PD.pdf

11M-274A-FO

2 June 2011

Revision 3

PURCHASE DESCRIPTION

FOR

Force Calibration Press, Aircraft Platform Scales

1. SCOPE:

This purchase description specifies a 60,000 lbf Automated Scale Press to be used in the calibration of scales by the Precision Measurement Equipment Laboratory (PMEL). This press will utilize included system single-bridge load cells to calibrate scales of capacities 5,000, 10,000, 20,000, 30,000 and 60,000 lbf from 10 to 100% of scale capacity. Typical scales, which shall be calibrated on this press, utilizing

United States Air Force-approved distribution plates, rubber pads and hardened steel plates, are:

Intercomp P/N AC1-25, AC30-60, PT300 and GEC AN60-6 or MD400 and similar. (NOTE: This list is not all-inclusive.) Press shall, at a minimum, include a computer, controller system, press and load cells.

2. PERFORMANCE REQUIREMENTS:

2.1. Resolution: Resolution shall be no more than 1/5 of the Measurement Uncertainty (see PD paragraph 2.3 below).

2.2. Range: Press shall have a continuous range of 0 to 60,000 lbf minimum.

2.3. Measurement Uncertainty: System uncertainty shall be no more than 0.025% applied load.

2.3.1. Uncertainty Components: Uncertainty shall include the following error components, at a minimum:

2.3.1.1. Load Cell ASTM E74-06 Calibration’s Standard Deviation

2.3.1.1.1. This includes10 points increasing (all in 10% increments).

2.3.1.1.2. This is a 3-position (0, 120 and 240 degrees) calibration.

2.3.1.1.3. This utilizes a second or third-degree polynomial fit; fit includes all readings (a total of 30 Output and Force readings).

2.3.1.1.4. To determine the Type A Uncertainty component “Standard Deviation of

Load Cell”, first determine the Calibration Equation, using 30 Output and Force readings, per ASTM E74-06’s Equation 5:

210 FAFAAc where:

c = Calculated Output (mV/V)

F = Force (lbf)

A0…A2 = Coefficients of second or third-degree polynomial equation

Then calculate the differences between the curve and observed values:

nn bcd 11 b1…bn = Observed output values from calibration data (mV/V) at each Force d1…dn = Differences between fitted curve and observed values from data (mV/V) n = Values (n = 30: 3 rotations of 10 increasing(mV/V))

Finally, Type A Uncertainty component “Standard Deviation of Load Cell” is calculated using

ASTM E74-06’s Equation 6:

mn ddd s n m sm = Calculated standard deviation from second or third-degree polynomial equation

(mV/V) dn = See above m = Degree of polynomial fit (m = 2 or 3) n = See above

Place sm into Column 3 of the Uncertainty Budget (2.3.2). Do not multiply this value by 2.4, as directed in section 8.4 of ASTM E74-06. Divide the value entered into Column 3 by the calculated minimum output (determine this value by inserting the minimum force at which the load cell will be used into the first equation in 2.3.1.1.4 ), multiply by 100 and enter this value into Column 4.

Divide Column 4 by the k value in Column 5, and place this value into Column 6. Square Column

6 and place this value into Column 7.

2.3.1.1.5 To improve uncertainty budget’s load cell standard deviation, zero may be added as a checkpoint in the calibration. If this is done, there would be 33 increasing data points in section 2.3.1.1.3. and 2.3.1.1.4.

2.3.1.2. Load Cell Temperature Drift (Zero)

2.3.1.2.1. This temperature specification can be eliminated only if system can zero prior to use.

2.3.1.2.2. To determine the temperature effect on the load cell’s zero for a change of

3.6 degrees Celsius, perform the following in the Uncertainty Budget (2.3.2):

Enter the specification into Column 3 in terms of mV/V. Divide this number by the calculated minimum output (from 2.3.1.1.4), multiply by 100 and enter this value into Column 4. Divide Column 4 by the k value in Column 5, and place this value into Column 6. Square Column 6 and place this value into Column 7.

2.3.1.3. Load Cell Temperature Drift (Output)

2.3.1.3.1. In order to determine the temperature effect on the load cell’s actual rated output for a change of 3.6 degrees Celsius, perform the following in the

Uncertainty Budget (2.3.2): Enter the specification into Column 3 in terms of mV/V. Divide this number by the calculated minimum output (from 2.3.1.1.4), multiply by 100 and enter this value into Column 4. Divide Column 4 by the k value in Column 5, and place this value into Column 6. Square Column 6 and place this value into Column 7.

