Jigs & Fixtures
The terms jig and fixture are often used as interchangeable terms for work holding fittings, but they are different items of tooling used in the mass production process. The name describes their function. The use of jigs and fixtures increases accuracy, productivity, safety. They can also adapt a highly skilled job into a lower skills requirement imposing fixed procedure to the manufacturing process.
Typically jigs and fixtures will be made from steel, aluminium, polyurethane, or machined resin. Repeatability is the key factor in batch and mass production, if it right once then all subsequent parts are right.
The wider adoption of additive manufacturing techniques has offered an opportunity to generate complex jigs and fixtures alongside the manufacture of components and tooling, the common 3D CAD data providing high accuracy and simultaneous production. New possibilities lead to new capabilities. The ability to dramatically lower production times and costs on complex, low-volume components, is a game changer – agile and responsive to demands.
In the area of composite materials there is specific need for bespoke jigs and fixtures to allow accurate trimming while preventing movement in the composite piece, which can often be thin and therefore easily deflected or damaged during post-machining.
The global market for jigs and fixtures is reported to be over 50 million USD and are expected to continue to grow at a steady rate around 9% annually. This reflects the push for higher levels of automation, de-skilling of operations, and repeatability at speed.
Integrating machining operations, taking raw stock material through to finished product, involves different machines and automated transfer between these machines. If fully automated with no manual intervention this complex set of activities requires an array of jigs and fixtures. The operation of the jigs and fixtures will also be automated to synchronise with the movement of the component through its journey from stock to finished piece. Robotics become part of this jig and fixture system, the exact location and orientation of the product is known and controlled throughout. Once set up and trialled this type of system can be run at high speed and repeatability without manual intervention.
Jigs and fixtures are a major production overhead particularly in the aerospace industry. This has led to the development and use of flexible and reconfigurable jigs and fixtures. Reusability of reconfigurable jigs and fixtures makes them attractive for sustainable solutions as their components can be reused for several variants of families of products or assemblies.
What is a jig?
A jig is a guide for a tool. A simple example is a drilling jig – this guides the drill bit to drill at the desired location from a set height to a set depth. The physical location of the jig ensures repetitive accuracy and speeds up the process. Jigs are also used extensively in welding and a variety of other manufacturing tasks.
What is a fixture?
A fixture is a clamp or other fixing device which secures the workpiece to the machine bed in a prescribed location and orientation. For accuracy and repetitive tasks, a range of fixtures may be employed. Many manufacturing processes require post finishing, which requires versatile fixtures. Where production of components is done at elevated temperatures the parts may need to be clamped during cooling or post-curing to prevent distortion, careful design of fixtures can achieve this in a repeatable way.