CNC jigs and fixtures

Everything You Should Know About Jigs And Fixtures

Jigs and fixtures are two terms that often tend to be easily confused. In general, jigs refer to tools that hold or guide a cutting tool while it performs a repetitive operation. However, fixtures do not responsible for guiding a cutting tool but for keeping a workpiece steady in a fixed position or orientation. Both are essential tools in precision manufacturing. They can provide a stable and safe mounting point to support a workpiece, enhancing the finished parts’ accuracy, precision, dependability, and interchangeability. Using jigs and fixtures also helps manufacturers reduce errors, increase productivity, and reduce costs.

This article will explore jigs and fixtures, including their types, elements, benefits, applications, and differences. In addition, an introduction to how to manufacture jigs and fixtures will be put in the article. Read on and learn more information about jigs and fixtures.

What are Jigs?

Jigs are a tool that mainly helps control or guide the movement of a cutting tool like a drill and occasionally holds the workpiece simultaneously. Since their primary function is guiding and directing cutting tools, jigs are most typically employed for manual tasks, such as machining and drilling. In many circumstances, jigs are important for manufacturing because they help guarantee that parts are created to exact and repeatable standards.

A common jig use is drill bushings. They can aid with a drill’s proper positioning and angle as it passes through a workpiece. Therefore, a drill bushing leads to superior quality work and may also boost efficiency in production.

It should be noted that jigs are not necessary on CNC machines. These machines provide micron-level precision without assistance because the tool path is programmed digitally and stored in the machine’s memory. However, jigs are still utilized in smaller machine shops for help in manually machining specialized or customized parts and one-offs.

jigs and fixtures

Types of Jigs

Jigs are widely available tools in CNC machining and come in various types. The following are some frequent types of jigs used in machining processes.

Template Jig

The template jig is simple and ideal due to its accuracy. The plate has two holes and serves as a template fitted onto the workpiece. The drill can be guided through these template holes, and the needed holes on the workpiece are drilled in the same relative locations as on the template.

template jigs

Plate Jig

By integrating drill bushes on the template, a plate jig improves on the template jig. The plate jig drills holes in large parts while keeping the precise spacing between each hole.

Plate jigs

Angle-plate Jig 

An angle-plate jig is perfect for holding drill-ready parts at an angle to their mounting locators.

angle plate jig

Diameter Jig

A diameter jig is needed to drill radial holes in a cylindrical or spherical workpiece.

Diameter jigs

Channel Jig

A channel jig is a simple jig with a channel-like cross-section. The component is fitted within the channel and can be located and clamped by turning the knurled knob. In addition, the tool can be guided through the drill bush.

Channel jigs

Leaf Jig

A jig has a hinged leaf that can be swung open and closed for faster loading or unloading part. The hinged leaf does not encircle the part completely.

Leaf jigs

Ring Jig

To drill holes in circular flanged parts, a ring jig is used. The work is fastened firmly to the drill body, and the holes are drilled by directing the tool through drill bushes.

Ring jigs

Box Jig

Box jig is a box-like construction, and the work is tightly held within it. In this way, the work may be drilled or machined from multiple angles at a single setting, depending on which face of the jig is turned toward the tool.

Box jigs

What are Fixtures?

Fixtures are tools that precisely and firmly hold a workpiece at the desired position on the machine bed. By completely securing a workpiece, fixtures assure precision and repeatability. They can also be adjusted to hold a workpiece at a given angle, enabling cutting operations to be performed in various directions. Fixtures help reduce mistakes and ensure worker safety by preventing workpieces from being accidentally hurled from the work table. 

Fixtures are frequently used in machining processes, such as milling, turning, planning, slotting, and grinding operations. You can find it on automotive vehicle assembly and optical and laser scanning inspection systems. The application of fixtures also includes a material block fastened within a CNC machine and a vise placed on a workbench. Furthermore, fixtures are also required on an automotive assembly line to secure and guide vehicles throughout the welding and assembling process.

