In the world of manufacturing, the successful running of large production depends on a wide variety of factors. An example of such a factor is interchangeability to facilitate easy assembly as well as unit cost reduction. Mass production techniques demand an easy and fast method of positioning workpieces for operations that are accurate. One important tool to help achieve this is CNC fixtures.
CNC fixtures are production tools used in the manufacturing industries to precisely duplicate and manufacture interchangeable parts. They are specially designed to allow for a large number of components to be machined or assembled identically. In addition, they also help to ensure the interchangeability of such features. In a bid to enlighten you more, we have curated a complete guide on them based on our manufacturing experience over ten years. Read on to learn more from this guide.
What are CNC Fixtures?
To simply put, CNC fixtures are referred to as agents of positioning and stability. They are work holding tools that hold, support, and locate workpieces for specific machining operations on the CNC machine. They also help CNC engineers to ensure interchangeability and conformity during the process of production. This means that CNC fixtures help to encourage smooth CNC production.
Another benefit of CNC fixture is that it reduces the quantity of human efforts input in a production process. Having said this, many will use fixtures and a jig interchangeably, whereas they differ. A fixture differs from a fixture in that it does not guide the cutter’s movement but only supports, secures, and stabilize the workpiece during the machining process.
There are a wide variety of materials for CNC fixtures. They come in different configurations and sizes and are often made from stainless steel, mild steel, other steel alloys, and iron. They include the following:
√ High-Speed Steel
- Used for cutting tools like reamers, drills, and milling cutters
√ Carbon Steel
- Used for standard cutting devices and many more
√ Die Steel
- For press tools
- Contains 1% carbon, 0.5 – 1% tungsten, and minute manganese and silicon
√ Non-Shrinking Tool Steel
- Mostly used for intricate, fine press tools
- Contain high chromium and carbon
- Display little distortions during heat treatment
√ Mild Steel
- Most fixtures are made from mild steel
- Cheapest of all materials
- Features less than 0.3% carbon
√ Cast Iron
- Used for odd shapes in some laborious fabrication
- Contains over 2% carbon
- Features self-lubricating properties
√ Fiber and Nylon
- Soft lining materials to prevent damage as a result of clamping pressure to the workpiece
Classification of CNC Fixtures
When it comes to classifying, most manufacturers get it all wrong. This is because it can be confusing at times. Hence the reason for this section of this guide. It may be frustrating for beginners to understand the tool idea. However, we have shed more light on this to help you understand the logic behind the classification. In a bid to simplify it, we will classify it using different factors. They include:
- Classification according to Use
- Classification according to Machining Operations
- Classification according to Power & Strength
Classification According to Use
For easy understanding, you can categorize CNC fixtures according to their uses. For this type of classification, they are of 5 different varieties, including
√ Universal Fixture
This type of CNC fixture applies to any kind of workpiece. They feature easy adjustment and replacement ability to suit any type of workpiece.
√ Assembled Fixture
This type of fixture can only be selected after taking into consideration the type of workpiece. This means that you can only use this type of workpiece according to the requirements of your workpiece. Assembling is through a special method, and it depends on the need. However, you can remove or re-use them when necessary.
√ Modular Fixture
This fixture offers easy re-configuration and reconstruction ability to suit any workpiece. They are ideal in handling any workpiece, and they feature interchangeable components. With this fixture, users have access to a better and more flexible machining process.
√ Combination Fixture
This type of CNC work holding is ideal for workpieces of differing shapes and sizes according to the machine tools. They come in varieties of shapes and sizes.
√ Special Fixtures
Special Fixtures are CNC work holding tools ideal for a specific workpiece. Their mode of action offers a unique advantage in terms of stability which helps to achieve fast operations and convenience during the process.
Classification According to Machining Operations
You can also classify CNC fixtures according to the type of CNC operation. You can distinctly categorize these tools into 5 different groups. However, there are other types not mentioned in this category. The idea is you can organize them according to the CNC operation. They include:
√ Milling Fixtures
Milling fixtures are CNC fixtures used in the CNC milling process. They help to achieve easy and safe milling operations to ensure quality end products.
√ Turning Fixture
Turning fixtures are fixtures that are commonly used in CNC turning operations. This operation becomes easier and helps to ensure the precision of the process.
√ Drilling Fixture
Drilling Fixtures are those fixtures with application in the CNC drilling process. This drilling operation is a popular process in the CNC manufacturing space. The work of these fixtures is to offer support and hold the workpiece to ensure accurate drilling of holes in a workpiece.
√ Grinding Fixture
Grinding fixtures are fixtures that have application in the CNC grinding processes. The main goal is to effectively hold the workpiece to ensure precision during the grinding process. These fixtures are very common in the CNC machining industry.
