How to Choose a Part Feeder: Flex Feeder

two flex feeders with robotic arm

Success in manufacturing can be defined by a responsiveness to shifting market demands, aggressive deadlines, and handling ambiguity in specifications. That often means tooling design and product development overlap each other in a harried effort to reduce lead times. Concurrent creation of new products with automated inspection, assembly, and test capabilities by Andrews Cooper enables otherwise impossible breakthroughs in design, performance, and manufacturability.

This includes integrating the right part feeder into your automated manufacturing environment. Part feeding systems come in a variety of types, but flex feeders (also known as flexible feeders and flexible part feeders) are extremely efficient at handling multiple part geometries with a single feeder system. That means manufacturers can better accommodate frequently changing product development under tight time constraints.

It’s important to keep in mind flexible part feeders are not right for every automation system. Andrews Cooper can assist in identifying and implementing the right part feeding system for your unique needs.

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Types of part feeding systems

The following table summarizes the characteristics of the most common feeder types to help you weight the tradeoffs.

Chart describing the various types of part feeding systems including flex feeders, bowl feeders, magazine feeders, tape & reel, and more

What is a flex feeder?

A flex feeder is a part feeder system that, combined with a vision system and a robotic arm, adds parts into an automated process. All together, they are typically comprised of the following elements:

A) Part Hopper – Holds bulk parts
B) Feed Deck – Vibratory surface where parts are separated from each other
C) Vision System – Used to locate X, Y, and theta locations of parts and to determine their orientation
D) Robot – Used to pick parts from the feed deck

Two flex feeders with a vision system above and a robotic arm to move parts from the feed deck

For this flex feeder assembly we utilized an Epson robotic arm

The feed deck separates parts unloaded from the hopper so that a vision system (comprised of one or more cameras) can analyze their shape, orientation, and position. A vision system allows the robot to locate a part on the feed deck, pick it up, and then transfer it for assembly.

Do you have the right part type for a flex feeder?

Part geometry, size, and material matter. Part characteristics that are critical to vision need to be considered such as contrast with background, clean part edges and datums presented to camera, tendency to clump, propensity of parts to overlap, stable resting orientation, etc. Part vibration and rubbing need to be considered, as not all applications will accommodate what is necessary for feeding. Input on the design of the parts that will be fed by flexible feeder system is important and can provide great benefit.

What part types work best with a flex feeder?

• Small components, between 1 mm and 120 mm
• Light weight parts, less than 80 g
• Parts free of residue (e.g., oil, grease, etc.)
• Parts that have a high probability of orienting correctly when dropped (facing up or down)
• Parts that are capable of being flipped over on demand

What part types Do Not Work best with a flex feeder?

• Parts that can easily entangle with each other or clump together (e.g., springs)
• Clear parts
• Parts that have few features to distinguish orientation when orientation is necessary
• Parts that overlap easily
• Highly fragile parts

The importance of developing your vision system

Vision development is foundational. The vision system development for a flex feeding system could perhaps be considered analogous to the mechanical development of a vibratory feeding system.

In the age of software, some might consider this a real benefit as a system can be updated through the connection of a programming cable rather than sending hard parts out for machining. Bottom line is effort and cost are still present but in different areas. The cost of vision hardware and software development will largely be driven by the complexity of the parts being fed.

What role do vibratory units play in flexible feeders?

Both the robotic arm and vision system are integral in terms of their ability to recognize and move parts. However, it’s the vibratory devices that ensure a continuous flow of parts. This includes the part hopper, which shakes parts onto the feed deck from the bulk part pile, and the feed deck itself, which further separates the items from each other for the vision system to identify.

By varying the frequency, duration, and direction of the vibration on the part hopper, you can control the dispense rate of parts. The same principle holds true for most feed decks where frequency, duration and direction adjustments directly affect how parts move. This means specific vibration settings can shift parts forward or backward on the deck, or even flip them over. If parts clump or bunch-up at the end of the feed deck, vibration adjustments can push those parts back from the end to be separated.

Are there ways to enhance a flexible part feeding system?

While the basic flex feeder configuration can handle many assembly requirements, it’s possible to integrate additional components to enhance the feeder operation. These include:

• Pre-bulk Feeder – Used to keep a constant supply of parts in the part hopper.
• Purge Bin – Used to unload remaining parts during lot or product change out.
• Feed Deck Plate – Can be changed to provide high contrast between the part and background. Textures can also be applied to increase feed rates or to limit the rolling of round parts

Always plan for testing

When throughput is influenced by so many factors, having a plan for testing is critical to an efficient part feeding process.

• Distribution of parts available to pick. Feeder size with respect to part size is a critical factor that intersects with physical part characteristics described above. Naturally, the fewer parts available the more feeder cycles required for a given throughput.
• Dependencies exist between operations. Picking and feeding are not able to be performed in parallel due to dependencies between feeder action, vision find, and robot positioning that does not obstruct vision.
• Available footprint provides options. For higher throughput applications, be prepared to add a second feeder and vision system to a robot pick and place station and/or consider how to buffer parts downstream of the robot.
• Feeder deck development is needed. How the parts interact with the feeder deck is critical and there are many options for various textures and materials that may provide benefit. Work with the feeder vendor to do testing as soon as possible.
• Bulk hopper feeding should not be overlooked. Be prepared to send the feeder vendor enough parts to fill a bulk hopper, as feeding issues that arise when feeding out of a bulk hopper impact everything downstream.

two flex feeders with robotic arm

What are the advantages of a flex feeder?

Flexible feeders offer some distinct advantages over other feeding systems:

• Flexible – The same part flex feeder can be configured to handle different parts with little or no effort, thereby reducing downtime and improving equipment utilization. It’s also favorable where tight schedules require tooling design and product development to overlap.
• Robust – Parts are less prone to jamming which means fewer system interruptions.
• Efficient – Product changeovers may be carried out very quickly, especially true if able to leverage a universal chuck (although some software adjustments may be necessary on the vision system).

Making the Decision

Choosing the right part feeding system can be overwhelming. Especially when you think about the various tradeoffs of each system. Plus, the financial commitments that go along with each are no small matter.

AC has a wealth of knowledge and a collaborative team of experienced staff to identify and integrate the right feeder into your environment. Flexible feeders might be the right fit if you consider both the complexity of your parts and the throughput requirements of your assembly system. Global supply chain shortages and ongoing customer demands may further make flex feeders an ideal choice.

Read more about manufacturing automation

Contributors:

AC Employee - Automation

PM Manager

AC Employee - Automation

Principle Mechanical Engineer

AC Employee - Automation

Senior Mechanical Engineer

AC Employee - Automation

Senior Controls Engineer

AC Employee - Automation

Staff Controls Engineer

AC Employee - Automation

Technical Writer

Lindsay Fritz Palmer - Marketing Manager

Marketing Manager

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