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Marking Processes for Use in Harsh Environments:

 Donald L. Roxby

CiMatrix Symbology Research Center

5000 Bradford Drive NW, Suite A

Huntsville, AL 35805

 

James O. Hornkohl

University of Tennessee Space Institute

411 B. H Goethert Parkway

Tullahoma, TN 37388 

Abstract

As a result of concerns related to the introduction of unapproved parts into our nations aircraft fleets, the Aircraft Transportation Association (ATA) released standards (SPEC 2000- http://www.spec2000.com/) directing manufacturers to apply machine-readable markings to aircraft parts.  The standard addresses both bar codes and Data Matrix symbols and focuses primarily on standard formats to exchange information between airlines and their suppliers. Boeing and Airbus have adopted the requirements of SPEC 2000 and imposed its requirements on their major subcontractors and suppliers.  Adoption, however, was slowed because SPEC 2000 failed to provide guidance related to how to safely apply Data Matrix symbol markings to the wide range of materials and substrates to be identified.  Recognizing the problem, the National Aeronautic and Space Administration (NASA) released a Data Matrix marking standard (NASA-STD-6002) and how-too handbook (NASA-HDBK-6003) in July 2002 (see web site: http://standards.nasa.gov/). These documents were released in advance of actual flight-testing to head off safety concerns related to DPM.  Subsequent engine ground testing conducted by Solar Turbines and overhaul process testing conducted by the United States Air Force, however, clearly indicated that current Data Matrix symbol marking processes are rendered unreadable after being subjected to harsh operational environments and overhaul processes.  The direct part marking (DPM) processes that failed during these tests were dot peening, gas assisted laser etch (GALE), laser bonding, laser engraving, laser etch, laser induced surface improvement (LISI) and laser shot peening. 

These findings have caused tremendous concerns within the federal government and spurred the creation of a joint government/industry consortium to research and solve this problem. The National Center for Manufacturing Sciences (NCMS) assumed leadership of the project with technical oversight provided Robotic Vision Systems Inc. (RVSI).  

Development Team

The first task undertaken by the NCMS was the establishment of a broad based consortium to identify and solve problems associated with part identification markings subjected to harsh environments.  Team members were solicited from the federal government, the aircraft manufacturing, aircraft operators, the symbol marking and reading industry and academia. Once established, the team developed an action plan, and conducted an evaluation to clearly identify the problems associated with marking and reading of machine-readable symbols applied to parts subjected to harsh environments.      

Problem Identification

The team visited a number of military logistic depots and overhaul facilities to witness operations and overhaul processing first hand and to discuss marking and reading issues directly with the users.  The facilities visited were:  

  • US Air Force Materiel Command, Hill Air Force Base, UT 

  • US Army Anniston Depot, AL  

  • US Army Corpus Christi Army Depot, TX  

  • US Coast Guard Aircraft Repair & Supply Center, Elizabeth City, NC 

  • US Marine Corp Air Station, Cherry Point, NC

  • US Navy Naval Air Station, Patuxent River, MD

The wide range of components associated with aircraft, tracked vehicles, and weapons systems of various types were evaluated prior to use, during operations, and after overhaul.  As a result of these evaluations, the consortium identified five major problems requiring resolution. These problems are identified as follows:

  1. Part identifiers are routinely damaged and rendered unreadable after being subjected to harsh operational and overhaul processes.

  2. Products and procedures are needed to restore marking contrast in the field. 

  3. Marking systems are not available for field marking (post delivery hardware).   

  4. Readers are needed to locate, image, and decode markings covered over with protective coatings and/or paints. 

  5. 2-D technology is not adequately addressed by industry and military standards.

Categorization of parts subjected to harsh operations and/or overhaul

The team isolated the marking and reading problems identified at the sites visited into three major hardware categories. These are:

  1. Engine/Auxiliary Power Units (APUs) - Parts that become discolored when subjected to high temperatures and/or covered with combustion contaminants
    and fluids. Included in this category are turbine blades, disks, shafts, compressor parts, combustion components and housings.

