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General Knowledge

 

Safety

First of all, safety is the most emphasis in a machining workshop to prevent any accidents occurred. Each student receives a safety handout when they walk into the workshop first time. Tutors will explain all the designated safety rules very detail and how to do when accidence is occurred unfortunately. Students must ask if they have any problem to understand the rules and must follow the safety rules during their training to protect themselves and other people in the workshop.

 

Cutting Speed

Cutting Speed in machining is defined as how fast of the material pass through the edge of cutting tool. The unit is normally written as m/min. Too fast of the cutting speed will damage the cutting tool and cause the poor surface finishing. If else, will decrease the productivity. Different types of cutting tool to cut different material are valued to different Cutting Speed. The most common used Cutting Speed are listed as the following table.

Tool Material
High Speed Steel (m/min)
Carbide (m/min)
Workpiece Material
Mild Steel
22 -- 28
150
Stainless Steel
12
70
Medium Carbon Steel
20
140
Brass
45 - 90
180
Aluminum
Up to 300
Up to 300

Spindle Speed

Spindle Speed of the machine is calculated by an equation to determine how fast of the machine to run. The equation is:

N is the spindle speed of different machining operation such as turning, milling, drilling and grinding. It is normally marked with RPM, the revolution per minute.

CS is stand for cutting speed which mentioned at the above.

d is the diameter of the cutting tool when operate milling, drilling, and grinding, but is the diameter of workpiece when operate turning.

Feed Rate

Feed Rate of machining is determined how fast of the cutting tool travel on the workpiece during operation and the value of turning is between 0.1mm to 0.15mm normally and directly select on a centre lathe. Feed Rate of milling is calculated by an equation

F = fuN

F is the feed rate and can be selected on the feed gear box of the milling machine.

f is the feed coefficient and valued between 0.1mm to 0.15mm..

u is number of cutting edge of the milling cutter. This is because of milling operation is a multi-point cutting method.

N is the spindle speed that we have calculated.

Cutting Fluid

Cutting Fluid is widely applied in most of the machining operation to reduce the heat generated by friction and improve the surface finishing. It mainly classified by water base and oil base and the most common used is water base cutting fluid. It is mixed by soluble oil and water in 1:5 to 1:15 depending on different brand name of the soluble oil. Some material is no need to apply cutting fluid such as cast iron, brass, and bronze.

Material Control

If there are a lot of components made by using a material, you must be reminded to control the used of the material. The longest component must manufacture at the beginning time. If it is corrupted, it can be modified to make the shorter component.


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