A Jig is a device that holds a piece of work product and guides the tools operating on it. For example, jigs hold a part in manufacturing or test securely when performing precision tasks like drilling or tapping holes or measuring electrical / mechanical features. On the other hand, fixtures don't guide a manufacturing tool but hold a work piece accurately during machining operations for example. A standard vise is a typical household example of a fixture. Hand tools are typically standard devices for performing specific assembly or test operations. They typically do not hold the part. They can be standard or customized to fit and / or operate in a specific way usually for productivity and capability enhancement purposes. We have often created them to ease the job and avoid repetitive injury.
Differences aside, jigs, hand tools and fixtures make a substantial difference. These tools increase productivity, improve the repeatability of part features, and make part assembly and disassembly easier. In addition, nearly all automated industrial manufacturing processes rely on jigs and fixtures to consistently build parts that function correctly.
For mass production, fixtures play a significant role in locating and supporting the work product in process and should be designed with utmost care and precision.
Our team’s knowledge of various manufacturing processes enables them to design & develop high-precision devices without any impact on the required shapes/profiles. We ensure that jigs and fixtures are solid and well-designed by keeping these best practices in mind.
Best practices for designing fixtures and jigs:
Compare the cost of current production with the expected cost of production, using the new tool, and make sure that the cost of building the new tool is not more than the expected gain. Tool costs are typically amortized over time/quantity. If the payback period/quantity is too great for a particular business to accommodate financially speaking, there must be other reasons to support its creation (quality, capability, consistency).
Use geometry that makes misalignment errors obvious (pins, reference edges, outlines, etc.)
Consider how the jig, hand tool or fixture will fit into the overall production workflow. Then, create a design that uses the fewest steps. It should recognize the details of the previous process and post process to make sure workflow is smooth and intuitive.
Consider the type and capacity of the device. Make sure it fits the production line timing and does not create a bottleneck. If it does, you may need to make duplicates to keep up.
If fastening parts together, consider tool access and user ergonomics in the development effort.
Clamping
The clamping should not cause any permanent deformation in the workpiece.
Decide upon locating points and outline the clamping arrangement. Clamping near a reference point (datum) is often best for stability and repeatability reasons.
The location should ensure equal distribution of forces throughout all sequences of operation.
Avoid complicated clamping arrangements.
As much as possible, use quick-acting clamps.
Make some locating points adjustable as appropriate.
Handling
Design a jig or fixture that doesn't need human assistance to hold a part during secondary operations.
If a human operator is needed, design jigs and fixtures for one-handed operation. This way, operators can use one hand to hold the fixture and the other for part positioning or stabilizing.
Provide handles wherever these will make handling easy.
Provide abundant clearance wherever you can.
Consider the method of ejecting the finished output and transferring it to the next.
Consider how the fixture is stored / maintained for future use.
Testing
Before using it in the operation, test the device to insure:
Comfort / ergonomics for user
It won't damage parts if used properly.
Meets expected life and accuracy performance.
It has an assigned and tracking tool number in centralized database. This should include proper documentation with 3D CAD models and 2D mechanical drawings and a Bill of Materials. Use revision control for future updates if needed long term.
It has proper labeling for tool numbers and for safety.
Expected results are clearly described for output functionality / quality.
Jigs and fixtures can be manufactured using many ways including CNC machining and 3D printing. In general, 3D printing offers several advantages. For many jigs and fixtures 3D printing can be much less expensive. Also, 3D printing offers engineers the flexibility to frequently re-optimize design or simply replace a worn component. Machined fixtures can offer greater accuracy and wear resistance.
Custom hand tools often can start with a OTS tool that has good ergonomics and be modified to perform a new function. This is often a much faster and more effective approach than creating one from scratch.
Contact us if you need help with any of these.