  2. Exterior Vehicle Parts - Parts that are damaged as a result of impact with foreign substances and/or are made illegible by contamination and corrosion. Included in this category are helicopter rotor blades, propellers, exterior structural components, windshields and similar items.      

  3. Parts Subjected to Overhaul - Parts that are subjected to sever overhaul and repair processes. Included in this category are landing gear assemblies including struts, wheels, and brakes, transmissions, gear boxes, etc. Also included in this category are selected small arms parts used in M16 A1/A2 rifles, M9 pistols, M60 machine guns, and other similar weapons.

Conditions causing part identification damage

Symbol reading problems are a direct result of conditions that prevent the decoding software from determining a difference between the light and dark data cells within the symbol.  The team   isolated the following specific causes for the reading problems at the sites visited: 

  • Abrasion/impact damage, e.g., foreign object strikes, sand blasting, shot peening, etc.

  • Corrosion/oxidation, e.g., parts exposed to salt fog, spray, splash, etc.

  • Contamination, e.g., dirt build-up, burnt oil, fluid staining, etc.

  • Color change caused by heat or UV exposure

  • Material removal during paint stripping and surface cleaning operations  

  • Coatings applied over markings during plating and painting operations

After a close evaluation of the damaged markings, it was determined that a high percentage of the markings applied to surfaces that were corroded, oxidized, or contaminated could be restored to readable status by cleaning the marked surface using approved processes and materials. The team recommended that industry develop a symbol contrast restoration kit and associated procedure to restore markings in the field.   MonodeÔ Marking Products, Inc. (http://www.monode.com/) is currently developing symbol restoration kits for this purpose. These kits will typically contain the following components: 

  • Cleaning cloths

  • DoD approved surface cleaning agents

  • Surface scuffing materials, e.g., scotchbrite pads  

  • Electrolysis type cleaning system to remove oxidation layers

  • Light and dark colored backfill media

  • Protective clear coats  (MIL-HDBK-132)

  • Corrosion inhibitors

  • Instructions to outline the process and requirements for removing contaminates, oxide films, heat induced discoloration, corrosions products and foreign contamination from metallic and non-metal surfaces.

NASA MSFC has undertaken a project to develop readers to capture symbol images that are subsequently covered with protective coatings and/or paints. Information related to these activities can be obtained at web site: http://techtran.msfc.nasa.gov/tech_ops/2D_matrix.pdf 

The team agreed that new marking processes would need to be developed to support the marking of parts that are subjected to environments where surface damage can be expected during operations or overhaul.     RVSI, working with the marking device manufacturers, agreed to take this issue on.  

Identification of marking processes that will survive harsh environments

To support this effort, RVSI and Hill AFB, UT conducted additional marking tests to identify criterion that could be used in the select the new Data Matrix marking processes need to support the identification of parts subjected to harsh environments. These criteria are:  

Criteria for Intrusive markings

Recessed markings (cast, forged, impressed or cut) must be more than 0.05-inches below the surface with data cells shaped in the form of a cone or pyramid with a 2 to1 base-to-height aspect ratio.  The point of the markings must be rounded to provide a .005 (0.127 mm) to .010-inch  (0.254 mm) spherical radius to reduce compressive stresses. Backfill materials can be applied after overhaul to improve readability. 

  • Raised marking (cast or forged) must be more than 0.05-inches above the surface with data cells shaped in the form of a cone or pyramid with a 2 to 1 base-to-height aspect ratio.

Criteria for Additive markings

  • Additive materials must be raised more then 0.05-inches above the surface with data cells shaped in the form of a cone or pyramid. Cells must be formed with a 2 to 1 base-to-height aspect ratio.

  • Additive materials must be equal to or more durable then the substrate, i.e., provide increased wear resistance, corrosion resistance and surface hardness. 

  • Additive materials with data cells formed with flat or rounded tops must provide a mark-to-substrate contrast level difference of more then 20 percent.   

