Thursday, 23 February 2017

Machine tools machinability and calculations

Machining is achieved by knowing the machine parts, feed rates and the proper speeds based on the rigidity of the workpiece as well as cutting tool. Turning process works to remove material from the rotating workpiece surface and reducing its diameter for each spindle revolution or rpm, this operation could be taper turning, form turning, and contour turning, drilling, knurling, threading or boring.

Spindle speed is calculated as rpm= (CS*320)/D where rpm represents revolutions per minute of the cutter or workpiece, CS=cutting speed, D=diameter
Feed rate is the multiplication of calculated speed, number of teeth of the cutter and chip load(feed per tooth).
Feed per tooth=feed/(spindle speed*number of flutes)
Straight cut depth when cutting threads on the lathe=0.6134*pitch

Range of feed per revolution for roughing on a lathe machine:
Work material
High speed steel
carbide
Inches
millimetres
inches
millimetres
Mild steel
0.010-0.020
0.25-0.5
0.015-0.035
0.4-0.9
Tool steel
0.010-0.020
0.25-0.5
0.015-0.035
0.25-09
Cast iron
0.015-0.025
0.4-0.65
0.015-0.030
0.4-0.75
aluminum
0.015-0.030
0.4-0.75
0.015-0.035
0.4-0.9
brass
0.015-0.025
0.4-0.65
0.015-0.030
0.4-0.75

Other operations are:
About boring machining, cutting is performed inside the material either horizontal or vertical.
Milling machine allows work part to be fed past a rotating tool with edges.
Further, hacksaw machine is used for linear reciprocating motion while bandsaw helps with linear continuous motion.
Finishing improves the product appearance could be done with filing.
Knurling helps to form ridges increasing the diameter of the workpiece unto 0.030 inch and this process should be performed with high feed rate and at low spindle speed.
Grinding produces required sizes with fine finishing.

Durable and reliable metalworking machines as follows
Lathe Machine
Drilling Machine
Bandsaw Machine 



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