Engineering Pick-and-Place Devices

In this lesson, students apply what they know about magnetic interactions to engineer a device that can pick up and place metal paper clips for a metal factory.

• Engineers who want to use magnets need to know about magnetic properties of materials and how magnets exert a force on other magnetic materials.
• Engineers can use magnets when they design technologies that need to attract or repel objects without coming into contact with them.
• A magnetic field applies either a pushing (repulsion) or a pulling (attractive) force to other magnets within it.
• Because magnets can attract other magnetic materials, they can be used to pull toward them other magnets or magnetic materials, such as those containing iron.
  
  

• How can magnets attract or repel magnetic objects?
• What affects whether or not metal paper clips are pulled toward a magnet?
• How could magnets be used to pick up objects from the ground?
• What would engineers need to think about when designing a device that can pick up objects?
  
  

Misconception: All metals are attracted to magnets.

Fact: Not all metals are attracted to magnets. Iron, cobalt, and nickel are the three naturally occurring metals that are attracted to magnets.

Misconception: Larger magnets are always stronger than smaller magnets. 

Fact: A magnet’s strength depends on the materials that make it up. With two magnets of the same material, the larger magnet will be stronger than the small magnet. But in magnets made up of different materials, the smaller magnet may actually be stronger than the larger magnet.

Attract : to pull together

Repel : to push apart

Magnet : an object that produces a magnetic field; has a north and south pole; attracts or repels other magnets or magnetic materials such as iron

Magnetic Field : the area around a magnet that attracts or repels other magnets and magnetic materials such as iron

Permanent Magnet : an object that stays magnetized without electricity

Temporary Magnet : an object that acts like a permanent magnet when it is within a strong magnetic field

Magnets Have Magnetic Fields

A magnet is any object that produces a magnetic field. A magnetic field is the area around a magnet that attracts or repels other magnets or magnetic materials such as iron.

A magnetic field applies a force to other magnets or magnetic materials within it. This force can be a push or a pull.

All magnets have a north pole and a south pole. The north pole of one magnet always attracts the south pole of another. This is a pulling force.

However, two north poles will always repel each other. Two south poles will also repel each other. These are pushing forces.

Magnets are useful. They can attract or repel magnets or magnetic materials without touching Them. But objects are only affected by a magnet within its magnetic field. A magnet’s magnetic field is invisible. It moves from the magnet’s north pole to its south pole.

Stronger magnets have a larger magnetic field. A magnet’s strength depends on its material. There are different kinds of magnets depending on their properties.

Permanent magnets stay magnetized without electricity. Refrigerator magnets are permanent magnets.

Temporary magnets act like a permanent magnet when they produce a strong magnetic field. They lose their magnetism when the magnetic field goes away. Paperclips and iron nails are temporary magnets.

Many objects that have iron are magnetic. They can be permanent magnets or temporary magnets. It depends on how they are made.

In this lesson, students use information from a scenario to help them define the main problem facing a factory, which needs engineers to design a device that must use magnets to lift and move as much metal as possible from one station to another in a specific amount of time. Students work in teams to come up with possible solutions to solve the problem. Once they have built a prototype, they carry out a procedure for testing it to see how well it solves the problem.