1. What are the main responsibilities of the employer and the employee under Health and Safety Act 1992?
Answer :
Duties of employers:
Every employer shall take all practicable steps to ensure that no action or inaction of any employee while at work harms any other person.
Duties of employees
Every employee shall take all practicable steps to ensure-
(a) the employee’s safety while at work (including by using suitable protective clothing and suitable protective equipment provided by the employer
(b) that no action or inaction of the employee while at work causes harm to any other person.
(health and sefatey in employment act 1992, 2014)
2. In marking the choice of which type of cutting fluid to use, many factors have to be considered. Name two of the important factors?
Answer: selection of the cutting fluid generally depends on the types of machining process whether coolant, lubricant or both are required. Though selection for the effective cutting fluid depends the various factors which are type of machining , tool and workpiece materials, cutting speed, and the method of application.
For example: machining process with slower cutting operation and where tools are exposed to high pressure in such cases fluid with good lubricating characteristics is required. Whereas, selection for the fluid is changed in high speed operation as in high speed operation temperature rises significantly so that fluid which has good cooling capacity and with some lubricity is required.
(manufacturing engineering and technology, 2014, p. 617)
3. What is the purpose of chip breakers in the Turning Process?
Answer: purpose of chip breaker in turning process:
- chip breaker controls the flow of the chip during machining.
- Eliminates the long chips as it can be hazard.
- Also reduce the heat.
- Reduce the intendancy of the vibration.
(manufacturing engineering and technology, 2014, p. 607)
4. What effect would decrease the cutting speed have on tool life of a milling cutter?
Answer: Because high cutting speed increases the temperature which results into the shorting of the tool.
(manufacturing engineering and technology, 2014, p. 585)
5. Name two ways work can be held on a cylindrical grinder?
Answer: Universal grinding: In universal grinding, both the workpiece and the wheel axes can be moved and swivelled around a horizontal plane, thus permitting the grinding of tapers and other shapes
Thread grinding: thread grinding is done cylindrical grinders, using specially dressed wheels matching the shape of the thread.
(manufacturing engineering and technology, 2014, p. 748)
6. how is feed specified on a drilling machine?
Answer:
|
(drill feeds and speeds, n.d.)
7. What is the difference between truing and dressing a grinding wheel?
Answer: dressing is the process of a conditioning, producing sharp new edges on worn grains on the grinding surface of a wheel
Truing: truing is the process of producing a true circle on a wheel that has become out of round.
(manufacturing engineering and technology, 2014, p. 744)
8. In wire cut EDM, why does electrode wear not affect the accuracy of the cut?
Answer: Because electrode doesn’t touches the workpiece.
(manufacturing engineering and technology, 2014, p. 781)
9. What is concurrent engineering?
Answer: Concurrent engineering also known as integrated product development (IPD) its methodology is based on the parallelisation of task which means preforming the task concurrently. Concurrent engineering prefers to an approach to new product development in which all other engineering functions like design engineering, manufacturing engineering and other functions are integrated together in order to reduce the elapsed time required to bring new product to the market.
(concurrent engineering , 2017)
10. In welding, what do the letters GTAW stand for?
Answer: Gas tungsten arc welding
(GTAW, 2017)
11. Define break-even point when comparing two types of machines making the same part?
Answer: Break-even perspective are the purpose which offers precisely disguise its costs. Therefore these methods not lead to any benefit or reduction. When two different machines are making same part, the purpose of which is to offers disguise costs.
12. In machining operations, how does forming differ from generating?
Answer: generating: generating machining operations of the workpiece are dependent on the feed or the movement of the cutting tool which involves different turning operations such as straight cutting, taper turning, peripheral milling and profile milling.
Whereas forming machining operations is based workpiece geometry dependent on the tool geometry. Cutting edge of the tool and surface of the work part has the reverse shape example: form turning, broaching, drilling.
