TECHNICAL SPECIFICATION 0F RAM-B BALL SCREWS 1. SCOPE:

This specification establishes the requirement for procurement of raw material, manufacture and inspection of components, assembly, shop testing, running-in, cleaning, packing and shipment of ball screw assemblies for requirements as detailed below :-

2. CONTENTS

The provisions of this specification are presented under the following section headings:

Section Applicable specification and drawing 3 Requirement of ball screw assemblies 4 Manufacturing requirements 5 Inspection and Performance testing 6 Certification required 7 Requirement after placement of order 8 Packing and shipping 9 Quality Surveillance 10 Shipping release 11

3. APPLICABLE SPECIFICATIONS AND DRAWINGS:

Latest issues of the specifications listed below, in effect of the time of manufacture, constitute a part of this specification to the extent specified herein. In the event that certain provisions of the specifications listed below conflict with the requirements of these specifications, the requirement of this specification shall govern.

3.1 SPECIFICATIONS

ASTM-A564 Specification for precipitation hardening alloy bars, forgings and forging stocks for high temperature service.

ASTM – 370 Standard methods and definitions for testing of steel products. ASTM – E18 Standard methods for tests for Rockwell hardness and Rockwell

superficial hardness of metallic materials. ASTM – E138 Specification for wet magnetic particle testing. ASTM – A388 Recommended practice for Ultrasonic testing and inspection of Heavy

forgings. PP-E-438 Specifications for Hard Chrome plating.

3.2 DRAWINGS: 3.2.1 Bearing Ball Screw assembly - Type FM-B (RMN) M1-35221-1288-GA-R-0S1 (REF NPC-35221-56 GA) - Ball Screw assembly

M1-35221-1289-GA-R-0S1 (REF NPC-35221-0058-DD-R0)-Big Ball Screw M1-35221-1290-DD-R-0S1 (REF-NPC-35221-57 DD) - Big Ball nut

The drawings, procedures (manufacturing), inspection, shop testing, running-in,

cleaning, and packing for Ram-B Ball screw & Nut assembly Type: FM-B (RMN) for MAPS fuelling machines shall be followed as per the specification and procedures against the earlier purchase orders CMM/MAPS/FHU/39486/PO-57491 Dated 05/02/2013

4. REQUIREMENT OF BALL SCREW ASSEMBLIES: 4.1 Overall sizes:

Features and overall sizes of the ball screw assemblies shall be as per drawings listed in section 3.2 above.

4.2 Supplier shall carry out detailed design to meet the dimensional and other requirements specified on the drawings mentioned above and in this Specification. Detailed drawings prepared by the Supplier for manufacturing the components and assembly shall be furnished to the Purchaser for review and approval. After approval, 6 (six) sets of reproducible of all drawing shall be furnished to the Purchaser for his records. The Ball Screw Assemblies are to be manufactured as per the following requirements.

4.3 Materials of construction:

All materials used to manufacture the components and other parts forming part of the Ball Screw Assemblies shall be corrosion resistant and be suitable for water service. Materials of construction of Ball Screw Assemblies shall be as follows: Screw Shafts of type FM-B(RMN) Precipitation hardening stainless steel to

ASTM: A564 Gr.630 vacuum degassed and electro slag refined. Precipitation hardened to condition H1025 achieving hardness RC 38 min.

Ball Nuts for type FM-B(RMN) Precipitation hardening stainless steel to ASTM:A564 Gr.630 vacuum degassed and electro slag refined – Precipitation hardened to condition H 925 achieving hardness RC 38 min.

Ball return tubes Precipitation hardening stainless steel to 17-7PH, ASTM:A564 Gr.631 vacuum degassed and electro slag refined – Precipitation hardened to condition H 900 achieving hardness RC 38-42 min.

Balls Stellite 19 PM, Hardness RC 46 – 51. NOTE: M/s Hoover precision stellite 19 PM balls with 1.5% to 2.4% carbon content and a surface finish of Ra 0.05 micron, for ram B and latch ball screw & nut assemblies is acceptable in place of Stellite 19 PM balls. 

4.3 Ball Tracks

Ball tracks in ball screw shafts and ball nuts shall be precision ground and shall be of Gothic arch profile with conformity of 53%.

4.4 Balls

Balls used in all Ball Screw Assemblies shall be precision ground and shall confirm to AFBMA Gr. 25 or better. Three axis X-ray shall be carried out on all balls. Balls shall be free from any defects.

4.5 Ram B ball screw rear end shall be drilled as per the Drawing M-1&2/ 35221 / 1297 /DD

REV-0 4.6 100 numbers of 1/8” dia x 1.5 inch length inconel X 750 spring pins shall be supplied

along with three B- ram ball screw assembly. For specification of the pin except length refer drawing MAPP / 35221 / 1297 / DD rev-0.

4.7 Design parameters and Operating Conditions of Ball Screw Assemblies are shown in

Table-1.

TABLE – 1

S. No Description Type FM-B (RMN)

1. Screw Moves linearly

2. Nut Rotates

3. Attitude in which the ball screw assemblies

operate

Horizontal

4. Medium in which ball screw assemblies operate Water

PH 9.5 to 10.5

5. Temperature of Medium Normal 120

Maximum – 175

6. Pressure of medium kg/Sq. cm 110

7. Dia of screw shaft in mm 78.6

8. Total length of screw shaft (mm) 3222

9. Length of nut in mm 344

10. Dia of balls in mm 6.35

11. Pitch, mm (right hand single start) 12.700

12. Radial backlash, mm 0.060 /0.090

13. Pitch Error

a) 0.025 mm in 300mm

b) ± 0.100mm cumulative

over entire travel.

14. Conformity of ball track profile. 53%

15. Contact Angle 450 - 500

300 rpm (nut)

24 rpm (nut)

16.

16.1

16.2

Max. speed

Operating speed high

Operating speed - low - (One speed only)

17.

17.1.

17.2

Rate of travel (max.)

