tungsten carbide tip tamping tool(s), hereinafter referred as “TCTT", for on track
tamping machine deployed over Indian Railways. 1.1 The specification has been
SPECIFICATION OF TUNGSTEN CARBIDE TIP TAMPING TOOL (TCTT) FOR ON-TRACK TAMPING MACHINES (Specification No. TM/HM/6/320) 1.0
Scope: This specification covers technical requirements of manufacture and supply of tungsten carbide tip tamping tool(s), hereinafter referred as “TCTT", for on track tamping machine deployed over Indian Railways.
The specification has been drawn to stipulate the performance and quality requirements of the TCTT, in an objective manner without reference to any specific manufacturer. If a supplier feels that his TCTT can generally meet the performance and quality requirements of the TCTT but does not fully satisfy a particular clause of the specification, then he shall furnish clause-wise details of deviations along with remarks in his offer.
The supplier should be aware of various types of tamping tool(s) used on tie tamping machines of Plasser & Theurer make in operation on Indian Railways to avoid fitment and functional problem at later stage.
References: IS: 2004-1991 IRS-SL.NO.R-16/95 IS: 5517-1993 IS: 228 – 1987 IS: 1499-1977 IS: 4163- 2004 IS: 1500- 2005 IS: 9862-1981 IS: 1875-1992 IS: 1387:1993 IS: 1608:1995
Carbon steel forging for general engineering purpose – specification (3rd revision) Specification for steel axles for carriage and wagons. Steels for hardening and tempering-Specification (second revision). Method of chemical analysis of pig iron, cast iron and plain carbon and low – alloy steels Method for Charpy Impact Test (U notch) for metals (first revision). Determination of inclusion content in steel by microscopic method. Method for Brinell hardness tests for steel (first revision) Specification for ready mixed paint, brushing, bituminous, black, lead-free, acid, alkali, water and chlorine resisting. Specification for carbon steel billets, blooms, slab and bars for forging (5th revision). General Requirements for the Supply of Metallurgical Materials (second Revision). Mechanical Testing of Metals – Tensile Testing ( 3rd Revision).
IS: 4667- part-IV – 2001 IS: 4667- part-3-2001 ASTM-E-112
Chemical analysis of Silver- copper brazing alloys (Ag,Cu,Cd,Zn) Electrolytic method. Chemical analysis of Silver- copper brazing alloys –Determination of ‘Ni’ Standard Test methods for determining average grain size.
Manufacture of steel for TCTT:
TCTT shall be manufactured from quality steel made by electric or basic oxygen process. The steel should be of killed quality. The continuously cast steel or specially treated steel can also be used provided such steel can meet the laid down specification of steel. The TCTT manufacture shall furnish a certificate of having obtained raw material of requisite quality from a reputed source, conforming to the stipulated chemical composition and manufacturing process of steel.
Chemical composition: The Ladle analysis of the steel, when carried out by the method specified in the relevant para of IS: 228- 1987 or any other established instrumented/chemical method, shall conform to the chemical requirements of composition stipulated for Gr40Ni6Cr4 Mo2 to IS: 5517-1993 as under. Table-1 Steel to be used for manufacture of TCTT Constituent
C Mn Si Ni Cr Mo S P
0.35 to 0.45 0.40 to 0.70 0.10 to 0.35 1.20 to 1.60 0.90 to 1.30 0.10 to 0.20 0.035 max 0.035 max
(*) (Vanadium to the extent of 0.15 to 0.25% may be added for achieving the desired mechanical properties by specific agreement with the purchaser). 3.3
Chemical analysis: The manufacturer shall supply a complete chemical analysis of each cast of the steel and batch of forged and heat-treated TCTT, whenever required to do so by the purchaser or the inspecting official.
Product analysis: Product analysis shall be carried out on the finished TCTT. Variation in case of such product analysis from the Ladle analysis shall be within permissible limits as stipulated in table 2 indicated below. Table –2 Permissible variations in chemical analysis of TCTT with respect to the chemical composition of parent steel (%) Constituent C Mn Si Ni Cr Mo S P
Permissible variation + 0.02% + 0.04% + 0.03% + 0.05% + 0.05% + 0.05% + 0.005%, - 0.000% + 0.005%, - 0.000%
Sufficient discard shall be made from either end of each ingot to ensure freedom from piping, harmful segregation in case of forging manufactured from ingot route.
Manufacturing process for TCTT with respect to tungsten carbide inserts:
The typical mechanical properties of tungsten carbide inserts with respect to hardness and density shall not be below HRA 84 (or equivalent value in Hv-10 scale) and 13.2 g/cm3 respectively. Transverse rupture strength and ultimate compressive strength shall not be less than 2800 N/mm2 and 2750 N/mm2 respectively. Manufacturer shall provide the test certificates including testing procedures/methodology and reference technical documents to the purchaser/inspecting authority in this regard. Flatness shall be within 0.15 mm. Suitable size of the tungsten carbide inserts shall be used for higher impact, wear resistance and better brazing. Detailed shape of the tungsten carbide inserts must be provided before sintering to avoid grinding post brazing operations.
