Recommended
More Related Content
What's hot
What's hot (20)
Similar to Unit 2_serial number restoration.pptx
Similar to Unit 2_serial number restoration.pptx (20)
More from Suchita Rawat
More from Suchita Rawat (20)
Recently uploaded
Recently uploaded (20)
Unit 2_serial number restoration.pptx
- 3. Forensic Implication of Serial number restoration This Photo by Unknown Author is licensed under CC BY-SA
- 4. METHODS OF APPLICATION Dye stamping Metal substrate Rolling Substrate that can be damaged by sudden impact
- 5. METHODS OF APPLICATION Hot Stamping Polymer substrate Pin stamping
- 6. METHODS OF APPLICATION Engraving Plastic substrate Laser Etching
- 7. METHODS OF APPLICATION Embossing Thin metal plates Traditional Printing methods
- 8. Methods Used to Obliterate Serial numbers *Filing or grinding/Peening/over stamping/center punching/substitution/drilling/ wielding/chemical l reagents
- 9. Restoration Methods: Metals Forensic practitioners are often confronted with die-stamped serial numbers that have been ground off metal substrates. This is particularly common in cases involving theft of motor vehicles or the use of firearms. methods employed for recovering obliterated serial is ‘chemical etching’ and ‘heat treatment’ Sample preparation: finer grades of waterproof abrasive paper Reference: Houck & Max M (2013)
- 10. Restoration Methods: Metals (Chemical etching) Reference: Houck & Max M (2013) For recovering obliterated numbers, the method relies on the phenomenon that the rate of reaction between the applied chemicals and the substrate can differ in the damaged and undamaged areas Method of application: electropolishing
- 11. Restoration Methods: Metals (Heat treatmen Heat Treatment Restoration of the obliterated serial number on cast iron and limited extent to aluminum alloys. Advantage: fast compared to chemical etching In this method, the obliterated area is heated until the metal glows a light cherry red. This results in the release of the residual tensile stresses and allows the compressed area to bulge above the surroundings (Figure 5). After heating, the area is lightly rubbed with abrasive paper, which removes any soot or oxide layer from the raised characters
- 12. Restoration Methods: Metals (Magnetic particle method) recovery of serial numbers on small objects such as firearms. In this technique, the object is magnetized and then sprayed with fine magnetic particles. The particles are attracted to regions on the surface, where a crack or other damage has occurred. Advantage: nondestructive Limitations: To magnetize, the object requires either running a high amperage electric current through it or placing the object in contact with a large magnet. Not possible for the serial number stamped on an engine still fitted into a motor vehicle
- 13. Restoration Methods: Metals Ultrasonic Cavitation Recovery of obliterated serial numbers in metal objects is possible if they are placed into a water bath, which is excited by an ultrasonic sound frequency. Formation of bubbles in liquid are of high energy and have the capability to etch metal surfaces Advantage: of being applicable to a wide variety of metals and not requiring the use of chemicals. Disadvantage : only suitable for small objects. It is also destructive
- 14. X-Rays The method has been successfully used to locate serial numbers that have been hidden with paint or body filler, or by welding another piece of metal on top of the original.
- 15. Methods for restoration of obliterated SN on wood , leather, rubber, plastic and painted number plate Wood (punched marks) :jet of steam while for hard wood pretreat with a solution of caustic soda (NaOH) or potash (KCL) Leather (Clean the surface with cotton-wool swab soaked in chloroform or 2N caustic soda solutions and examine under ultraviolet light ) Rubber (lightly swabbing with petrol or even on occasions carbon-disulphide)
- 16. Methods for restoration of obliterated SN on wood , leather, rubber, plastic and painted number plate Ethanol, ethyl ether Wash away the fresh paint and the fresh number with chloroform or dioxan followed by X-ray shadowgraph
- 17. LIMITATION of Serial number Restoration Drilling and welding, Centre punching (obliteration method) Laser Labelling (addition of serial number)
- 18. CASE STUDIES SERIAL NUMBER RESTORATION
- 20. Case I: Tata Xenon pickup truck Source: Sharma & Jha (2015). * M A T 4 6 4 2 0 3 C S K 0 2 4 1 0 *
- 21. Case II: Trailer truck Source: Sharma & Jha (2015). 4 4 7 2 0 7 M T Z 3 0 1 7 2 5
- 22. Case III: Truck Source: Sharma & Jha (2015). * M A T 4 1 6 4 7 1 A 7 E 2 1 9 9 4 *
- 23. Case IV: Truck Source: Sharma & Jha (2015). 4 2 6 0 3 1 G S Z 7 2 9 7 7 0
- 24. Case V: Motorcycle Source: Sharma & Jha (2015). 0 2 M * 8 E 3 6 6 0 4 * cannot be deciphered
- 25. References Houck, Max M. "Serial Number." (2013): 43-47. Sharma, M., & Jha, S. (2015). Analysis of Obliterated Vehicle Identification Numbers: Five Case Studies.