2.3.1.4. Load Cell Creep (2 minutes minimum), Worst Case

2.3.1.4.1. In order to determine the maximum creep effect on the load cell’s output for a time of 2 minutes, perform the following in the Uncertainty Budget (2.3.2).

Enter the worst-case specification into Column 3 in terms of mV/V. Divide this number by the calculated minimum output (from 2.3.1.1.4), multiply by 100 and enter this value into Column 4. Divide Column 4 by the k value in Column 5, and place this value into Column 6. Square Column 6 and place this value into

Column 7.

2.3.1.5. Indicator Uncertainty

2.3.1.5.1. There may be multiple contributors on this specification; such as if a

Signal Conditioning card and A/D card are used there would be multiple errors associated with the combination, based on their compatibility and performance specifications. List each separately, as necessary. Four errors associated with a typical indicator’s measurement are Linearity, Temperature Influence, Drift and

Accuracy, which may or may not be applicable for the system. See 2.3.2 also.

2.3.1.6. Indicator Resolution

2.3.1.7. Stability

2.3.1.7.1. Stability is defined as the ability of the machine to control the force it applies and then produce and maintain a stable reading (no change in reading) within 20 seconds. Stability also includes any standard deviation from the average reading displayed.

2.3.1.8. Load Cell Side Load Sensitivity (Load Cell to Working Surface)

2.3.1.8.1. This sensitivity error relates multiple errors from the perpendicularity of the load cell to the Working Surface (see 4.1.4.3) and utilizes the Load Cell characteristic “Side Load Sensitivity” to determine the uncertainty in terms of % of reading, as it relates to either applied load or mV/V. At a minimum, the perpendicularity error shall include the following four (4) dimensional error components:

2.3.1.8.1.1. Load Cell Perpendicularity to Working Surface

2.3.1.8.1.1.1. Perpendicularity between the Standard Load Cell and Working

Surface throughout Working Height Area (see 4.1.4.5).

2.3.1.8.1.2. Working Surface Deflection

2.3.1.8.1.2.1. This parameter is measured under maximum load, over the

Working Surface (see 4.1.4.3).

2.3.1.8.1.3. Working Surface Flatness

2.3.1.8.1.3.1. This is the flatness of the Working Surface (see 4.1.4.3).

2.3.1.8.1.4. Working Surface Repeat Reading

2.3.1.8.1.4.1. This is the repeat reading value of the Working Surface (see

4.1.4.3).

2.3.2. Uncertainty Budget: Uncertainty budget shall be provided in a similar format as the example in Figure 1 below. Budget shall be provided for each load cell, unless stated that each error component is identical for each load cell used with the system (this includes resolution).

2.3.2.1. This uncertainty budget was created assuming the press utilizes one single bridge load cell for operation and measurement at any given time.

2.3.2.1.1. If the press utilizes a separate single bridge load cell for initial control, this uncertainty budget shall reflect that selection.

2.3.2.1.2. This separate load cell will not be calibrated.

Figure 1:

Sample Uncertainty Budget for Each Load Cell with System:

Section

Component

Value

Value, reading

Distribution

Type, Divisor

Adjusted

Component

(Using Divisor)

Squared

Type A Uncertainties

2.3.1.1

Load Cell

Standard

Deviation sm (mV/V)

Normal, k = 1

Type B Uncertainties

2.3.1.2

Load Cell

Temperature

Zero Effect,

3.6 degrees C

Rectangular, k = 1.732

2.3.1.3

Temperature

Output Effect,

3.6 degrees C

2.3.1.4

Creep, 2 minutes

2.3.1.5 Indicator

Linearity

Temperature

Influence

Indicator Drift

Accuracy

2.3.1.6

Resolution

2.3.1.7 Stability

(Control)

2.3.1.8 Load Cell Side

Load Sensitivity

TOTAL ALLOWABLE (2.3) Sum of squares 0.00015625 k = 1, sq rt (Sum) 0.0125 k = 2 0.025 % rdg

2.4. Units: Display Resolution shall be in pounds force.

2.5. Reliability: All items shall maintain Measurement/TI Uncertainty specification (2.3.2) over a period of 12 months, minimum, without recalibration, with the exception of the following: Load

Cell Drift shall not exceed 0.025% applied load over that 12 month period of time. This is in addition to the components stated in Section 2.3.2.