  • Additive materials must be melted into the substrate to form a metallurgical bond with the part surface

Using the criteria noted above, RVSI conducted a technology search to identify processes that could be refined to produce Data Matrix symbol markings. Seven candidates were identified, which are described as follows:  

Investment casting

The investment cast symbols were produced by entering the desired product identification data into a data encode software package to create the instructions required to generate a two-dimensional (2-D) Data Matrix symbol.  This information is transferred to an intermediate software package where three-dimensional (3-D) data (symbol height or depth and shape) and insert dimensions are added.  The marking is ideally recessed in the mold to form a raised symbol in the finished product.  The resulting data is then converted to a software format that is recognized by 3-D systems (http://www.3dsystems.com/) thermojet printer’s solid modeling CAD program.  A print initiation key is then depressed to begin the printing operation.   

This is done by sweeping a piezo-electric print head that sprays tiny droplets of a paraffin-based thermopolymer back and forth over the work area to form solid 3-D part identification insert.  The resulting insert is than pressed into a recess in the user’s product mold for subsequent casting.  

The integration of thermojet solid object printing technology into the mold and cast marking process provides the user community with a means to interject automatic parts identification and data collection into manufacturing functions.  This can be accomplished without changing existing operations and with minimal cost or disruption of activities.   

 ¼-inch Square Wax Mold Produced Using Solid Object Printing Technology

 

Investment Cast Marking Created from Thermojet Wax Mold  

Sand Casting

The sand cast markings are developed by laser engraving a representation of the Data Matrix symbol directly into the sand cast mold using a laser specially configured for deep engraving.  The FOBA Laser Systems (http://www.fobalaser.com/) laser utilized for this purpose can product symbols of varying sizes and to any depth required.  It can also cut data cells with shapes (cone or pyramid) that reflect light away from the reader lens, there by, creating the contrast required for successful reading  (see illustration below).   

Laser Cutting Pattern Used To Cut Symbol Data Cells Into Sand Cast Mold

 

Cross Section of Sand Cast Symbol Designed to Provide Artificial Contrast for Successful Decoding

Forging

Forged markings can be created using an automated method for transferring representations of the Data Matrix symbol markings containing unique part identification numbers or symbols to forged parts using laser deposition (for recessed markings) and deep laser engraving technology (for raised markings).  This is accomplished by inputting part identification information into a symbol encode software program that converts ASCII data into a two-dimensional (2-D) Data Matrix™ symbol format.  The two-dimensional symbol format is then electronically transmitted to a Computer Assisted Drawing (CAD) program where data cell shape and height information are added to form a three-dimensional (3-D) representation of the desired marking.  This information is then transmitted to an Optomec (http://www.optomec.com) laser configured for deposition or FOBA Laser Systems (http://www.fobalaser.com/) laser configured for deep engraving. The lasers are used to apply the three-dimensional (3-D) symbol onto a metal insert that is placed into a recess in the product mold. The marking applied to the insert is then transferred to the part during subsequent casting or forging operations.    Contrast for reading is obtained by creating data cells shapes that reflect light away from the reader.  

  Forging Inserts Created Using Deep Laser Engraving

Dot Peen (refined to produce deeper marking)

Dot peen markings physically survive harsh operational conditions and overhaul processes but become extremely difficult to after being subjected to these conditions, primarily because the   symbol losses the reflectivity needed to produce the necessary contrast for reading. This can be accomplished by utilizing a larger stylus (>0.158-inches - 4mm) and increasing marking depth to greater then 0.03-inches.  Markings to be subjected to harsh environmental conditions should be made using multiple dots per data cells, which provide increased shadowing and light reflection and makes it easier for the decoding software to distinguish data cells from the substrate damage.  Examples of multiple data cell patterns are shown in the following illustration.  Double striking the dots can increase depth.   

Multiple Data Cell Patterns Recommended To Increase Symbol Size And Improved Readability

Laser Engineered Net Shaping (LENS)

Laser-Engineered-Net-Shaping (LENS) utilizes the heat from an Nd-YAG laser to form a small weld-pool on the surface of the part to be marked.  Simultaneously, metallic powder is injected into the molten pool, building up a feature.  3-D CAD software is used to manipulate the marking head or the X/Y table holding the part to deposit the data matrix identification symbol.  The injected metallic material does not have to be of the same material as the part, and can be chosen to be corrosion resistant, wear-resistant, or with any other desirable characteristic.  LENS-deposited materials offer a rough surface finish, providing good light reflection.  LENS is compatible with all common steels, titanium, aluminum, nickel, and copper alloys. 