Operating Speed – high

Operating Speed – Low

3800 mm/min (screw shaft)

3050 mm/min(screw shaft)

305 mm/min (screw shaft)

18. Maximum axial load in operation in both directions

544 Kgf. (Tensile and Compressive)

19. Max. thrust load when stalled in ‘Kgf’ with screw shaft fully extended

3400 Kgf. (Compressive)

20. Service life required 254 X 10^6 mm of travel cumulative of backward and forward strokes.

21. Preload on nut for torque measurement and running

910 Kgf.

22. Maximum torque for 21 above 25 Kgf-cm 23. No. of ball circuits in each assembly 4 24. Type of ball circuits in each assembly External 25. 25.1 25.2

Number of balls Number of balls in each ball circuit Total number of balls in assembly

75 300

5. MANUFACTURING REQUIREMENTS: 5.1 General

Components of the Ball Screw Assemblies shall be manufactured with best possible workmanship to ensure trouble free operation and satisfactory service life.

5.2 Cleanliness: Good clean conditions shall be maintained during all stages manufacturing, assembly and

shop testing of ball screw assemblies. Assembly and testing shall be done in a dust free controlled atmosphere room.

5.3 Raw material for manufacture of components: Raw material for manufacturing the components of ball screw assemblies shall be as per

4.3 above and our drawings listed in 3.2 above. Material conforming to ASTM: A564 shall be procured in solution-annealed condition. Prior to precipitation hardening to conditions H900, H925, etc., the raw material stock shall be rough machined with a finish machining allowance of 3mm or less. Precipitation hardening shall be done as per 5.5.1 below.

5.4 Raw material identification:

All materials used for manufacture of components of ball screw assemblies and designated with ASTM or BS or DIN Standards shall be tested as required by such standards and this specification. Proof in the form of certified test reports or mill test certificates that the required tests have been carried out at source will be acceptable. If original mill test certificates are not available, the tests shall be performed by the Supplier. Copies of all materials test certificates shall be furnished to the Purchaser.

5.5 Heat Treatment 5.5.1 Precipitation Hardening Heat Treatment

Precipitation hardening shall be carried out as per the following procedures: H925 Condition Heat to 5000 C ± 5 0 C, hold at this temperature for 4 hours and air-

cool to room temperature. H1025 Heat to 550 deg. C ± 5 deg. C hold at this temperature for 4 hours

and air cool to room temperature. H900 Heat to 4820 C ± 5 0 C, hold at this temperature for 1 hour and air

cool to room temperature.

5.5.2 Heat Treatment procedures for precipitation Hardening: All heat treatment operations shall be carried out to established procedures so as to achieve the desired physical properties. Copies of these procedures shall be furnished to the purchaser for his comments before commencing hear treatment.

5.5.3 Heat Treatment Equipment:

Precipitation hardening heat treatment shall be carried out in electrically heated forced air circulation furnaces that have been checked for temperature uniformity. Thermocouples, temperature controllers and temperature recorders shall be calibrated as a whole for accuracy of indication of job temperature within ± 5 0 C. Temperature uniformity of the working zone of the furnace shall be within ± 5 0C at the difference holding temperatures.

5.5.4 Heat Treatment Records :

Time-temperature charts shall be maintained for all heat treatment operations and shall be kept identified with the components that have been heat-treated. Copies of time temperature charts for all heat treatment operations shall be furnished to the purchaser for his records.

5.5.5 Witness places during Heat Treatment:

At least one 250mm long witness piece per heat treatment batch and per raw material heat shall be used along with the materials being heat treated. These witness pieces shall be of appropriate size and be representative of material being precipitation hardened. From each witness piece three standard 12.00mm dia, tensile test specimen and three charpoy V-notch impact test specimen as per ASTM: A370 and a circular slice, 25mm thick, for checking hardness shall be machined. If the diameter of the witness piece does not permit machining of 3 impact tensile and impact test specimens, adequate length of

witness piece shall be used for machining 3 tensile and 3 impact test specimens per heat treatment batch and per raw material heat.

5.5.6 Stress Relief :

If necessary, the screw can be straightened in the cold condition followed by stress relieving at 500 0 C. max, for about 2 hours.

5.6 Properties to be achieved after precipitation hardening :

After precipitation hardening heat treatment, three (3) standard 12mm dia, tensile test specimens, 3 charpy V-notch impact test specimens 10mm x 10mm and a 25mm thick slice shall be machined from the witness piece/witness pieces. The tensile and impact test specimens shall be as per ASTM: A370 and these shall be tested in qualified testing machines. Hardness shall be checked across two perpendicular diameters of the 25mm thick slice. Properties obtained for the different precipitation hardening heat treatments shall be as follows:

Condition H1025 H925 H900 UTS (min) in kg/sq.mm 100 120 135 Y.S. (min) at 0.2% strain in kg/sq.mm

103 110 120

% Elongation (min) 12 10 10 % Reduction in area (min) 45 38 35 Hardness Range RC 35-42 RC 38-45 RC 40 - 47 Impact absorbed energy value 2.1 kg-m 0.7 kg-m -

5.7 Cleaning and passivation:

After finish machining and inspection but prior to assembly all components shall be thoroughly cleaned with acetone to remove all traces of cutting oil, other contaminations etc.

6.0 INSPECTION AND PERFORMANCE TESTING:

Supplier shall be responsible for and shall provide for and perform all inspection and testing specified in this specification. Inspection and testing shall be conducted to a manner satisfactory to and shall be subject to approval by the Purchaser.

6.1 Inspection 6.1.1 Ultrasonic Examination of Raw materials: After heat treatment, the entire length of each screw shaft bar, ball nut forging and other

raw material shall be ultrasonically examined by straight beam and angle beam methods, by qualified personnel in accordance with ASTM: A 388 (Recommended practice for

Ultrasonic Testing and Inspection of Heavy Forgings). Supplier shall furnish a procedure for ultrasonic examination proposed to be carried out by him. The procedure shall be subject to approval by the Purchaser.

