Halil_Kayhan_030070090_9th_week_definitions

1. Solid-State Welding:

In solid state welding, coalescence of the part surfaces is achieved by pressure alone, heat and pressure. For some solid state processes, time is also a factor. If both heat and pressure are used, the amount of heat by itself is not sufficent to cause melting of the work surfaces. In other words, fusion of the parts would not occur using only the heat that is externally applied in the processes. In some cases, the combination of heat and pressure, or the particular manner in which pressure alone is applied, generates sufficient energy to cause localized melting of the faying surfaces. Filler metal is not added in solid state welding.

(Fundamentals of Modern Manufacturing: Materials, Processes, and Systems, Mikell P. Groover, p.732)

Solid-State Welding(new)(Manufacturing)

The principle of solid state welding is that if two metals whose surfaces are free from contamination are forced together with a great enough force they will form a joint. In some solid state welding processes. such as cold pressure welding, no heat is applied but is generated during the process. However, in most processes heat is applied to improve the bonding between surfaces. This type of welding process can be classified as either electrical, chemical or mechanical solid state welding.
(Peter Scallan, Process Planning: The Design/Manufacture Interface, page 140)

The new one is better.

2. Visual Testing

Visual testing (VT) is by far the most powerful inspection method available. Because of its relative simplicity and lack of sophisticated equipment, some people discount its power. However, it is the only inspection method that can and should be applied during each step of the welding process,rather than after the weld has been made, it is the only method that can actually increase the qualityof fabrication and reduce the generation of welding defects.Most standards require that all welds be visually inspected. Visual inspection begins long before an arc is struck. Materials that are to be welded must be examined for quality, type, size, cleanliness,and freedom from defects. The pieces to be joined should be checked for straightness, flatness, anddimensions. Alignment and fit up of parts should be examined. Joint preparation should be verified.Procedural data should be reviewed, and production compliance assured. All of these factors precede any welding that will be performed.During welding, visual testing includes verification that the procedures used are in compliance with the welding procedure specification. Upon completion of the weld bead, the individual weld passes are inspected for signs of porosity, slag inclusion, and any weld cracks. Bead size, shape, and sequences can be observed. Interpass temperatures can be verified before subsequent passes are applied. Visual inspection can ensure compliance with procedural requirements. Upon completing the weld, the size, appearance, bead profile, and surface quality can be inspected. Visual testing should be performed by the weld inspector, as well as by the welder. Good lighting and eye sight is imperative. In most fabrication shops, some type of auxiliary lighting is required for effective visual inspection. Magnifying glasses, gauges, and workmanship samples all aid in visual testing.

(Geng H., Manufacturing Engineering Handbook, p. 21.39)

Visual Testing(New)(Inspection)
The installation rrisst be visually inspected before testing begins. The aim of the visual inspoction is to confirm that all equipment and accossones are undamaged and comply with the relevant British and European Standards, and 31S0 that the installation has boon securely and correctly erected. IEE Regulation 611.3 gives a checkIct for the initial v;sual inspection of an installation, including:

• connection of conductors;
• identification of conductors;
• routing of cables in safe zones;
• selection of conductors for current-carrying capacity and volt drop;
• connection of single-pole devices for protection or switching in phase conductors only;
• correct connection of socket outlets, lampholders, accessories and equipment;
• presence of fee barriers. suitable seals and protection against thermal effects;
• methods of 'Basic Protection' against electric shock, including the insulation of live parts and placement of live parts out of reach by fitting appropriate barriers and enclosures;
• methods of 'Fault Protection against electric shock including the presence of earthing conductors for troth protective bonding and supplementary bonding.
• prevention of detrimental influences (e.g. corrosion);

( Trevor Linsley, Basic Electrical Installation Work, page 282)
The new one is better.


3. Biodegradable Polymers (New)(Material)
No older one
Biodegradability and compostability arc clearly defined by the scientific community and were legally incorporated into a Standard by the American Society for Testing and Materials (AsTm), under reference ASTM D 6400- 99, in July 1999. Similar definitions have been recognised in several countries around the world, the most significant being DIN CERTCO 54900 in Germany. Harmonisation of the definitions was carried out through the International Biodegradable Products Institute (BM), which signed a memorandum of understanding with the Japanese Biodegradable Plastics Society and the German DIN CERTCO.
The ASTM defines a biodegradable plastic as a degradable plastic in which the degradation results from the action of naturally occurring microorganisms such as bacteria, fungi and algae. Composting is defined as a managed process that controls the biological decomposition of biodegradable materials into a humus-like substance called compost; the aerobic and mesophilic and thermophilic degradation of organic matter to make compost; the transformation of biologically decomposable materials through a controlled process of bio-oxidation that proceeds through mcsophilic and thermophilic phases and results in the production of carbon dioxide, water, minerals and stabilised organic matter (compost or humus).
Following the international agreement on definitions for biodegradable plastics, specified periods of time, disposal pathways and standard test methodologies were incorporated into the definitions. Standardisation organisations such as CEN, International Standards Organisation (ISO) and American Society for Testing and Materials (ASTM) were consequently encouraged to develop standard biodegradation tests so these could be determined. Society further demanded non-debatable criteria for the evaluation of the suitability of polymeric materials for disposal in specific waste streams such as composting or anaerobic digestion. Biodegradability is usually just one of the essential criteria. besides ecotoxicity and effects on waste treatment processes.

(David K. Platt,Rapra Technology Limited, Biodegradable Polymers: Market Report, page 1951)