear warheads. But as early as 1968, Hans Bethe and I warned that a missile defense that cannot deal with feasible countermeasures is worse than no defense at all. That, unfortunately, characterizes the midcourse interceptor system under development by the Pentagon. My colleagues and I have shown, for example, how balloons released by an ICBM could serve as credible decoys for a tumbling warhead, itself encased in a similar balloon, thus preventing intercept of a nuclear payload.

On the other hand, boost-phase intercept (BPI)-striking the missile before its rocket engine has driven it to full ICBM speed-has a real capability against the Taepo Dong 2 ICBM that North Korea has been expected to test since 1998. BPI would work against North Korea because the territory is small and almost surrounded by international waters. But progress has been slow in developing BPI, in large part because the administration has emphasized the ineffective midcourse system and to some extent because BPI would be more difficult to use against a missile launched from the much larger territory of Iran and, until the recent war, Iraq. Yet solving the most urgent problem first-North Korea-has some merit.

“Terminator-6, this is Warlord-6, FRAGO follows … move from checkpoint 2 to checkpoint 4 and secure LZ Condor for 2nd Battalion’s air assault. Be there by 2300. Make sure you’re there before the birds are!”

With these words, an anti-tank platoon leader’s mind reels. He turns on his red lens flashlight, unfolds his map, consults his PLGR (precise lightweight GPS receiver), and peruses his graphics. A few minutes later, the platoon leader awakens his driver. The platoon leader net calls his platoon to get ready to move, gives the destination grid, briefs the reason they are moving, and then waits for the platoon vehicles to move out.

Invariably, one of the following events follows: a known minefield strike halts all movement; elements break contact; direct fire contact with “unknown elements” in the darkness impels the platoon to break contact; or impacting mortar rounds disrupt the platoon’s mission.

In the end, the platoon may or may not reach its assigned objective and accomplish its task.

At the Joint Readiness Training Center (JRTC), the above scenario must be the most flexible in the battalion. the platoons’ mobility and lethality continually boost the task force’s agility and flexibility. During sustained operations, hasty missions are the order of the day. To help their platoons in ensuring success, Delta Company commanders should develop a “15-minute” checklist for the platoons. This checklist should contain mission-critical items for each member of the platoon to execute prior to starting the mission. Sample events are shown in Table 1. These actions are not surprising. They are in everyone’s precombat inspection (PCI) checklist. But units must carry compressed checklists and be able to use them effectively in 15 minutes or less. All too often, platoons move out from point A to point B without any real preparations because of higher headquarters’ emphasis on “moving out now!” Subsequently, there is no individual situational awareness, weapon system readiness, or contingencies for making contact.

All drivers must know the route. All Soldiers need to know a frequency and call-sign they can reach if they need indirect fire support. Every vehicle needs to know updated minefield locations and the locations of friendly forces they may be passing through. Leaders need to know a scheme of maneuver (movement formation, transitioning to bounding overwatch, preplanned indirect fire targets, etc.).

Commanders need to drill their platoons with sample scenarios so that they will be able to respond effectively. The difference between “speed” and “haste” has to be emphasized. When platoon members become proficient at conducting key pre-mission tasks, their success, confidence, and ability to execute aggressively will improve significantly.

Table 1–Sample checklist

PL/PSSÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â TC:

Develop plan (10 minutes)Â Â Â Â Â Â Â PCI commo, ensure freqs loaded (5 min)
–movement techniques           Review map, prepare to copy plan (3
min)
–weapon mixture                Prep NVGs (2 min)
–fire support, C2 frequencies  PCI commo, ensure freqs loaded (5 min)
–minefield locations
–enemy activity in vicinity

GUNNER:Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DRIVER:
Prep weapon system (7 min)Â Â Â Â Â Â Check oil/fuel levels (3 min)
PCI ammo (3 min)Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Tighten load plan (5 min)
Prep NVGs (2 min)

ALL: Disseminate plan (WARNO + :11 thru WARNO +15) via FM or face to
face.

At the time this article was written, Major Perry Beissel and Sergeant First Class Marco Garcia were the anti-tank/heavy weapons company senior observer controllers for Task Force 2 with JRTC Operations Group, Fort Polk, Louisiana.