LENS gives a small heat-affected-zone in the part.  LENS markings can be resistant to abrasion and chemical reactions.  LENS marking will protrude above a surface since this process adds material to an existing substrate (see illustrations below).

Schematic Illustration of the LENS process

 

 A Molybdenum disk marked with stainless steel raised lettering. 

New Deep Laser Engraving Process

Deep Laser Engraving is an outgrowth of a patented 3D laser engraving process.  The 2D code cells are cones similar to Dot Peen markings but much deeper.  This greater depth makes a non-reflective hole that appears dark to the reader.  The actual depth can vary according to the size of the cells and the type of material marked.  Since the mark is recessed into the part, operations and overhaul do not greatly affect the marking.  The cone shape of the holes is the result of the natural taper of laser cutting and software manipulation.  This cone shape also helps prevent abrasive media from becoming trapped in the holes as it would in micro-milling.  The laser cutting pattern is virtually identical to the one used to cut data cells into sand cast molds. 

Deep Laser Engraving has:

  • No consumables to replace

  • No cutters to wear out or break

  • Variable cell size, shape and depth

  • Consistent high contrast even after overhaul processes including heat treat

  • Can be sized to fit in small marking areas

  • Can be applied to irregularly shaped parts and into deep recesses

  • Can be applied over uneven (i.e. cast) and curved surfaces

Laser Induced Surface Improvement (LISI)

LISI marking is a process developed by the University of Tennessee Space Institute Center for Laser Applications (http://view.utsi.edu/cla/). The LISI™ process (http://www.utsi.edu/Research/LISI/index.html) is similar to laser bonding except that the metallic additive material is melted into the host substrate to form an improved alloy with high corrosion resistance and wear properties.  Because in the LISI™ process the additive material is alloyed into the substrate, more laser energy is required than with laser bonding.  The process is performed in three parts that involve the spraying of a metallic based paint onto the surface, followed by a laser operation that alloys the additive metals with the substrate material.  After marking, the remaining water based paint is washed off using tap water or a commercial cleaning agent to expose the marking.  Through the selection of materials, markings can be created that can be imaged by both optical and sensor readers, while also providing better wear and corrosion resistance than the substrate metal.  LISI™ mark characteristics are controlled by precise focusing of the laser beam, control of the laser power, and control of the rate at which the laser beam is swept over the surface being marked.

The LISI™ process provides the following characteristics:

  • Produces high contrast markings for easy decoding

  • Allows the creative selection of surface properties

  • Requires little or no surface preparation

  • Requires no special environment (e.g., a vacuum)

  • Only affects the surface region (a few microns to millimeters deep)

  • Results in minimal heat affected zone

  • Does not chip or delaminate

  • Is environmentally friendly

  • Can be selectively located and varied

  • Can be applied in small or recessed areas

LISI Marking Applied to Aluminum

LISI materials are available from the Warren Paint and Color Company located in Nashville, TN and Ferro Corporation’ Glass Decoration Division (http://www.ferro.com/) located in Washington, PA.

LISI™ Data Matrix markings have been applied with both CO2 and Nd:YAG lasers of sufficient strength to metal mild steel.  A 90-watt or better YAG is preferred over the CO2 because the YAG wavelength is more easily and efficiently absorbed by metals.

Micro-Milling

The micro-milled markings were produced using a modified multi-axis CNC milling machine manufactured by Servo Products Company. The machine is designed to accept carbide-tipped engraving, drilling, or milling tools that can cut representations of Data Matrix symbol into most surfaces. The machines can be set to mark at pre-determined depths so that markings can be engineered to survive the harshest of environments or to accept the appropriate amount of backfill material to make them visible to sensor readers designed to image markings covered over with paint.    Marking quality is controlled by adjusting the depth of cut, air pressure (force), cutting speed (rotation), travel time (feed) and dwell time.  

Marking readability can be improved by backfilling the marking recesses with a material of contrasting color.  Micro-cut markings can be applied to glass, plastic, phenolic, ferrous and non-ferrous metals.

