Question

Explain the summary in details about the “Journal of Materials Processing Technology 106(2000) 173-183, Advances in materials applied in civil engineering K. Flaga. These explanations should be 1000 words or more

Answer 1

Materials processing Technology:

For easy storage and transport, materials are generally changed into simple shapes after collection and initial processing. For example, metals are changed into sheets, bars, boards or rods timbers are cut into boards and wooden sticks; and plastic materials are
converted into plastic grains, plastic boards and plastic strips, etc. (a) Metallic sheet and bar (b) Boards
The purpose of cutting, forming, joining and surface processing of materials is to make products suit our needs. These processes are called ‘Material Processing’. For example, metals are used to make tools , timbers are used to make chairs and plastics are
used to make stationery .To raise the quality of the artefacts, we should have a comprehensive understanding on various kinds of material processing technology.

Methods of materials processing:

There may be various ways to produce an object. For example, hand tools such as saws and files, and machines like sawing machine and milling machine are all suitable for making an L-shape
metallic workpiece. So, which is the best material processing method?
Normally, the best method is the one which incurs the lowest production cost and fits all requirements of the artifacts. For example, appropriate size and preciseness, suitable surface-processing, time limit and quantity. Costs always include fixed cost and variable cost.
shows the typical relationships between cost and quantity of production. (a) Fixed cost (b) Variable cost
Fixed cost is the cost which is independent from changes in quantity of production, say cost of purchasing machines and rent for workplace, etc. However, if quantity of production is large enough to an extent that additional machines are needed, fixed cost will be triggered up
Variable cost refers to the cost that increases with the quantity of production. For example, electricity expenses for operation of machines and expenses on the purchase of raw materials.The larger the quantity of production, the lower the fixed cost that each product shares, while there is no change in variable cost.
Processing methods such as cutting, joining and surface-processing which suit the requirements for products should be listed out before calculating and comparing production cost

a)cutting method:

The following factors should be considered when choosing the best cutting method:
1. Limitation of resources
2. Size and shape of workpiece
3. Material of workpiece
4. Surface quality and preciseness
5. Quantity of production

With the advancement in technology, production methods are developed from traditional manual ones to speedy and mass production in large-scale factories using huge amount of labour
and machinery.

(a) Mass production
Total production cost includes fixed cost and variable cost. Relationships between total
cost and quantity of products Average cost of producing each product can be calculated by dividing total cost with the quantity of products produced.indicates that there is a negative relationship between total cost and quantity of products. The more the products produced, the lower the average cost. (a) Change in total cost (b) Change in average cost .Producers may lower production cost by means of mass production. At the same time, they can lower the selling price of their goods in order to raise sales and competitiveness of the product. Total profit will also be increased if products can be sold at a large scale. At the same time, consumers will also benefit. For example, production of a car by one technician needs lots of time and extremely high cost compared with mass production in cars factories. However, not every product can be produced by mass production. For example, civil aircrafts may not be mass produced as operation cost for them is very high and lower manufacturing cost is not efficient to stimulate demand. Special technology and methods are needed to speed up the process of mass production. First of all, a product is broken down into different components, and each component is to be processed by different workers. Processed parts are then assembled into the final product. Since every worker is responsible for one production procedure only, workers can concentrate on their own procedures and have their skills practised, thus raising the efficiency of production at the end. Moreover, templates, jigs, fixtures and simplified procedures are designed by technical engineers to save production time
(i) Templates
In order to have mass production of products with similar qualities, product size and shapes should be standardized. However, lots of working time will be spent if workers have to do the measurement on every product they process. Templates are aids designed by engineers according to the size and processing procedures of the workpieces. Workers can do the processing work efficiently by placing the workpiece onto the template and follow the dimensions. This not only increases production efficiency, but also lowers opportunities for workers to make mistakes.

(ii) Fixtures and jigs
Fixtures are devices used to fix and hold the workpieces and their functions are similar to that of templates. Strictly speaking, traditional holding tools (e.g. vice) also fall in this category. However, fixtures usually have specific functions and are used with lathe, milling machine and grinding machine. Specified processing procedures can proceed once the workpiece is clamped by fixtures. Since there is no need to carry out measurement, the chance for workers to make mistakes is small.Jigs are also devices for holding and fixing position of workpieces. Jigs, especially bits of drills, can direct the cutting at the same time. They make bits fixed to a point when drilling begins. Drilling procedure can be started once the workpiece is clamped by the fixture. This not only saves time from adjusting position for drilling, but also lowers the possibility of making mistakes. (b) Assembly line
Parts should be assembled to form final products after individual processing. Usually,
engineers would design an assembly line to raise the speed and efficiency of product assembling.

Since every worker is responsible for a simple processing procedure in an assembly line, workers can perform their work skillfully and rapidly, and hence raise the production efficiency. Some factories even make use of various technologies to improve their production, for example, finding the most simple and direct procedure by analyzing workers’ motions; applying ergonomics on reducing the distance and time spent on hand moving. However, workers should be allowed to
have rests frequently in order to avoid over-exhaustion.
(c) Production line
Production line results from replacing workers in assembly line with different processing procedures. Many procedures that are operated by man in the past are now by automatic machinery. For example, clocks can be assembled automatically by machines. This
method is efficient in saving labour cost as well as in raising production speed and quality. Hence, more and more factories use automatic production line to have 24-hour production to raise production to a greater extent. Production line is also useful for large-scale car producers but investment is great as it is expensive to purchase, install and maintain automatic production devices. Therefore, labour-intensive production may still be more economical for areas with cheap labour.