Descrição: Featuring strategies employed in Lean, this volume describes the experiences of organizations using TWI more than 60 years after the Training Within Industry program turned the U.S. into the indust...
Bahan presentasi tentang Training Within Industry. Skill yang perlu dimiliki dalam SUPERVISORY. Skill yang harus dikuasai oleh Supervisor, Manager, DirekturFull description
Exercise, learn how to interpret weld defect. Latihan, interpretasi cacat lasan. Untuk mendownload, silakan kunjungi link berikut: http://www.ziddu.com/download/11659427/BacaFilm02rev.pdf…Full description
Intensifying Screens Radiographic film is usually sandwiched between two intensifying screens There are three main there are three main types of intensifying screens
Lead Intensifying Screens Film placed between 2 intensifying screens Intensification action achieved by emitting particulate radiation (electrons/beta) Generally lead of 0.02mm to 0.15mm Front screen shortens exposure time and
Image Formation When radiation passes through an object it is differentially absorbed depending upon the materials thickness and any differing densities The portions of radiographic film that receive sufficient amounts of radiation undergo minute changes to produce the latent image (hidden image) 1. The silver halide crystals are partially converted into metallic silver to produce the latent image
2. The affected crystals are then amplified by the developer, the developer completely converts the affected crystals into metallic silver
Processing Systems Development Metallic Silver converted into Black metallic silver 3-5 min at 20OC Main Constituents Developing agent metol-hydroquinone Accelerator keeps solution alkaline Restrainer ensures only exposed silver halides converted Preservative prevents oxidation by air Replenishment
Purpose – to ensure that the activity of the developer and the developing time required remains constant Guideline – 1. After 1m2 of film has been developed, about 400 ml of replenisher needs to be added
Film Processing Fixer Supplied as a liquid concentrated acid mixed to 1 part fixer to 3 parts water Fixing temperatures for manual processing 20oC Fixing times are twice the clearing time, clearing time about 3 minutes, fixing time about 6 minutes During the fixing process agitation should take place to avoid light spots on the radiograph
Film Processing Washing / Drying After washing in running water the films may be placed in a wetting agent to reduce surface tension this results in even drying, preventing black streaky marks on the radiograph Before drying excess water should be removed with the use of a squeegee Drying should take place in a dust free environment
Film Characteristic Curve Information which can be obtained from a films characteristic curve The position of the curve on the exposure axis gives information about the films speed
Film Characteristic Curve Information which can be obtained from a films characteristic curve
The position of the curve on the exposure axis gives information about the films speed The gradient of the curve gives information on the films contrast
Film Characteristic Curve Information which can be obtained from a films characteristic curve
The position of the curve on the exposure axis gives information about the films speed The gradient of the curve gives information on the films contrast The position of the straight line portion of the curve against the density axis will show the density range within which the film is at its optimal
Changing Density Density achieved 1.5 Density required
Density
2.5
2.5
Determine interval between logs 1.8 - 1.3 = 0.5 Antilog of 0.5 = 3.18 Therefore multiply exposure by 3.18 (measured density is lower than the required density)
Determination of Exposure X-ray exposures are less straight forward because the wavelength and intensity are variable X-ray exposures are determined by the following By using exposure charts By reference to previous exposure records
By trial and error test shots By a combination of the above
