Fixtures are core tools to ensure workpiece stability and machining accuracy. Whether it is a simple fixture or a complex modular fixture, selecting and designing the right fixture can greatly improve production efficiency and reduce scrap rate. In this guide, we will explore the types of CNC fixtures, their uses, and their importance in different applications. Whether you are a novice or an industry veteran, this article will help you have a more comprehensive understanding of the selection and optimization methods of fixtures, So that your processing projects are more efficient and reliable.
What Is A CNC Fixture?
CNC fixture is a device for fixing workpieces. It is usually used in CNC machining process. It ensures that the workpiece maintains a stable position and posture during machining through a specific mechanical structure and clamping force, so that the machine tool can accurately process the workpiece according to the preset program.
Imagine that we need to CNC process a precision component, then the role of the fixture is very critical. It can firmly fix the part and effectively guarantee the requirements of high-precision processing, which is crucial to production quality.
Application Of CNC Fixture
CNC fixtures are mainly used in CNC machining. The most common application is to clamp the workpiece, reduce clamping errors, and improve production time. CNC fixtures are one of the key factors in improving production efficiency and product quality in modern manufacturing.
- Workpiece fixation : In CNC machining, the CNC fixture firmly fixes the workpiece on the machine table through reliable clamping force. Fixing parts is the most important part of CNC machining. The stability of parts improves accuracy and production efficiency.
- Improved precision : We all know that high-precision fixtures can reduce the clamping error of the workpiece, thereby improving manufacturing accuracy. For example, in precision mold processing, the use of specially designed CNC fixtures can achieve a dimensional accuracy of ±0.01mm for the mold.
- Maximize spindle usage time : Using reasonable fixture design can help us reduce the clamping and adjustment time of the workpiece, thereby reducing downtime and improving productivity. For high-volume production, the use of fixtures is particularly important.
Types Of CNC Fixtures
There are many types of CNC clamps . From an operational perspective, milling, turning, grinding, drilling, and reaming fixtures all show their unique abilities to ensure processing stability and accuracy. Classified by use, CNC vise, angle, modular and other clamps are unique. When processing in various industries, they firmly fix the workpiece, significantly improve the accuracy, maximize the spindle usage time, and are a powerful assistant for efficient production.
Fixtures Classified By Operation
Milling Fixture
Milling fixtures are specially designed for milling processes. They have high strength and vibration resistance. They are usually made of alloy steel to ensure high stability and durability. They are suitable for multi-axis milling of complex geometries. In aviation manufacturing, they are often used to process large wing structures to ensure a precision of ±0.03mm during multi-faceted milling, improving the overall quality and safety of the components.
If we want to process complex flat parts, especially in the aviation, mold and automotive industries , we must check whether the clamping mechanism is intact before using the fixture . After long-term use, we should lubricate it regularly to reduce wear and maintain rigidity to avoid processing errors.
Turning Fixture
Three-jaw chucks are suitable for round workpieces and irregular workpieces. They are mostly made of cast iron, are strong and durable, and can be used for workpieces of various sizes. In the processing of automobile engine crankshafts, three-jaw chucks can ensure stability under high speed operation, and the concentricity can reach 0.05mm.
in lathe processing, especially suitable for the rotation processing of precision parts in the fields of automobiles, home appliances and aviation. It can adapt to workpieces of various shapes and sizes, but we must regularly calibrate the concentricity of the chuck to avoid the increase of scrap rate caused by workpiece eccentricity, and check whether the clamping force meets the standard.
Grinding Fixture
The grinding fixture is made of high-hardness material and pays great attention to the balanced design. It can reduce vibration during high-speed rotation, ensure the surface finish and stability of the processed surface, and is suitable for high-precision grinding. In mold manufacturing, the surface roughness Ra of the injection mold core can be controlled below 0.2μm by using the grinding fixture to process the injection mold core, meeting the high finish requirements.
Grinding fixtures are widely used in molds, precision bearings, medical devices and other processing fields that require extremely high surface quality. We usually ensure that the fixture surface is clean to prevent fine particles from affecting the accuracy. Regularly replace the clamping parts to maintain processing consistency.