(Forming and Generating Method in Lathe Machine Operations, 2016)
13. What are the two forms of broaching and what types of machine is used for each form?
Answer: surface broaches: surface broches which generally used for cutting flat surface. Broches includes slab, slot, contour, dovetail, pot ( for precision external shapes) and straddle.
Internal broaches: internal broaches which is generally used for close-tolerance hole. Broches includes hole keyway, internal gear, rifling (for gun barrels).
(manufacturing engineering and technology, 2014, p. 684)
14. What is difference between a CNC machining centre and a universal milling machine?
Answer: cnc machining centre is computer controlled program, which takes the instruction from the computer to select and control tools that used for cutting or shaping the metal to new product. Whereas universal milling machine is fitted with table so that it can have motion in all direction and also diving head which has ability to change gears so they can perform milling operation in all the direction.
(manufacturing engineering and technology, 2014, pp. 703,705,669)
15. State an essential requirement for a lathe, which is intended to be used with diamond tooling
Answer: diamond tooling is done when we have to give good surface finish and critical dimension for example: for polishing granite
(manufacturing engineering and technology, 2014, p. 614)
16. What type of machining process would be used to cut an external keyway in a shaft?
Answer: machining process used to cut keyways in a shaft is keyway broaching also known as spline broaching
(coupling answers, 2014)
17. Define what is meant by CAD CAM?
Answer: CAD: computer aided design
CAD, which basically based on the principle of creating a technical drawing using different software like AUTOCAD, SOLIDWORKS, and PRO-E
CAM: computer aided manufacturing
Whereas CAM is referred as an software use to control manufacturing process like controlling machining tool which gives high precision. Machine used on the principle of CAM is known as CNC computer numerical control machine.
(wikipedia , 2017)
18. Name two materials used to produce EDM electrodes for a sink type machine
Answer: The materials which are commonly used for the making sinker EDM electrode are graphite, brass or copper tungsten. Graphite is used because of its superior machining capabilities and wearability, and copper is used because of its fine finish requirements.
(qualitty EDM, 2008)
19. What feature controls the cutting speed of a milling centre?
Answer: As we know the cutting speed V in peripheral milling is the surface speed of the cutter
V = πDN
Where D is the cutter diameter and N is the rotational speed of the cutter.
Thus cutting speed is directly dependent on the diameter and as well as the rotational speed of the cutter.
(serope kalpakjian, 2014)
20. What is the main difference in the type of materials that can be machined when using either EDM or Water Jet cutting process?
Answer: water jet cutting process: non-conductive material such as glass. Wood, plastic, ceramic
EDM: material needs to be electrical conductive as EDM cuts through sparks such as graphite and metal
(advanced manufractruring , 2005)
21. Compare 2 of the following casting processes on surface finish, accuracy, type of pattern and cost
a. Sand moulding
b. Shell moulding
c. Gravity die casting
d. Pressure die casting
Answer:
|
Sand moulding |
Shell moulding |
|
|
Surface finish |
Not good machining, forging, may required to obtain the required shape followed by the quality control |
Good surface finish |
|
Accuracy |
Dimensionally accurate |
High precision |
|
Type of pattern |
Match plate pattern |
Many pattern |
|
Cost |
Low cost |
Low cost |
(manufacturing engineering and technology, 2014, pp. 705,711)
22. Explain the purpose for which the investment casting process is used. Indicate the type of material that can be cast and some general estimate of the finish and accuracy obtained
Answer: Purpose: knee replacement
Type of material: ferrous and non-ferrous metal alloys.