The composition and properties of silver alloy brazing powders should be approximately either Silver 49% - 51%, Cu 14.5% - 16.5%, Zn 13.5% - 17.5%, Cd 15% -17%, Ni 2.5% - 3.5%, other content 0.15% or Silver 49% - 51%, Cu 19% 20%, Zn 26% - 28%, Ni 2.5% - 3.5%, other content 0.15%.The solidus, and liquidus temperature shall not be below 1170o F, 1270o F and braze temperature should be in the range of 1270 o F to 1500 o F respectively.
The brazing shall be done by electronic induction braze machine/ furnace brazing using induction coil or similar automatic brazing equipment. . Excess silver solder should be limited to 1mm on the top of tungsten carbide inserts. Braze material should be present under all tungsten carbide inserts. Tungsten carbide inserts are joined with the steel spade of TCTT by brazing. To ensure good brazed joint,
minimum shear strength of the brazed joint shall be checked on a representative sample (to be provided by the manufacturer) and the minimum shear strength of the joint shall not be less than 8.0 kg/ mm2 5.4
The TCTT shall be provided with TCTT removing mechanism, which should be able to withstand pull out pressure for safe removal of TCTT from tamping arm holder and shall have forged TCTT remover ring.
The TCTT shall have suitable shape for easy penetration into the ballast.
The taper of the shank shall match with the taper of TCTT arm holder (eye) of tamping unit. Taper angle shall be correctly maintained as per the requirement of Plasser & Theurer machines
The forged monolithic TCTT shall be manufactured from steel ingots rolled or forged down to bloom size but shall be finally shaped to profile by forging only, under a hammer or a press. Pneumatic / electro-hydraulic / belt drop forge hammers / hydraulic forge press of adequate capacity for delivering adequate energy or force required for deformation during closed die forging of TCTT shall be used. The profile shall follow the contour of the TCTT.
The minimum cross section of the ingots shall not be less than twice the maximum cross section of bloom and the minimum cross section of bloom shall not be less than thrice the maximum cross section of the forged TCTT.
For continuously cast bar/billets a minimum reduction ratio of 6:1 between the cast product and the final product is essential. However, higher reduction ratio may be mutually agreed upon between the manufacturer and the purchaser at the time of inquiry and order.
The TCTT shall be profile forged and then machined to match the required dimensions for key, proper taper of TCTT shank and flatness of its spade.
All forged TCTT shall be shot blasted to ensure cleanliness of the surface. Shot/sand blasting shall be done by use of sand or iron shots of size 0.75 - 1.0 mm size.
The forged TCTT shall be hardened (quenched) and tempered to achieve the desired mechanical properties throughout the cross section of the component. It should be designed in such a way that it is able to achieve desired mechanical properties and tempered martensite microstructure. Duration of travel from furnace to quenching should be such that the hardening temperature remains within stipulated range. Heat treatment parameters shall be as under: Hardening temp Quenching medium Tempering temp
- 830 o to 850 o C - Oil (Servo quench 107 or equivalent) - 550 o to 600o C
The above heat treatment cycles are indicative for guideline only. Actual heat treatment cycles have to be established through process approval. All the stages
of heat treatment with various temperature ranges of processes shall be clearly brought out in QAP. 7.1
The manufacturer is required to develop and document heat- treating standards that describe the processes, process control procedures and record keeping requirements. These documents are intended to ensure that products are properly heat treated. Furnace temperature for heat treatment shall be controlled by pyrometers having associated recording equipments that produce timetemperature record charts that are identified by date and furnace number. Each cast heat of TCTT, relevant to the cast heat bloom shall be subjected for stipulated heat treatment processes completely to achieve the required microstructure which will be the actual representative heat batch, one sample will be selected randomly from the same batch for conducting the relevant metallurgical tests. i) ii) iii)
The prescribed heat treatment. The serial number (if not available, then cast heat/heat batch number) of the casting of TCTT. Heat treatment log-sheet for each process.
All the pyrometers shall be calibrated every three months. Records of timetemperature chart, furnace log sheet and pyrometer calibrations will be maintained for three (3) years and made available to the purchaser on demand.
Quality of product: The TCTT shall be free from surface and internal forging defect i.e. laps, seams, bursts, cracks, pits, porosity, improper edges etc. which may impair the end use. The TCTT shall be supplied to the prescribed dimensions and tolerances as per drawing.