Fixtures are commonly found in CNC machining centers and other automated production equipment. CNC machines may direct and control their cutting tools without jigs, but they will not function effectively if the workpiece is not maintained safely.

Types of Fixtures

Fixtures are tools or devices holding, supporting, and positioning components during manufacturing processes. Below are the common types of fixtures:

Turning Fixtures

Turning fixtures are often fixed on the machine spindle’s nose or a faceplate. When necessary, the fixture may need to be equipped with a counterweight or balance the unbalance fixture. In general, turning fixtures are useful for more complex lathe-made parts.

Turning

Milling Fixtures

Milling fixtures are generally fixed on the nose of the machine spindle or a faceplate and are held in place by the workpieces. The table is adjusted and positioned correctly around the cutter. Before beginning the process, the workpieces are placed in the fixture’s base and clamped.

Milling

Drilling Fixtures

Drilling fixtures, which consist of a hole and a bushing, are occasionally used in place of (or in addition to) jigs.

Broaching Fixtures

Often, broaching fixtures are used on multiple broaching machines to locate, hold, and support workpieces during operations. Keyway broaching operations are an example of these operations. And keyway broaching operations include keyway broaching, hole broaching, and so on.

Broaching

Indexing Fixtures

Multiple components require machining on various surfaces for their machined surfaces or shapes to be uniformly spaced. And these elements must be indexed in the same number as the number of surfaces to be machined. The holding devices, such as jigs or fittings, are designed to carry an indexing mechanism. An indexing fixture is one with such a device.

Indexing

Grinding Fixtures

Grinding fixtures might be regular work-holding devices like chucks, mandrels, shaped jaw chucks, magnetic chucks, etc. They are used to support a workpiece during grinding operations.

Regarding external surface grinding, cylindrical grinding uses plain or tapered mandrels. The bore is used to locate and hold the workpiece on the mandrel, allowing the exterior surface to be machined properly concentric to the bore. 

And for internal grinding, the chuck is the most often used fixture. The fixture has the same design as turning and boring fixtures for holding irregularly shaped components.

Boring Fixtures

The boring fixtures incorporate nearly all the prevailing principles of jig and fixture design. Their construction does not need to be as robust as milling fixtures because they never must withstand as heavy cutting loads as involved in milling operations.

boring

Tapping Fixtures

Tapping fixtures are specifically designed to place and securely hold identical workpieces to cut internal threads in drilled holes. Such fittings will always be required for odd-shaped and unbalanced parts, especially when these parts are to be performed the tapping process on a mass scale.

Duplex Fixtures

Duplex fixtures hold two comparable components at the same time and machines these two components at two separate stations at the same time.

Duplex

Welding Fixtures

Welding fixtures can retain and support the different welded components in their right places while preventing them from distorting. The clamping must be light yet robust, and clamping elements must be placed away from the welding region. The fixture must be quite sturdy and stiff to survive the welding forces.

Assembly Fixtures

The purpose of assembly fixtures is to support various components in the correct relative position during assembly.

Main Elements of Jigs and Fixtures

Jigs and fixtures may look like simple tools, but they are comprised of several elements. The main elements of jigs and fixtures are listed below:

Body: The bulk of a jig or fixture is its body. The body is a plate, box, or frame structure that holds the components to be machined. The body needs to be strong and rigid to withstand significant forces.

Locating Elements: These elements are placed on workpieces in the precise location for cutting tools. They are typically made from hardened steel.

Grinding and Setting Elements: These elements guide the cutting tool in the case of a jig and aid in correct tool movement in the case of a fixture.

Clamping Elements: These elements hold the workpiece securely in place and resist cutting forces.

Indexing Elements: Indexing elements are not always available. However, many workpieces are indexed for distinct places to execute machining operations on various surfaces or locations. Sometimes, these elements must be incorporated into a jig or fixture.

Positioning Elements: These have various fastening devices and are used to secure the jig or fixture to the machine at the right location.

Bushings: Typically constructed of tool steel, bushings are used in some jigs to guide the operation of the machine tool.