Surface finish: good surface finish
Accuracy: high precision
(manufacturing engineering and technology, 2014, pp. 271-272)
23. Explain clearly the difference between the HOT and COLD chamber die casting processes, giving the types of material casting in each process
Answer: Hot-chamber process use a piston to forces a certain volume of metal into the die cavity through a gooseneck and nozzle
2.Cold-chamber process is where molten metal is poured into the injection cylinder (shot chamber)
(manufacturing engineering and technology, 2014, pp. 278-279)
24. Giving examples of each show the difference between injection moulded and compression moulded plastic parts
Answer:
|
Injection moulded plastic |
Compression moulded plastic |
|
in injection moulded is used with thermoplastic polymers |
Compression moulding is used with thermosetting plastics |
|
for example: injection moulding is used for making chair. machine has three main parts i.e. injection unit, mould and clamp. process starts when plastic is poured into hopper from where plastic pallet moves to the barrel of injection unit inside, a screw transports the pallets forward t. heater bands wrapped around the barrel warms up the plastic pallets. as the pellets are moved forward by the screw, they gradually melt, and are entirely molten by the time they reaches the front of the barrel. once enough molten plastic is in the front of the screw it rams forward like the plunger of a syringe. in a matter of seconds, the screw injects the molten plastic into the empty part of the mould called the cavity image. the plastic solidifies in under a minute the mould opens and the part is ejected. |
for example: compression moulding is used to make rubber boots for which plastic is pre heated and then poured into the mould and held there for few minutes at fixed temperature and then finished product is then removed from the mould and then can be machined for further better finish or removal of the waste |
|
(plastic injection molding , 2015) |
(manufacturing engineering and technology, 2014, pp. 512,520) |
25. What is the main difference between Hot Rolling and Cold Rolling, Giving examples of each process?
Answer:
|
Hot rolling |
Cold rolling |
|
Low tolerance |
High tolerance |
|
More Malleable |
Increase strength of material through strain Harding as much as 20% |
|
High temperature up to 1000’F |
Low temperature equal to room temperature |
|
Sink when cooled down |
More precise dimensions |
|
Hot rolled steel is used in situations where precise shapes and tolerances are not required For example: used in welding and I-beam |
cold rolled steel is used in situations where precise shapes and tolerances are required. For example: used in production of metal furniture or desks. |
(n.d.). Retrieved from https://www.metalsupermarkets.com/difference-between-hot-rolled-steel-and-cold-rolled-steel/
administration, n. z. (2014, april 4). health and sefatey in employment act 1992. Retrieved from new zealand legislation: http://www.legislation.govt.nz/act/public/1992/0096/latest/DLM278829.html
concurrent engineering . (2017, march 7). Retrieved from wikipedia : https://en.wikipedia.org/wiki/Concurrent_engineering
coupling answers. (2014, december 2). Cutting Keyways – Broaching, Keyseating, Wire-Cut EDM, Shaping, & Milling . Retrieved from coupling answer: http://www.couplinganswers.com/2014/12/cutting-keyways-broaching-keyseating.html
crayons, s. (Director). (2015). plastic injection molding [Motion Picture].
drill feeds and speeds. (n.d.). Retrieved from viking drill and tool : http://www.vikingdrill.com/viking-Drill-FeedandSpeed.php
Forming and Generating Method in Lathe Machine Operations. (2016, februray 17). Retrieved from mechaenical engineering: https://basicmechanicalengineering.com/forming-and-generating-method-in-lathe-machine-operations/
government, n. z. (1992, jan 1). health and safety employment act 1993. Retrieved from New Zealand legislation : http://www.legislation.govt.nz/act/public/1992/0096/latest/DLM279232.html
GTAW. (2017, march 11). Retrieved from wikipedia : https://en.wikipedia.org/wiki/Gas_tungsten_arc_welding
metalsupermaket. (2014, septemeber 14). difference between hot rolled and cold rolled steel . Retrieved from metal supermarket : https://www.metalsupermarkets.com/difference-between-hot-rolled-steel-and-cold-rolled-steel/
qualitty EDM. (2008). Electrical discharge machining (EDM). Retrieved from qualitty EDM: http://www.qualityedm.com/sinkeredm.html
serope kalpakjian, s. R. (2014). manufacturing engineering and technology. new york: pearson.
sme. (2005, october 1). Retrieved from advanced manufractruring : http://advancedmanufacturing.org/waterjet-vs-edm/
wikipedia . (2017, march 24). cad/cam. Retrieved from wikipedia : https://en.wikipedia.org/wiki/Computer-aided_manufacturing
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