2.6. Safe Overload: Each load cell shall have a minimum Safe Overload of 150% of capacity.

2.7. Warm-Up Time:

2.7.1. Total system warm-up time shall not exceed 120 minutes. This does not include time required for system to acclimate to the environment prior to use.

2.7.2. Warm-up time when switching load cells shall not exceed 15 minutes, if applicable.

3. FUNCTIONAL REQUIREMENTS:

3.1. Automated/Manual Control: System shall be capable of operating both Manually and

Automatically from 0 to 60,000 lbf. The system shall not require the operator to first operate the machine manually, and then switch to automated control at a higher force.

3.1.1. System shall produce a stable reading within a minimum of 20 seconds.

3.2. User Interface: User shall interact with computer via keyboard and mouse.

3.3. Test/Calibration Run Example:

3.3.1. A typical calibration run shall include, at a minimum, the following: User turning power on, warm-up time (using timer on screen), Prompt to move ram to designated location (user inputs # inches to begin), User places scale in center of Press Working Surface Area along with required load distribution plates, User selects appropriate Scale Calibration File or creates Scale Calibration Test File/Script, Machine prompts user to begin exercising a scale three (3) times to full scale and asks if proper Standard Load Cell is installed, Machine prompts user to begin Center Calibration points, Machine prompts user to ensure proper

Standard Load Cell is installed to begin calibration, Machine prompts user to take reading after stabilization (this continues until all Center Calibration Points have been performed).

After all Center Calibration Points have been performed, Machine shall prompt user to perform the Shift Test IAW NIST Handbook 44’s Section 2. All Machine prompts shall include an option to abort/save test run.

3.4. Ancillary Equipment: All mounting equipment, such as load cell adapters, shall be provided to operate system with its included calibration load cells.

3.4.1. Mounting Fixture and Indicator: In addition to operational ancillary equipment, one set of a mounting fixture with an indicator shall be provided with each unit to verify the perpendicularity (see 2.3.1.8.1.1) using an Electronic or Mechanical Indicator.

3.4.1.1. Mounting Fixture shall rigidly mount the Indicator to the press ram.

3.4.1.2. The Indicator shall be used to measure the Perpendicularity of the Working

Travel Area in reference to an Air Force-owned 18 inch Granite Square that will be stood on Working Surface.

3.4.1.3. Measuring Range shall be, at a minimum, twice the stated Load Cell

Perpendicularity over the Working Height Area (2.3.1.8.1.1).

3.4.1.4. Indicator’s Accuracy/Tolerance shall not exceed one-fourth (1/4) of the stated

Load Cell Perpendicularity over the Working Height Area (2.3.1.8.1.1).

3.4.1.5. Resolution shall not exceed the Indicator’s Accuracy/Tolerance (3.5.1.3).

4. MECHANICAL & PHYSICAL REQUIREMENTS:

4.1. Display: Display shall show, at a minimum, the following information:

4.1.1. Designated test file (title), to include test points and all readings entered in a chart form.

4.1.2. Current Applied Force, whether or not the press/ram is in operation.

4.1.3. Status of Machine shall include, at a minimum, increasing force, prompt for technician to take reading and prompt for operator to change load cell.

4.1.4. Dimensions and Weight of Press (excluding controller, PC and accompanying cabinet)

4.1.4.1. Height shall not exceed 84 inches.

4.1.4.2. Overall Footprint (depth and width) shall be no more than 64 inches each.

4.1.4.3. Working Surface Area, free from obstructions, shall be no less than 58 inches deep by 40 inches wide.

4.1.4.3.1. The front side of the Working Surface Area, when facing the ram, shall be no less than 38 inches from the press ram and the back shall be no less than

20 inches from the ram.

4.1.4.4. Overall Height Area (Travel) shall be from 0 to 12 inches, minimum.

4.1.4.5. Working Height Area shall be no less than 2.5 inches and no more than 10 inches.

4.1.4.6. Weight shall not exceed 5000 lbs.

4.1.5. Components:

4.1.5.1. All essential components shall be corrosion-proof. Preventative maintenance, such as oiling, can be required in order to retard rust and promote necessary function.