Fixtures

Benefits of Using Jigs and Fixtures

Using the jig and fixture in any machining operation has many benefits. Here are the main advantages of jigs and fixtures: 

Increased Productivity

Jigs and fixtures significantly reduce the time required to mark, measure and clamp workpieces for each operation. By allowing quick and consistent setups and tool/workpiece positioning, jigs, and fixtures speed up production and increase throughput. Parts can be manufactured and inspected efficiently with minimal handling or adjustment required.

Improved Quality

Jigs and fixtures provide a precise guide or support for cutting tools, measuring equipment, and workpieces. This results in components produced to the same high standards with accurate dimensions and minimum variability. The risk of errors and defects is reduced, minimizing scrap and rework. Quality can be controlled effectively even when using less skilled labor. 

Reduced Cost

Jigs and fixtures assist in accelerating manufacturing processes, lowering total labor costs per part. For example, the raw material may swiftly align and set up in a well-designed custom fixture. It would take considerably longer to set up using standard fixtures. Scrap rates are also lowered since the likelihood of faulty parts is much reduced.

Accurate Tool Guidance

Jigs guide the movement and positioning of cutting tools during operations like drilling. They allow tools to be fed and oriented precisely for quality results. Fixtures securely support workpieces during machining or measurement.

Increased Interchangeability

Jigs and fixtures manufacture multiple identical pieces, enabling a high degree of part interchangeability. Components can be used without selection or fitting, as they are produced to uniform specifications. This reduces final assembly time and the requirement to have replacement parts available. 

Reduced Wastage

By precisely guiding cutting tools and workpieces during operations, jigs, and fixtures help avoid errors and misalignments that can lead to wasted material. Scrap and rejected parts are minimized, resulting in cost savings. Material yield and efficiency are maximized using jigs and fixtures.    

Increased Safety

Jigs and fixtures rigidly clamp workpieces, reducing risks from sharp tools or moving parts. They minimize the need for operator intervention in dangerous areas. Setups also provide a safer working environment, even for inexperienced staff. 

Reduced Manpower Needs

Jigs and fixtures automate production by speeding up operations and reducing the need for measurement, judgment, and manipulation on each cycle. This decreases labor demands and the level of operator skill required. Staffing overheads and training costs are lowered, with less specialized expertise needed to achieve results.

Application of the Jigs and Fixtures

Jigs and Fixtures are commonly used because of their benefits. Some of the applications are as follows:

  • Jigs are used to do bulk drilling, reaming, and tapping.
  • Fixtures are used in milling, bulk turning, and grinding.
  • Guiding the tools for machining contours.
  • Mass production of automobile parts.
  • Continuous production part inspection in manufacturing industries.
  • Cutting the ingots in the steel plant.
  • For drilling flanges and holes at all needed angles.
  • For multi-spindle machining.
  • In the refrigeration business.
  • Pump assembly process.

What are the Differences Between a Jig and Fixture?

What is the distinction between a jig and a fixture? Jigs and fixtures are two common tools used in mass-production processes. People frequently use the two terms interchangeably, although they serve different purposes. The following are some key distinctions between jigs and fixtures.

Primary Function

The primary distinctions between jigs and fixtures are in their functionality. A jig directs the cutter to work on a workpiece’s designated location. It also helps to support and locate the part. However, the fixture only secures, supports, and locates the workpiece. It does not direct the machine part.  

Weight

Another factor to consider is weight, with jigs being lighter than fixtures. Fixtures are heavier because they must endure the huge cutting force and vibration.

Complexity

When a jig and a fixture are compared, the machinist agrees that jigs are easier to operate. Before executing an operation on a fixture, machinists require certain skills.

Gauge Blocks

For jigs, gauge blocks are unnecessary, and Jig feet are used in construction. Regarding fixtures, gauge blocks may be provided for effective handling. In its construction, such feet are not used.

Design

The construction of jigs is more complicated than that of fixtures.

Make Contact with the Tool 

Fixtures are not required to come into touch with a machine part since they are designed to fit the part. Conversely, a jig must come into contact with the tool to correctly fix the angle and position.