A screw shaft bar or ball nut forging shall be unacceptable;

a) If ultrasonic examination results show one or more reflections, which produce indications, accompanied by total loss of back reflection, not associated with or attributable to the geometric configuration. Complete loss in back reflection is assumed when the back reflection falls below 5% of full calibration amplitude.

b) If presence of crack is indicated in the material. c) If ultrasonic examination reveals indications greater than those indicated by a 1.2 mm

(3 /64”) diameter flat bottomed hole, 12mm (1/2”) deep. 6.1.2 Fluorescent wet Magnetic particle Inspection: All finish ground surfaces of screw shaft; ball nut etc. shall be inspected by fluorescent

wet magnetic particle method as per ASTM: E138. Supplier shall furnish a procedure for fluorescent wet magnetic particle inspection proposed to be carried out by him. The procedure shall indicate all relevant details such as surface preparation, details of machine used, its voltage and current rating, sequence of operation, details of machine used, its voltage and current rating, sequence of operation, specification of particles used etc. The procedure shall be subject to approval of purchaser.

The following relevant indications are unacceptable:-

Crack or linear indication. Rounded indications with dimensions greater than 1.5mm. Four or more rounded indications in a line separated by 1.5mm or less edge to edge. Ten or more rounded indications in any 40 square cm. of surface area with major

dimensions of this area taken in the most unfavorable location relative to the indications being evaluated.

Any indication that is believed to be non relevant shall be regarded as defect until it is re-examined to verify whether actual defects are present.

6.1.3 Inspection of satellite balls: Stellite-19 PM balls shall be inspected by 3-axis x-ray method for crack detection. 6.1.4 Dimensional Inspection :

Supplier shall carry out 100% dimensional inspection of all components and furnish these dimensional inspection reports to the Purchaser. Such inspection shall include the following indicated on Purchaser’s drawings and drawings prepared and furnished by the supplier and approved by the Purchaser. The Nut Ball thread minor diameter noted as 81.50 ± 0.05 mm instead of dia 82.45/82.25 mm as per the MAPS drawing. All the relevant drawings of earlier purchase order are also attached herewith for reference.

All dimensional details including concentricity, square ness, run out, straightness etc. of components of ball screw assemblies.

Surface finish, where specified. Thread sizes-with ring or plug gauges. Gothic arch profile conformity – for checking this a procedure shall be furnished by

the supplier. Dimensional inspection of the balls to confirm the AFBMA grading.

6.2 Inspection of the ball screw assemblies:

Inspection of Ball Screw Assemblies shall be examined thoroughly and cleaned of all cutting oil. After assembly the ball nut shall be moved over the entire length of the ball track on the screw shaft to ensure free and smooth movement. The following tests shall be performed on ball screw assemblies.

6.2.1 Inspection for pitch error: Each ball screw assembly shall be inspected using laser set up for pitch error by

measuring accurately and recording the axial distance traversed by the ball nut as the screw if rotated through full evolutions. Details of the set up, accuracy of measurement, procedure for calibration and procedure for measurement of pitch error shall be furnished to the purchaser for approval. Pitch error shall not exceed the requirement given in Table-1. Results shall be submitted in the form of a graph for each ball screw assembly.

6.2.2 Inspection for backlash:

Each ball screw assembly shall be inspected by suitable method for measurement of backlash at 3 places along the length of ball track selected at random. Backlash shall not exceed the requirements given in Table-1.

6.2.3 Inspection for inclination to overhaul:

The ball nut shall be moved to one end of the ball track of screw shaft. This end of the screw shaft shall be slowly raised with the other end resting on a firm surface. The minimum angle of inclination of the screw shaft, at which the ball nut starts rotating and moves smoothly, shall not exceed 350. This shall be repeated at least thrice to get close values of the angles of inclination required for smooth movement. No lubricant shall be used in this test.

6.3 Performance testing of ball screw assemblies:

Each ball screw assembly shall be subjected to performance test, carried out with the screw shaft horizontal and suitably supported as called up in respective assembly drawing. The ball nut shall be preloaded to force indicated in Table-I using pre-calibrated disc springs and preloading ball nut/using oil hydraulic cylinder.

6.3.1 Run-in of all screw assemblies:

Each ball screw assembly shall be run in preloaded as above and as shown in respective drawings. The screw shaft shall be rotated so that ball nut traverses the complete length of travel. Movement of ball nut shall be free without binding, uniformity smooth and without vibrations. Ball deflectors/liners shall be checked for any damage or change of shape after cyclic test.

6.3.2 Torque Measurement: Static torque and running torque required to rotate the screw shaft to traverse the ball nut with and without preload shall be measured at the screw end for the entire length of travel of the ball nut and these shall meet requirements indicated in Table-1. Maximum torque value over the full range of travel shall not be more than 30% of the lowest torque value.

7.0 Certification required while dispatching the ball screw assemblies:

At the time of dispatching the ball screw assemblies six (6) copies of certificates, inspection reports and test reports covering all aspects of inspection and testing, signed by a responsible technical representative of the supplier shall be furnished to the Purchaser. When inspection or testing is sub-contracted to an outside agency, the certificates/reports shall be signed by a responsible technical representative of such agency and countersigned by the Supplier. The certificates shall be appropriately correlated with the components they represent and the serial number of the ball screw assembly in which the components have been installed. In particular the following certificates/test reports shall be furnished to the Purchaser for each of the Ball Screw Assemblies supplied under this specification.

7.1 Test Certificates for Raw Material and Bought-out Items Original manufacturer’s test certificates shall be furnished to the Purchaser for the

following : 7.1.1 Material to ASTM:A564 The test certificates shall contain information on chemical composition, heat-treatment

undergone (i.e. temperature at which held, time held, temperature to which cooled etc.) steel mill heat number etc.

7.1.2 Stellite Balls

Manufacturers certificates should give details of chemical composition, heat treatment undergone, hardness achieved, Surface finish after lapping, non-destructive examination carried out and its result, AFBMA Grade to which the balls belong and other details.

7.2 Heat Treatment records :

Time temperature charts of all heat treatment operations carried out shall be certified and furnished (refer 5.5.4)

7.3 Certificates for Mechanical Properties and Hardness:

Results of tests for mechanical properties impact values and hardness shall be recorded systematically for each precipitation hardening heat treatment batch, certified and furnished to the Purchaser. In addition, following hardness checks shall also be made and reported in the certificates.

