Machining Accuracy of Machine Tool

Turning, milling, planing, grinding, drilling, boring, the highest precision of these machine tools and the tolerance levels that can be achieved by various processing methods are all here:

1: Turning

A cutting process in which the workpiece is rotated and the turning tool moves in a straight or curved line in a plane. Turning is generally carried out on a lathe to process the inner and outer cylinder, end surfaces, conical surfaces, forming surfaces and threads of the workpiece.

The turning precision is generally IT8-IT7, and the surface roughness is 1.6-0.8μm.

1) Rough turning strives to use large cutting depth and large feed rate to improve turning efficiency without reducing the cutting speed, but the machining accuracy can only reach IT11, and the surface roughness is Rα20-10μm.

2) Semi-Finishing and finishing cars should adopt high speed and small feed and cutting depth as far as possible, machining accuracy up to IT10 -- IT7, and the surface roughness is Rα10-0.16μm.

3) The high-speed precision turning of non-ferrous metal parts with the fine-refined diamond turning tool on the high-precision lathe can make the machining accuracy reach IT7-IT5, and the surface roughness is Rα0.04-0.01μm. This kind of turning is called "mirror turning ".

2. Milling

Milling refers to the use of rotating multi-edge tools to cut workpieces, and it is a highly efficient processing method. It is suitable for processing planes, grooves, various forming surfaces (such as splines, gears and threads) and special shapes of molds, etc. According to the same or opposite direction of the main movement speed and workpiece feed direction during milling, it is divided into down milling and up milling.

The machining accuracy of milling is generally up to IT8-IT7, and the surface roughness is 6.3-1.6μm.

1) The machining accuracy during rough milling is IT11-IT13, and the surface roughness is 5-20μm.

2) The machining accuracy of semi-finish milling is IT8—IT11, and the surface roughness is 2.5-10μm.

3) The machining accuracy of finishing milling is IT16—IT8, and the surface roughness is 0.63—5μm.

3. Planing

Planing processing is a cutting method in which a plane tool is used to make a horizontal relative linear reciprocating motion on the workpiece, and it is mainly used in the shape machining of the parts.

The machining accuracy of planing can generally reach IT9-IT7, and the surface roughness is Ra6.3-1.6μm.

1) The rough planing precision can reach IT12-IT11, and the surface roughness is 25-12.5μm.

2)The precision of semi-finishing planing can reach IT10-IT9, and the surface roughness is 6.2-3.2μm.

3) The precision of finishing planing can reach IT8-IT7, and the surface roughness is 3.2-1.6μm.

4. Grinding

Grinding refers to the processing method of using abrasives and abrasive tools to remove excess material on the workpiece. It belongs to finishing and is widely used in the machinery manufacturing industry.

Grinding is usually used for semi-finishing and finishing, and the accuracy can reach IT8-IT5 or even higher. The surface roughness is generally 1.25-0.16μm.

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.

5. Drilling

Drilling is a basic method of hole processing. Drilling is often carried out on drilling machines and lathes, but also on boring machines or milling machines.

The machining accuracy of drilling is relatively low, generally only reaching IT10, and the surface roughness is generally 12.5-6.3μm. Drilling and reaming are often used for semi-finishing and finishing.

6. Boring

Boring is an inner diameter cutting process that uses tools to expand holes or other circular contours. Its application range generally ranges from semi-rough machining to finishing. The tools used are usually single-edged boring tools (called boring bars).

1) The boring accuracy of steel materials can generally reach IT9-IT7, and the surface roughness is 2.5-0.16μm.

2) The machining accuracy of precision boring can reach IT7-IT6, and the surface roughness is 0.63-0.08μm.

Note:

Machining accuracy is mainly used to characterize the fineness of the produced product and is a term used to evaluate the geometric parameters of the processed surface. The standard for measuring the machining accuracy is the tolerance level, from IT01, IT0, IT1, IT2, IT3 to IT18, there are a total of 20,where IT01 means the parts of the processing accuracy is the highest, IT18 means the parts of the processing accuracy is the lowest. General factories and mining machinery belongs to IT7 level, and general agricultural machinery belongs to IT8 level.Product parts according to the function of the different, the need to achieve different processing precision, the choice of processing form and processing technology is also different.