The item shall not exhibit excessive pitting of essential components, which would inhibit proper function of the equipment.

4.1.5.2. Each calibration load cell and required components shall be easily transported to a calibration facility via reusable transit case.

4.1.5.2.1. A single reusable transit case shall be provided for each Load Cell and its accompanying components. The cases shall provide protection against shock and vibration during shipment via government or commercial carrier. Case shall be Brand Name or equal to ECS Composites Part Number 00017529 revision B.

Case interior must be modified to accommodate load cell with integrated cable

(4.1.5.6) and any required adapters.

4.1.5.3. Perpendicularity of ram throughout Working Height Area (see paragraph 4.1.4.5) must be measurable using mounting fixture and indicator (see paragraph 3.4.1) and

Granite Square to verify documented Side Load Sensitivity. The Side Load Sensitivity shall be based on a measured perpendicularity of 0.0003 inches or larger due to uncertainties associated with the measurement process, equipment and laboratory environment. Perpendicularity is measured at 45˚ intervals around the press ram using provided equipment and Air Force-owned Starrett 18 inch Granite Square.

4.1.5.4. Flatness and Repeat Reading of Working Surface Area (see paragraph 4.1.4.3) shall be measurable using an Electronic Leveling System and Repeat Reading Gage.

Flatness shall not exceed 50% of the measured Perpendicularity. Flatness of the

Working Surface is considered a component of the documented Perpendicularity.

Repeat Reading shall not exceed 50% of the measured Flatness. Flatness is measured using Air Force-owned Mahr Federal Electronic Leveling System. Repeat Reading is measured using Air Force-owned Starrett Repeat Reading Gage.

4.1.5.5. Press’s Working Surface Area shall be easily leveled upon installation using threaded bottom supports.

4.1.5.6. Integrated load cell cables shall be 6-wire and 10 +/- 1 feet each in length.

4.1.5.7. Hydraulic fluid reservoir shall have two shut-off valves; one is a safety valve near the interface to the press’s hydraulic lines and one shall be near the bottom of the reservoir for draining purposes.

4.1.5.8. All adapter designs and materials used to adapt to the system’s press ram shall ensure that the applied (hydraulic) force is aligned with the load cell axis. All adapters shall be made to withstand a force equal to at least 300 % Load Cell Capacity.

4.2. Model and Serial Number Identification:

4.2.1. Item’s Part Number/Model Number, Manufacturer and Serial Number shall be identified clearly on the item in a location visible to the operator. See UID requirement clause in basic contract.

4.3. Operating Environment/Storage: Item is not intended to be stored in an environment outside the normal operating conditions.

4.3.1. Operating Temperature: Item shall operate in an ambient temperature of 67 to 79 degrees

Fahrenheit without loss of required performance.

4.3.2. Operating Humidity: Item shall operate in an environment with 20 to 50% Relative

Humidity without loss of required performance.

4.4. Facility Requirements:

4.4.1. Electrical Power and Connections: Item shall operate on no more than one 220 V single phase 60 Hz 20 A and one standard 110 V AC 60 Hz 20 A outlets.

4.4.2. Safety:

4.4.2.1. Documentation shall be provided to support the means by which electrical safety considerations have been addressed. This documentation shall consist of a minimum of a citation of a UL or ANSI identified standard or equivalent United States Standard to which the equipment conforms.

4.4.2.2. Pressure relief (change in range) shall be automated and have a manual override.

4.4.2.3. Press shall have a manual mechanical override, in which the user can move the press ram up and down in case of emergency.

5. CONTROLLER REQUIREMENTS:

5.1. Interchangeability:

5.1.1. When firmware or software upgrade is anticipated by a manufacturer during the life of this contract, the contractor shall contact AFMETCAL for concurrence. If AFMETCAL concurs with the proposed upgrade all previous units shall be updated to this upgrade.

5.1.2. All firmware or software provided under this contract shall be at the same version, revision and revision date at the completion of the contract.