7.3.1 At least at 5 places along the length of each screw shaft.

7.3.2 At least 2 places on each ball nut and deflector.

7.3.3 At least 1% satellite balls chosen at random shall be inspected for hardness. The balls

used for hardness test shall not be used in the assembly.

7.4 Certified reports of all non-destructive examinations carried out.

7.5 Certificates for smooth run-in of all ball screw assemblies.

7.6 Test Reports for torque measurements (ref. 6.3.2 above)

7.7 Angle of screw shaft for ball nut to overhaul (ref 6.2.3)

7.8 Measurement of pitch error.

7.9 Dimensional inspection of all components prior to assembly.

7.10 Conformity to Gothic arch profile (ref. 6.1.4)

7.11 Report on backlash inspection (ref.6.2.2)

7.12 Report on straightness inspection.

7.13 Record of number of balls used in each nut assembly.

These reports may be copied and submitted in the form of History docket

7.14 Certificate for completeness and compliance for the specification requirements.

8. REQUIREMENT AFTER PLACEMENT OF ORDER

8.1 Drawings Fully dimensioned drawings of screw shaft, ball nut, ball deflectors & recirculation tubes,

ball screw assembly etc. and containing information on ball dia., pitch, Pitch error, details of Gothic arch profile etc. (ref. 4.2) shall be furnished to the purchaser for approval.

8.2 Quality control Plan

Before commencing manufacture, manufacturer shall furnish quality control plan to facilitate the purchaser to plan stages at which quality surveillance will be carried out by him or his authorized agency.

8.3 Manufacturing, inspection and testing procedures are to be furnished by the Supplier.

Verification and approval of these procedures and drawings mentioned in 8.1 above are for the benefit of the Purchaser and shall not relieve the supplier from full responsibility for ensuring correct interpretation of drawings and specifications and for completeness and accuracy of the shop drawings and procedures furnished by the supplier. Before commencing manufacture, supplier shall furnish the following procedures and drawings for approval by Purchaser.

8.3.1 Procedure for precipitation hardening heat treatments (ref 5.5.2) 8.3.2 Procedure for ultrasonic inspection (ref 6.1.1) 8.3.3 Procedure for wet magnetic particle inspection (ref 6.1.2) 8.3.4 Procedure for Run-in of ball screw assemblies (ref 6.3.1) 8.3.5 Procedure for testing of torque measurements and inclination to overhaul (ref 6.3.2 &

6.2.3) 8.3.6 Procedure for cleaning (ref 5.7) 8.3.7 Procedure for packing of ball assemblies together with appropriate drawing for the crate

and the internal supports and protective packing. 9. PACKING AND SHIPPING: 9.1 Preservation The supplier shall protect all components of the ball screw assemblies and its spares

against corrosion and damage during shipment and storage. Packing shall be suitable for storing the ball screw assemblies for a minimum 5 years.

9.2 Packing After completion of all testing the ball screw assemblies shall be cleaned and dried

thoroughly. Cloth bags containing adequate quantities of dried desiccants (silica gel) shall be tied on screw shafts at 1m intervals. Then each ball screw assembly shall be vacuum-sealed in a transparent polyethylene jacket. This shall again be sealed in a

second jacket containing packets of dried desiccant material. The second jacket shall be of cloth reinforced aluminum foil backed polyethylene.

Ball screw assemblies, preserved and packed as above, shall be individually placed in a

robust wooden box with 100mm wide intermediate supports at one-meter intervals. The intermediate supports shall be such as to completely encircle the ball screw shafts and shall be suitably cushioned with foam. The inside of the wooden box shall be lined with moisture proof material. Each wooden box containing ball screw assembly shall be stiffened with encircling steel angle frames placed at approx. 1.5m intervals. The steel angle frames shall be rugged and strong to withstand handling during loading and unloading. A drawing showing the method of packing shall be forwarded to the Purchaser for his approval.

10. QUALITY SURVEILLANCE: Quality surveillance and expediting relating to all aspects of the contract shall be carried

out by the purchaser or his authorized representative, for which purpose supplier and his sub-contractors shall:

(i) Allow access at all reasonable times during manufacture, assembly and testing to

(a) the premises in which the work is being carried out (b) the drawings and/or tooling involved (c) the gauges, instruments, testing equipment etc. required for inspecting the work. Prints of the drawings shall be made available for inspection and retention, if so desired.

(ii) Produce an inspection plan to the Purchasers satisfaction and notify him when checkpoints on the plan are imminent so that the Purchasers representative may be present, whenever necessary.

(iii) Obtain acceptance of the material in the form of a shipping release from the Purchasers representative before effecting shipment.

11. SHIPPING RELEASE Delivery must not take place until the purchaser has been notified and written acceptance

of the equipment has been obtained.

M-1&2 / 35221 / 1297 / DD

Material: ASTM A 564 GRADE 630 H-1035, HRC 35-42

TOLERANCE : 0.01 FOR THREE PLACES 0.05 FOR TWO PLACES

UNIT : MM UNLESS SPECIFIED.

3.937

35.56

Ø 3.10 MM DRILL

A

A

SECTION A -A

2 3 4"16 UNC 2A(REF)

RAM-B BALL SCREW REAR END

TECHNICAL SPECIFICATION OF LATCH BALL SCREWS 1. SCOPE:

This specification establishes the requirement for procurement of raw material, manufacture and inspection of components, assembly, shop testing, running-in, cleaning, packing and shipment of ball screw assemblies for requirements as detailed below :-

2. CONTENTS

The provisions of this specification are presented under the following section headings:

Section Applicable specification and drawing 3 Requirement of ball screw assemblies 4 Manufacturing requirements 5 Inspection and Performance testing 6 Certification required 7 Requirement after placement of order 8 Packing and shipping 9 Quality Surveillance 10 Shipping release 11

3. APPLICABLE SPECIFICATIONS AND DRAWINGS:

Latest issues of the specifications listed below, in effect of the time of manufactgure, constitute a part of this specification to the extent specified herein. In the event that certain provisions of the specifications listed below conflict with the requirements of these specifications, the requirement of this specification shall govern.