Branding: All TCTT shall be branded with TCTT manufacturer’s code, batch no., month and year of manufacture by hot stamping during forging itself. Cold punching on the forging shall not be permitted. From the batch no. of the finished TCTT, the process flow and composition of raw materials should be identifiable.
Sampling for test:
Random sampling shall be done in accordance with clause 14 of IS: 5517-1993. Each component found suitable after visual inspection shall be checked for their dimensional characteristics as per relevant drawings. TCTT found satisfactory with regard to all these dimensional characteristics shall be accepted subject to testing as per clause 3.2, 3.4 and 11.0 of this specification.
Forged and properly heat-treated TCTT shall be submitted in identifiable batches of maximum 100 nos. and each batch shall contain forging from only one cast. The selection of forged TCTT for testing as specified in clause 11.0 and 3.3 shall be at the rate of one forging per one batch or part thereof. The sampling frequency shall be one test per cast per heat treatment batch.
One additional sample for each 500 numbers of forging of TCTT manufactured shall be selected for macro-examination.
5% TCTTs selected through random sampling shall be checked for hardness as per para 13.3.
Testing of TCTT:
Tensile test shall be carried out in accordance with IS: 1608-1995. The test piece shall be taken from the central portion of the TCTT. The tensile strength, yield strength and percentage elongation obtained from test piece shall be as under, Tensile strength 0.2% proof stress Elongation % min
1100 – 1250 N/mm2 880 N/mm2 11 %
Impact test shall be carried out in accordance with the requirement of IS: 15981977. Sample test piece shall be prepared from the TCTT. The minimum impact strength obtained through Izod impact test shall be 41 Joules at 20o C.
Micro examination sample shall be taken from the tensile test specimen. The microstructure shall be tempered martensite and shall be uniform and typical of the heat treatment imparted to the forging. The sampling frequency shall be one test per cast per heat treatment batch.
The sample shall be drawn from the same location as that of the tensile test specimen. The grain size determined as per ASTM-E-112 shall not be coarser than 5. The sampling frequency shall be one test per cast per heat treatment batch.
Inclusion rating of the steel shall be determined in accordance with IS: 4163- 2004 from the tensile test specification. The inclusion rating shall not be worse than 2.5 both thick and thin to IS: 4163 - 2004.
Macro examination shall be carried out on the transverse section of the forged TCTT. After polishing, the transverse cross sectional surface of the forged TCTT, on examination with a magnification factor 5 or less, must not reveal any harmful discontinuity. The macro examination shall clearly indicate the presence of grain flow, which shall follow the contour of the forging.
All TCTT shall be inspected visually for presence of harmful surface defects arising out of manufacturing operation. The forging shall be free from defects mentioned at clause 8.0
All TCTT shall be tested by magnetic particle method, both by longitudinal and circular magnetization and shall not reveal any harmful surface cracks / defects. The forgings revealing harmful surface defects shall be rejected. All forgings shall be demagnetized after the magnetic particle test.
One TCTT of each heat treated batch shall be tested for hardness in accordance with IS: 1500- 2005. `Method for Brinell Hardness Tests for Steel' and shall conform to hardness range of 330 to 380 BHN. The manufacturer shall provide testing facilities. Hardness values shall be determined at three different locations of the TCTT i.e. shank, middle and on the tamping blade of the TCTT.
The physical and other properties of the tungsten carbide inserts and braze material shall conform to Para 5.1 to 5.3 of this specification.
Inspection: The material shall be inspected by Indian Railways' official(s) to ensure supply as per stipulation in this specification. Certificate of inspection and approval for dispatch of TCTT shall be issued by the nominated officer(s) as per Annexure-1. For this purposes the supplier shall provide all necessary facilities including equipment and material required for testing free of cost. He shall also produce all relevant documents/certificates in respect to properties, source and quality etc. of the material. Copies of the Maker's certificate guaranteeing the performance of the TCTT shall be supplied in duplicate among with the delivery of each equipment.
The inspecting official shall carry out the checking of all records/certificates and their relevant metallurgical tests contained in Para 3.1, 3.3, 5.0, 11.0, 12.0 & 13.0 at the manufacturer’s premises before the dispatch of TCTT to consignee.
15.2 If the results of the product analysis do not meet the composition requirements given in table 1 of clause 3.3 of this specification, two new samples shall be taken from different pieces from the same batch. Should the two analyses satisfy the requirements, the lot represented shall be accepted. Should either of the two fail, the material shall be taken as not complying with the standard. 15.3
If the results of the product analysis do not meet the requirements given in clause 11.0 of this specification, two new samples shall be taken from different pieces from the same batch. Should the two analyses satisfy the requirements, the lot
represented shall be accepted. Should either of the tests fail, the material shall be taken as not complying with the standard. 15.4
If the samples selected fail to meet the requirement given in para 5.0, 12.0 & 13.0 of this specification, two further samples shall be selected from same heat treatment batch. The consignment shall be considered to conform to the requirements if both the additional tests are satisfactory. .