Engraved & Backfilled Marking Made With Servo Products Micro-Miller

Drilled Marking Made With Servo Products Micro-Miller

Stencil - Thermal Spray (VAVD, HVOF, Arc, and Flame Spray)

Thermal spray is a “family” of particulate/droplet consolidation processes capable of forming metals and intermetallics into coatings or freestanding structures. During the process, powders, wires, or rods are injected into combustion or arc-heated gas jets, where they are heated, melted or softened, accelerated, and directed toward the surface, or substrate, being coated. On impact at the substrate, the particles or droplets rapidly solidify, cool, contract, and incrementally build up to form a deposit.  Increased attention is being paid to thermal spray processes for marking because of their ability to consolidate virtually any material that has a stable molten phase, producing coatings or deposits exhibiting relatively homogeneous, fine-grained microstructures. Symbols are produced using heat resistant stencils cut using mechanical micro-profilers, drills or laser cutting devices. The height of the marking corresponds to the thickness of the stencil. Since the tops of the data cells are flat in shape and do not reflect light differently then the substrate, the material deposited must be of a color that contrasts with the surface of the part being marked for successful optical reading.  Non-optical reading is supported by spraying materials that differ from the substrate and can be easily detected by the sensor.   

Close Up Of Thermal Spray Marking

Material testing to determine marking effects on substrate

Application of a data matrix to a part, particularly a safety or mission critical part, raises two questions.  (1) What will the marking process do to my part?  (2) What marking process will make the most durable mark in my part’s environment?  Quantitative answers to these questions become more important when aggressive, and hence more intrusive, marking processes are used to improve mark durability in harsh operational and refurbishment environments.  Investment casting, sand casting, forging, micro-milling and dot peen marking processes are already approved for use in both government and commercial applications.  As part of the NCMS 2D Marking project, Deep Laser Engraving, LENS, LISI, GALE, and Thermal Spray marking methods were applied to test coupons that were then subjected to various testing procedures to determine the loss of fatigue life caused by each of the marking methods and mark durability.   

This testing was performed by the University of Tennessee Space Institute (UTSI).  Many of the test coupons were prepared by UTSI from a variety of metal alloys, and sent to other team members of the NCMS 2D project who marked the test coupons using their marking methods and returned the marked coupons to UTSI for testing.  Other team members prepared their own test coupons, marked them, and sent them to UTSI for testing.

Fatigue testing

Because fatigue testing gives a quantitative measure of the loss of fatigue life caused by application of mark, it is one of the most important tests related to the safety of a particular marking method.  A fatigue coupon is narrowed toward its center to intentionally weaken the coupon in a reproducible way.  The testing methodology is to manufacture a batch of identical coupons from a specified material, mark many of the coupons grouped by the marking process, and then measure the fatigue life of both the marked and unmarked coupons.  The coupon ends are clamped in the opposing jaws of a testing machine that applies periodic axial forces of known amplitude and frequency.  The periodic forces are continually applied to the coupon until it fractures or until a prescribed number of cycles are reached.  The number of load cycles the coupon withstands before breaking is a measure of its fatigue life. Comparison of the fatigue life, measured in the number of cycles before failure under known loading, of marked fatigue coupons with the life of identical but unmarked fatigue coupons gives a measure of the damage caused by the marking process.   The following figure gives fatigue testing results for laser bonding, laser engraving, and machine engraving on 4340 steel.  Laser engraving is seen to significantly degrade the fatigue life while laser bonding is rather non-intrusive.


The fatigue testing results are comparable when 6061 aluminum is marked as seen in the following figure:
 

 

Corrosion testing

A salt spray of specified duration and salt concentration was selected for the corrosion tests.  Marks newly applied to test coupons are read using a RVSI DMX Verifier.  The coupons are then placed in the salt spray for a specified time, and then again read using the DMX Verifier.  This process is repeated until the mark is made unreadable by corrosion.  The comparison of results for various marking methods applied to various materials gives an indication of the relative corrosion resistance of the various material-marking method combinations.