- 26. This Photo by Unknown Author is licensed under CC BY-SA
Editor's Notes
- Die stamping- An ‘inverse positive’ of the character to be stamped is created and then applied to the substrate under sudden pressure. Rolling A similar process to die stamping, where the characters to be stamped are applied to the substrate with a slower, steadier pressure.
- Hot stamping A heated die is used to produce an impressed character in a polymer. Pin stamping Small pins are used to form individual dots on the substrate, using an impact process; the process is analogous to dot matrix printing.
- Laser etching The serial number is burned into the substrate by applying a laser. Nonindustrial engraving The substrate is cut away, leaving marks that form the serial number.
- Embossing Similar to die stamping or rolling but is used on thin metal plates to produce a raised print appearance. The die is pushed on to the plate from behind. Traditional printing methods A variety of printing techniques can be used to apply serial numbers, especially on adhesive labels or cloth stock.
- Filing or grinding—The original number is filed away or ground down with a power grinder, followed by polishing, and then over-stamping with a new number. Peening—This involves hammering the surface with a round punch to hide the number. Over-stamping—Here, a new number is simply stamped over the old. Center-punching—The surface bearing the number is obliterated with a pointed punch Substitution—An iron plate bearing a new number is pasted or welded over the original surface. Drilling—This removes the number and the surrounding metal with a drill. The cavity is usually filled up with either lead solder or welding material. Welding—The surface is heated with either an oxy-acetylene welder or an arc-welder until the metal flows.
- Note that a number of factors may influence how far into the substrate the damaged area extends. These include the composition of the material, as well as the force used to stamp the number. If the surface is ground off deeply enough, it is possib le that all traces of the damaged area will be obliterated Before either method can be applied, the surface must be prepared. This involves removing as much as possible in the way of residual irregularities, in order to obtain as smooth a surface as possible using finer grades of waterproof abrasive paper (known as ‘wet and dry’ paper) should be used to gradually smooth out the surface, with the best results being obtained from a mirrorlike finish.
- The solutions are generally applied by wiping them across the surface of the substrate with a cotton wool or cloth swab. This process is repeated regularly, and the surface is observed closely between applications. form a dam of plasticine around the area, then pour the etching solution into this to a depth of 2–5 mm
- Cast iron is a group of iron-carbon alloys with a carb on content of more than 2 to 4 percent . They therefore stand out in contrast to the dark surroundings. There is no specific temperature at which a heat treatment recovery will take place. Factors including the depth of the impression and the exact composition of the substrate will affect the temperature required
- n this case, the driver of a Tata Xenon pickup truck was stopped by the police and subsequently found to be transporting 500 kg of Doda Chura (poppy straw—the dried, upper portion of the opium poppy, minus the seeds). examined the chassis and engine of the truck. It was evident that grinding and rubbing had been performed in the area of the chassis number. The number plate was missing from the engine. We were able to successfully restore the original numbers of the pickup truck. The following process is utilized when peening is observed (Images 1.1-1.5): First, prepare the surface using a file to polish and clear the damage caused by the pointed punch. Next, treat the surface with the solution shown in the flow chart for the iron-based chassis. The solution can be applied continuously for about 9 to 12 hours, or over the course of 2 to 3 days for 5 hours per day. Photographs should be taken before and after each step to document the process.
- an individual claimed that his trailer truck was stolen, and that the thief had tampered with the chassis and engine numbers and re-painted the vehicle. Our team treated the original position of the chassis number and the newly stamped chassis number.
- In this case, one truck was found in a jungle by a night surveillance team of the highway police. The number could not be traced by the police at that time, so the police called our team to examine the chassis number. Our team treated the newly stamped chassis number that was placed over the position of the original chassis number.
- In this case, one truck was detained by the Road Transport Office during an inspection that found the registration certificate and other papers related to the truck did not match.
- Case V: Motorcycle In this case, a motorcycle was stopped at a checkpoint when officials noticed the motorcycle did not display the same number on its chassis as it did on its engine.