Drilling Jig
bit is guided by a precision drill sleeve to ensure high precision and consistency of the processed holes. It is suitable for multi-hole processing and batch production, and the positioning error is less than ±0.1mm. For example, in home appliance production, we usually use a drilling fixture to drill mounting holes on the refrigerator shell to ensure consistency between batches and improve assembly efficiency.
The drilling fixture is suitable for multi-hole processing operations in the fields of electronic equipment, automotive parts and building components. Because of its accurate positioning and high hole consistency, it can reduce the need for secondary processing and improve production efficiency and yield rate. However, the drill sleeve needs to be replaced regularly to prevent wear and affect positioning accuracy, and the drill bit should also be checked for sharpness before processing .
Hole Expansion Fixture
The hole expansion fixture is equipped with a high-hardness guide sleeve, which can ensure the cylindricity and surface finish of the hole expansion process, and the error is controlled within 0.01mm, which is suitable for high-precision processing scenarios. If we use it to process the bearing hole of the automobile engine, it basically ensures that the accuracy after hole expansion meets the installation requirements and improves the overall performance of the engine.
It is widely used in hole correction processing with high precision requirements, such as in the automotive, aerospace and precision machinery fields. We need to ensure that the guide sleeve is not damaged before expanding the hole , and pay attention to tool cooling during processing to extend its service life.
Clamps Classified By Purpose
CNC Vise Clamps
CNC vise clamps are compact in structure and can clamp up to 5-20kN. They are usually made of aluminum alloy or cast iron and are suitable for clamping small workpieces. In the electronics industry, vise clamps are used to process mobile phone housings to ensure stable positioning and improve processing accuracy.
It is very suitable for clamping and processing small and medium-sized parts, such as precision instrument components or small electronic products. It is easy to operate and is especially suitable for small and medium-sized batch processing. Regularly checking whether the clamping force is uniform can avoid loosening of the workpiece due to insufficient clamping.
Angle Clamp
The angle fixture is equipped with a precise angle adjustment mechanism, which can be adjusted to an accuracy of ±0.1° to meet the processing requirements of specific bevels or tilt angles. It is generally used to process the bevels of wing support components to ensure accurate angles and improve assembly quality.
It is widely used in scenarios that require specific angle processing, such as mold manufacturing, machining, etc. Its angle is adjustable, suitable for multi-angle parts processing, and can help us reduce the time of multiple clamping.
Modular Fixtures
Modular fixtures are composed of multiple standard modules made of aluminum alloy, steel, etc., which can be flexibly combined to adapt to different workpiece shapes and sizes. If we are manufacturing automotive parts, modular fixtures can help us shorten the design and manufacturing cycle.
It is suitable for small batch processing of multiple products and can shorten the fixture design time by 30%-50%. The connection between modules should be firm to avoid loose combination affecting the clamping accuracy.
Bench Fixture
Bench fixtures are often used for auxiliary processing, such as flat-nose pliers and bench vises. They are mostly made of medium carbon steel and have good strength and durability. During manual finishing, bench fixtures are used to fix the workpiece to facilitate filing and grinding operations.
It is suitable for manual processing scenarios, such as trimming, cleaning and assembly of parts. It is highly versatile and can quickly fix workpieces, suitable for a variety of scenarios. However , attention should be paid to the parallelism of the fixture surface to ensure that the clamping is firm and uniform.
Clamping Fixture
The clamping fixture fixes the workpiece mechanically or hydraulically, with a clamping force range of 10kN-100kN, which can adapt to workpieces of different shapes and materials. It is used for the processing of large mechanical parts, and the hydraulic clamping system provides stable clamping force to prevent the workpiece from shifting.
It is especially suitable for heavy-duty machining scenarios and can ensure the stability of our parts during machining . We need to regularly maintain hydraulic systems or mechanical components to ensure stable clamping and safe operation.