Whether Fitted to the Machine

Depending on the task they are used for, jigs may be held or fastened to a table. Furthermore, jigs do not require extra equipment when employed in heavy labor, even though they may need to be clamped. Fixtures, on the other hand, require clamping and accessories to work properly.

How to Manufacture Jigs and Fixtures?

When quantities are small, CNC machining would be chosen as a manufacturing process for making jigs and fixtures. When the geometry is too complex or expensive to create, 3D printing is the most logical approach. The two methods are explained below.

3D Printing

3D printing is the more popular method, with several benefits over CNC machining. It is less expensive and quicker, allowing manufacturers to re-optimize design. 3D printing jigs and fixtures can enable more design complexity at a lower cost. Manufacturers can also add other features to increase the jig and fixture’s performance. 

When using 3D printing, consider the following points can achieve high-performance, durable jigs and fixtures.

  • Verify the dimensional accuracy of the fixture using metrology tools.
  • To improve rigidity, use ribs and fillets.
  • Use metal threaded inserts to increase durability.
  • After completing secondary operations, loosen the bolt and relieve clamping forces to avoid warping.
  • Use springs to ease ejection.

CNC Machining

When employing CNC machining, it would be best to account for debris in your design plan. As a result, manufacturers can leave a gap in the jig to allow burrs to form without interfering with the tool. However, gaps, grooves, and pockets where chips can expand into wedges must be avoided. 

After manufacturing, you must validate for form and function of the jig and fixture. Engineers should compare the finished tool to the original CAD model to ensure accurate dimensions. A verified and dimensionally correct jig and fixture should perform their function without tilting, bending, or moving.

Jig and Fixture Design Considerations

Some recommended design considerations will enhance the overall functioning of jigs and fixtures. The following are some important design considerations:

  1. Machining fixtures must be perfectly aligned to provide maximum precision. As a result, it’s critical to constrain the fixture. However, it would be best if you avoided over-constraint because it might introduce inaccuracies. 
  2. Design jigs and fixtures that can be operated with one hand wherever possible. This allows operators to grip the fixture with one hand while positioning or stabilizing the part with the other.
  3. Design a jig or fixture that does not require human intervention to hold the part during secondary operations.
  4. Create a design using the fewest steps possible. This reduces cycle times and fatigue-inducing repetitive actions.
  5. Choose geometries that highlight misalignment faults. This can help to reduce workplace injuries.
  6. Consider how the jig or fixture will integrate into the whole manufacturing process.
  7. A jig or fixture’s material must be carefully selected. For example, if the jig or fixture is used for many parts, it must be made of a durable material like hardened steel. Alternative materials include plastic and wood.

Summary

Manufacturers frequently prioritize increasing production efficiency and productivity. In this case, jigs and fixtures are such tools that manufacturers need. Jigs and fixtures can improve the manufacturing process’s reliability, precision, and quality while reducing production cycle times and enhancing worker safety. In this way, it is possible to enable the production of better parts.

If you want to seek an experienced manufacturing partner for creating your jigs and fixtures, LEADRP is the right one you need. We provide various machining operations and prototyping services to help bring your ideas to life. Contact us today to get started. Upload your CAD model and have access to instant quotations.

References

What are Jigs and Fixtures? – From Reid Supply

Types of Jigs and Fixtures – From Prescient Technologies

FAQs

Jigs are commonly used to guide a cutting tool and operations like drilling, reaming, and tapping. The jig assists in securing the raw material in position so that it does not move or deflect during drilling, resulting in accurate holes without requiring costly CNC machines. 

Fixtures help hold and position workpieces during manufacturing operations such as machining, grinding, broaching, milling, and fabrication. Fixtures are employed in fabrication to precisely position weldments for increased productivity and prevent the part from warping during welding. 

The materials used in making a jig and fixture include steel (stainless, hard, carbide, mild, high speed), cast iron, hardened aluminum, plastic( derlin, nylon, and PC), bronze, etc.

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