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Magnetic Attraction? How to Build a Better Gripping Application

SCHUNK feature SCHU_EGM_Rohteil_2_1118.jpg
Matt Smith from SCHUNK explores the reasons for choosing a magnetic gripping solution.

Grippers are critical in robotics and automation. A good portion of the advances in robot and automation capabilities comes down to the capabilities of the grippers. Magnetic grippers are designed for reliable and precise loading and unloading of various ferromagnetic workpieces.

Only a brief current pulse is required for activation and deactivation. The piece is held reliably even in an emergency-stop situation. Users get the benefit of energy efficiency and process reliability, but more importantly, some automation applications can’t be accomplished without magnetic grippers.

When moving ferromagnetic pieces that require maximum holding forces in confined spaces, magnetic gripping is the answer. Many pieces can be handled without the need for set-up efforts. Plus, magnetic grippers don’t require the cleared space needed for finger grippers.

We caught up with Matt Smith, applications engineer at SCHUNK, to walk us through the application process when using magnetic grippers.

Design News: What type of applications work well with magnetic gripping?

Matt Smith: Applications for magnetic gripping must be ferrous, iron, or steel. We consider the shape of the workpiece and how it will be handled. The two things that we look for are the thickness of the metal and the weight of the workpiece. These are important to consider when selecting a magnet because the shape of the magnet affects the depth of penetration, and the weight of the part leads us to the number of magnets needed to lift the part safely.

Typical applications are raw steel parts such as tubing, solid shafts, metal plates, and square tubing. Magnets excel at handling parts that touch each other and cannot be picked up with traditional grippers. An example would be square (box) tubing that is stacked on a pallet. Traditional grippers use fingers that grip the sides of the tube which in this case are blocked by the neighboring part. Magnets can grip on one surface so individual parts can be picked up without disturbing the part next to it.

The following video shows the magnetic gripper in action:

DN: Who is involved in designing the application? What technical abilities do participants need to have?

Matt Smith: Magnetic gripping applications are directed to our applications engineering department. It takes time and experience to fully understand the nuances of magnetic gripping, and we have several team members with years of experience who can recommend solutions for these applications.

The team members who work with magnetic gripping have been trained to understand how the workpiece geometry works with the different types of magnets. Some calculations help us evaluate the part and then cross-reference this information to the type of magnet selected.

DN: What is the process of creating the application?

Matt Smith: Often, we look at solutions using mechanical grippers such as parallel grippers or centric grippers. Once we have exhausted all possibilities it soon becomes clear that magnetic gripping is the only solution.

Other times the application is suited for magnetic gripping, and at that point, it is just selecting the proper gripper size for the application.

In some cases, the magnet needs special tooling called pole extensions to help contain the part. For instance, cylinders and pipes need to have a form fit so they don’t roll off the magnet face during acceleration. We offer this service and work with our customers to provide a complete solution ready to work.

DN: What type of testing is involved in ensuring quality?

Matt Smith: We have a test facility - our CoLab - where we have many of our products on the shelf for testing customer parts. About 1/3 of the applications that are submitted require testing. The results are documented in a presentation with pictures and descriptions and given to the customer as proof of concept. Simultaneously we provide our calculations and results so that their engineering team can verify the application.

DN: How is the application monitored over time to ensure things continue effectively and smoothly?

Matt Smith: Normally our customers are in direct contact with their local sales rep. Since these team members live in the customer’s immediate area, it’s easy for them to follow up and monitor the application as it’s being commissioned. If any problems arise, we can respond quickly and make changes on the fly.

Rob Spiegel has covered manufacturing for 19 years, 17 of them for Design News. Other topics he has covered include automation, supply chain technology, alternative energy, and cybersecurity. For 10 years, he was the owner and publisher of the food magazine Chile Pepper.

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