Universal Clamp
Universal fixtures are as versatile as their name suggests , such as chucks and flat-nose pliers, which are suitable for clamping various types of workpieces, and the positioning accuracy is generally between ±0.1-±0.5mm. In preliminary turning, universal chucks are used to fix shaft parts and quickly complete preliminary roughing.
General fixtures are suitable for preliminary processing and low-precision requirements, such as rough processing and clamping of conventional parts. However, if you want to process high-precision parts , you need to use them in combination with special fixtures to avoid affecting the processing results due to insufficient precision.
Fixtures Classified By Power Supply Type
Magnetic Clamp
Magnetic clamps use permanent magnet or electromagnetic technology to adsorb workpieces, with uniform adsorption force and no mechanical damage, suitable for thin plate processing. In precision mold processing, magnetic clamps adsorb thin-walled steel plates to improve processing flatness and ensure an accuracy of ±0.01mm.
Magnetic clamps are suitable for processing flat and thin-walled parts made of ferromagnetic materials, such as mold parts and metal sheets. They clamp quickly without mechanical damage and are suitable for high-precision parts processing . However, we need to ensure that the workpiece is in full contact with the magnetic clamp, otherwise it will affect the adsorption effect and processing accuracy.
Hydraulic Clamp
The hydraulic system generates a strong clamping force, which is suitable for the processing of large or high-strength workpieces, and the clamping force can be adjusted in a wide range. In the construction machinery manufacturing, hydraulic clamps are used to fix excavator parts to ensure processing accuracy and stability.
It is widely used in large-scale machinery manufacturing and high-strength parts processing, such as shipbuilding and aviation industry. Its clamping force is stable and suitable for high-load processing, but we need to check the hydraulic system regularly to prevent oil pipe leakage or insufficient clamping force.
Pneumatic Clamps
Pneumatic clamps are powered by compressed air and move quickly, making them suitable for high-frequency clamping operations in automated production lines. In the processing of automotive parts, pneumatic clamps achieve fast clamping, save production time, and improve processing efficiency. They are fast and flexible to operate, making them suitable for the efficient production of small and medium-sized parts, such as electronic product housings and automotive parts. During the production process, we need to ensure that the air source pressure is stable to avoid insufficient clamping force or unsmooth movement.
Mechanical Fixture
Mechanical clamps achieve clamping through mechanical structures such as screws or cams. They have a simple structure and low cost, and are suitable for most conventional processing. They have low operating costs and are easy to maintain. Mechanical parts need to be calibrated regularly to ensure clamping accuracy and stability.
Special Fixture
Pit Plate Fixture
The pit plate fixture is designed with grooves or pits to locate workpieces of specific shapes, suitable for clamping and processing complex geometric parts. In high-precision aviation parts processing, the pit plate fixture is used to fix complex contour parts with a positioning accuracy of ±0.05mm.
It has accurate positioning and easy operation , and is suitable for high-precision processing of irregular-shaped parts, such as in the fields of aerospace and mold manufacturing. During the processing, we need to ensure that the workpiece fits tightly with the fixture to avoid errors caused by poor positioning.
Vacuum Fixture
The vacuum fixture uses the principle of vacuum adsorption to fix the workpiece. It is suitable for workpieces with flat surfaces that are not suitable for conventional clamping, such as glass or plastic. It is used to process display glass to ensure smooth adsorption, no scratches on the processed surface, and the vacuum degree is maintained above -0.08MPa. It is suitable for precision processing of glass, plastic and other non-metallic materials.
It has stable adsorption and avoids mechanical damage, and is suitable for workpieces with high requirements for surface finish. However, the adsorption surface must be kept clean to prevent impurities from affecting the vacuum adsorption effect.
Chuck Fixture
Chucks are commonly found on lathes. There are three-jaw and four-jaw types, which are suitable for clamping workpieces of various shapes and have high positioning accuracy. They are used for turning high-precision shaft parts. The three-jaw chuck ensures concentricity within 0.05mm. They are suitable for machining shaft and rotating parts, such as automotive parts and mechanical equipment bearings.
