Turning machines, milling machines, planing machines, grinding machines, drilling machines, boring machines, the highest precision of these machines and the tolerances that can be achieved by the various machining methods are all here.
I. Turning
The workpiece is rotated and the turning tool moves in a straight or curved line within the plane to carry out themachiningTurning is usually carried out on a lathe and is used to machine the internal and external cylindrical surfaces of the workpiece, as well as the end surfaces, and the conical surfaces, including the forming surfaces and threads.
In turning, the accuracy is usually in the range of IT8 to IT7, while the accuracy ofsurface roughnessThen it is in the value of 1.6 μm to the value of 0.8 μm.
(1) In rough turning, the goal is to improve turning efficiency by adopting a large depth of cut and a large feed under the condition of not reducing the turning speed, but the machining accuracy is only up to IT11, and the surface roughness is in the range of Rα20 to 10μm.
(2) When semi-finish turning, try to use high speed, and at the same time, also use a smaller feed, and also use a smaller depth of cut, machining accuracy can reach IT10 to IT7, surface roughness is Rα10 to 0.16μm.
(3) The use of fine repair diamond turning tools, in the high-precision lathe, high-speed precision turning of non-ferrous metal parts, can make the machining accuracy of IT7 to IT5, the surface roughness of Rα0.04 to 0.01μm, such turning is called ”mirror turning”.
Milling
Milling refers to the use of rotating multi-flute tools to cut the workpiece, which is a highly efficient processing method, suitable for processing flat surfaces, suitable for processing grooves, suitable for processing a variety of shaped surfaces such as splines, gears, and threads, but also suitable for processing the special shape of the mould, etc., according to the milling of the main movement speed direction with the direction of the workpiece feed is the same or the opposite direction of the situation is also divided into the smooth milling and reverse milling. According to whether the direction of the main motion is the same or opposite to the direction of the workpiece feed during milling, it is also divided into smooth milling and reverse milling.
When milling, the machining accuracy can usually reach IT8 to IT7, while the surface roughness is between 6.3 and 1.6 μm.
(1) For rough milling, the machining accuracy is in the range of IT11 to IT13, and the surface roughness is between 5 and 20 μm.
(2) For semi-finish milling, the corresponding machining accuracy is in the range of IT8 to IT11, and the surface roughness is in the range of 2.5 to 10μm.
(3) When fine milling is used, the machining accuracy can be achieved within the range of IT16 to IT8, and the surface roughness is in the range of 0.63 to 5μm.
III. Planing
Planing is a cutting method that uses a planing knife to make the workpiece reciprocate in a horizontal relative straight line, which is mainly used in the shape processing of parts.
With planing, it is generally possible to achieve an accuracy of IT9 to IT7, while the surface roughness is in the range of Ra6.3 to 1.6μm.
(1) After rough planing, the accuracy is in the range of IT12 to IT11, and the surface roughness is in the range of 25 μm to 12.5 μm.
(2) Semi-finish planing accuracy of IT10 to IT9 with surface roughness in the range of 6.2 to 3.2 μm is achievable.
3) Finish planing, which is capable of achieving an accuracy of IT8 to IT7, while the surface roughness is 3.2 to 1.6 μm.
iv. grinding
Grinding is the process of removing excess material from a workpiece by using abrasives and grinding tools, which is a finishing process in the machine building industry and is widely used.
Generally speaking, grinding is often used in semi-finishing and finishing operations with an accuracy of IT8 to IT5 or even higher, and surface roughnesses of 1.25 to 0.16 μm.
(1) The surface roughness of precision grinding is 0.16-0.04μm.
(2) The surface roughness of ultra-precision grinding is 0.04-0.01μm.
(3) The surface roughness of mirror grinding can reach below 0.01μm.
V. Drilling
One of the basic methods of hole machining is drilling, which is often carried out on top of a drilling machine, drilling can actually be carried out on a lathe, drilling can also be carried out on a boring machine, and drilling can also be carried out on a milling machine.
When drilling, the machining accuracy is relatively low, usually only up to IT10, the surface roughness is generally in the range of 12.5-6.3μm, after the completion of the drilling, often use the reaming and reaming way to carry out semi-finishing and finishing.
Boring
Boring, is a cutting process that involves the use of a tool to enlarge the inside diameter of a hole or other circular contour, the application of which, generally, is from semi-rough machining to finish machining, using a tool, usually a single-edged boring tool, which is also known as a boring bar.
(1) Boring accuracy for steel materials, generally can achieve the standard of IT9 to IT7, the surface roughness is in the range of 2.5 to 0.16μm.
(2) The machining accuracy obtained by precision boring can reach the value range of IT7 to IT6, while its surface roughness is between 0.63 and 0.08μm.
Notes:
Machining accuracy is a term used to evaluate the geometrical parameters of a machined surface, which characterises the degree of fineness of the manufactured product. Measurement of machining accuracy used in the standard is the tolerance level, tolerance level from IT01, IT0, IT1, IT2, IT3 has been ranked to IT18, IT01, IT0, IT1, IT2, IT3 to IT18 a total of 20, IT01 is indicated by the part machining accuracy is at the highest level, IT18 is indicated by the part machining accuracy is at the lowest level, the general plant and mining machinery with IT7 level accuracy, general agricultural machinery with IT8 level accuracy. General factory and mining machinery with IT7 level accuracy, general agricultural machinery with IT8 level accuracy. Product parts according to the function of the difference, the need to achieve the machining accuracy is not the same, the choice of processing forms andProcessingIt will also be different.
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