5.2. Software Identification: Software version shall automatically display upon startup.

5.3. Software Warranty:

5.3.1. The contractor shall warrant that the software product meets this purchase description and is free from defects in design and operation and will perform to stated specifications from the date of shipment through warranty expiration date of the equipment. The contractor's

Commercial Warranty or Addendum shall include verbiage to assure the following minimum requirements are satisfied. All other clauses of the contractor's warranty shall remain in effect unless they contradict the requirements stated below.

5.3.2. The contractor shall (at no additional cost) update, or replace the software product as necessary to correct any deficiencies identified in the software. Replacement software shall meet or exceed the requirements in this purchase description, shall not require additional training to operate and be warranted for the remainder of the original warranty.

5.3.3. The contractor shall bear transportation costs for all replacement products.

5.4. Operating System and Software: All software must run under Windows 7 (Ultimate or

Professional operating system latest version release). All software must run under Windows 7 as a non elevated user. Windows XP shall not be provided.

5.5. Hardware:

5.5.1. Controller: A controller is required which can efficiently operate under the Microsoft

Windows 7 Professional operating system. All major components of the system must be commercially available and fully supportable by commercial sources. Where specific brands are identified in this specification, no substitutes are allowed without prior approval from the Government. The Controller must meet or exceed Windows 7 Professional hardware requirements..

5.5.2. Processor: Processor shall be an Intel Pentium 1.8 GHz clock speed or faster 32-bit(x86) or 64-bit(x64).

5.5.3. Memory: System shall have no less than 2 GB RAM of system memory.

5.5.3.1. USB: System shall have at least four integrated USB Version 2.0 compliant port.

5.5.3.2. Video: DirectX 9 graphic device with WDDM1.0 or higher driver.

5.5.3.3. Display Panel: System shall have a minimum 15-inch LCD Color display panel with at least 1280 x 1024 resolution.

5.5.3.4. Hard Drive: System shall have a 100 GB hard drive, minimum.

5.5.3.5. DVD-ROM/CD-RW Drive: System shall have a DVD-R Drive with a speed of at least 16X.

5.6. Additional Hardware:

5.6.1. System shall include a laser printer. Printer and controller shall have the following general characteristics and capabilities.

5.6.1.1. Seamless compatibility and integration with rest of system.

5.6.1.2. Size must fit in/on provided equipment rack.

5.6.1.3. The printer Height/Width/Depth shall not exceed 12 x 14 x 16 in.

5.6.1.4. Weight shall not exceed 30 lbs.

5.6.1.5. Print speed shall at a minimum be 20 ppm.

5.6.1.6. Printer Resolution shall at a minimum be 600 x 600 dpi.

5.6.1.7. Printer shall accept Letter size (8.5 x 11 in) paper.

5.6.1.8. Printer shall interface via USB.

5.6.2. Controller shall have USB port to accommodate printer and provide the printer cable.

5.6.2.1. Size shall be such that all electronic components fit in/on provided equipment rack. Rack dimensions shall be no greater than 72 inches tall, 48 inches wide and 36 inches deep.

5.6.3. System shall include any other hardware necessary to meet the requirements of this PD.

5.7. Software:

5.7.1. Software shall have a minimum of four major sections, which can be selected from the opening screen:

5.7.1.1. Scale Calibration Test Files/Scripts

5.7.1.1.1. Here the user creates a Scale Calibration Test File, which includes:

5.7.1.1.1.1. Center Calibration Applied Force Values

5.7.1.1.1.2. Center Calibration Number of Runs

5.7.1.1.1.3. Shift Test Applied Force

5.7.1.1.1.4. Shift Test Number of Runs

5.7.1.1.1.5. Calibration Procedure

5.7.1.1.1.6. Text Section for Comments

5.7.1.2. Scale Calibration Files (Directory)

5.7.1.2.1. Here the user selects a Scale Calibration Test File that has already been written. It is also where the scale calibration file information is shown and filled in by the user. The user shall have the option to save the scale calibration data without finishing, but program shall prompt user to save upon exiting. In addition, upon exit the program will prompt user to raise ram 3 inches, and then return to the opening screen. This pre-programmed 3 inches shall be changeable in the user settings.

5.7.1.3. Standard Calibration File(s)

5.7.1.3.1. This is where the user shall input calibration data on the standard load cells and any other calibration devices used in the system, such as a Load Cell

Simulator. This section shall display each load cell’s range, ID # and calibration due date, in addition to calibration data. All required information for other calibrated items, such as the ID #, calibration due date and calibration data for a

Load Cell Simulator, shall also go here.