Extensive salt spray corrosion testing was performed on marks placed on 2024 aluminum alloy by laser bonding.  The following figure shows the degradation of mark readability with increasing hours of exposure to salt spray.

Q-FOG salt spray corrosion chamber

One mark failed to read after 8 hours of exposure, but this data point appears to be an outlier inconsistent with the other data on the graph.  The following figure shows the mark Verifier:

 

RVSI DMX Verifier image and readings from a new mark on 2024 aluminum.
image and reading of a new mark on 2024 aluminum before exposure to salt spray.  After 8
hours of exposure the same mark gave the following Verifier image and readings.
 

 

 

RVSI DMX Verifier image and readings after 8 hours in salt spray chamber.

 

In comparison with the previous figure, the degradations of the optical quality of the mark image and of the Verifier readings are clear.

Erosion testing

Erosion testing of a mark gives an indication of the mark’s durability under impact of sand, dirt, and other particulates.

The above figure shows the sand feeder on a PLINT TE 68 gas jet erosion apparatus.  Sand of specified characteristics is aspirated from the grove in a rotating wheel fed by a sand hopper.  By controlling wheel rotation, air pressure, and air flow rate, one can produce a reproducible jet of air containing a certain concentration of sand particles having a certain range of velocities directed to the mark on a test coupon.  As in corrosion testing, marks are read before and after being subjected to the harsh environment, and the relative merits and deficiencies of the various material-marking method combinations are revealed.

Temperature cycling

Another test of mark durability is exposure to a range of temperatures.  Will the mark remain readable after the marked part has been exposed to the temperatures of its normal operating environment?  The following two figures show a mark being heated to red hot

A LISI mark on a Solar Turbine engine component heated to red hot.

and the discoloration produced by the heating.

LISI mark after being heated red hot.

 

Concluding remarks on materials testing

 

Although final evaluation and reporting of data acquired in the NCMS 2D Marking project remains, some preliminary results can be reported.  In their current implementations, deep laser engraving and LISI marking are too intrusive to be applied to safety critical components.  Although a major goal of the NCMS project was simply to grade various marking methods as safe or unsafe, declaration of a marking method as unsafe should be viewed as a temporary situation forced upon us by the current state of technical art. Also, laboratory fatigue testing ignores the fact that a mark might be unsafe if applied to a particularly critical area of a component but quite safe if applied to less critical of higher strength.  For example, deep laser engraving produces very durable marks, a very important attribute.  The performance of laboratory fatigue testing on coupons that were specially prepared in a materials testing laboratory and then marked by deep laser engraving quantifies the fact that deep laser engraving is rather intrusive, but this testing says nothing about how the laser engraving process might be altered to reduce it intrusiveness, that post processing marked parts might greatly reduce the intrusiveness of the marking process, or that the marking process might be completely safe if one carefully chooses where on the part to locate the mark.  The effects on component fatigue life of the precise path of the laser beam, the combination of laser power and processing time, and laser wavelength in laser engraving have not been sufficiently evaluated.  Also, the post processing of laser engraved components should be studied.  For many metal components, their manufacture consists of a precise sequence of tightly controlled process steps.  It is essentially certain that some marking methods that at face value are too intrusive and therefore unsafe will be quite benign if only the marking is done at the correct time during the standard manufacturing process.  In a few cases, the concept of making a marking method safe by simply applying the mark at the correct time might even apply to retrograde marking, the marking of existing parts.  For example, Hill AFB shot peens some parts brought to them for repair and refurbishment.  Whether deep laser engraving would be benign if such parts were marked before shot peening remains an unanswered but interesting question. 

As with deep laser engraving, LISI marks have unique, valuable properties, and their intrusiveness can most likely be reduced by tuning the marking process, post processing of LISI marked parts, and careful selection of area to be marked.  Again, the post processing might consist of simply applying the LISI mark at the correct step of the part’s manufacturing process.  The LISI process alloys new material into a metal substrate.  Therefore, a LISI mark has an elemental composition different from that of the metal to which it was applied.  The different elemental composition of the mark means that its X-ray fluorescent signature is different from the substrate on which it lies.  Thus, LISI marks are possible “read through paint” marks, marks that can be read even though they have been painted over and are invisible to the naked eye.  While lacking the very high durability of marks made by deep laser engraving or machine engraving, LISI marks possess sufficient resistance to corrosion, erosion, and temperature cycling to make them usable in many situations. 

