Manufacturing engineers understand that following the 3-2-1 method for locating a part establishes three mutually perpendicular datum planes. Three points are needed to establish the primary plane, two points for the secondary plane, and one point for the tertiary plane. But when it comes to designing a robust process in a high-volume or automated production environment, there are some key points that’ll make your operation trouble free with greater reliability.

1. How do I keep chips from nesting and accumulating on the fixture?

In high-volume production, chips can pile up. This is why it’s important to design proper chip shedding on fixtures by eliminating flat shelves and creating sloped surfaces to provide a path for chips to flow inside the work zone. External hydraulic tubing on the fixture can also cause chips to get hung up. To prevent this, gun drill the fixtures and use a manifold to internally plumb the hydraulic lines needed for the fixture actuation.

2. How do I keep chips from collecting on locators?

Supply machine-filtered coolant through the fixture to spray nozzles mounted on the fixture close to the locators. This prevents chips from becoming lodged between the part and the locator; causing a defect, especially in an automated load scenario.

3. If a chip does interfere with locating the part, how do I catch it?

A machine feature called an air seat detect can check to determine if a part is seated against a locator. It measures the air pressure differential at the locator. This is accomplished with a 1mm hole in the locator connected to a steady air supply. Air flows freely before the part is loaded. Once the part is loaded and seated on the locator, the airflow is constricted. A digital pressure sensor measures the pressure differential and indicates if there’s a problem.

4. What will help prevent part misloads?

Designing part guides on the fixture helps the operator load the part in the correct orientation. Part guides also offer ergonomic benefits as the operator can more easily locate the part. In addition, they can protect the fixture from damage caused by slamming the part into areas not intended to touch the part.

5. How do I free up robot load time

On horizontal machining centers (HMCs), gravity can cause a part to fall away from the locators on the fixture prior to clamping. In an automated load scenario, some integrators will use the robot to hold the part in place until the clamp initiates. With part retention on the fixture, the part will stay in position ready for the clamp sequence to begin and free up the robot to move on to its next task.

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