cnc machining fabrication

How to choose the right fixture for CNC machining

Why is the production efficiency of the same CNC machine tool several times different? It is very likely that because of the difference in fixtures, inappropriate fixtures reduce the production efficiency of CNC machine tools.

Fixing the blank or workpiece is an essential step in CNC machining. There are many types of fixtures for CNC machine tools. Once the fixture is improperly selected, it may cause vibration, impact, breakage of the tool tip, loose workpiece, etc., thereby damaging the workpiece and the tool, resulting in errors in the processed products.

A common fixture is a clamping device, generally designed as two parts, one part is fixed on the processing platform and cannot be moved, and the other part is composed of one or more movable parts, which can be used to clamp blanks or workpieces. Usually made of mild steel, stainless steel and other alloy steels.

Before choosing a CNC fixture, you must first understand the processing characteristics and types of CNC fixtures. Machinery manufacturing is divided into three types: single piece, multi-variety small batch, multi-variety large batch and so on.

Generally speaking, modular fixtures are suitable for small batch production.

Building blocks/combination clips

Combination clamps, also known as “building block clamps”, are composed of a series of clamp parts with standardized designs, different functions, different specifications and different sizes. “Building blocks” (various machine tool fixtures) can be quickly assembled according to processing requirements.

Modular fixtures save design and manufacturing time, thereby greatly shortening production preparation time, thereby effectively shortening the small batch production cycle and improving production efficiency.

In addition, the modular fixture also has the advantages of high positioning accuracy, great flexibility of the fixture, reusable, energy and material saving, and low cost of use.

In mass production, the setup time of the workpiece may account for 10-30% of the entire machining cycle. Therefore, for large-scale processing, it is necessary to use special fixtures with fast positioning and fast clamping (releasing), and three types of machine tool fixtures can be preferred: hydraulic/pneumatic fixtures, permanent magnet fixtures and fixture bases.

Hydraulic/Pneumatic Grips:

Hydraulic/pneumatic clamps are special clamps that use hydraulic or pneumatic components as power sources to achieve workpiece positioning, support and compression. The mutual position of workpiece, machine and tool can be determined accurately and quickly.

The positioning accuracy of the workpiece is guaranteed by the fixture, the machining accuracy is high, and the positioning and clamping process is fast, which saves a lot of time for the loosening of the workpiece clamping. At the same time, it has the advantages of compact structure, multi-station clamping, high-speed heavy cutting, automatic control and so on.

Due to the above advantages of hydraulic/pneumatic clamping, it is suitable for CNC machine tools, machining centers, flexible production lines, especially for high-volume processing.

Electric permanent magnet clip

Electromagnetic permanent magnet clamp is a new type of clamp designed using the latest magnetic circuit principle, using new permanent magnet materials such as neodymium iron boron as the magnetic source. The clamping and loosening process only takes about 1 second, which greatly shortens the clamping time. These clamps are suitable for small and large scale production with clamping force above 450Kgf.

The electric permanent magnet clamp can greatly reduce the clamping time, reduce the number of clamping times, and improve the clamping efficiency. Many machining methods have shown that electromagnetic permanent magnet fixtures can greatly improve the comprehensive machining efficiency of CNC machine tools and machining centers. The positioning and clamping elements of conventional machine tool fixtures take up a lot of space, and electromagnetic permanent magnet fixtures lack these space-consuming components.

It has the advantages of fast clamping speed, easy to realize multi-station clamping, multi-face processing, stable and reliable clamping, energy saving, automatic control and so on. It is not only suitable for small batch production, but also for large batch production.

Fixture base

The smooth clamping seat can effectively shorten the manufacturing cycle of special fixtures and shorten the manufacturing preparation time, thereby shortening the entire cycle of mass production and improving production efficiency. At the same time, the manufacturing cost of the special jig can be reduced. Therefore, the smooth clamping base is particularly suitable for high-volume production with tight cycle times.

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