3.1 SPECIFICATIONS

ASTM-A564 Specification for precipitation hardening alloy bars, forgings and forging stocks for high temperature service.

ASTM – 370 Standard methods and definitions for testing of steel products. ASTM – E18 Standard methods for tests for Rockwell hardness and Rockwell

superficial hardness of metallic materials. ASTM – E138 Specification for wet magnetic particle testing. ASTM – A388 Recommended practice for Ultrasonic testing and inspection of Heavy

forgings.

ASTM – E165 Specification for Dye Penetrant testing (DP test is for materials not covered under MPI).

PP-E-438 Specifications for Hard Chrome plating (enclosed as part of tender).

3.2 DRAWINGS: 3.2.1 Ball Screw assembly The drawings bearing MAPS and NPC drawing numbers viz.: M1/35221/1291/GA Rev.0

and NPC/35221/0054 Rev.0 and NPC/35221/0055 Rev.0.. The drawings, procedures(manufacturing), inspection, shop testing, running-in, cleaning, packing for Latch Ball screw & Nut assembly Type : FM-L(RM) for MAPS fuelling machines shall be followed as per the specification and procedures against the earlier purchase order CMM/MAPS/FHU/39486/PO-57491 Dated 05/02/2013

4. REQUIREMENT OF BALL SCREW ASSEMBLIES: 4.1 Overall sizes:

Features and overall sizes of the ball screw assemblies shall be as per drawings listed in section 3.2 above.

4.2 Materials of construction:

All materials used to manufacture the components and other parts forming part of the ball screw assemblies shall be corrosion resistant and be suitable for water service. Materials of construction of ball screw assemblies shall be as follows : Ball nuts for type FM-L (RM), Ball return tubes and screw shaft of types FM-L (RM) ball screw assemblies

Precipitation hardening stainless steel to ASTM:A564 Gr.630 vaccum degassed and electro slag refined. Precipitation hardened to condition H925 achieving hardness RC 38 min.

Balls Stellite 19 PM, Hardness RC 46-51. NOTE: M/s Hoover precision stellite 19 PM balls with 1.5% to 2.4% carbon content and a surface finish of Ra 0.05 micron, for ram B and latch ball screw & nut assemblies is acceptable in place of Stellite 19 PM balls. 

4.3 Supplier shall carry out detailed design to meet the dimensional and other requirements specified on the drawings mentioned above and in this specification. Detailed drawings prepared by the supplier for manufacturing the components and assembly shall be furnished to the purchaser for review and approval. After approval, 6 (six) sets of reproducible of all drawings shall be furnished to the purchaser for his records. The Ball screw assemblies are to be manufactured as per the following requirements.

4.4 Ball Tracks

Ball tracks in ball screw shafts and ball nuts shall be precision ground and shall be of Gothic arch profile with conformity of 52% - 53%. Ball tracks shall be right hand single start threads.

4.2 Balls

Balls used in all Ball screw assemblies shall be precision ground and shall confirm to AFBMA Gr. 25 or better. Three axis X-ray shall be carried out on all balls. Balls shall be free from any defects.

4.3 Special screws

60 nos. of latch ball nut ball pickup tube mounting special screws with original washers shall be supplied along with three latch ball screw assembly

4.4 Design parameters and operating conditions of ball screw assemblies are shown in the

following Table-1. TABLE – 1

S. No Description Type FM-L (RM) 1. Screw Rotates 2. Nut Travels Linearly 3. Attitude in which the ball screw assemblies

operate Horizontal

4. Medium in which ball screw assemblies operate Water PH 9.5 to 10.5

5. Temperature of Medium Deg. C Normal 120 Maximum – 175

6. Pressure of medium kg/Sq. cm 110 7. Dia of screw shaft in mm 44 8. Total length of screw shaft (mm) 375 9. Length of nut in mm 238 10. Dia of balls in mm 3.962 11. Pitch, mm right hand single start 6.350 12. Radial backlash in mm 0.030 /0.060 13. Pitch Error

0.010 mm in 200mm -

14. Conformity of ball track profile. 52% to 53% 15. Contact Angle 450 - 500

- 100 rpm (shaft)

16. 16.1 16.2

Max. speed Operating speed high Operating speed - low - (One speed only)

17. 17.1. 17.2

Rate of travel (max.) Operating Speed – high Operating Speed – Low

1895 mm/min (nut) 625 mm/min (nut) -

18. Maximum axial load in operation in both directions

825 Kgf. (Tensile and Compressive

19. Max. thrust load when stalled in ‘Kgf’ with screw shaft fully extended

825 Kgf. (Compressive)

20. Service life required 26 X 10^6 mm of travel cumulative of backward and forward strokes.

21. Preload on nut for torque measurement and running

458 Kgf.

22. Maximum torque for 17 above 40 Kgf-cm (includes supporting bearings frictional torque).

23. Type of ball recirculation External 24. 24.1 24.2

Number of balls Number of balls in each ball circuit Total number of balls in assembly

75 150

5. MANUFACTURING REQUIREMENTS: 5.1 General

Components of the Ball Screw Assemblies shall be manufactured with best possible workmanship to ensure trouble free operation and satisfactory service life.

5.2 Cleanliness: Good clean conditions shall be maintained during all stages manufacturing, assembly and

shop testing of ball screw assemblies. Assembly and testing shall be done in a dust free controlled atmosphere room.

5.3 Raw material for manufacture of components: Raw material for manufacturing the components of ball screw assemblies shall be as per

4.2 above and our drawings listed in 3.2 above. Material conforming to ASTM: a564 shall be procured in solution-annealed condition. Prior to precipitation hardening to conditions H900, H925, etc., the raw material stock shall be rough machined with a finish machining allowance of 3mm or less. Precipitation hardening shall be done as per 5.5.1 below.