The points we wish to make with the above comments is that there are no “bad” or “unsafe” marks.  The real issues with regard to safety critical parts are precise specification of (1) the marking process, (2) the post processing of marked parts, (3) the location of the mark.

Exposure of markings to harsh environments

All of the marking processes determined to be safe for use in safety critical applications  were subjected to operational (flight tests) by the USCG and overhaul environments conducted by the USCG.  Additional marked samples were also provided to BF Goodrich, GE Aircraft Engines and Solar Turbine for additional evaluation. The overhaul processes that the marked samples were subjected to are as follows:  

Blasting Processes

  • Abrasive Blast per MIL-STD-1504, Abrasive Media (Plastic Media) per MIL-P-85891

  • Abrasive Blast per MIL-STD-1504, Abrasive Media (Glass Media) Per MIL-G-9954

  • Abrasive Blast per MIL-STD-1504, Abrasive Media (Garnet Media) Per MIL-A-21380

  • Abrasive Blast per MIL-STD-1504. Abrasive media (Aluminum Oxide)

  • Abrasive Blast per MIL-STD-1504, Abrasive Media (Grit Media) Per MIL-G-5634

  • Shot Peen per AMS-S-13165, Intensity 0.006A to 0.010A, Shot S-230 to S-330

Stripping Processes

  • Paint Strip per MIL-STD-871 (T.O. 4S-1-182)

  • Temper Etch per MIL-STD-867

  • Chrome Plate Stripper MIL-STD-871

  • Cadmium Plate Strip per MIL-STD-871 (T.O. 4S-1-182, with Phosphoric Acid Dip)

  • Nickel Plate Strip per MIL-STD-871

  • Electrodeless Nickel Plate Strip per MIL-STD-871

  • Flame Spray Strip per MIL-STD-871

  • HVOF Strip per MIL-STD-871

  • IVD Strip per MIL-STD-871

Acid Dip

  • Phosphoric or Sulfuric Acid

Heat Treat

  • 2000 degrees F

Marking standards update

The information gained during the NCMS Parts Marking Program has been submitted to the following marking groups for inclusion into their respective standards.

  • DoD LOG AIT Office - Dan Kimball, Joint Interoperability and Standardization, Tel: (703) 767-1598 

  • USAF - Mark Reboulet, MIL-STD-130, Tel.: (937) 257-7181

  • NASA - Fred Schramm, NASA-STD-6002 & NASA-HBK-6003, Tel. (256) 544-0823

  • ISO – Matthew Williams, ISO TC 20, IS0/IEC WD 15415.8 (pending) & ISO/IEC WD 15426‑2 (Pending), Tel. (202) 371-8443

  • Delta Airlines – Judy Harrison (Chairperson of Permanent Bar Code Task Force under ATA), ATA SPEC2000, Tel.: (404) 714-5481

  • IAQG – Philippe Removille, IAQG-9132 (pending), Tel.: 011 33 16 987 8313

Summary

In summary, our team has established that safe direct part marking processes are commercially available to meet the most the demanding use environments.  Our team has taken steps to provide on-line training to assist users in selecting the proper marking processes (www.uidsupport.com) and has provided updates related to our testing to all applicable organizations for inclusion into government and industry standards and related documents.         

RVSI and its partners are dedicated to helping government and industry to develop solutions to difficult marking and materials problems and in moving technology out of the laboratories and into the commercial marketplace.  Specific questions can be directed to either facility at the following addresses:

Symbology Research Center

5000 Bradford Drive NW, Suite A

Huntsville, AL 35805

Donald L. Roxby, Director

Tel: (256) 830-8123

Fax: (256) 895-0585

Email: dlroxby@hiwaay.net

University of Tennessee Space Institute

411 B. H. Goethert Parkway

Tullahoma, TN 37388

James O. Hornkohl

Tel: (931) 393-7491

Fax: (931) 454-2271

Email: jhornkoh@utsi.edu

 

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