It is flexible to operate, firmly clamped, and suitable for clamping workpieces of various shapes. We should regularly clean the debris in the chuck to prevent insufficient clamping force or eccentricity from affecting the processing results.
The following is a table that is more convenient to understand , covering the types, characteristics, examples, scope of application, advantages and precautions of CNC fixtures:
| type | Features | Examples | Scope Of Application | Advantages | Precautions |
| Milling Fixture | Made of high-strength alloy steel, good vibration resistance and high positioning accuracy | Machining large wing structures | Complex plane parts processing | High precision, suitable for mass production | Lubricate and inspect the clamping mechanism regularly |
| Turning Fixture | The three-jaw chuck is self-centering, and the four-jaw chuck is suitable for irregular workpieces | Crankshaft machining to ensure high speed stability | Precision parts rotation processing | Flexible operation, suitable for mass production | Calibrate concentricity and check clamping force |
| Grinding Fixture | High hardness material, balanced design, high surface finish | Injection mold core processing to meet high finish requirements | Mould and precision bearing processing | Improve surface finish and reduce polishing steps | Clean the fixture surface and replace the clamping parts regularly |
| Drilling Jig | Precision drill sleeve guide, hole position error is less than ±0.1mm | Refrigerator casing drilling | Multi-hole processing, mass production | Improve consistency and reduce secondary processing | Check the drill sleeve for wear and keep the drill bit sharp |
| Hole Expansion Fixture | High-precision guide sleeve, cylindrical error less than 0.01mm | Engine bearing hole expansion | Hole correction processing | High surface finish, improved processing efficiency | Ensure that the guide sleeve is not damaged and pay attention to the cooling of the tool |
| Vise Clamps | Aluminum alloy or cast iron material, suitable for processing small and medium-sized workpieces | Mobile phone shell processing | Small and medium-sized parts clamping and processing | Simple operation and flexible adjustment | Check the clamping force regularly to avoid loosening |
| Angle Clamp | Adjustable angle accuracy up to ±0.1°, suitable for processing specific inclined surfaces | Processing the inclined surface of the wing support component | Bevel parts processing | High flexibility, reducing multiple clamping time | Make sure the angle is adjusted firmly |
| Modular Fixtures | Multi-module combination to adapt to various workpieces | Suspension system parts processing | Multi-variety small batch processing | Shortened design time and flexible assembly | Make sure the module is firmly connected |
| Magnetic Clamp | Permanent magnetic or electromagnetic adsorption, no mechanical damage | Adsorption of thin-walled steel plates to improve processing flatness | Flat and thin-walled parts processing | Uniform adsorption, suitable for high-precision processing | Maintain full contact to prevent adsorption effect from decreasing |
| Hydraulic Clamp | The hydraulic system provides strong clamping force, suitable for large workpiece processing | Fixing excavator parts | Large machinery manufacturing | Stable clamping force improves production efficiency | Check the hydraulic system regularly to prevent leakage |
| Vacuum Fixture | Vacuum adsorption principle, suitable for workpieces with flat surface | Display glass processing, no scratches | Glass and plastic processing | Avoid mechanical damage and ensure stable adsorption | Keep the surface clean to prevent impurities from affecting the adsorption effect |
| Chuck Fixture | Three-claw and four-claw designs are suitable for workpieces of various shapes | Turning high-precision shaft parts | Shaft and rotating parts processing | Flexible operation and high positioning accuracy | Clean the chuck to ensure clamping force and concentricity |
Common Mistakes To Avoid When Selecting CNC Fixtures
There are many pitfalls when we choose CNC fixtures. For example, the compatibility between fixtures and machine tools, the mismatch between size and power, etc. In addition, maintenance requirements are often forgotten, and about 30% of failures are caused by this. The cost of fixtures is not limited to the purchase price, and its versatility is also easily underestimated, so we need to reasonably consider the selection of suitable fixtures to ensure processing efficiency.
- Ignoring compatibility with CNC machines : Different CNC machines differ in table size, travel, spindle power, etc. The fixture must be compatible with these parameters of the machine.