5.4 Raw material identification:

All materials used for manufacture of components of ball screw assemblies and designated with ASTM or BS or DIN Standards shall be tested as required by such standards and this specification. Proof in the form of certified test reports or mill test certificates that the required tests have been carried out at source will be acceptable. If

original mill test certificates are not available, the supplier shall perform the tests. Copies of all materials test certificates shall be furnished to the Purchaser.

5.5 Heat Treatment 5.5.1 Precipitation Hardening Heat Treatment

Precipitation hardening shall be carried out as per the following procedures : H925 Condition Heat to 5000 C ± 5 0 C, hold at this temperature for 4 hours and air-

cool to room temperature. H900 Heat to 4820 C ± 5 0 C, hold at this temperature for 1 hour and

5.5.2 Heat Treatment procedures for precipitation Hardening:

All heat treatment operations shall be carried out to established procedures so as to achieve the desired physical properties. Copies of these procedures shall be furnished to the purchaser for his comments before commencing hear treatment.

5.5.3 Heat Treatment Equipment:

Precipitation hardening heat treatment shall be carried out in electrically heated forced air circulation furnaces that have been checked for temperature uniformity. Thermocouples, temperature controllers and temperature recorders shall be calibrated as a whole for accuracy of indication of job temperature within ± 5 0 C. Temperature uniformity of the working zone of the furnace shall be within ± 5 0C at the difference holding temperatures.

5.5.4 Heat Treatment Records :

Time-temperature charts shall be maintained for all heat treatment operations and shall be kept identified with the components that have been heat-treated. Copies of time temperature charts for all heat treatment operations shall be furnished to the purchaser for his records.

5.5.5 Witness places during Heat Treatment:

At least one 250mm long witness piece per heat treatment batch and per raw material heat shall be used along with the materials being heat treated. These witness pieces shall be of appropriate size and be representative of material being precipitation hardened. From each witness piece three standard 12.00mm dia, tensile test specimen and three charpoy V-notch impact test specimen as per ASTM: A370 and a circular slice, 25mm thick, for checking hardness shall be machined. If the diameter of the witness piece does not permit machining of 3 tensile and impact test specimens, adequate length of witness

piece shall be used for machining 3 tensile and 3 impact test specimens per heat treatment batch and per raw material heat.

5.5.6 Stress Relief :

If necessary, the screw can be straightening in the cold condition followed by stress relieving at 500 0 C. max. for about 2 hours.

5.6 Properties to be achieved after precipitation hardening :

After precipitation hardening heat treatment, three (3) standard 12mm dia, tensile test speciments, 3 charpy V-notch impact test speciments 10mm x 10mm and a 25mm thick slice shall be machined from the witness piece/witness pieces. The tensile and impact test specimens shall be as per ASTM: A370 and these shall be tested in qualified testing machines. Hardness shall be checked across two perpendicular diameters of the 25mm thick slice. Properties obtained for the different precipitation hardening heat treatments shall be as follows:

Condition H1025 H925 H900 UTS (min) in kg/sq.mm 100 120 135 Y.S. (min) at 0.2% strain in kg/sq.mm

103 110 120

% Elongation (min) 12 10 10 % Reduction in area (min) 45 38 35 Hardness Range RC 35-42 RC 38-45 RC 40-47 Impact absorbed energy value 2.1 Kg-m 0.7 Kg-m -

5.7 Cleaning and passivation:

After finish machining and inspection but prior to assembly all components shall be thoroughly cleaned with acetone to remove all traces of cutting oil, other contaminations etc.

6.0 INSPECTION AND PERFORMANCE TESTING:

Supplier shall be responsible for and shall provide for and perform all inspection and testing specified in this specification. Inspection and testing shall be conducted to a manner satisfactory to and shall be subject to approval by the Purchaser.

6.1 Inspection 6.1.1 Ultrasonic Examination of Raw materials: After heat treatment, the entire length of each screw shaft bar, ball nut forging and other

raw material shall be ultrasonically examined by straight beam and angle beam methods, by qualified personnel in accordance with ASTM: A 388 (Recommended practice for

Ultrasonic Testing and Inspection of Heavy Forgings). Supplier shall furnish a procedure for ultrasonic examination proposed to be carried out by him. The procedure shall be subject to approval by the Purchaser.

A screw shaft bar or ball nut forging shall be unacceptable;

a) If ultrasonic examination results show one or more reflections, which produce indications, accompanied by total loss of back reflection, not associated with attributable to the geometric configuration. Complete loss in back reflection is assumed when the back reflection falls below 5% of full calibration amplitude.

b) If presence of crack is indicated in the material. c) If ultrasonic examination reveals indications greater than those indicated by a 1.2 mm

(3 /64”) diameter flat bottomed hole, 12mm (1/2”) deep. 6.1.2 Fluorescent wet Magnetic particle Inspection: All finish ground surfaces of screw shaft, ball nut etc. shall be inspected by fluorescent

wet magnetic particle method as per ASTM: E138. Supplier shall furnish a procedure for fluorescent wet magnetic particle inspection proposed to be carried out by him. The procedure shall indicate all relevant details such as surface preparation, details of machine used, its voltage and current rating, sequence of operation, details of machine used, its voltage and current rating, sequence of operation, specification of particles used etc. The procedure shall be subject to approval of purchaser.

The following relevant indications are unacceptable:-

Crack or linear indication. Rounded indications with dimensions greater than 1.5mm. Four or more rounded indications in a line separated by 1.5mm or less edge to edge. Ten or more rounded indications in any 40 square cm. of surface area with major

dimensions of this area taken in the most unfavorable location relative to the indications being evaluated.

Any indication that is believed to be non relevant shall be regarded as defect until it is re-examined to verify whether actual defects are present.

6.1.3 Inspection of satellite balls: Stellite-19 PM balls shall be inspected by 3-axis x-ray method for crack detection. 6.1.4 Dimensional Inspection :

Supplier shall carry out 100% dimensional inspection of all components and furnish these dimensional inspection reports to the Purchaser. Such inspection shall include the following indicated on Purchaser’s drawings and drawings prepared and furnished by the supplier and approved by the Purchaser.

All dimensional details including concentricity, square ness, run out, straightness etc. of components of ball screw assemblies.