The components shall be carefully protected with three coats of ready mixed paint, brushing bituminous black to IS: 9862 - 1981 or with any other equivalent antirust compound approved by the purchaser, allowing sufficient drying time between each coat. Packing of the TCTT must withstand the weight of the tool and tungsten carbide nibs must be protected to prevent damage while handling. Holding area must be oiled with rust preventing oil.
Performance monitoring of TCTT:
The average service life of TCTT shall be guaranteed for tamping of 325 km with limiting wear being not more than 20% of the original surface area of the ballast squeezing face/side of TCTT spade. There should not be any breakage of TCTT or inserts or spade or in-service TCTT arm holder taper problem, which may render the TCTT unserviceable. The purchaser shall ensure to achieve the above mentioned service life of the TCTT for which necessary provisions are provided in the contract /payment conditions.
During service, the observations shall be recorded by the operator of machine on the joint measurement programme containing following details. i) ii) iii) iv) v) vi) vii) viii) ix)
Date of inspection, Tamping machine, Type of ballast, Total track km tamped, Number of insertions, Width and height of spade of all TCTT, Taper of TCTT shank Condition of TCTT arm bore Taper of TCTT arm holder
At the time of replacement of TCTT, following details shall be recorded to determine their average service life. The service life of all TCTT of the same set may vary depending upon their location i) ii) iii) iv) v) vi) vii)
Date of installation Date replacement, Total nos. of insertion Km tamped, Measurement of the size of spade of the TCTT, Reasons for replacement, Location (type) of TCTT.
Required manual / instructions for installation, removal and upkeep of the TCTT shall be supplied by the manufacturer.
Tungsten carbide inserts should not chip out or break by their occasional hitting with concrete sleepers, rock, rail pieces, loose fish plate, foundation stone, etc buried inside ballast.
Criteria for TCTT condemnation: The spade area of TCTT determines the life of TCTT. When this area falls below stipulated limit TCTT shall be replaced. For the purpose of condemnation, the effective reduced area of TCTT spade should not be less than 80% of the original surface area of the TCTT spade given by the OEM of tie tamping machine.
Wet instrumental analysis method for chemical analysis of steel and facilities for the estimation of Silver brazing alloys are available
The firm should, preferably, be equipped with Universal Testing Machine of adequate capacity for tensile yield, elongation and bend tests.
The following Microscopic examination facilities should be available: Metallurgical Microscope with magnification upto 500 x. Preparation of metallographic test specimen.
The firm should be equipped with minimum one No. Magnaflux crack detector of adequate amperage for longitudinal and circular magnetization of the TCTT.
Brinell Hardness Tester with standard calibration test pieces is available. Instrument suitable for the inspection of physical properties hardness on Rockwell (A scale) of Tungsten carbide inserts, welding and TCTT should be available with the manufacturer.
The firm should, preferably be equipped with a dedicated proof load test set-up with capacity up-to 25t and with facility of recording load-deflection characteristics of the product.
All required measuring instruments / gauges in adequate number should be available i.e. micrometers, dial gauges, vernier calipers, GO, NO-GO gauges for all-important dimensions of the product.
Quality control requirements:
There should be a system to ensure the traceability of the product from raw material stage to finished product stage. This system should also facilitate to identify the raw material composition from the finish product stage.
Ensure that there is a Quality Assurance Plan for the product detailing various aspects: Organizational Chart Flow Process Chart Stage inspection details Various parameters and to ensure control over them.
The QAP shall be available as per the requirements.
Ensure that proper analysis is being done on regular basis to study the rejection at various internal stages and it is documented.
Ensure that prior to release of dies for production it should be dimensionally checked in all respects including its mounting on the forging equipment.
Ensure that critical inspection of the first forging and last forging of a production run is essentially carried out to ascertain behavior of the dies in operation and product quality.
Ensure that all the relevant specifications, code; standards are available with the firm. Details of common and patented specification shall be furnished along with tender document so as to facilitate inspection and avoid supply of spurious items.
Infrastructure and quality control work related with manufacture of Tungsten Carbide Tip Tamping Tool shall be documented and furnished along with tender
Individual component suppliers should be certified ISO-9001 which include supplier of steel, forging tungsten carbide silver solder brazing and welding operations.
The manufacturer may be following exceeding technical specification, which may be different in order to achieve higher service life of "TCTT". In case of any such deviations, manufacturer shall furnish technical details and supporting relevant codes and specification with tender documents and as and when required by the purchaser.