√ Boring Fixture
Boring Fixtures are Fixtures used for CNC boring operations. CNC boring is a machining process involving the enlargement of holes already drilled via CNC drilling. To hold the workpiece during this operation, boring fixtures are used.
Classification According to Power & Strength
CNC fixtures can be classified according to the source of the power in question. In this section, we will categorize them into 6 different types according to the source of power and strength. They include:
- Electric fixture.
- Hydraulic fixture.
- Magnetic fixture.
- Manual fixture.
- Pneumatic fixture.
- Vacuum fixture
CNC fixtures offer varieties of benefits for their users. They have made the process of CNC machining to be more precise, less time-consuming, and hassle-free from a human factor point of view. The benefits include and are not limited to the following:
√ Increase in Productivity
CNC fixtures offer amazing benefits to productivity by eliminating individual marking, frequent checking, and positioning. It also reduces the time of operation due to an increase in feed, speed, and depth of cut due to high clamping rigidity.
√ Improved Quality & Interchangeability
Also, they help to facilitate the manufacturing of parts in large quantities featuring a high degree of precision, accuracy, uniform quality, as well as interchangeability at a competitive cost.
√ Reduction in Cost of Production
Due to the use of CNC fixtures, there is an increasing level of production, easy assembly, reduction in scrap, and labor cost saving. All these factors result in an ultimate decrease in a unit of production.
√ Reduction in Skillful Setting
When you use them for your workpiece, there is no need for the skillful setting of the workpiece on your tool. As a result, you can employ unskilled or semi-skilled machine operators to save the cost of labor.
Factors & General Rules to Consider When Designing a CNC Fixture
Getting to know the right design or using the right CNC fixture is accompanied by a wide variety of understanding. Below are things to note to solve this issue.
√ Tolerance Level Improvement
Always note that the CNC work-holding fixture setting improves the accuracy and operation’s tolerance
√ Be Aware of When Clamping is Needed
Clamping style will hugely affect the quality of end products. Do not clamp when it is not needed during the operation.
√ Reference Important Surfaces
To avoid confusion, do not reference many surfaces. Referencing important workpieces on the tool is necessary to achieve lesser operational time.
√ Conscious of Cost
One important factor to note when designing a custom CNC work-holding fixture is to be economical. Users need to know the number of parts for production and the number of fixtures needed for such operations.
Typical Manufacturing Ways for Fixtures
CNC Machining and 3D Printing are the two typical manufacturing processes for creating CNC fixtures.
The most common manufacturing process for creating fixtures is CNC machining. For design and guideline considerations, we can maintain tolerances of ±0.05 in typical sizes and quantity for typical size. No amount is too small and too large in the manufacturing of CNC fixtures.
However, 3D printing is another viable option for manufacturing fixtures for other plastics and metals beyond machining. This is ideal, especially when the geometry is too costly or too difficult to machine. The rule is choosing the right technology that fits better for a particular application.
In comparison, CNC machining of fixtures is considered because it offers superior surface finished, greater precision, stronger materials, and many more. On the other hand, 3D printing comes in handy for a lower cost, volume runs, and turnaround time. It is also ideal for smaller than usual, complex, or irregular shapes. Also, 3D printing can help to reduce costs when producing multiple fixtures.
Essential Features of Fixture
When considering a fixture, the following are essential features of an institution, or the fixture must meet the following requirements;
- Idle time reduction: Should enable easy unloading and clamping such that idle time is at minimum
- Standardization or Replaceable part: The supporting and locating surfaces of the tool should allow for easy replacement and standardization to achieve interchangeable production
- Cleanliness of machining process: the design of the tool must be such that there is no much wasting time in cleaning burrs, scarfs, chips, and many more.
- Coolant Provision: The tool should be designed such that there is provision to cool the swarfs and chips are washed away.
- Hardened Surfaces
- Pads & Inserts
- Fool Proofing
- Initial Location
- Easy manipulation
- Clamp Position
- Economic soundness
- Easy Manipulation
- Ejecting Devices
In the manufacturing industry today, CNC fixtures are known and used for a wide variety of applications. This is true, especially where the CNC machining process is used. The application is integrated with different types of operations in the production process. They are applicable in the below applications.
- CNC grinding
- CNC milling
- CNC turning
- CNC slotting
- CNC planning
- CNC drilling, and many more.
Having said this, they use two properties, including positioning and clamping for their mode of function. In the CNC machining industry, these two properties help to secure and guide the manufacturing processes.
Designing and manufacturing are all fun and rewarding for professionals. However, the reverse is the case for others; some components are difficult to hold and process. With this article, you won’t have any problem as regards those mentioned above. At RapidDone, our expert team prides itself in providing direct solutions for complex CNC fixture manufacturing problems, thus, it makes sure we can offer quality machining parts. Your happiness is our happiness, so put us to the test experience as we take on a new project in fixture manufacturing solutions using either CNC machining or 3D printing.