Surface finish, where specified. Thread sizes-with ring or plug gauges. Gothic arch profile conformity – for checking this a procedure shall be furnished by

the supplier. Dimensional inspection of the balls to confirm the AFBMA grading.

6.2 Inspection of Ball Screw Assemblies shall be examined thoroughly and cleaned of all

cutting oil. After assembly the ball nut shall be moved over the entire length of the ball track on the screw shaft to ensure free and smooth movement. The following tests shall be performed on ball screw assemblies.

6.2.1 Inspection for pitch error: Each ball screw assembly shall be inspected using laser set up for pitch error by

measuring accurately and recording the axial distance traversed by the ball nut as the screw if rotated through full evolutions. Details of the set up, accuracy of measurement, procedure for calibration and procedure for measurement of pitch error shall be furnished to the purchaser for approval. Pitch error shall not exceed the requirement given in Table-1. Results shall be submitted in the form of a graph for each ball screw assembly.

6.2.2 Inspection for backlash:

Each ball screw assembly shall be inspected by suitable method for measurement of backlash at 5 places along the length of ball track selected at random. Backlash shall not exceed the requirements given in Table-1.

6.2.3 Inspection for inclination to overhaul:

The ball nut shall be moved to one end of the ball track of screw shaft. This end of the screw shaft shall be slowly raised with the other end resting on a firm surface. The minimum angle of inclination of the screw shaft, at which the ball nut starts rotating and moves smoothly, shall not exceed 350. This shall be repeated at least thrice to get close values of the angles of inclination required for smooth movement. No lubricant shall be used in this test.

6.3 Performance testing of ball screw assemblies:

Each ball screw assembly shall be subjected to performance test, carried out with the screw shaft horizontal and suitably supported as called up in respective assembly drawing. The ball nut shall be preloaded to force indicated in Table-I using pre-calibrated disc springs and preloading ball nut/using oil hydraulic cylinder.

6.3.1 Run-in of all screw assemblies:

Each ball screw assembly shall be run in preloaded as above and as shown in respective drawings. The screw shaft shall be rotated so that ball nut traverses the complete length of travel. Movement of ball nut shall be free without binding, uniformity smooth and without vibrations. Ball deflectors/liners shall be checked for any damage or change of shape after cyclic test.

6.3.2 Torque Measurement: Static torque and running torque required to rotate the screw shaft to traverse the ball nut with and without preload shall be measured at the screw end for the entire length of travel of the ball nut and these shall meet requirements indicated in Table-1. Maximum torque value over the full range of travel shall not be more than 30% of the lowest torque value. Assembly shall be cleaned off all lubrication before this test and test shall be carried out without any lubrication.

7.0 Certification required while dispatching the ball screw assemblies:

At the time of dispatching the ball screw assemblies six (6) copies of certificates, inspection reports and test reports covering all aspects of inspection and testing, signed by a responsible technical representative of the supplier shall be furnished to the Purchaser. When inspection or testing is sub-contracted to an outside agency, the certificates/reports shall be signed by a responsible technical representative of such agency and countersigned by the Supplier. The certificates shall be appropriately correlated with the components they represent and the serial number of the ball screw assembly in which the components have been installed. In particular the following certificates/test reports shall be furnished to the Purchaser for each of the Ball Screw Assemblies supplied under this specification.

7.1 Test Certificates for Raw Material and Bought-out Items Original manufacturer’s test certificates shall be furnished to the Purchaser for the

following: 7.1.1 Material to ASTM:A564 The test certificates shall contain information on chemical composition, heat-treatment

undergone (i.e. temperature at which held, time held, temperature to which cooled etc.) steel mill heat number etc.

7.1.2 Stellite Balls

Manufacturers certificates should give details of chemical composition, heat treatment undergone, hardness achieved, Surface finish after lapping, non-destructive examination carried out and its result, AFBMA Grade to which the balls belong and other details.

7.2 Heat Treatment records :

Time temperature charts of all heat treatment operations carried out shall be certified and furnished (refer 5.5.4)

7.3 Certificates for Mechanical Properties and Hardness:

Results of tests for mechanical properties impact values and hardness shall be recorded systematically for each precipitation hardening heat treatment batch, certified and furnished to the Purchaser. In addition, following hardness checks shall also be made and reported in the certificates.

7.3.1 At least at 5 places along the length of each screw shaft.

7.3.2 At least 2 places on each ball nut and deflector.

7.3.3 At least 1% satellite balls chosen at random shall be inspected for hardness. The balls

used for hardness test shall not be used in the assembly.

7.4 Certified reports of all non-destructive examinations carried out.

7.5 Certificates for smooth run-in of all ball screw assemblies.

7.6 Test Reports for torque measurements (ref. 6.3.2 above)

7.7 Angle of screw shaft for ball nut to overhaul (ref 6.2.3)

7.8 Measurement of pitch error.

7.9 Dimensional inspection of all components prior to assembly.

7.10 Conformity to Gothic arch profile (ref. 6.1.4)

7.11 Report on backlash inspection (ref.6.2.2)

7.12 Report on straightness inspection.

7.13 Report of number of balls used in each nut assembly.

7.14 Certificate for completeness and compliance for the specification requirements.

These reports may be copied and submitted in the form of History docket

8. REQUIREMENT AFTER PLACEMENT OF ORDER

8.1 Drawings Fully dimensioned drawings of screw shaft, ball nut, deflectors & recirculation tubes, ball

screw assembly etc. and containing information on ball diameter, Pitch error, details of Gothic arch profile etc. (ref. 4.2) shall be furnished to the purchaser for approval.

8.2 Quality control Plan

Before commencing manufacture, manufacturer shall furnish quality control plan to facilitate the purchaser to plan stages at which quality surveillance will be carried out by him or his authorized agency.

8.3 Manufacturing, inspection and testing procedures are to be furnished by the Supplier.

Verification and approval of these procedures and drawings mentioned in 8.1 above are for the benefit of the Purchaser and shall not relieve the supplier from full responsibility for ensuring correct interpretation of drawings and specifications and for completeness and accuracy of the shop drawings and procedures furnished by the supplier. Before commencing manufacture, supplier shall furnish the following procedures and drawings for approval by Purchaser.

