Introduction to CNC machining accuracy
In the machining process of precision mechanical parts, the following points are introduced to control the machining accuracy: geometric accuracy refers to the accuracy of geometric shapes such as surfaces or axes of parts, such as whether the line is straight, whether the surface is flat, whether the normal sections on the cylinder are round, etc. The allowable variation range is represented by “geometric tolerance”. The smaller the geometric tolerance number, the higher the shape accuracy; Dimensional accuracy: dimensional accuracy refers to the accuracy of the dimension of the part after machining, expressed in “dimensional tolerance”. When the dimensions of parts are the same, the higher the accuracy, the smaller the tolerance number; Positional accuracy: positional accuracy refers to the accuracy of the mutual position between the surfaces of the parts, such as whether the two planes are parallel, vertical, coaxial, etc., expressed in “positional tolerance”. Holding these points, the machining accuracy of precision mechanical parts is easier to control.
The above is a brief introduction to the machining accuracy of precision mechanical parts. Thank you for sharing!
ken. tang@chengcg.com
Introduction to CNC machining auxiliary fixture
In the field of machining industry, some complex parts are difficult to process, and auxiliary fixtures will be used to process them. There are many kinds of auxiliary fixtures to see the difference:
First, understand the general fixture: the general fixture refers to the fixture that has been standardized and can be used to process different workpieces within a certain range. For example, three jaw chuck and four jaw single action chuck on lathe, flat pliers, indexing head and rotary worktable on milling machine, etc. This kind of fixture is generally produced by professional factories and often provided to users as machine tool accessories. It is characterized by wide adaptability and low production efficiency. It is mainly suitable for the production and processing of single and small batch parts; Special fixture: special fixture refers to a fixture specially designed for a certain process of a workpiece. It is characterized by compact structure, rapid, convenient and labor-saving operation, which can ensure high parts processing accuracy and production efficiency, but the design and manufacturing cycle is long and the manufacturing cost is high. When the product is changed, the fixture will be scrapped because it can no longer be used. It is only applicable to production and processing with fixed products and large batch; Universal adjustable fixture and group fixture: it is characterized in that some components of the fixture can be replaced and some devices can be adjusted to adapt to the processing of different parts. The fixture used for group machining of similar parts is called group fixture. Compared with group fixture, the machining object of universal adjustable fixture is not very clear, and the scope of application is wider.
There are also combined fixtures: combined fixtures refer to fixtures assembled from a set of pre manufactured standard components and parts according to the machining requirements of mechanical parts. Manufactured by professional manufacturers, it is characterized by flexibility, versatility, short manufacturing cycle and repeated use of components. It is especially suitable for trial production of new products and single piece small batch production and processing. Traveling fixture: traveling fixture is a fixture used on automatic line. The fixture should not only clamp the workpiece, but also be integrated with the workpiece, move from one station to the next along the automatic line, and process different processes.
In the process of machining mechanical parts, they are classified according to the machine tools used: due to the different working characteristics and structural forms of various machine tools, different requirements are put forward for the structure of the fixtures used. According to the different machine tools used, fixtures can be divided into: lathe fixture, milling machine fixture, drilling machine fixture, boring machine fixture, grinder fixture, gear machine tool fixture and other machine tool fixtures. Classification by clamping power source: according to the different clamping power sources used by the fixture, it can be divided into: manual fixture, pneumatic fixture, hydraulic fixture, gas-liquid fixture, electric fixture, magnetic fixture, vacuum fixture, etc.
The above is the introduction of auxiliary fixture for machining mechanical parts. Thank you for sharing!
ken. tang@chengcg.com
Method for processing nylon material by CNC
In the field of machining, different processing processes are selected for different material processing. Now the processing method of lower plastic nylon material is discussed. Nylon material belongs to plastic. When machining a hole less than 30mm in diameter, due to the narrow space in the hole and difficult heat dissipation, it is necessary to reduce the lathe speed to less than 300 rpm and cool it with cutting fluid; Slow and uniform drilling and timely chip removal; When the drill bit is about to penetrate through the hole, it needs to be more careful to reduce the drilling speed. The cutting fluid or cooling water must be sprayed evenly to the orifice position.
Secondly, when machining holes larger than 30mm in diameter with nylon materials, first sharpen the drill bit to facilitate processing and avoid damage to the workpiece; Reduce the lathe speed to less than 180 rpm. For holes larger than 55mm, the lathe speed can be reduced to about 60 rpm; Drill in slowly and at a uniform speed, remove chips in time and spray sufficient cutting fluid; When the bit is out of the hole, be careful of the withdrawal speed. When the lathe processes small diameter holes, the speed shall be less than 60 rpm; When drilling at a constant speed and low speed, the operator must stabilize the tailstock handle to prevent the drill bit from being quickly brought into the hole by the lathe, resulting in product cracking; The cutting fluid is sprayed evenly.
For nylon material excircle processing, it is best to use white steel tools instead of alloy tools. The tools should be kept sharp; The lathe speed shall not be less than 200 rpm; Proper feed speed can improve machining accuracy and surface finish.
The above is a brief discussion on the methods of CNC processing plastic nylon materials. Thank you for your attention.
ken. tang@chengcg.com
Causes of rust in chrome plating of 45# steel
Why does chrome plating on 45# steel rust? In fact, 45# steel chrome plating will not rust. If there is rust, there must be a reason. Let’s have a look
There are several reasons for the rust of chrome plating of spare parts during the processing of mechanical parts,
- The part is not thrown to the position during chrome plating, and the chrome plating chemical solution cannot hold the part surface, so it will rust after use for a period of time;
- The mechanical parts are not placed in the liquid medicine for enough time, so that the chromium plating layer on the surface is thin, and the surface will rust if it is scratched during the assembly of mechanical parts;
- When the surface is chrome plated, the temperature of the liquid medicine is not enough, so that the machined parts can not meet the treatment requirements, and it will be easy to rust later! The inquirer listened to us and understood why 45# steel rusted after chrome plating. This is also caused by incorrect chromium plating surface treatment and addition process.
The above is 45# why the chrome plating of steel rusts. Thanks for sharing!
ken. tang@chengcg.com
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