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OVERVIEW OF GEAR MANUFACTURING PROCESS

We have seen "Classifications of gears“and "Gear terminology" in our previous post, where we have discussed the types of gear and various terms used in gear mechanism.

Now it’s time to discuss a very important article i.e. Manufacturing process of gears, this article deals with the complete understanding of manufacturing process of gears with selection of suitable raw material for securing good quality of gear.

Let us think about the various materials used these days as raw materials for producing gears. I have heard three types of base materials, those are mentioned here steels, for producing the gears.
  1. Steels
  2. Plastic and composites
  3. Wood
Steels are the most common materials used as raw material in manufacturing of gears. Now as we know there are number of grades of steel, so which one will be better to select from cost and quality point of view.

Also see:

Pressure angle in gear

I will prefer to use EN9, EN19 and EN24 grade of alloy steel to use as raw material in manufacturing the gears. EN24 will be better choice to use as raw material in manufacturing the gears. Hardness of EN24 will be approximate 302 BHN but we can further harden EN24 up to 600 BHN.


EN24 grade alloy steel is easily machinable, having with good tensile strength and better shock resistance as well as having good resistance against wear and tear.

We are considering here the manufacturing process of external gear only such as spur gear and helical gear with external teeth.

Normally, there are two techniques for manufacturing the gears. First technique deals with the cutting of teeth, finishing of teeth and other required operations for securing the desired gear tooth profile e.g. hobbing, shaping and honing etc. while second technique deals with conventional process such as milling, drilling and grinding. First technique, as we have discussed above, will be explained here to manufacture the gears.

Planning team will secure the drawings and specifications of the gear from the user and simultaneously will plan for suitable raw materials.



Material will be cut as per drawing and specification of gear



Cut material will be processed now on a lathe machine to secure the gear blank by turning on lathe.



Gear blank will be processed on hobbing machine for gear cutting as shown in figure, hobbing process normally leaves burs on gear teeth and these burrs will be removed in next step.

 
Above mentioned metal burrs will be removed on de-burring machine.  After removing the burrs from gear, we will go for heat treatment process of gear.

Heat treatment of gear will be carried out to increase the service life and performance of gears by changing the metallurgical, chemical and mechanical properties.

Black oxide finishing provision for avoiding corrosion action over gear
After gear finishing, each gear will be placed in individual box to deliver in good quality to user. 

Let us go ahead with our next article in engineering maintenance category.

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