8.3.1 Procedure for precipitation hardening heat treatments (ref 5.5.2) 8.3.2 Procedure for ultrasonic inspection (ref 6.1.1) 8.3.3 Procedure for wet magnetic particle inspection (ref 6.1.2) 8.3.4 Procedure for Run-in of ball screw assemblies (ref 6.3.1) 8.3.5 Procedure for testing of torque measurements and inclination to overhaul (ref 6.3.2 &

6.2.3) 8.3.6 Procedure for cleaning (ref 5.7) 8.3.7 Procedure for packing of ball assemblies together with appropriate drawing for the crate

and the internal supports and protective packing. 9. PACKING AND SHIPPING: 9.1 Preservation The supplier shall protect all components of the ball screw assemblies and its spares

against corrosion and damage during shipment and storage. Packing shall be suitable for storing the ball screw assemblies for a minimum 5 years.

9.2 Packing After completion of all testing the ball screw assemblies shall be cleaned and dried

thoroughly. Cloth bags containing adequate quantities of dried desiccants (silica gel) shall be tied on screw shafts. Then each ball screw assembly shall be vaccum-sealed in a transparent polyethylene jacket. This shall again be sealed in a second jacket containing

packets of dried desiccant material. The second jacket shall be of cloth reinforced aluminium foil backed polyethylene.

Ball screw assemblies, preserved and packed as above, shall be individually placed in a

robust wooden box with 100mm wide intermediate supports at one-meter intervals. The intermediate supports shall be such as to completely encircle the ball screw shafts and shall be suitably cushioned with foam. The inside of the wooden box shall be lined with moisture proof material. Each wooden box containing ball screw assembly shall be stiffened with encircling steel angle frames placed at approx. 1.5m intervals. The steel angle frames shall be rugged and strong to withstand handling during loading and unloading. A drawing showing the method of packing shall be forwarded to the Purchaser for his approval.

10. QUALITY SURVEILLANCE: Quality surveillance and expediting relating to all aspects of the contract shall be carried

out by the purchaser or his authorized representative, for which purpose supplier and his sub-contractors shall:

(i) Allow access at all reasonable times during manufacture, assembly and testing to

(a) the premises in which the work is being carried out (b) the drawings and/or tooling involved (c) the gauges, instruments, testing equipment etc. required for inspecting the work. Prints of the drawings shall be made available for inspection and retention, if so desired.

(ii) Produce an inspection plan to the Purchasers satisfaction and notify him when checkpoints on the plan are imminent so that the Purchasers representative may be present, whenever necessary.

(iii) Obtain acceptance of the material in the form of a shipping release from the Purchasers representative before effecting shipment.

11. SHIPPING RELEASE Delivery must not take place until the purchaser has been notified and written acceptance

of the equipment has been obtained.

NOTES: 1) All raw materials required for manufacture of these assemblies shall be

suppliers responsibility. No FIM will be issued. 2) QAP shall be submitted for approval prior to starting any manufacturing

activity. For review of QAP or any other manufacturing documents a minimum of 15 working days from the date of receipt of such documents are required. Delay in review and approval of QAP cannot be cited as reason for delay in supply of material and cannot be a reason for waiver of LD clause.

3) Approval of QAP or any other manufacturing document by the purchaser’s

representative shall not be a reason for not meeting the requirements specified in drawing / technical specification.

4) Previous DCRs cannot be considered as precedence and cannot be quoted for

approval of DCRs. 5) Review and approval of DCR shall take a minimum of 15 working days

from the date of receipt of DCR at the office of purchaser’s representative and any delay in review and approval cannot be cited as reason for delay in effecting supply.

6) Heat treatment, hard chrome plating and nitriding if any should be carried out at

sources approved by NPCIL. Relevant heat treatment certificates, time temperature chart and hard chrome plating certificate should be furnished

7) Assembly components shall be checked for 100% dimensions. Dimension and geometric features achieved should be recorded in the form of a report and should be furnished to NPC QS Engineer.

8) THREE History Docket which contain copies of purchase order, drawings,

procedures, raw material test certificates, dimensional and inspection report, test report and important correspondence etc. shall be furnished with supply.

9) Assemblies shall be adequately packed to avoid damage in transit. Each

of the components shall be suitably identified by part no and drawing no: through tags.

10) Item no:1 – Ram-B Ball screw assembly & Nut assembly Type : FM-B(RMN),

the drawings, procedures(manufacturing), inspection, shop testing, packing, supply and guarantee of Ram-B Ball screw assembly & Nut assembly Type : FM-B(RMN) for MAPS fuelling machines as per the specification and procedures as per the earlier purchase orders CMM/MAPS/FHU/30662/PO/51038 Dt.25/10/2005 (QAP ref No.2052253) and CMM/OP/53-35-9-2909/PO/30396 Dt.03/04/2012 (QAP ref No.2120471).

11) Item no:2 – Latch Ball screw & Nut assembly Type : FM-L(RM), the drawings,

procedures(manufacturing), inspection, shop testing, packing, supply and guarantee of Latch Ball screw assembly & Nut assembly Type : FM-L(RM) for MAPS fuelling machines as per the specification and procedures as per the earlier purchase orders CMM/MAPS/FHU/30895/PO/51208 Dt.15/12/2005 (QAP ref No.2052591).

12) The drawings, QAP plan and approved procedures for the above Ball screws

shall be as per the earlier purchase orders mentioned against each type may be followed, however all the relevant drawings of Ram-B and Latch Ball screws is attached herewith for reference.

13) The budget provision is provided for procurement of two Latch ball screws and

one Ram-B ball screw(estimation amount of Rs.40.00 lakh) in this year RE 2012-13. The budget provision for two Latch ball screws and two Ram-B ball screws(estimation amount of Rs.60.00 lakh) in the next financial year 2013-14. The delivery of the ball screws are to be made as per the budget provision and the same to be mentioned in the tender document as well as in the purchase order..