For example, if the fixture is too large and exceeds the range of the machine tool worktable, it will not be able to be installed and used normally. If the clamping force required by the fixture exceeds the range that the machine tool spindle power can withstand, it may cause machine tool failure or reduced processing accuracy.
- Ignoring The Maintenance Requirements Of The Fixture : The fixture needs regular maintenance during use, such as cleaning, lubrication, and checking the wear of the clamping components. If these maintenance requirements are ignored, the fixture may have problems such as insufficient clamping force and reduced positioning accuracy, affecting processing quality and production efficiency. According to a survey, about 30% of fixture failures are caused by long-term lack of maintenance.
- Underestimating Fixture Costs : The cost of fixtures not only includes the purchase price, but also includes the subsequent maintenance costs, service life, and hidden costs such as increased scrap rate caused by fixture problems. For example, some low-priced fixtures may seem to save costs in the short term, but due to their poor accuracy retention and easy damage, they may lead to frequent fixture replacement and increase long-term cost investment.
- Ignoring The Versatility Of The Fixture : When selecting a fixture, you should try to consider whether it can flexibly adapt to workpieces of different shapes, sizes and processing technologies. If the fixture has a single function, when the processing task changes, it may need to be replaced frequently, increasing production preparation time and cost.
For example, modular fixtures, due to their combinability, can meet the processing needs of various workpieces to a certain extent, and improve the versatility and utilization of fixtures.
FAQs
Are CNC Fixtures Interchangeable Between Different CNC Machines?
Generally speaking, not all CNC fixtures are interchangeable between different machine tools. This depends on the model and specifications of the machine tool, as well as the connection method between the fixture and the machine tool, the working range, etc. Even for the same type of machine tool, if the worktable size, T-slot specifications, etc. are different, the fixture may not be interchangeable.
What Types Of Fixtures Are Used On CNC Machines?
CNC machine tools can use many types of fixtures, such as the milling fixtures, turning fixtures, hydraulic fixtures, pneumatic fixtures, magnetic fixtures, etc. mentioned above. The specific type of fixture to be used depends on the requirements of the processing technology, workpiece shape and size, etc.
How Do I Choose The Best Material For Making Jigs And Fixtures?
When selecting fixture materials, you need to consider many factors. For the fixture parts that bear greater cutting force and wear, high-strength alloy steel or tool steel can be selected. For fixtures that require light weight and certain strength, aluminum alloy is a good choice. For some special environments such as high-temperature processing, heat-resistant alloy materials may be required. At the same time, the cost, machinability and heat treatment performance of the material must also be considered.
What are 3 Benefits Of Using A Clamp Or Fixture?
The first is to improve processing accuracy, through precise positioning and clamping, to reduce the displacement and deformation of the workpiece during processing，the second is to improve production efficiency, reduce clamping time and adjustment time, so that the machine tool spindle can have more time for effective processing，the third is to improve processing consistency and ensure the stable processing quality of the same batch of workpieces.
What Is The Difference Between A Fixture, A Clamp, And A Vise?
A fixture usually refers to a device used to position and support the workpiece during the machining process. It is usually relatively fixed on the machine tool and focuses on the positioning of the workpiece. A clamp emphasizes the clamping function of the workpiece to ensure the stability of the workpiece during machining. A vise is a common type of clamp that mainly clamps the workpiece by opening and closing the jaws. It is often used to clamp small parts and is simple to operate and has strong versatility.
What Is The Difference Between A Clamp And A Fixture?
The fixture is mainly used to clamp the workpiece so that it will not move during the processing, while the fixing device focuses on determining the correct position of the workpiece in the machine tool coordinate system to provide an accurate reference for processing. The two cooperate with each other in function to ensure the smooth progress of processing.
Conclusion
CNC fixtures play a critical role in the CNC machining process of modern manufacturing. Different types, application ranges, design points, and avoiding common mistakes in the selection process, whether you are a professional engaged in mechanical processing or a learner in related fields, in-depth knowledge of CNC fixtures will help you achieve better results in actual work and study.