On August 13, 2005, SSgt Futrell and SrA Strom were serving on standby duty for the 2nd Bomb Wing Explosive Ordnance Disposal Flight when an emergency request for assistance came in from the local police department in Tool, Texas. An Alcohol, Tobacco, and Fire Arms raid of a drug lab there had yielded one AT-4 Anti-Tank rocket. Tool, Texas, is located approximately 3 hours driving distance from Barksdale AFB, La. Demonstrating exceptional resourcefulness and quick thinking, the team implemented a new and novel idea to minimize the chance of wasting scarce tax payer dollars or damaging vital equipment by deploying unnecessarily. By carefully scrutinizing real-time photos taken by the responding officers, the team was able to determine that the rocket was not 100 percent safe for the local authorities to handle. SSgt Futrell and SrA Strom directed the local officials to stay clear of the area, checked their equipment, loaded their response vehicles, and completed a thorough Operational Risk Management (ORM) assessment to ensure they were fully prepared to deploy, perform their duties, and return safely. The team was acutely aware that many illicit drug labs raided previously had been booby-trapped to discourage intervention. They also realized that the individuals responsible for assembling this particular lab had demonstrated at least some familiarity with military ordnance. After driving to the scene, the team cautiously entered the site using integrated combat tactics. While completing their initial reconnaissance, the team encountered no other weapons other than the AT-4 launcher. After securing the immediate area, they ensured the 2,000 square-foot house and adjoining 3-acre lot were safe and turned over the crime scene to local law enforcement officers for investigation. Upon closer inspection, the AT-4 launcher was found to be empty, something which could not be determined from the photographs reviewed back at the base. This team demonstrated exceptional ORM techniques, professionalism, selfless courage in a potentially hostile environment, and an unrivalled commitment to safety, underscoring Barksdale’s strong safety partnership with the surrounding civilian communities.

Though the part is destined to soar, the method of machining is often slow and earthbound. For aircraft structural components, a common approach to machining involves laying the part beneath a gantry. That gantry may move at a relatively slow feed rate because it carries three spindles at a time. Certain large aircraft parts will continue to benefit from this approach, particularly long and narrow stringers. However, a single high speed spindle moving at high feed rates may be able to machine some monolithic parts fast enough to compete with the productivity of a gantry making three identical pieces at once. And when the high speed spindle machines in a horizontal configuration, both quality and efficiency stand to improve in a variety of ways.

In fact, where aircraft part production is concerned, “high speed” and “horizontal” go together. High speed machining is about making chips fast, and horizontal machining is about getting those chips out of the way of the cutter. A horizontal design also saves on floor space, and certain newly developed machines for large aircraft parts employ work-changing that takes advantage of a horizontal orientation.
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Examples of such machines can be found in the “MAG” line of machining centers from Makino (Mason, Ohio). The five-axis horizontals in this line are designed for aircraft parts too large for typical CNC machining centers. Each MAG machine includes a 30,000-rpm, 60-kW spindle and a combination of CNC features that permit precision milling at high feeds. Models ranging in size from 4 to 16 meters of travel in X feature linear motors for this longest axis. One of these models, the MAG4, features a rotating work indexer that places tables on opposing faces like the opposite sides of a coin. While one table holds a part inside the work zone for horizontal machining, the other table locates outside the work zone for setup of the next part. To switch from one part to the next, the indexer flips to reverse these tables. (See photo on page 92.)

Buying a machine like this is no idle purchase for any shop. Much of the payback has to come from the opportunity to realize a significantly more streamlined process for milling large parts. But some of the return on investment can also result simply from the switch to horizontal high speed machining, and the many process advantages this change can deliver that are specific to aerospace production.

Mark Waymouth of Makino’s aerospace group is one person frequently asked to articulate those advantages. The various benefits he cites can be divided into six categories:

1. The chips are down (and out of the way)

Aircraft part production maybe the only application in which the push broom is a critical tool for precision metalworking.

Getting chips out of the way of the cut is important to both the reliability of the tool and the quality of the part. On a vertical machine such as a gantry mill, that can make sweeping between cycles an essential part of the process.

Horizontal machining eliminates the need to spend time and labor cost on this manual chip removal, because the chips fall away instead. It also reduces the various hazards that result from having chips accumulate while the cycle is underway. Less recutting of chips can result in both a better machined finish and more consistent tool life.

2. One tool may be better than three

Machining one workpiece at a time instead of machining three at once can dramatically streamline tool management. Gone is the need to change tools manually, because the toolchanger on the one-spindle machining center takes care of this. Gone too is the need to own and inventory three identical tooling sets at once.

Using one tool at a time also means it’s no longer necessary to set tools to precise dimensions so that three tools can share a common offset. At best this tool setting is time-consuming and entails labor expense, but generally it also leaves measurable error from tool to tool that limits how accurately parts can be machined when they are cut in unison. The single spindle makes it possible to machine to tighter tolerances, because machining offsets are tailored to the dimensions of one tool alone.

3. Ending blending

Reduced recutting of chips, along with the elimination of dimensional discrepancies between simultaneous tools, results in a more accurate surface with a better finish. Also enhancing the surface quality is high speed machining itself, which involves lighter cuts and therefore lower cutting forces.

The combination of these factors can let a shop avoid hand blending of machined parts. With high speed horizontal machining, the machined surface becomes the finished surface.

4. Replace three fixtures with one (maybe zero)

Replacing three spindles with one not only eliminates the need for redundant tool sets, but also eliminates the need to own and maintain redundant fixtures.

Meanwhile, high speed machining itself may reduce the part’s fixturing requirements. Cutting forces are lighter, so clamping forces can be lighter as well. It may become practical to machine the part out of a solid block. Using a “picture frame” approach that leaves tabs around the part to secure it to the rest of the block, until the machining is done and these tabs are cut away. With this approach, the only necessary workholding components are the clamps that secure the block to the table.