5.7.1.3.2. Calibration Data: The computer shall be used to store all calibration data.

Load Cell does not need to store any information.

5.7.1.3.2.1. Calibration data shall include the following:

5.7.1.3.2.1.1. Force values and mV/V output values, minimum of 11 points.

5.7.1.3.2.1.2. Data required accounting for any deviation/offset from these values incurred from the electronics, such as deviation due to signal conditioner, line loss or corrections made using Load Cell Simulator.

5.7.1.4. Manual Mode

5.7.1.4.1. Mode shall allow user to manually initiate movement of press ram (both up and down) and also take readings via user’s keyboard keystroke or mouse click using Scale Calibration Test Files/Scripts (see 5.7.1.1).

5.7.2. Guided Calibration:

5.7.2.1. Scale Calibration section shall have a guided calibration, which will prompt the user through the calibration. This shall be user-selectable (can be turned off).

5.7.3. Calibration Reports: System shall be able to export data into Microsoft Excel 2007 formats, at a minimum, as well as print them in any of the saved formats. Data shall include all information included in sections 5.7.1.1.1 (for that test file) and 5.7.1.3 (for that calibration).

5.7.4. Operations Files: All files mentioned in section 5.7.1 shall be saved, editable and retrievable.

5.7.5. One copy of Microsoft Excel 2010, latest release, shall be provided.

6. OPERATOR’S MANUAL:

6.1. Manual shall be IAW DD1423 and Data Item Descriptions, and shall also include, at a minimum, the following information:

6.1.1. Setup/installation of system.

6.1.2. Procedure on how to use/operate system, complete with drawings/diagrams.

6.1.2.1. This shall include switching out load cells, if applicable.

6.1.3. Procedure on how to calibrate system, complete with drawings/diagrams.

6.1.3.1. This shall include switching out load cells, if applicable.

6.1.4. Drawing/Diagrams and instructions needed for manual alignment/adjustment of working parts.

6.1.5. Drawing/Diagrams and instructions required for completing any required/scheduled maintenance, including non-destructive testing, visual inspection and lubrication.

6.1.5.1. This shall also include a list of support equipment required to accomplish any maintenance.

6.1.6. A list of peripheral support equipment required to accomplish all calibrations and adjustments.

6.1.7. Information on any internal adjustments made during operation.

6.1.8. Definitions of all changeable settings/configurations.

6.1.9. Instructions on how to access settings/configurations.

6.1.10. Complete parts breakdown with manufacturer and part number of all components, including any Signal Conditioning Cards, Analog-to-Digital Cards and Load Cell

Simulators.

7. INSTALLATION AND TRAINING:

7.1. The contractor shall be responsible for providing one copy, either CD or DVD, which describes and demonstrates the installation/setup of the system on-site to assure the system is fully functional and meets the requirements of this purchase description. This CD/DVD shall also contain all required training information (stated below in 7.1.1).

7.1.1. Training shall cover at least the following areas:

7.1.1.1. Operation procedures including setup procedures

7.1.1.2. Calibration procedures

7.1.1.3. Adjustment procedures

7.1.1.4. Location of components

7.1.1.5. Equipment required for adjustments

7.1.1.6. Troubleshooting procedures

7.1.1.7. Any sections of the Owner’s Manual not already covered

7.2. Facility requirements for installation and setup shall be identified by the contractor no less than

30 days prior to the date of delivery of first shipped unit.

7.3. CD/DVD shall be delivered with first shipped unit.

7.4. Contractor shall grant AFMETCAL the right to copy CD/DVD in its entirety (see Attachment to

Purchase Description – Data Requirements for the Government Purpose License Agreement).

8. TESTING:

This item will be inspected and accepted at destination as stated in the contract. The item will be checked with test equipment with parameters equal to or better than those required to assure that specified performance parameters are met. Test equipment used shall have first echelon certification directly traceable to the National Institute of Standards Technology (NIST) or other approved equivalent international laboratory. Tests will be performed to assure that the item meets the requirements of this purchase description. Such testing at destination does not relieve the contractor of performing all inspections and quality checks at the point of manufacture as necessary to assure performance as specified herein.

Attachment:

Data Requirements