Jigs or fixtures? The two terms are easy to confuse. You’ll often find them paired together and despite sharing similar functions, the two are not interchangeable.
Let’s learn the subtle differences between these manufacturing tools by examining how they are used to improve manufacturing quality, reduce production costs, and automate work.
What is a Jig?
A jig is a device used in securing a workpiece and machine part on a workstation. It is secured to the CNC machine tools such as a cutter, where it dictates the location and motion.
That means, in a way, it guides such machining tools. Jigs are unique such that when they move, the tool becomes stationary.
Jigs are often used in drilling, reaming, counterboring, tapping and other one-dimensional machining operations or applied as guides for tools or templates. Special cramping jigs that ensure squareness are often used as well.
Another common application for a jig is a drill bushing that helps guide a drill bit through the surface of the workpiece to ensure correct positioning and angle.
Since the advent of automation and computer numerical controlled (CNC) machines, jigs are often not required because the tool path is digitally programmed and stored in the machine’s memory.
However, jigs are still used in smaller machine shops to support manual machining of special or custom parts and one-offs.
Types of Jigs
Jigs are common devices in CNC machining, and they come in different and various types. Below are the common types of jigs used in machining operations.
#1. Template Jigs.
These jigs are simple and ideal due to their accuracy. They also have tremendous speed. However, machinists use them more for accuracy than speed.
Template jigs are used in many ways. For example, you can fit them over, on, or into the workpiece. However, they are not usually clamped.
#2. Angle-Plate Jigs.
Angle plate jigs are ideal for holding parts prepared for drilling at angles to their mounting locators.
#3. Plate Jigs.
Plate jigs are like template jigs with the same ways of use. However, unlike template jigs, they have built-in clamps to hold the workpiece.
#4. Leaf Jigs.
They have a hinged leaf which makes it easy to load and unload parts. The hinged leaf does not surround the part completely.
What Is a Fixture?
Fixtures are often used in milling, turning, planning, slotting, grinding, and other multidimensional machining processes, as well as automotive vehicle assembly and optical, laser scanning inspection systems.
The material block clamped inside a CNC machine and a vise sitting on a workbench are also fixtures.
Fixtures are also essential in an automobile assembly line to secure and guide cars through the welding and assembly process differences aside, both jigs and fixtures are tools that make a significant difference.
They increase productivity, improve the repeatability of parts, make part assembly and disassembly easier and help create a safer working environment
Nearly all automated industrial manufacturing processes rely on jigs and fixtures to consistently build parts that function properly. Engineers can make sure their jigs and fixtures are strong and well-designed by keeping these key considerations in mind.
There’s an old saying among machinists – fixtures are where you make your money. If you’re good at making fixtures that save time, you’ll turn a bigger profit. Or so the saying goes.
Types of Fixtures
Most machinists are not familiar with fixture classification. No wonder they have a problem with selecting the right one for their operation.
The types of fixtures illustrated below are based on three things: machining operations, uses, and power sources. The list will be summarized.
Types of Fixtures Based on the CNC Machining Operation
- Turning Fixtures.
- Milling Fixtures.
- Drilling Fixtures.
- Boring Fixtures.
- Grinding Fixtures.
There are other types of fixtures based on the type of machining operation. We have concluded that every CNC machining operation that needs a fixture takes the operation’s name.
Therefore, for CNC machining operations like honing and lapping, you have CNC honing fixtures and CNC lapping fixtures, respectively.
Types of Fixtures Based on their Uses
- Universal Fixtures.
- Special Fixtures.
- Assembled Fixtures.
- Modular Fixtures.
- Combination Fixtures.
Types of Fixtures Based on their Power Source
- Manual fixture.
- Pneumatic fixture.
- Hydraulic fixture.
- Electric fixture.
- Magnetic fixture.
- Vacuum fixture.
Combining Jigs and Fixtures to Improve Precision
Using jigs and fixtures together helps achieve the manufacturing precision required for products to function properly. Take a look at your doors, cabinets, and shelving. The holes for the door’s knob, latch, and hinges require precise placement or guidance for drilling.
The same with cabinets with dovetail cuts or shelving holes on the cabinet sides. Without jigs and fixtures, books would slide off the shelf, drawers would be flimsy, and doors wouldn’t close properly.
How to Manufacture Jigs and Fixtures
CNC machining is the most common manufacturing process for creating jigs and fixtures since volumes are typically low. In some cases, 3D printing is the most logical process when the geometry is too difficult or costly to machine.
It’s important to note that not all jigs and fixtures need to be made of metal. For many applications, plastic will reduce costs and meet your performance requirements.
Rapid manufacturing isn’t going to replace your current machine shops, but when utilized properly it can be a valuable tool for producing blanks for jigs and fixtures or less critical parts that don’t require high precision.
For a handful of parts, we recommend our CNC machining capabilities for your most common jigs or fixtures. If your part requires a more intricate geometry that’s difficult to machine, we would recommend 3D printing.
For high-volume needs, rapid injection molding can produce 25 to 10,000+ parts in a number of engineering-grade thermoplastics.
Design
Before designing a jig and fixture, there are some things you must know. Below is a highlight of the common things you must know
- Study the component.
- Study locating elements.
- Know the type and capacity of the machine.
- Know the loading and unloading arrangement.
- Get to know the clamping arrangement.
- Study the power devices and safety arrangement devices.
- Know the clearance between the jig or fixtures and their components.
- Study of ejecting devices, table fixing arrangement, and the indexing device.
Materials Use in Making the Jig and Fixture
Materials used for jigs and fixtures need to possess specific qualities to ensure durability and effectiveness. Common materials include hardened steel, cast iron, aluminum, and even plastics like Delrin.
Hardened steel is often preferred for its exceptional strength and wear resistance, making it suitable for high-production environments. Cast iron offers stability and vibration dampening, making it suitable for machining fixtures.
Aluminum is chosen for lightweight applications or when corrosion resistance is necessary. Plastics like Delrin are used for non-marring or non-abrasive applications, as they reduce the risk of damaging delicate workpieces.
The choice of material depends on factors such as the type of operation, workpiece material, and budget constraints.
Advantages of Using Jigs and Fixtures
There are many advantages of using the jig and fixture in any machining operation. Below are a few important ones:
- Better Productivity and Efficiency: Because the two tools eliminate a workpiece’s alignment, a machine’s idle time is reduced, which improves productivity and efficiency.
- Decreases Manufacturing Cost: Their use decreases the product manufacturing cost while increasing productivity and quality.
- Improvement in Quality of Product: They remove the need for machinists to manually sets parts apart during operation. Therefore, this removes the human chance of creating error and improves quality.
- Easy to Manufacture Complex and Heavy Tools: They enable machinists to manufacture heavy and complex-shaped parts easily. This is because the two tools hold the workpiece rigidly during the machining operation.
- Improves Safety: Since the jig and fixture are directly involved in the workpiece and machine, they remove the involvement of humans, thereby increasing safety
Applications of Jigs and Fixtures
The uses of jigs and fixtures include:
- Metalworking: Used in machining operations like drilling, milling, and grinding.
- Welding: Helps position and hold parts for welding.
- Assembly: Aids in assembling various components accurately.
- Inspection: Ensures consistent inspection of parts.
- Woodworking: Used in woodworking tasks for precision.
- Automotive: Essential in manufacturing automotive parts.
- Electronics: Used in the production of electronic devices.
- Aerospace: Ensures precision in aerospace component fabrication.
- Medical Devices: Helps assemble precise medical equipment.
- Jewellery Making: Aids in crafting intricate jewelry pieces.